,,principles ,,and ,,practice --,,of-- ,,agricultural ,,analysis4 ,a ,,manual ,,for ,,the ,,estimation ,,of ,,soils1 ,,fertilizers1 ,,and ,,agricultural ,,products4 ,,for ,,the ,,use ,,of ,,analysts1 ,,teachers1 ,,and ,,students ,,of ,,agricultural ,,chemistry4 ,,volume ,i4 ,,soils4 ,,by ,,harvey ,w4 ,,wiley1 ,,chemist ,,of ,,the ,u4 ,s4 ,,department ,,of ,,agriculture4 ,,easton1 ,,pa41 ,,chemical ,,publishing ,,co41 #ahid4 ,,copyright1 #ahie1 ,,by ,,harvey ,w4 ,,wiley4 ,,preface ,,to ,,volume ,,first4 ,in this volume ,i have endeavored to place in the hands of teachers and students of ,agricultural ,analysis1 and of analysts generally1 the principles which underlie the science and art of the analysis of soils and the best approved methods of conducting it4 ,in the prosecution of the work ,i have drawn freely on the results of experience in all countries1 but especially in the matter of the physical examinations of soils1 of this country4 ,science is not delimited by geographic lines1 but an author is not to be blamed in first considering favorably the work of the country in which he lives4 ,it is only when he can see nothing of good outside of its own boundaries that he should be judged culpable4 ,it has been my wish to give full credit to those from whose work the subject-matter of this volume has been largely taken4 ,if1 in any case1 there has been neglect in this matter1 it has not been due to any desire on my part to bear the honors which rightfully belong to another4 ,with no wish to discriminate1 where so many favors have been extended1 especial acknowledgments should be made to ,messrs4 ,hilgard1 ,osborne1 ,whitney1 and ,merrill1 for assistance in reading the manuscript of chapters relating to the origin of soils1 their physical properties1 and mechanical analysis4 ,with the wish that this volume may prove of benefit to the workers for whom it was written ,i offer it for their consideration4 ,h4 ,w4 ,,wiley4 ,,washington1 ,d4 ,c41 ,beginning of ,january1 #ahie4 ,,table ,,of ,,contents ,,of ,,volume ,,first4 ,,part ,,first4 ,introduction1 pp4 #a-bg4--;,definitions2 ,origin of soil2 ,chemical elements in the soil2 ,atomic masses2 ,properties of the elements2 ,relative abundance of the elements2 ,minerals occurring in rocks2 ,classification of minerals4 ,rocks and ,rock ,decay1 pp4 #bh-dc4--,types of rocks2 ,microscopical ,structure of ,rocks2 ,composition of rocks2 ,color of rocks2 ,kinds of rocks2 ,eruptive rocks4 ,origin of ,soils1 pp4 #dc-fc4--;,decay of rocks2 ,effect of latitude on decay2 ,action of water2 ,action of vegetable life2 ,action of worms and bacteria2 ,action of air2 ,classification of soils2 ,qualities and kinds of soils2 ,humus2 ,soil and subsoil2 ,authorities cited in part first4 ,,part ,,second4 ,taking ,samples for ,analysis1 pp4 #fe-hf4--;,general principles2 ,general directions for sampling2 ,method of ,hilgard2 ,official ,french method2 ,caldwell's1 ,wahnschaffe's1 ,peligot's1 and ,whitney's methods2 ,samples for moisture2 ,samples for permeability2 ,samples for staple crops2 ,method of the ,royal ,agricultural ,society2 ,method of ,grandeau2 ,method of ,official ,agricultural ,chemists2 ,method of ,lawes2 ,instruments for taking samples2 ,principles of success in sampling4 ,treatment of ,sample in the ,laboratory1 pp4 #hg-ic4--,preliminary examination2 ,treatment of loose soils2 ,treatment of compact soils2 ,miscellaneous methods2 ,authorities cited in part second4 ,,part ,,third4 ,physical ,properties of ,soils1 pp4 #ie-aja4--,the soil as a mass2 ,color of soils2 ,odoriferous matters in soils2 ,specific gravity2 ,apparent specific gravity4 ,relation of ,soil to ,heat1 pp4 #ajb-ajc4--,sources of soil heat2 ,specific heat2 ,absorption of solar heat4 ,determination of ,specific ,heat1 pp4 #ajd-aaj4--;,general principles2 ,method of ,pfaundler2 ,variation of specific heat4 ,soil ,thermometry1 pp4 #aaa-aae4--;,general principles2 ,frear's method of stating results2 ,method of ,whitney and ,marvin4 ,applications of ,soil ,thermometry1 pp4 #aae-aaf4--;,absorption of heat2 ,conductivity of soils for heat4 ,cohesion and ,adhesion of ,soils1 pp4 #aaf-aag4--;,behavior of soil after wetting2 ,methods of determining cohesion and adhesion2 ,adhesion of soil to wood and iron4 ,absorption by ,soils1 pp4 #aag-acj4--;,general principles2 ,summary of data2 ,cause of absorption2 ,deductions of ,warington1 ,way1 and ,armsby2 ,selective absorption of potash2 ,influence of surface area2 ,effect of removal of organic matters2 ,importance of soil absorption2 ,methods of determining absorption2 ,statement of results2 ,preparation of salts for absorption4 ,relations of ,porosity to ,soil ,moisture1 pp4 #aca-aej4--;,definition of porosity2 ,influence of drainage2 ,capacity of soil for moisture2 ,determination of porosity2 ,whitney's method2 ,relation of fine soil to moisture2 ,wolff's and ,wahnschaffe's method2 ,petermann's method2 ,mayer's method2 ,volumetric determination2 ,wollny's method2 ,heinrich's method2 ,effect of pressure on water capacity2 ,coefficient of evaporation2 ,determination of capillary attraction2 ,inverse capillarity2 ,determination of coefficient of evaporation2 ,wolff's method2 ,water given off in a water-free atmosphere2 ,porosity of soil for gases2 ,determination of permeability in the field4 ,movement of ,water ,through ,soils3 ,lysimetry1 pp4 #aea-agj4--,porosity in relation to water movement2 ,methods of water movement2 ,capillary movement of water2 ,causes of water movement2 ,surface tension of fertilizers2 ,methods of estimating surface tension2 ,preparation of soil extracts2 ,lysimetry2 ,relative rate of flow of water through soils2 ,measurement of rate of percolation2 ,authorities cited in part third4 ,,part ,,fourth4 ,,mechanical ,,analysis4 ,the ,flocculation of ,soil ,particles1 pp4 #aga-ahe4--,relation of flocculation to mechanical analysis2 ,effect of potential of surface particles2 ,destruction of floccules2 ,suspension of clay in water2 effect of chemical action2 ,theory of ,barus2 ,physical explanation of subsidence2 ,separation of soil into particles of standard size2 ,mechanical separation2 ,sifting with water4 ,separation of ,soil ,particles by a ,liquid1 pp4 #ahe-bjg4--;,classification of methods of silt analysis2 ,methods depending on subsidence of soil particles2 ,methods of ,khn1 ,knop1 ,wolff1 ,moore1 ,bennigsen1 and ,gasparin2 ,method of ,osborne2 ,schloesing's method4 ,separation of ,soil ,particles by a ,liquid in ,motion1 pp4 #bjg-bdg4--;,general principles2 ,nbel's ,apparatus2 ,method of ,dietrich2 ,method of ,masure2 ,method of ,schne2 ,mayer's method2 ,osborne-,schne method2 ,statement of results2 ,berlin-,schne method2 ,hilgard's method2 ,colloidal clay2 ,properties of pure clay2 ,separation of fine sediments2 ,weighing sediments2 ,classification of results2 ,comparison of methods4 ,miscellaneous ,determinations1 pp4 #bdg-bha4--,mechanical determination of clay2 ,effect of boiling on clay2 ,general conclusions2 ,distribution of soil ingredients2 ,percentage of silt by classes2 ,interpretation of silt analysis2 ,number of soil particles2 ,surface area of soil particles2 ,logarithmic constants2 ,mineralogical examination of silt2 ,microscopical examination2 ,petrographic microscope2 ,forms and dimensions of particles2 ,silt classes2 ,crystal angles2 ,refractive index2 ,polarized light2 ,staining silt particles2 ,cleavage of soil particles2 ,microchemical examination of silt particles2 ,petrographic examination of silt particles2 ,separation of silt particles by specific gravity2 ,separation with a magnet2 ,color and transparency2 ,value of silt analyses2 ,authorities cited in part fourth4 ,,part ,,fifth4 ,estimation of ,gases in ,soils1 pp4 #bhb-cjj4--;,carbon dioxid2 ,aqueous vapor2 ,maximum hygroscopic coefficient2 ,absorption of aqueous vapors2 ,oxygen and air2 ,general method of determining absorption2 ,special methods2 ,diffusion of carbon dioxid2 ,general conclusions2 ,authorities cited in part fifth4 ,,part ,,sixth4 ,chemical ,analysis of ,soils1 pp4 #cja-cdb4--,preliminary considerations2 ,order of examination2 ,determination of water in soils2 ,general conclusions2 ,estimation of organic matter in soils2 ,estimation of humus2 ,estimation of carbonates in arable soils4 ,digestion of ,soils with ,solvents1 pp4 #cdb-ceb4--,treatment with water2 ,with water saturated with carbon dioxid2 ,with water containing ammonium chlorid2 ,with water containing acetic acid2 ,treatment with citric acid2 ,with hydrochloric acid2 ,with nitric acid2 ,with hydrofluoric and sulphuric acids4 ,determination of the ,dissolved ,matter1 pp4 #ceb-cfg4--,methods of the ,official ,agricultural ,chemists2 ,hilgard's methods2 ,belgian methods2 ,bulk analysis4 ,special ,methods of ,soil ,analysis1 pp4 #cfg-dbh4--;,determination of potash2 ,potash soluble in concentrated acids2 ,soluble in dilute acids2 ,estimation as platinochlorid2 ,german ,station methods2 ,raulin's method2 ,russian method2 ,italian method2 ,smith's method2 ,international method2 ,dyer's method2 ,estimation of total alkalies and alkaline earths2 ,french method for lime2 ,estimation of actual calcium carbonate2 ,estimation of active calcareous matter2 ,russian method for lime2 ,assimilable lime2 ,german lime method2 ,estimation of magnesia2 ,estimation of manganese2 ,estimation of iron2 ,estimation of phosphoric acid2 ,estimation of sulfuric acid2 ,estimation of chlorin2 ,estimation of silica2 ,simultaneous estimation of different elements2 ,estimation of kaolin in soils4 ,estimation of ,nitrogen in ,soils1 pp4 #dbh-deh4--,nature of nitrogenous principles2 ,method of ,official ,agricultural ,chemists2 ,hilgard's method2 ,moist combustion method of ,mller2 ,soda-lime method2 ,treatment of soil containing nitrates2 ,volumetric method with copper oxid2 ,estimation of ammonia2 ,amid nitrogen2 ,volatile nitrogenous compounds2 ,late methods of the ,official ,agricultural ,chemists2 ,authorities cited in part sixth4 ,,part ,,seventh4 ,oxidized ,nitrogen in ,soils1 pp4 #dei-dif4--,organic nitrogen2 ,nitric and nitrous acids2 ,conditions of nitrification2 ,production of nitric and nitrous acids2 ,production of ammonia2 ,order of oxidation2 ,occurrence of nitrifying organisms2 ,nitrifying power of soils2 ,culture of nitrifying organisms2 ,isolation of nitrous and nitric ferments2 ,classification of nitrifying organisms2 ,sterilization2 ,thermostats for cultures2 ,conclusions4 ,determination of ,nitric and ,nitrous ,acids in ,soils1 pp4 #dif-eca4--;,classification of methods2 ,extraction of nitric acid2 ,the nitric oxid process2 ,schloesing's method2 ,warington's method2 ,spiegel's method2 ,schulze-,tiemann method2 ,de,koninck's method2 ,schmitt's process2 ,merits of the ferrous salt method2 ,mercury and sulfuric acid method2 ,lunge's nitrometer2 ,utility of the method2 ,the indigo method4 ,determination of ,nitric ,nitrogen by ,reduction to ,ammonia1 pp4 #eca-edb4--;,classification of methods2 ,method of the ,official ,agricultural ,chemists2 ,german method2 ,devarda's method2 ,stoklassa's process2 ,sievert's variation2 ,variation of the sodium-amalgam process2 ,schmitt's method2 ,process of ,ulsch2 ,reduction by the electric current2 ,copper-zinc and aluminum-mercury couples4 ,iodometric ,estimation of ,nitric ,acid1 pp4 #edc-edh4--,method of ,de,koninck and ,nihoul2 ,method of ,gooch and ,gruener4 ,estimation of ,nitric and ,nitrous ,acids by ,colorimetric ,comparison1 pp4 #edh-egj4--;,delicacy of the process2 ,hooker's carbazol method2 ,phenylsulfuric acid method2 ,estimation of nitric in presence of nitrous acid2 ,metaphenylenediamin method for nitrous acid4 ,sulfanilic acid test2 ,naphthylamin process2 ,use of starch as indicator2 ,method of ,chabrier2 ,ferrous salt method2 ,potassium ferrocyanid method2 ,collecting samples of rain water4 ,determination of ,free and ,albuminoid ,ammonia1 pp4 #egj-ege4--,nessler process2 ,ilosvay's reagent2 ,authorities cited in part seventh4 ,,part ,,eighth4 ,special ,examination of ,waters1 pp4 #egf-ehc4--,total solid matter2 ,estimation of chlorin2 ,estimation of carbon dioxid2 ,boric acid4 ,special ,treatment of ,muck ,soils1 pp4 #ehc-eia4--,sampling2 ,water content2 ,organic carbon and hydrogen2 ,total volatile matter2 ,estimation of sulfur2 ,estimation of phosphoric acid2 ,estimation of humus2 ,special study of soluble matters in muck4 ,unusual ,constituents of ,soil1 pp4 #ehj-eic4--;,estimation of copper2 ,estimation of lead2 ,estimation of zinc2 ,estimation of boron2 ,authorities cited in part eighth4 ,index1 pp4 #eid-fjg4 99 99 99 99 99 ,,corrections4--,page #aab1 second line from bottom1 read 8,fig4 #ad0 instead of 8#ac40 ,page #aeh1 insert 8and determining soluble matters therein0 after 8flow0 in paragraph #agb1 third line4 ,page #dfh1 paragraph #dbc1 read 8calcium carbonate about #bjj milligrams10 instead of 8calcium carbonate1 or gypsum fifty milligrams40 ,page #eeg1 read 8red-yellow0 instead of 8blue0 in seventh line from bottom4 ,,illustrations ,,to ,,volume ,,first4 ,page4 ,plate1 figures #a-f4 ,to face #bi ,figure #g4 ,microscopic structure of sandstone #cf #h4 ,microstructure of crystalline limestone #ci #i4 ,microstructure of ,gneiss #dj ,plate1 figure #aj4 ,view on the broad branch of ,rock ,creek1 #dh ,washington1 ,d4 ,c41 to face ,figure #aa4 #hb #ab4 #hd #ac4 ,regnault's apparatus for determining the specific heat #aje of soils #ad4 ,soil thermometer #aac #ae4 ,zalomanoff's apparatus for determining absorption of #abf salts by soils #af4 ,mller's apparatus to show absorption of salts by #abg soils ,plate1 figure #ag4 ,capacity of the fine soil for holding moisture4 #acf ,method of ,wolff modified by ,wahnschaffe1 to face ,figure #ah4 ,fuelling's apparatus #adj #ai4 ,apparatus to show capillary attraction of soils for #ade water ,plate1 figure #bj4 ,apparatus for determining coefficient of #adh evaporation1 to face ,figure #ba4 ,method of ,heinrich #aej #bb4 ,method of ,welitschowsky #afb #bc4 ,ground plan and vertical section of lysimeters and #aff vaults showing position of the apparatus ,plate1 figure #bd4 ,deherain's apparatus for collecting drainage #afh water1 to face ,figure #be4 ,knop's silt cylinder #aij #bf4 ,siphon cylinder for silt analysis #aia #bg4 ,bennigsen's silt flasks #aie #bh4 ,nbel's elutriator #bjh #bi4 ,dietrich's elutriator #bji #cj4 ,masure's silt apparatus #baa #ca4 ,schne's elutriator #bab #cb4 ,schne's elutriator outflow tube #bac #cc4 ,schne's elutriator1 arrangement of apparatus #bad #cd4 ,schne's apparatus for silt analysis1 modified by #bba ,mayer #ce4 ,hilgard's churn elutriator #bbf #cf4 ,improved ,schne's apparatus with relay #bbh #cg4 #beg ,plate1 figure #ch4 ,to face #bfd figures #ci-dd4 figures #de-ej4 figures #ea-ef4 ,figure #eg4 ,machine for making mineral sections #bfg #eh4 ,thoulet's separating apparatus #bgb #ei4 ,harada's apparatus #bge #fj4 ,brgger's apparatus #bgf #fa4 ,apparatus of ,wlfing #bgg #fb4 ,schloesing's soil-tube for collecting gases #bia #fc4 ,schloesing's apparatus for collecting gases from soil #bib #fd4 ,schloesing's apparatus for determination of carbon #bic dioxid #fe4 ,knorr's apparatus for the determination of carbon #cch dioxid #ff4 ,bernard's calcimeter #cci #fg4 ,smith's muffle for decomposition of silicates #cha #fh4 ,apparatus by ,sachsse and ,becker #dja ,plate1 figures #fi and #gj4 ,to face #dhj ,figure #ga4 ,sterilizing oven #dia #gb4 ,autoclave sterilizer #dib #gc4 ,arnold's sterilizer #dic #gd4 ,lautenschlger's thermostat #did #ge4 ,schloesing's apparatus for nitric acid #eja #gf4 ,warington's apparatus for nitric acid #eje #gg4 ,spiegel's apparatus for nitric acid #eji #gh4 ,schulze-,tiemann's nitric acid apparatus #eaa #gi4 ,de,koninck's apparatus #ead #hj4 ,end of delivery-tube #ead #ha4 ,schmidt's apparatus #eaf #hb4 ,lunge's nitrometer #eai #hc4 ,lunge's improved apparatus #eba #hd4 ,lunge's analytic apparatus #ebc #he4 ,stoklassa's nitric acid apparatus #ece #hf4 ,variation of the sodium amalgam process #ecg #hg4 ,mc,gowan's apparatus for the iodometric estimation of #edd nitric acid #hh4 ,apparatus of ,gooch and ,gruener #edg #hi4 ,method of ,chabrier #eff #ij4 ,schaeffer's nitrous acid method #efh #ia4 ,retort for distilling ammonia #egb #ib4 ,gooch's apparatus for boric acid #eha #ic4 ,apparatus for determining sulfur #ehg ,,part ,,first4 ,,introduction4 #a4 ,definitions4--,the term soil1 in its broadest sense1 is used to designate that portion of the surface of the earth which has resulted from the disintegration of rocks and the decay of plants and animals1 and which is suited1 under proper conditions of moisture and temperature1 to the growth of plants4 ,it consists1 therefore1 chiefly of mineral substances1 together with some products of organic life1 and of certain living organisms whose activity may influence vegetable growth either favorably or otherwise4 ,the soil also holds varying quantities of gaseous matter and of water1 which are important factors in its functions4 #b4 ,origin ,of ,soil4--,agriculturally considered1 the soil proper is the older and more thoroughly disintegrated superficial layer of the earth1 which has been longest exposed to weathering and the influences of organic life4 ,it is usually from six to twelve inches1 but occasionally several feet in depth4 ,the subsoil1 which lies directly under this1 is not as a rule so thoroughly disintegrated1 since it is protected in a measure by the overlying soil4 ,it usually contains less organic matter than the soil4 ,there is a freer circulation of air in the soil than in the subsoil1 and the metallic elements usually exist therein as higher oxids4 ,there is usually a notable difference in color between the soil and subsoil1 and frequently a very sharp color line separating the two4 ,geologically considered1 the soil is that portion of the earth's crust which has been more or less thoroughly disintegrated by weathering and other forces from the original rock formations1 or from the sedimentary rocks1 or from the unconsolidated sedimentary material4 ,the soil has1 therefore1 the same essential constitution as the general mass of the earth1 except that this dbris has been subjected to the solvent action of water and the influence of vegetable growth4 ,preliminary to the proper understanding of the methods of the analysis of soils1 there should be some definite knowledge concerning the composition of the earth's crust1 so that the analyst may understand more thoroughly the origin and nature of the material he has to deal with1 and thereby be better equipped for his work4 #c4 ,the ,chemical ,elements ,present in the ,soil4--,the chemical elements present in the soil are naturally some or all of those which were present in the original rocks4 ,for analytical purposes relating to agriculture1 it is not necessary to take into account the rare elements which may occur in the soil1 but only those need be considered which are present in some quantity and which enter as an important factor into plant growth4 ,of the whole number of chemical elements less than twenty are of any importance in soil analysis4 ,these elements may be grouped into two classes1 the non-metals1 and the metals as follows3 ,non-metals4 ,metals4 ,oxygen1 ,aluminum1 ,silicon1 ,calcium1 ,carbon1 ,magnesium1 ,sulfur1 ,potassium1 ,hydrogen1 ,sodium1 ,chlorin1 ,iron1 ,phosphorus1 ,manganese1 ,nitrogen1 ,barium4 ,fluorin1 ,boron4 #d4 ,atomic ,masses4--,for the purpose of facilitating the calculation of results the latest revised table of atomic masses is given below4 ,all the known elements are included in this table for the convenience of analysts who may have to study some of the rarer elements in the course of their work4 ,this table represents the latest and most trustworthy results reduced to a uniform basis of comparison with oxygen #af as starting point of the system4 ,no decimal places representing large uncertainties are used4 ,when values vary1 with equal probability on both sides1 so far as our present knowledge goes1 as in the case of cadmium 7#aaa4h and #aab4b71 the mean value is given in the table4 ,,table ,,of ,,atomic ,,masses ,,of ,,the ,,elements4 ,revised by ,f4 ,w4 ,clarke1 ,chief ,chemist of the ,united ,states ,geological ,survey1 to ,january #ast1 #ahid4 ,name4 ,symbol4,atomic mass4 ,aluminum ,al #bg ,antimony ,sb #abj ,arsenic ,as #ge ,barium ,ba #acg4dc ,bismuth ,bi #bjh4i ,boron ,b #aa ,bromin ,br #gi4ie ,cadmium ,cd #aab ,cesium ,cs #acb4i ,calcium ,ca #dj ,carbon ,c #ab ,cerium ,ce #adj4b ,chlorin ,cl #ce4de ,chromium ,cr #eb4a ,cobalt ,co #ei ,columbium,a,cb,nb #id ,copper ,cu #fc4f ,erbium ,er #aff4c ,fluorin ,f #ai ,gadolinium ,gd #aef4a ,gallium ,ga #fi ,germanium ,ge #gb4c ,glucinum,b ,gl,be #i ,gold ,au #aig4c ,hydrogen ,h #a4jjh ,indium ,in #aac4g ,iodin ,i #abf4he ,iridium ,ir #aic4a ,iron ,fe #ef ,lanthanum ,la #ach4b ,lead ,pb #bjf4ie ,lithium ,li #g4jb ,magnesium ,mg #bd4c ,manganese ,mn #ee ,mercury ,hg #bjj ,molybdenum ,mo #if ,neodymium ,nd #adj4e ,nickel ,ni #eh4g ,nitrogen ,n #ad4jc ,osmium ,os #aij4h ,oxygen,c ,o #af ,palladium ,pd #ajf4f ,phosphorus ,p #ca ,platinum ,pt #aie ,potassium ,k #ci4aa ,praseodymium,pr #adc4e ,rhodium ,rh #ajc ,rubidium ,rb #he4e ,ruthenium ,ru #aja4f ,samarium ,sm #aej ,scandium ,sc #dd ,selenium ,se #gi ,silicon ,si #bh4d ,silver ,ag #ajg4ib ,sodium ,na #bc4je ,strontium ,sr #hg4f ,sulfur ,s #cb4jf ,tantalum ,ta #ahb4f ,tellurium ,te #abe ,terbium ,tb #afj4j ,thallium ,tl #bjd4ah ,thorium ,th #bcb4f ,thulium ,tu #agj4g ,tin ,sn #aai ,titanium ,ti #dh ,tungsten ,w #ahd ,uranium ,u #bci4f ,vanadium ,v #ea4d ,ytterbium ,yb #agc ,yttrium ,yt #hi4a ,zinc ,zn #fe4c ,zirconium ,zr #ij4f ,footnote ,a3 ,has priority over niobium4 ,footnote ,b3 ,has priority over beryllium4 ,footnote ,c3 ,standard or basis of the system4 ,,properties ,,of ,,the ,,elements4 ,following is a brief description of the most important elements occurring in the earth's crust in respect of their relations to agriculture4 #e4 ,oxygen exists in the free gaseous state in the atmosphere of which it constitutes about one-fifth by bulk1 whilst in combination with other elements it forms nearly half the weight of the solid earth1 and eight-ninths by weight of water4 ,it enters into combination with all the other elements1 except fluorin1 forming what are known as oxids1 and with many of the elements it unites in several proportions1 forming oxids of different composition4 ,combined with silicon1 carbon1 sulfur1 and phosphorus1 it forms an essential part of the silicates1 carbonates1 sulfates1 and phosphates1 most of which are very abundant and all of which are very widely distributed in the earth's crust4 ,in this form it is exceedingly stable and is rarely set free4 ,with the exception of the oxids of silicon these oxids seldom occur uncombined with the metals as constituents of rocks or soils4 ,the oxids of iron very commonly occur as such in rocks and soils1 and play a very important part in organic life4 ,the several oxids of iron very frequently determine the color of soils2 as the iron in a soil is more or less oxidized1 or as it is exposed more or less to access of air1 the color of the soil changes4 ,these oxids of iron also play an important part in the absorption capacities of soils for moisture and other physical conditions of soils1 and also in the oxidation of organic matters in the soil4 ,many organic substances1 and even the roots of growing plants when deprived of free access of air1 can readily secure oxygen from the iron oxid1 thus reducing the iron to a lower form of oxidation1 the oxygen being used for the oxidation of the organic matter or for the needs of the growing plant2 while the lower oxid of iron can more readily take up oxygen of the air and again be converted into a higher oxid1 ready again to give up a part of its oxygen and thus serve as a carrier4 #f4 ,silicon never occurs in the free state1 but combined with oxygen it forms silica1 which constitutes more than one-half of the earth's crust4 ,the oxid of silicon occurs in the very common form of quartz1 and likewise1 as silicate of alumina1 lime or magnesia4 ,silicon forms an essential part of many minerals1 such as the feldspars1 amphiboles1 pyroxenes1 and the micas1 besides being an essential ingredient of many other minerals4 ,silica is relatively very slightly affected by the ordinary forces concerned in the decay of rocks1 and even after the crystals of feldspars1 micas1 and other common minerals occurring in rocks have been disintegrated the silica remains as hard grains of sand1 forming the bulk of most soils4 ,by far the larger part of silicon in soils is in the form of grains of quartz or silica4 ,this form1 however1 is probably chemically inert in regard to plant growth1 but it plays a very important part in the physical structure of soils and in the physical relation of soils to plant growth4 #g4 ,carbon as an elementary substance occurs as diamond and graphite and in an impure form as anthracite and bituminous coals4 ,in peats and mucks carbon is the chief constituent4 ,this substance is also contained in the organic matters of the soil known as humus1 and the relation of the carbon to nitrogen often throws important light upon the amount and character of the nitrogenous matters4 ,in composition with oxygen it forms the chief food of growing plants1 the carbon of the carbon dioxid of the air being elaborated into the tissue of the plants and the oxygen returned to the atmosphere4 ,the content of carbon dioxid in the air is from three to five parts per thousand by volume4 ,as carbonates this element helps to form some of the most important ingredients of the earth's crust1 namely1 limestones1 marbles1 dolomites1 etc41 and in an organic form it is found in the shells of the crustaceans4 ,the calcareous matter of the soil1 that is1 the carbonates of the earths therein found1 are of the highest importance from an agricultural point of view4 ,the carbonates in the soil not only favor the process of converting nitrogenous bodies into forms suitable for plant food1 but also exert a most potent influence on the physical state of the soil and its capacity for holding water and permitting its flow to and from the rootlets of the plant4 #h4 ,sulfur occurs in nature in both the free and combined state4 ,in the free state it is found in volcanic regions such as ,sicily1 ,iceland1 and the western ,united ,states4 ,its usual form of occurrence is in combination with the metals to form sulfids1 or with oxygen and a metal to form sulfates4 ,sulfur and iron combine to form iron pyrites or iron disulfid 7,fe,s71 while sulfur1 oxygen1 and calcium are found in gypsum1 an important fertilizing compound4 ,sulfur plays an important part in the nourishment of plants1 being found in them both as sulfuric acid and in organic compounds4 ,methods for estimating the sulfur in both forms will be found in another part of this manual4 #i4 ,hydrogen is a colorless1 invisible gas1 without taste or smell4 ,it occurs free in small proportions in certain volcanic gases1 and in natural gas1 but its most common form is in combination with oxygen as water 7,h,o71 of which it forms #aa4ac per cent by weight4 ,it also occurs in combination with carbon to form the hydrocarbons1 such as the mineral oils 7petroleum1 etc47 and gases4 ,hydrogen is of no importance to agriculture in a free state1 but water is the most important of all plant foods4 #aj4 ,chlorin occurs free in nature only in limited amounts and in volcanic vents4 ,its most common form is in combination with hydrogen1 forming hydrochloric acid1 or with the metals to form chlorids4 ,it combines with sodium to form sodium chlorid or common salt 7,na,cl71 which is the most abundant mineral ingredient in sea water and which can usually be detected in rain and ordinary terrestrial waters4 ,in this form1 also1 it exists as extensive beds of rock salt1 which is mined for commercial purposes4 ,chlorin is found uniformly in plants and must be regarded as an essential constituent thereof4 ,common salt applied to a soil modifies its power of attracting and holding water4 #aa4 ,phosphorus never occurs in nature in a free state but exists in combination in greater or less quantities in all soils4 ,its combinations are also found in large deposits of minerals known as phosphorite and apatite and as so-called pebble deposit and phosphate rock4 ,phosphorus in some sort of combination is one of the most essential elements in animal and plant food4 ,in animals its compounds form almost all of the mineral matter of the bones1 and in plants they are the chief constituents of the ash of seeds4 ,the mineral deposits of phosphorus1 as well as bones1 are chiefly tri-calcium phosphate1 while the slag compound resulting from the basic treatment of iron ores rich in phosphorus is a tetra-calcium salt4 ,the pebble deposits and some rock phosphates are supposed to be of organic origin1 derived from the remains of marine1 terrestrial1 and aerial animals4 ,cereal crops remove about twenty pounds of phosphoric acid per acre from the soil annually and grass crops about twelve pounds4 ,the total phosphoric acid removed annually by the cereal and grass crops in the ,united ,states is nearly four billion pounds4 ,gautier#a calls attention to the fact that the oldest phosphates are met with in the igneous rocks such as basalt1 trachyte1 etc41 and even in granite and gneiss4 ,it is from these inorganic sources1 therefore1 that all phosphatic plant food must have been drawn4 ,in the second order in age ,gautier places the phosphates of hydro-mineral origin4 ,this class not only embraces the crystalline apatites but also those phosphates of later formation formed from hot mineral waters in the jurassic1 cretaceous1 and tertiary deposits4 ,these deposits are not directly suited to nourish plants4 ,the third group of phosphates in order of age and assimilability embraces the true phosphorites containing generally some organic matter4 ,they are all of organic origin4 ,in caves where animal remains are deposited there is an accumulation of nitrates and phosphates4 ,not only do the bones of animals furnish phosphates but they are also formed in considerable quantities by the decomposition of substituted glycerids such as lecithin4 ,the ammonia produced by the nitrification of the albuminoid bodies combines with the free phosphoric acid thus produced1 forming ammonium or diammonium phosphates4 ,the presence of ammonium phosphates in guanos was first noticed by ,chevreul more than half a century ago4 ,if such deposits overlay a pervious stratum of calcium carbonate1 such as chalk1 and are subject to leaching a double decomposition takes place as the lye percolates through the chalk4 ,acid calcium phosphate and ammonium carbonate are produced4 ,by further nitrification the latter becomes finally converted into calcium nitrate4 ,in like manner aluminum phosphates are formed by the action of decomposing organic matter on clay4 ,davidson1#b explains the origin of the ,florida phosphates by suggesting that they arose chiefly through the influx of animals driven southward during the glacial period4 ,according to his supposition the waters of the ocean1 during the cenozoic period contained more phosphorus than at the present time4 ,the waters of the ocean over ,florida were shallow and the shell fish existing therein may have secreted phosphate as well as carbonate of lime4 ,this supposition is supported by an analysis of a shell of lingula ovalis1 quoted by ,dana1 in which there were #he4gi per cent of lime phosphate4 ,in these waters were also many fishes of all kinds and their dbris served to increase the amount of phosphatic material4 ,as the land emerged from the sea came the great glacial epoch driving all terrestrial animals southward4 ,there was1 therefore1 a great mammal horde in the swamps and estuaries of ,florida4 ,the bones of these animals contributed largely to the phosphatic deposits4 ,in addition to this1 the shallow sea contained innumerable sharks1 manatees1 whales1 and other inhabitants of tropical waters1 and the remains of these animals added to the phosphatic store4 ,while these changes were taking place in the quaternary period1 the ,florida ,peninsula was gradually rising1 and as soon as it reached a considerable height the process of denudation by the action of water commenced4 ,then there was a subsidence and the peninsula again passed under the sea and was covered with successive layers of sand4 ,the limestones during this process had been leached by rain water containing an excess of carbon dioxid4 ,in this way the limestones were gradually dissolved while the insoluble phosphate of lime was left in suspension4 ,during this time the bones of the animals before mentioned by their decomposition added to the phosphate of lime present in the underlying strata1 while some were transformed into fossils of phosphate of lime just as they are found to-day in vast quantities4 ,wyatt1#c explains the phosphate deposits somewhat differently4 ,according to him1 during the miocene submergence there was deposited upon the upper eocene limestones1 more especially in the cracks and fissures resulting from their drying up1 a soft1 finely disintegrated calcareous sediment or mud4 ,the estuaries formed during this period were swarming with animal and vegetable life1 and from this organic life the phosphates were formed by decomposition and metamorphism due to the gases and acids with which the waters were charged4 ,after the disappearance of the miocene sea there were great disturbances of the strata4 ,then followed the pliocene and tertiary periods and quaternary seas with their deposits and drifts of shells1 sands1 clays1 marls1 bowlders1 and other transported materials supervening in an era when there were great fluctuations of cold and heat4 ,by reason of these disturbances the masses of the phosphate deposits which had not been infiltrated in the limestones became broken up and mingled with the other dbris and were thus deposited in various mounds or depressions4 ,the general result of the forces which have been briefly outlined1 was the formation of bowlders1 phosphatic dbris1 etc4 ,wyatt therefore classifies the deposits as follows3 #a4 ,original pockets or cavities in the limestone filled with hard and soft rock phosphates and dbris4 #b4 ,mounds or beaches1 rolled up on the elevated points1 and chiefly consisting of huge bowlders of phosphate rock4 #c4 ,drift or disintegrated rock1 covering immense areas1 chiefly in ,polk and ,hillsboro counties1 and underlying ,peace ,river and its tributaries4 ,darton1#d ascribes the phosphate beds of ,florida to the transformation of guano4 ,according to this author two processes of decomposition have taken place4 ,one of these is the more or less complete replacement of the carbonate by the phosphate of lime4 ,the other is a general stalactitic coating of phosphatic material4 ,darton further calls attention to the relation of the distribution of the phosphate deposits as affecting the theory of their origin1 but does not find any peculiar significance in the restriction of these deposits to the western ridge of the ,florida peninsula4 ,as this region evidently constituted a long narrow peninsula during early miocene time it is a reasonably tentative hypothesis that during this period guanos were deposited from which was derived the material for the phosphatization of the limestone either at the same time or soon after4 ,darton closes his paper by saying that the phosphate deposits in ,florida will require careful1 detailed geologic exploration before their relations and history will be fully understood4 ,according to ,dr4 ,n4 ,a4 ,pratt the rock or bowlder phosphate had its immediate origin in animal life and to his view the phosphate bowlder is a true fossil4 ,he supposes the existence of some species in former times in which the shell excreted was chiefly phosphate of lime4 ,the fossil bowlder1 therefore1 becomes the remains of a huge foraminifer which had identical composition in its skeleton with true bone deposits or of organic matter4 ,perhaps the most complete exposition of the theory of the recovery of waste phosphates1 with especial reference to their deposit in ,florida1 has been given by ,eldridge4#e ,he calls attention to the universal presence of phosphates in sea water and to the probability that in earlier times1 as during the miocene and eocene geologic periods1 the waters of the ocean contained a great deal more phosphate in solution than at the present time4 ,he cites the observations of ,bischof1 which show the solubility of different phosphates in waters saturated with carbon dioxid4 ,according to these observations apatite is the most insoluble form of lime phosphate1 while artificial basic phosphate is the most soluble4 ,among the very soluble phosphates1 however1 are the bones of animals1 both fresh and old4 ,burnt bones1 however1 are more soluble than bones still containing organic matter4 ,not only are the organic phosphates extremely soluble in water saturated with carbon dioxid1 but also in water which contains common salt or chlorid of ammonium4 ,the presence of large quantities of common salt in sea water would1 therefore1 tend to increase its power of absorbing lime phosphates of organic origin4 ,it is not at all incredible1 therefore1 to suppose that at some remote period the waters of the ocean1 as indicated by these theories1 were much more highly charged with phosphates in solution than at the present time4 ,according to ,eldridge1 the formation of the hard-rock and soft phosphates may be ascribed to three periods3 ,first1 that in which the primary rock was formed2 second1 that of secondary deposition in the cavities of the primary rock2 third1 that in which the deposits thus formed were broken up and the resulting fragments and comminuted material were redeposited as they now occur4 8,the first of these stages began probably not later than the close of the older miocene1 and within the eocene area it may have begun much earlier4 ,whether the primary phosphate resulted from a superficial and heavy deposit of soluble guanos1 covering the limestones1 or from the concentration of phosphate of lime already widely and uniformly distributed throughout the mass of the original rock1 or from both1 is a difficult question4 ,in any event1 the evidence indicates the effect of the percolation of surface waters1 highly charged with carbonic and earth acids1 and thus enabled to carry down into the mass of the limestone dissolved phosphate of lime1 to be redeposited under conditions favorable to its separation4 ,such conditions might have been brought about by the simple interchange of bases between the phosphate and carbonate of lime thus brought together1 or by the lowering of the solvent power of the waters through loss of carbonic acid4 ,the latter would happen whenever the acid was required for the solution of additional carbonate of lime1 or when1 through aeration1 it should escape from the water4 ,the zone of phosphate deposition was evidently one of double concentration1 resulting from the removal of the soluble carbonate thus raising the percentage of the less soluble phosphate1 and from the acquirement of additional phosphate of lime from the overlying portions of the deposits40 8,the thickness of the zone of phosphatization in the eocene area is unknown1 but it is doubtful if it was over twenty feet4 ,in the miocene area the depth has been proved from the phosphates in situ to have been between six and twelve feet40 ,the deposits of secondary origin1 according to ,eldridge1 are due chiefly to sedimentation1 although some of them may have been due to precipitation from water4 ,this secondary deposition was kept up for a long period1 until stopped by some climatic or geologic change4 ,the deposits of phosphates thus formed in the ,florida peninsula are remarkably free from iron and aluminum1 in comparison with many of the phosphates of the ,west ,indies4 ,the third period in the genesis of the hard rock deposits embraces the time of formation of the original deposits and their transportation and storage as they are found at the present time4 ,the geologic time at which this occurred is somewhat uncertain but it was probably during the last submergence of the peninsula4 ,in all cases the peculiar formation of the ,florida limestone must be considered4 ,this limestone is extremely porous and therefore easily penetrated by the waters of percolation4 ,a good illustration of this is seen on the southwestern and southern edges of ,lake ,okeechobee4 ,in following down the drainage canal which has been cut into the southwest shore of the lake the edge of the basin1 which is composed of this porous material may be seen4 ,the appearance of the limestone would indicate that large portions of it have already given way to the process of solution4 ,the remaining portions are extremely friable1 easily crushed1 and much of it can be removed by the ordinary dredging machines4 ,such a limestone as this is peculiarly suited to the accumulation of phosphatic materials1 due to the percolation of the water containing them4 ,the solution of the limestone and consequent deposit of the phosphate of lime is easily understood when the character of this limestone is considered4 ,shaler1 as quoted by ,eldridge in the work already referred to1 refers to this characteristic of the limestone and says that the best conditions for the accumulation of valuable deposits of lime phosphate in residual dbris appear to occur where the phosphatic lime marls are of a rather soft character2 the separate beds having no such solidity as will resist the percolation of water through innumerable incipient joints such as commonly pervade stratified materials1 even when they are of a very soft nature4 ,eldridge is also of the opinion that the remains of birds are not sufficient to account for the whole of the phosphatic deposits in ,florida4 ,he ascribes them to the joint action of the remains of birds1 of land and marine animals and to the deposition of the phosphatic materials in the waters in the successive subsidences of the surface below the water line4 #ab4 ,nitrogen as a mineral constituent of soils1 is found chiefly in the form of nitrates1 but1 owing to their solubility1 they can not accumulate in soils exposed to heavy rain-falls4 ,the gaseous nitrogen in the soil is also of some importance1 since it is in this material that the anaerobic organisms which accumulate on the rootlets of some plants probably act in the process of the fixation of atmospheric nitrogen in a form accessible to plants4 ,nitrogen in the free state1 it is believed1 is not directly absorbed into the tissues of plants4 ,it is necessary that it be oxidized in some way to nitric acid before it can be assimilated4 ,the importance of nitrogen as a plant food can not be too highly estimated4 ,it is as necessary to plant growth and development as water1 phosphoric acid1 lime1 and potash1 and far more costly4 ,while a large quantity of nitrogen exists in the air in an uncombined state1 it is1 nevertheless1 one of the least abundant of the elements of high importance in plant nutrition4 ,the conservation and increase of the stores of available nitrogen in the soil is one of the chief problems occupying the attention of agricultural chemistry4 ,nitrogen1 which is not immediately available for the growth of plants1 is conserved and restored by natural processes in various ways4 ,the waste nitrogen finds its way sooner or later to the sea1 and is restored therefrom in many forms4 ,sea-weeds of all kinds are rich in recovered nitrogen4 ,many years ago ,forchhammer#f pointed out the agricultural value of certain fucoids4 ,many other chemists have contributed important data in regard to the composition of these bodies4 ,jenkins#g has shown from the analyses of several varieties of sea-weeds that in the green state they are quite equal in fertilizing value to stall manure1 and are sold at the rate of five cents per bushel4 ,these data are fully corroborated by ,goessmann4#h ,wheeler and ,hartwell#i give the fullest and most systematic discussion which has been published of the agricultural value of sea-weeds4 ,sea-weed was used as a fertilizer as early as the fourth century1 and its importance for this purpose has been recognized more and more in modern days1 especially since chemical investigations have shown the great value of the food materials contained therein4 ,to show the commercial importance of sea-weed1 it is only necessary to call attention to the fact that in #ahhe its value as a fertilizer in the ,state of ,rhode ,island was #fe1jdd1 while the value of all other commercial fertilizers was #afd1acc4 ,while sea-weed1 in a sense1 can only be successfully applied to littoral agriculture1 yet the extent of agricultural lands bordering on the sea is so great as to render its commercial importance of the highest degree of interest4 ,a large amount of nitrogen is also recovered from the sea in fishes4 ,it is shown by ,atwater#aj that the edible part of fishes has an unusually high percentage of protein4 ,in round numbers1 about seventy-five per cent of the water free edible parts of fish are composed of albuminoids4 ,some kinds of fish are taken chiefly for their oil and fertilizing value1 as the menhaden4 ,squanto1#aa an ,american ,indian1 first taught the early ,new ,england settlers the manurial value of fish4 ,immense quantities of waste nitrogen are further secured1 both from sea and land1 by the various genera of birds4 ,the well-known habit of birds in congregating in rookeries during the night and at certain seasons of the year tends to bring into a common receptacle the nitrogenous matters which they have gathered and which are deposited in their excrement and in the decay of their bodies4 ,the feathers of birds are particularly rich in nitrogen1 and the nitrogenous content of the flesh of fowls is also high4 ,the decay of remains of birds1 especially if it take place largely excluded from the leaching of water1 tends to accumulate vast deposits of nitrogenous matter4 ,if the conditions in such deposits be favorable to the processes of nitrification1 the whole of the nitrogen1 or at least the larger part of it1 which has been collected in this dbris1 becomes finally converted into nitric acid and is found combined with appropriate bases as deposits of nitrates4 ,the nitrates of the guano deposits and of the deposits in caves arise in this way4 ,if these deposits be subject to moderate leaching the nitrate may become infiltered into the surrounding soil1 making it very rich in this form of nitrogen4 ,the bottoms and surrounding soils of caves are often found highly impregnated with nitrates4 ,while for our purpose1 deposits of nitrates only are to be considered which are of sufficient value to bear transportation1 yet much interest attaches to the formation of nitrates in the soil even when they are not of commercial importance4 ,in many of the soils of tropical regions not subject to heavy rain-falls1 the accumulation of these nitrates is very great4 ,mntz and ,marcano#ab have investigated many of these soils to which attention was called first by ,humboldt and ,boussingault4 ,they state that these soils are incomparably more rich in nitrates than the most fertile soils of ,europe4 ,the samples which they examined were collected from different parts of ,venezuela and from the valleys of the ,orinoco as well as on the shore of the ,sea of ,antilles4 ,the nitrated soils are very abundant in this region of ,south ,america where they cover large surfaces4 ,their composition is variable1 but in all of them carbonate and phosphate of lime are met with and organic nitrogenous material4 ,the nitric acid is found always combined with lime4 ,in some of the soils as high as thirty per cent of nitrate of lime have been found4 ,nitrification of organic material takes place very rapidly the year round in this tropical region4 ,these nitrated soils are everywhere abundant around caves1 as described by ,humboldt1 caves which serve as the refuge of birds and bats4 ,the nitrogenous matters1 which come from the decay of the remains of these animals1 form true deposits of guano which is gradually spread around1 and which1 in contact with the limestone and with access of air1 suffers complete nitrification with the fixation of the nitric acid by the lime4 ,large quantities of this guano are also due to the dbris of insects1 fragments of elytra1 scales of the wings of butterflies1 etc41 which are brought together in those places by the millions of cubic meters4 ,the nitrification1 which takes place in these deposits1 has been found to extend its products to a distance of several kilometers through the soil4 ,in some places the quantity of the nitrate of lime is so great in the soils that they are converted into a plastic paste by this deliquescent salt4 ,the theory of ,mntz and ,marcano in regard to the nitrates of soils1 especially in the neighborhood of caves1 is probably a correct one1 but there are many objections to accepting it to explain the great deposits of nitrate of soda which occur in many parts of ,chile4 ,another point1 which must be considered also1 is this3 ,that the processes of nitrification can not now be considered as going on with the same vigor as formerly4 ,some moisture is necessary to nitrification1 inasmuch as the nitrifying ferment does not act in perfectly dry soil1 and in many localities in ,chile where the nitrates are found it is too dry to suppose that any active nitrification could now take place4 ,the existence of these nitrate deposits has long been known4#ac ,the old ,indian laws originally prohibited the collection of the salt1 but nevertheless it was secretly collected and sold4 ,up to the year #ahba1 soda saltpeter was not known in ,europe except as a laboratory product4 ,about this time the naturalist1 ,mariano de ,rivero1 found on the ,pacific coast1 in the ,province of ,tarapac1 immense new deposits of the salt4 ,later the salt was found in equal abundance in the ,territory of ,antofogasta and further to the south in the desert of ,atacama1 which forms the ,department of ,taltal4 ,at the present time the collection and export of saltpeter from ,chile is a business of great importance4 ,the largest export which has ever taken place in one year was in #ahij1 when the amount exported was #ibg1bij1dcj kilograms2 of this quantity #fdb1ejf1ihe kilograms were sent to ,england and #hf1abd1hgj kilograms to the ,united ,states4 ,since that time the imports of this salt into the ,united ,states have largely increased4 ,according to ,pissis#ad these deposits are of very ancient origin4 ,this geologist is of the opinion that the nitrate deposits are the result of the decomposition of feldspathic rocks2 the bases thus produced gradually becoming united with the nitric acid provided from the air4 ,according to the theory of ,nllner#ae the deposits are of more modern origin and due to the decomposition of marine vegetation4 ,continuous solution of soils1 gives rise to the formation of great lakes of saturated water1 in which occurs the development of much marine vegetation4 ,on the evaporation of this water1 due to geologic isolation1 the decomposition of nitrogenous organic matter causes generation of nitric acid1 which1 coming in contact with the calcareous rocks1 attacks them1 forming nitrate of calcium1 which1 in presence of sulfate of sodium1 gives rise to a double decomposition into nitrate of sodium and sulfate of calcium4 ,the fact that iodin is found in greater or less quantity in ,chile saltpeter is one of the chief supports of this hypothesis of marine origin1 inasmuch as iodin is always found in sea and not in terrestrial plants4 ,further than this1 it must be taken into consideration that these deposits of nitrate of soda contain neither shells nor fossils1 nor do they contain any phosphate of lime4 ,the theory1 therefore1 that they were due to animal origin is scarcely tenable4 #ac4 ,boron occurs chiefly in volcanic regions1 but is much more widely distributed in the soil than formerly believed4 ,it is a regular constituent of the ash of many plants1#af and is1 therefore1 thought to be a true plant food4 ,it is one of the least abundant of the elements1 not occurring in sufficient quantity to find a place in the table showing their relative abundance1 which is to follow4 ,boracic acid is used to some extent as a preservative4 #ad4 ,fluorin does not occur free in nature1 but it exists chiefly in combination with calcium1 forming fluorspar1 and traces of it are found in sea water4 ,it occurs in bone1 teeth1 blood1 and the milk of mammals4 ,it is the only element that does not combine with oxygen1 and it can be isolated only with the greatest difficulty4 ,only very small traces of it are found ordinarily and it is usually not considered in the chemical analysis of soils4 ,fluorin is found1 however1 in considerable quantities in certain phosphate deposits4 #ae4 ,aluminum is1 probably1 next to oxygen and silicon1 the most abundant element of the earth's crust1 of which it is estimated to form about one-twelfth4 ,it has never been found1 in nature1 in the free state1 but commonly occurs in combination with silicon and oxygen1 in which form it is an abundant constituent of feldspar1 mica1 kaolin1 clay1 slate1 and many other rocks and minerals4 ,by the weathering of feldspar1 mica1 and other minerals containing aluminum1 kaolin or true clay is formed1 which is of the greatest importance in the constitution of the soil4 ,the compounds of aluminum are not so important as plant food as they are as the constituents of the soil1 forming a large part of its bulk1 and modifying in the most profound degree its physical properties4 ,it is the custom of some authors to use the word clay to designate the fine particles of soil which have in general the same relations to moisture and tilth as the particles of weathered feldspar1 etc4 ,in a strict chemical sense1 however1 the term clay is applied only to the hydrated silicate of alumina formed as indicated above4 ,the fertility of a soil is largely dependent on the quantity of clay which it contains1 its relations to moisture and amenability to culture being chiefly conditioned by its clay content4 ,the determination of the percentage of clay in soils is an operation of the highest utility in forming an opinion of the value of a soil on analytical data alone4 #af4 ,calcium is one of the commonest and most important elements of the earth's crust1 of which it has been estimated to compose about one-sixteenth4 ,it does not occur free in nature1 but its most common form is in combination with carbon dioxid1 forming the mineral calcite1 marble1 and the very abundant limestone rocks4 ,in this form it is slightly soluble in water containing carbon dioxid1 and hence lime has become a universal component of all soils and is very generally found in natural waters1 in which it furnishes the chief ingredient necessary for the formation of the shells and skeletons of the various tribes of mollusca and corals4 ,in combination with sulfuric acid calcium forms the rock gypsum4 ,lime is not only a necessary plant food1 but influences in a marked degree the physical condition of the soil and the progress of nitrification4 ,many stiff clay soils are rendered porous and pulverulent by an application of lime1 and thus made far more productive4 ,on account of its great abundance and low price1 it has not commanded the degree of attention from farmers and agricultural chemists which its merits deserve4 ,it forms an essential ingredient of plants and animals1 in the latter being collected chiefly in the bones1 while in plants it is rather uniformly distributed throughout all the tissues4 #ag4 ,magnesium occurs chiefly in combination with carbon dioxid or with lime and carbon dioxid in the mineral dolomite4 ,it is intimately associated with calcium and a trace of it is nearly always found where lime occurs in any considerable quantity4 ,the bitter taste of sea water and some mineral waters is due to the presence of salts of magnesia4 ,in combination with silica it forms an essential part of such rocks as serpentine1 soapstone1 and talc4 ,magnesia is not of much importance as a plant food nor as a fertilizing material4 #ah4 ,potassium combined with silica is an important element in many mineral silicates as1 for instance1 orthoclase4 ,granitic rocks usually contain considerable quantities of potassium1 and on their decomposition this becomes available for plant food4 ,in the form of chlorid1 potassium is found in small quantities in sea water1 and as a nitrate it forms the valuable salt known as niter or saltpeter4 ,potassium1 as is the case with phosphorus1 is universally distributed in soils1 and forms one of the great essential elements of plant food4 ,under the form of kainite and other minerals large quantities of potassium are used for fertilizing and for the manufacture of pure salts for commercial and pharmaceutical purposes4 ,the ordinary potassium salts are very soluble and for this reason they can not accumulate in large quantities in soils exposed to heavy rain-fall4 ,in the form of carbonate1 potassium forms one of the chief ingredients of hard wood ashes1 and in this form of combination is especially valuable for fertilizing purposes4 ,potash salts1 being extremely soluble1 are likely to be held longest in solution4 ,some of them1 are recovered in animal and vegetable life1 but the great mass of potash carried into the sea still remains unaccounted for4 ,the recovery of the waste of potash is chiefly secured by the isolation of sea waters containing large quantities of this salt and their subsequent evaporation4 ,such isolation of sea waters takes place by means of geologic changes in the level of the land and sea4 ,in the raising of an area above the water level there is almost certain to be an enclosure1 of greater or less extent1 of the sea water in the form of a lake4 ,this enclosure may be complete or only partial1 the enclosed water area being still in communication with the main body of the sea by means of small estuaries4 ,if this body of water be exposed to rapid evaporation1 as was doubtless the case in past geologic ages1 there will be a continual influx of additional sea water through these estuaries to take the place of that evaporated4 ,the waters may thus become more and more charged with saline constituents4 ,finally a point is reached in the evaporation when the less soluble of the saline constituents begin to be deposited4 ,in this way the various formations of mineral matter1 produced by the drying up of enclosed waters1 take place4 ,the most extensive potash deposits known are those in the neighborhood of ,stassfurt1 in ,germany4 ,the following description probably represents the method of formation of these deposits3#ag 8,the ,stassfurt salt and potash deposits had their origin1 thousands of years ago1 in a sea or ocean1 the waters of which gradually receded1 leaving near the coast1 lakes which still retained communication with the great ocean by means of small channels4 ,in that part of ,europe the climate was then tropical1 and the waters of these lakes rapidly evaporated but were constantly replenished through these small channels connecting them with the main body4 ,decade after decade this continued1 until by evaporation and crystallization1 the various salts present in the sea water were deposited in solid form4 ,the less soluble material1 such as sulfate of lime or #8anhydrite1' solidified first and formed the lowest stratum4 ,then came common rock salt with a slowly thickening layer which ultimately reached #cjjj feet1 and is estimated to have been #ac1jjj years in formation4 ,this rock salt deposit is interspersed with lamellar deposits of #8anhydrite1' which gradually diminish towards the top and are finally replaced by the mineral #8polyhalite1' which is composed of sulfate of lime1 sulfate of potash1 and sulfate of magnesia4 ,the situation in which this polyhalite predominates is called the #8polyhalite region' and after it comes the #8kieserite region1' in which1 between the rock salt strata1 kieserite 7sulfate of magnesia7 is imbedded4 ,above the kieserite lies the #8potash region1' consisting mainly of deposits of carnallite1 a mineral compound of muriate of potash and chlorid of magnesia4 ,the carnallite deposit is from #ej to #acj feet thick and yields the most important of the crude potash salts and that from which are manufactured most of the concentrated articles1 including muriate of potash40 8,overlying this region is a layer of impervious clay which acts as a water-tight roof to protect and preserve the very soluble potash and magnesia salts1 which1 had it not been for the very protection of this overlying stratum1 would have been long ages ago washed away and lost by the action of the water percolating from above4 ,above this clay roof is a stratum1 of varying thickness of anhydrite1 and still above this a second salt deposit1 probably formed under more recent climatic and atmospheric influences or possibly by chemical changes in dissolving and subsequent precipitation4 ,this salt deposit contains ninety-eight per cent 7often more7 of pure salt1 a degree of purity rarely elsewhere found4 ,finally1 above this are strata of gypsum1 tenacious clay1 sand1 and limestone1 which crop out at the surface40 8,the perpendicular distance from the lowest to the upper surface of the ,stassfurt salt deposits is about #ejjj feet 7a little less than a mile71 while the horizontal extent of the bed is from the ,harz ,mountains to the ,elbe ,river in one direction1 and from the city of ,madgeburg to the town of ,bernburg in the other40 ,according to ,fuchs and ,de,launy#ah the saline formation near ,stassfurt is situated at the bottom of a vast triassic deposit surrounding ,madgeburg4 ,the quantity of sea water which was evaporated to produce saline deposits of more than #ejj meters in thickness must have been enormous and the rate of evaporation great4 ,it appears that a temperature of #ajj would have been quite necessary1 acting for a long time1 to produce this result4 ,these authors therefore admit that all the theories so far advanced to explain the magnitude of these deposits are attended with certain difficulties4 ,what1 for instance1 could have caused a temperature of #ajj8 ,the most reasonable source of this high temperature must be sought for in the violent chemical action produced by the double decompositions of such vast quantities of salts of different kinds4 ,there may also have been at the bottom of this basin some subterranean heat such as is found in certain localities where boric acid is deposited4 ,whatever be the explanation of the source of the heat it will be admitted that at the end of the permian period there was thrown up to the northeast of the present saline deposits a ridge extending from ,helgoland to ,westphalia4 ,this dam established throughout the whole of ,north ,germany saline lagoons in which evaporation was at once established1 and these lagoons were constantly fed from the sea4 ,there was then deposited by evaporation1 first of all a layer of gypsum and afterwards rock salt1 covering with few exceptions the whole of the area of ,north ,germany4 ,but around ,stassfurt there occurred at this time geologic displacements1 the saline basin was permanently closed and then by continued evaporation the more deliquescent salts1 such as polyhalite1 kieserite1 and carnallite1 were deposited4 ,these theories account with sufficient ease for the deposition of the saline masses1 but do not explain why in those days the sea water was so rich in potash and why potash is not found in other localities where vast quantities of gypsum and common salt have been deposited4 ,it may be that the rocks composing the shores of these lagoons were exceptionally rich in potash and that this salt was1 therefore1 in a certain degree1 a local contribution to the products of concentration4 #ai4 ,sodium is never found free in nature1 but its most common form is in combination with chlorin as common salt1 an important ingredient of sea water4 ,combined with silica sodium is an important element in many silicates4 ,sodium1 although closely related to potassium chemically1 cannot in any case be substituted therefor in plant nutrition4 ,in combination with nitrogen it forms soda or ,chile saltpeter which is a valuable fertilizer on account of its content of nitric acid4 #bj4 ,iron is the most abundant of the heavy metals1 and occurs in nature both free and combined with other elements4 ,in the free state it is found only to a limited extent in basaltic rocks and meteorites1 but in combination with oxygen it is one of the most widely diffused of metals1 and forms the coloring matter of a large number of rocks and minerals4 ,in this form1 too1 it exists as the valuable ores of iron known as magnetite and hematite4 ,in combination with sulfur it forms the mineral pyrite1 ,fe,s4 ,the yellow and red colors of soils are due chiefly to iron oxids4 ,it is an important plant food1 although not taken up in any great quantity by the tissues of plants4 #ba4 ,manganese1 next to iron1 is the most abundant of the heavy metals4 ,it occurs in nature only in combination with oxygen1 in which form it is associated in minute quantities with iron in igneous rocks or in the forms known mineralogically as pyrolusite1 psilomelane and wad4 ,as the peroxid of manganese it occurs in concretionary forms scattered abundantly over the bottom of the deep sea4 ,it is found in the ash of some plants but is not believed to be an essential to plant growth4 #bb4 ,barium occurs in nature combined with sulfuric acid1 forming the mineral barite1 or heavy spar1 or with carbon dioxid forming the mineral witherite4 ,it is of small importance from an agricultural standpoint4 #bc4 ,relative ,abundance of the ,more ,important ,chemical ,elements4--,it will be of interest to the agricultural analyst to know as nearly as possible the relative abundance of the more important chemical elements4 ,this subject has been carefully studied by ,prof4 ,f4 ,w4 ,clarke in a paper read before the ,philosophical ,society of ,washington4#ai ,the materials considered in these calculations are the atmosphere1 the water1 and the solid crust of the earth to the depth of ten miles below the sea level4 ,of these materials the relative quantities of the three constituents named are as follows3 ,per cent4 ,atmosphere #j4jc ,water #g4jh ,solid crust of the earth to the depth of ten miles #ib4hi ,according to these calculations the relative abundance of the important elements composing the atmosphere1 the water of the ocean and the solid crust of the earth to the depth given is as follows3 ,solid crust1 ,ocean1 seven per ,mean1 including ninety-three per cent4 air4 cent4 ,oxygen #dg4bi per cent4 #he4gi per cent4 #di4ih per cent4 ,silicon #bg4ba #be4cj ,aluminum #g4ha #g4bf ,iron #e4df #e4jh ,calcium #c4gg #j4je #c4ea ,magnesium #b4fh #j4ad #b4ej ,sodium #b4cf #a4ad #b4bh ,potassium #b4dj #j4jd #b4bc ,hydrogen #j4ba #aj4fg #j4id ,titanium #j4cc #j4cj ,carbon #j4bb #j4jjb #j4ba ,chlorin #j4ja #b4jg #j4ae ,bromin #j4jjh ,phosphorus #j4aj #j4ji ,manganese #j4jh #j4jg ,sulfur #j4jc #j4ji #j4jd ,barium #j4jc #j4jc ,nitrogen #j4jb ,chromium #j4ja #j4ja ------------ -------------- ------------ #ajj4jj #ajj4jjj #ajj4jj #bd4 ,fluorin is not mentioned in this table but it is stated that its probable percentage is #j4jb to #j4jc making it thus slightly more abundant than nitrogen4 ,one of the chief points of interest in connection with this table is that the nitrogen which is regarded by most persons as one of the most abundant of the elements is almost the least abundant of those mentioned4 ,,the ,,minerals ,,occurring ,,in ,,rocks4 #be4 ,the ,soil1 as before stated1 being comprised almost exclusively of decayed rocks1 its characteristics would naturally be determined by the character of the minerals contained in the rocks4 ,a rock may be composed of a single mineral or an aggregation of several minerals4 ,according to the authority of the ,national ,museum#bj it may occur1 either in the form of stratified beds1 eruptive masses1 sheets or dikes1 or as veins and other chemical deposits of comparatively little importance as regards size and extent4 ,the mineral composition of rocks is greatly simplified by the wide range of conditions under which the commonest minerals can be formed4 ,thus quartz1 feldspar1 mica1 the minerals of the hornblende1 or pyroxene group1 can be formed from a mass cooling from a state of fusion2 they may be crystallized from solution1 or be formed from volatilized products4 ,they are therefore the commonest of minerals and are rarely excluded from rocks of any class1 since there is no process of rock formation which determines their absence4 ,most of the common minerals1 like the feldspars1 micas1 hornblendes1 pyroxenes1 and the alkaline carbonates possess the capacity of adapting themselves to a very considerable range of compositions4 ,in the feldspars1 for example1 lime1 soda1 or potash may replace one another almost indefinitely1 and it is now commonly assumed that true species do not exist1 but all are but isomorphous admixtures passing into one another by all gradations1 and the names albite1 oligoclase1 anorthite1 etc41 are to be used only as indicating convenient stopping and starting points in the series4 ,hornblende or pyroxene1 further1 may be pure silicate of lime and magnesia1 or iron and manganese may partially replace these substances4 ,lime carbonate may be pure1 or magnesia may replace the lime in any proportion4 ,these illustrations are sufficient to show the reason for the great simplicity of rock masses as regards their chief mineral constituents4 ,whatever may be the conditions of the origin of a rock mass1 the probabilities are that it will be formed essentially of one or more of a half a dozen minerals in some of their varieties4 ,but however great the adaptability of these few minerals may be they are1 nevertheless1 subject to very definite laws of chemical equivalence4 ,there are elements which they cannot take into their composition1 and there are circumstances which retard their formation while other minerals may be crystallizing4 ,in a mass of rock of more or less accidental composition formed under these widely varying conditions it may1 therefore1 be expected that other minerals will form1 in considerable numbers1 but minute quantities4 ,it is customary to speak of those minerals which form the chief ingredients of any rock1 and which may be regarded as characteristic of any particular variety1 as the essential constituents1 while those which occur in but small quantities1 and whose presence or absence does not fundamentally affect its character1 are called accessory constituents4 ,the accessory mineral which predominates1 and which is1 as a rule1 present in such quantities as to be recognizable by the unaided eye1 is the characterizing accessory4 ,thus a biotite granite is a stone composed of the essential minerals quartz and potash feldspar1 but in which the accessory mineral biotite occurs in such quantities as to give a definite character to the rock4 #bf4 ,classification ,of ,minerals4--,the minerals of rocks may also be conveniently divided into two groups1 according as they are products of the first consolidation of the mass or of subsequent changes4 ,this is the system here adopted4 ,we thus have3 7#a7 ,the original or primary constituents1 those which formed upon its first consolidation4 ,all the essential constituents are original1 but on the other hand all the original constituents are not essential4 ,thus1 in granite1 quartz and orthoclase are both original and essential1 while beryl and zircon or apatite1 though original1 are not essential4 7#b7 ,the secondary constituents are those which result from changes in a rock subsequent to its first consolidation1 changes which are due in great part to the chemical action of percolating water4 ,such are the calcite1 chalcedony1 quartz1 and zeolite deposits which form in the druses and amygdaloidal cavities1 of traps and other rocks4 ,below is given a list of the more common1 original and secondary minerals occurring in rocks4 ,it will be observed that the same mineral may1 in certain cases1 occur in both original and secondary forms4 ,the tables following were prepared by ,dr4 ,george ,p4 ,merrill4 ,,original ,,minerals4 #a4 ,quartz1 ,si,o4 #b4 ,the ,feldspars3 #b;a4 ,orthoclase4 ,anhydrous silicate of alumina with varying amounts of lime1 potash1 or soda and rarely barium4 #b;b4 ,microcline4 #b;c4 ,albite4 #b;d4 ,oligoclase4 #b;e4 ,andesite4 #b;f4 ,labradorite4 #b;g4 ,bytownite4 #b;h4 ,anorthite4 #c4 ,the ,amphiboles3 #c;a4 ,hornblende4 ,anhydrous silicates of lime and magnesia with iron and alumina in the dark varieties4 #c;b4 ,tremolite4 #c;c4 ,actinolite4 #c;d4 ,arfvedsonite4 #c;e4 ,glaucophane4 #c;f4 ,smaragdite4 #d4 ,the ,monoclinic ,pyroxenes3 #d;a4 ,malacolite4 ,anhydrous silicates of magnesia and lime with alumina and iron in the dark varieties4 #d;b4 ,diallage4 #d;c4 ,augite4 #d;d4 ,acmite4 #d;c4 ,aegerite4 #e4 ,the ,rhombic ,pyroxenes3 #e;a4 ,enstatite 7bronzite74 ,silicates of magnesia and iron4 #e;b4 ,hypersthene4 #f4 ,the ,micas3 #f;a4 ,muscovite4 ,anhydrous silicates of alumina with potash1 soda1 and iron4 #f;b4 ,biotite4 #f;c4 ,phlogopite4 #g4 ,calcite1 #h4 ,dolomite4 #i4 ,gypsum4 #aj4 ,olivine4 #aa4 ,beryl4 #ab4 ,tourmaline4 #ac4 ,garnet1 variable common form4 #ad4 ,vesuvianite4 #ae4 ,epidote4 #af4 ,zoisite4 #ag4 ,allanite4 #ah4 ,andalusite4 #ai4 ,staurolite4 #bj4 ,fibrolite4 #ba4 ,cyanite4 #bb4 ,scapolite4 #bc4 ,apatite4 #bd4 ,elaeolite and ,nepheline4 #be4 ,leucite4 #bf4 ,cancrinite4 #bg4 ,the ,sodalite ,group3 #bg;a4 ,sodalite4 #bg;b4 ,hayn 7noseau74 #bh4 ,zircon4 #bi4 ,chondrodite4 #cj4 ,cordierite4 #ca4 ,topaz4 #cb4 ,corundum4 #cc4 ,titanite 7sphene74 #cd4 ,rutile4 #ce4 ,menaccanite4 #cf4 ,magnetite4 #cg4 ,hematite4 #ch4 ,chromite4 #ci4 ,the ,spinels3 #ci;a4 ,pleonast4 #ci;b4 ,picotite4 #dj4 ,pyrolusite4 #da4 ,halite 7common salt74 #db4 ,fluorite4 #dc4 ,the ,elements3 #dc;a4 ,graphite4 #dc;b4 ,carbon4 #dc;c4 ,iron4 #dc;d4 ,copper4 #dd4 ,the ,metallic ,sulfids3 #dd;a4 ,galena4 #dd;b4 ,sphalerite4 #dd;c4 ,pyrrhotite4 #dd;d4 ,marcasite4 #dd;e4 ,pyrite4 #dd;f4 ,chalcopyrite4 #dd;g4 ,arsenopyrite4 ,,secondary ,,minerals4 #a4 ,quartz3 #a;a4 ,chalcedony4 #a;b4 ,opal4 #a;c4 ,tridymite4 #b4 ,albite4 #c4 ,the ,amphibole ,group3 #c;a4 ,hornblende4 #c;b4 ,tremolite4 #c;c4 ,actinolite4 #c;d4 ,uralite4 #d4 ,muscovite 7sericite74 #e4 ,the ,chlorites3 #e;a4 ,jefferisite4 #e;b4 ,ripidolite4 #e;c4 ,penninite4 #e;d4 ,prochlorite4 #f4 ,calcite 7and aragonite74 #g4 ,wollastonite4 #h4 ,scapolite4 #i4 ,garnet4 #aj4 ,epidote4 #aa4 ,zoisite4 #ab4 ,serpentine4 #ac4 ,talc4 #ad4 ,kaolin4 #ae4 ,the ,zeolites3 #ae;a4 ,pectolite4 #ae;b4 ,laumontite4 #ae;c4 ,prehnite4 #ae;d4 ,thomsonite4 #ae;e4 ,natrolite4 #ae;f4 ,analcite4 #ae;g4 ,datolite4 #ae;h4 ,chabazite4 #ae;i4 ,stilbite1 #aek4 ,heulandite4 #ael4 ,harmotome4 #af4 ,magnetite4 #ag4 ,hematite4 #ah4 ,limonite4 #ai4 ,siderite4 #bj4 ,pyrite4 #ba4 ,pyrrhotite4 ,,rocks ,,and ,,rock ,,decay4 #bg4 ,types ,of ,rocks4--,rocks may be divided in reference to their structure into four types3 ,first1 crystalline2 second1 vitreous2 third1 colloidal2 fourth1 fragmental4 ,of these classes there may be selected1 as types of the first order1 granite and crystalline limestone4 ,the second class is typically represented by obsidian4 ,rocks of this kind are confined to a volcanic origin4 ,the third class of rocks is completely amorphous in its structure and is less common than the others4 ,it is found only in rocks of chemical origin4 ,types of this class are the siliceous sinters1 opals1 flint nodules1 and many serpentines4 ,of the fourth class of rocks1 sandstone is typical1 being comprised wholly of fragments of rocks pre-existing4 ,the particles may be held together either by cohesion or by a cement composed of silica1 iron oxids1 carbonate of lime or clayey matter4 #bh4 ,the ,microscopical ,structure of ,rocks4--,a great deal more light is thrown upon the nature of rock materials by microscopical study than by their study in bulk4 ,the requisites for a microscopical study of rock are that the material should be cut into extremely thin laminae with parallel sides and polished so as to transmit the light freely4 ,the study of the crystalline structure of the material is then conducted by means of a microscope furnished with polarizing and analyzing appliances4 ,the light before passing through the mineral film is polarized by a ,nicol prism4 ,after passing through the film it is analyzed by a second ,nicol prism4 ,in this way the crystalline structure of the rock as affecting polarized light is distinctly brought out4 ,the thickness of the films examined should be from to of an inch4 ,illustration3 ,,fig4 #a4 ,microstructure of granite4 ,,fig4 #b4 ,microstructure of micropegmatite4 ,,fig4 #c4 ,microstructure of quartz porphyry4 ,,fig4 #d4 ,microstructure of porphyritic obsidian4 ,,fig4 #e4 ,microstructure of trachyte4 ,,fig4 #f4 ,microstructure of serpentine4 ,the method of rock study by thin microscopic sections is one of comparatively recent origin4 ,it is scarcely more than a dozen years since the process was fairly adopted by mineralogists4 ,the value of the method is based upon the fact that every crystalline mineral has certain definite optical properties4 ,therefore1 when a crystalline mineral is distorted or misshapen so as to be incapable of identification by the ordinary method1 it can be at once identified by its optical examination in the manner just described4 ,in this way not only can one mineral be distinguished from another1 but the crystalline system to which it belongs can be accurately pointed out4 ,the value of the method is well summed up by ,merrill1#ba who says that it is not merely an aid in determining the mineralogical composition of a rock1 but also1 which is often much more important1 its structure and the various changes which have taken place in it since its first consolidation4 ,rocks are not the definite and unchangeable mineral compounds they were once considered1 but are rather ever varying aggregates of minerals which even in themselves undergo structural and chemical changes almost without number4 ,another valuable result of such a study is illustrated by the discovery that the structural features of a rock are not dependent upon its chemical composition or geologic age1 but upon the conditions under which it cooled from the molten magma4 ,portions of the same rock may vary all the way from a wholly crystalline to a pure vitreous form4 ,some typical microstructures of crystalline rocks are shown in the accompanying figures #a-f4bb ,although this method of study has thus far been confined mainly to crystalline rocks1 its efficiency is by no means limited to them4 ,the fragmental rocks and their decomposed dbris to which the name soil is given are equally worthy of study by this method4 ,indeed1 the full value of a chemical analysis of any rock or soil can not be ascertained unless such an analysis is accompanied by a microscopic examination4 ,it is desirable to know not merely what there is in any soil1 but in what form these compounds exist4 ,to this latter question the chemical analysis as ordinarily made will give no clew4 ,in ,germany a beginning has been made in this line of work1 and ,american scientists are beginning to realize its importance4 ,an outline of this method of analysis will be given in the proper place4 #bi4 ,specific ,gravity4--,much information in regard to the properties of a rock1 or mineral constituent thereof1 may be derived from its specific gravity4 ,the internal structure of a rock may have much to do with its apparent specific gravity4 ,as an instance of this1 it may be stated that an obsidian pumice will float upon water1 buoyed up by the air contained in its vesicles1 while a compact obsidian of the same composition will sink immediately4 ,a careful discrimination must1 therefore1 be made between apparent and true specific gravity4 ,in general it may be said that crystalline rocks have a higher specific gravity than those of a vitreous nature4 ,the specific gravity is1 therefore1 largely dependent upon chemical and crystallographic properties2 for instance1 among siliceous rocks those which contain the largest amount of silica are the lightest1 while those with a comparatively small amount1 but rich in iron1 lime1 and magnesia1 are heaviest4 #cj4 ,chemical ,composition of ,rocks4--,rocks are often classified with respect to the chief mineral constituent which they contain4 ,rocks which are composed largely of lime are termed calcareous2 of silica1 siliceous2 of iron1 ferruginous2 and of clay1 argillaceous4 ,in respect of eruptive rocks1 it is customary to speak of those which show above sixty per cent of silica as acidic1 while those containing less than fifty per cent of silica and a correspondingly larger amount of iron1 lime1 and magnesia1 are spoken of as basic4 ,illustrations of the classification of rocks on the above principles are given below4#bc ,,stratified ,,rocks4 ,kind4 ,specific ,composition4 ,gravity4 ,calcareous3 ,compact limestone #b4f to #b4h ,carbonate of lime4 ,crystalline limestone ,compact dolomite #b4h to #b4ie ,carbonate of lime and magnesia4 ,crystalline dolomite ,siliceous3 ,gneiss #b4f to #b4g ,same as granite4 ,siliceous sandstone #b4f ,mainly silica4 ,schist #b4f to #b4h #fj to #hj per cent silica4 ,argillaceous3 ,clay slate 7argillite7 #b4e ,mainly silicate of alumina4 ,,eruptive ,,rocks4 ,specific ,per cent silica4 ,gravity4 ,acidic ,group3 ,granite #b4eh to #b4gc #gg4fe to #fb4ij ,liparite #b4ec to #b4gj #gf4jf to #fg4fa ,obsidian #b4bf to #b4da #hb4hj to #ga4ai ,obsidian pumice ,floats on #hb4hj to #ga4ai water4 ,intermediate ,group3 ,syenite #b4gc to #b4hf #gb4bj to #ed4fe ,trachyte #b4gj to #b4hj #fd4jj to #fj4jj ,hyalotrachyte #b4d to #b4e #fd4jj to #fj4jj ,andesite #b4ed to #b4gi #ff4ge to #ed4gc ,basic ,group3 ,diabase #b4ff to #b4hh #ej4jj to #dh4jj ,basalt #b4ij to #c4aj #ej4ei to #dj4gd ,peridotite #c4bb to #c4bi #db4fe to #cc4gc ,peridotite 7iron rich7 #c4hf #bc4jj ,peridotite 7meteorite7 #c4ea #cg4gj #ca4 ,color ,of ,rocks4--,the color of rocks is determined chiefly by the oxids of metals which they contain and the degree of oxidation of the mineral in each particular case4 ,there are1 however1 many colors of rocks which seem to depend not upon any particular mineral ingredient which they contain1 but upon some particular crystalline structure or physical condition4 ,the chief coloring matters in minerals are those which form colored bases such as iron1 manganese1 chromium1 etc4 ,the yellow1 brown1 and red colors1 common to fragmental rocks1 are due almost wholly to free oxids of iron4 ,the gray1 green1 dull brown1 and even black colors of crystalline rocks are due to the presence of free iron oxids or to the prevalence of silicate mineral rich in iron1 as augite1 hornblende1 or black mica4 ,rarely copper and other metallic oxids than those of iron are present in sufficient abundance to impart their characteristic hues4 ,as a rule1 a white or light-gray color denotes an absence of an appreciable amount of iron in any of its forms4 ,the bluish and black colors of many rocks1 particularly the limestones and slates1 are due to the presence of carbonaceous matter4 ,in still other cases1 and particularly the feldspar-bearing rocks1 the color may be due in part to the physical condition of the feldspar4 ,inasmuch as the color of rocks is due so largely to metallic oxids1 it is easy to see that they may undergo changes when exposed to weathering1 or the degree of oxidation may change1 and either1 together with changes in the physical structure of the rock1 may cause a distinct change in color4 ,luster is often considered in connection with color1 and is due almost exclusively to physical conditions4 #cb4 ,kinds of ,rocks4--,the rocks which form any essential part of the earth's crust are grouped under four main heads1 the distinction being based upon their origin and structure4#bd ,each of the main divisions may be subdivided into groups or families1 the distinction being based mainly upon chemical composition1 structure1 and mode of occurrence4 ,the four chief families are3 ,first1 aqueous rocks1 formed mainly through the agency of water as chemical precipitates or as sedimentary beds4 ,second1 aeolian rocks formed from wind-drifted materials4 ,third1 metamorphic rocks1 changed from their original condition through dynamic or chemical agencies1 and which may have been partly of aqueous and partly of igneous origin4 ,fourth1 igneous or eruptive rocks1 which have been brought up from below in a molten condition1 and which owe their present structural peculiarities to variations in composition and conditions of solidification4 #cc4 ,aqueous ,rocks4--,aqueous rocks may be divided into the following general classes3 ,first1 rocks formed as chemical precipitates4 ,second1 rocks formed as sedimentary deposits and fragmental in structure4 ,the second class may again be subdivided into rocks formed by mechanical agencies and mainly of inorganic materials2 and second1 rocks composed mainly of the dbris of plant and animal life4 ,in regard to the first form of aqueous rocks1 namely1 those formed as chemical precipitates1 it may be said that while their quantity is not large they are yet of considerable importance from an agricultural point of view4 ,they embrace those substances which1 having once been in a condition of vapor or aqueous solution1 have been deposited or precipitated1 either by cooling or by the evaporation of the liquor holding them in solution1 or by coming in contact with chemical substances capable of precipitating them4 ,the influence of water as a solvent is perhaps not fully appreciated4 ,its solvent influence will be noted particularly under the head of weathering or decay of rocks4 ,its importance1 however1 in producing stratified rocks has been very great4 ,water1 especially when under great pressure and at a high temperature1 has the power of dissolving many minerals4 ,this power is often greatly increased by the mineral matter previously in solution in the water or by the gases which it may contain4 ,as an illustration of the latter property1 the solvent action of water charged with carbon dioxid on limestone may be cited4 ,when mineral matters have been dissolved by the water in the ways mentioned and carried with the water beyond the condition where the solution has taken place1 new conditions are found favorable to the precipitation of the dissolved matters4 ,the water1 which before may have been very hot1 may reach a place where it cools1 and being a supersaturated solution1 the excess of the material is thrown down as the water cools4 ,on the other hand1 if the solution be due to the presence of carbon dioxid and the water reach a place where it is exposed to the air or where the pressure under which the abundance of the gas has been due is diminished1 the carbon dioxid will escape and the mineral matters which have been dissolved thereby will be precipitated4 ,the incrustations which often appear round the mouth of springs and the occurrence of stalagmites and stalactites in caves are illustrations of this action4 ,in respect of the formation of rocks as precipitates from a state of vapor we have scarcely any illustrations excepting in volcanic regions4 ,rocky materials with which we are generally acquainted are practically non-volatile at the highest temperature which can be secured on the earth's surface1 but it is possible that in the interior of the earth the temperature may be so high as to maintain many substances in a state of vapor4 ,they may1 in this case1 become disassociated so that the compounds or elements exist distinctly in a vaporous condition4 ,such a vapor transported to regions of diminished temperature would first of all on cooling permit a union of the chemical elements forming new compounds less volatile1 which1 of course1 would be at once precipitated4 ,the rocks and minerals formed in this way which are of some agricultural importance may be classified as follows3 ,oxids1 carbonates1 silicates1 sulfur1 sulfids1 sulfates1 phosphates1 chlorids1 and hydrocarbon compounds1 the most important from an agricultural point of view being the phosphates4 ,the second group of rocks1 namely those formed as sedimentary deposits1 differ from those just described in that they are comprised mainly of fragmental materials derived from the breaking down of pre-existing rocks4 ,the formation of fragmental rocks includes1 therefore1 the same processes as are active in the formation of arable soil4 ,they are deposited from water1 and are as a rule distinctly stratified4 ,through the action of pressure and the heat thereby generated1 or simply through the chemical action of percolating solutions1 such rocks pass over into the crystalline sedimentary forms known as metamorphic4 ,all metamorphic rocks1 however1 are not of a sedimentary origin4 ,for instance1 by pressure1 heat1 and the chemical changes thereby induced1 granite may be changed into gneiss and the latter would then be a metamorphic rock4 ,this group of sedimentary rocks and of sedimentary material1 either unchanged or metamorphosed1 is of vast extent and includes materials of widely varying chemical and mineralogical nature4 ,they form by far the greater portion of the present surface of the earth1 even the mountain ranges being composed mainly of this sedimentary material4 ,indeed1 in the whole of this country there is only a comparatively very small extent of igneous or irruptive rocks4 ,they are of great importance from a purely scientific1 as well as agricultural standpoint1 since they contain the fossil records of past geologic ages4 ,from them it is possible to study the variations in climate1 the meteorological conditions in circumstances and periods far remote1 and thus form some idea of the process by which the crust of the earth has been modified by natural forces from its original form to the present time4 ,the sedimentary rocks may be divided1 with sufficient accuracy for our purposes1 into two great classes3 ,first1 rocks formed by mechanical agencies and mainly of inorganic materials4 ,these are subdivided again as follows3 7a7 ,the arenaceous group4 7b7 ,the argillaceous group4 7c7 ,the volcanic group4 ,the second class of sedimentary rocks is formed largely1 or in part at least1 by mechanical agencies1 but is comprised chiefly of the dbris of plant and animal life4 ,it may be subdivided as follows3 7a7 ,the siliceous group1 such as infusorial earth4 7b7 ,the calcareous group1 fossiliferous formations1 limestone1 etc4 7c7 ,the carbonaceous group1 such as peat1 lignite1 coals1 etc4 ,the different classes of rock described above are distinguished by special qualities represented largely by the name4 ,the first division1 the arenaceous group1 is composed mainly of the siliceous or coarsely granular materials derived from the disintegration of older crystalline rocks1 which have been rearranged in beds of varying thickness through the mechanical agency of water4 ,they are1 in short1 consolidated or unconsolidated beds of sand and gravel4 ,in composition and texture they vary almost indefinitely4 ,many of them having suffered little during the process of disintegration and transportation are composed essentially of the same materials as the rocks from which they were derived4 ,the sandstones1 which are the type of these rocks1 vary greatly in structure as well as in composition1 in some the grains being rounded while in others they are sharply angular4 ,the microscopic structure of sandstone is shown in figure #g4bd ,the material by which the individual grains of a sandstone are bound together is usually the material of some of the other classes4 ,the calcareous1 ferruginous1 and siliceous cements being the chief ones4 ,this cementing substance is deposited among the granules forming the sandstone by percolating water4 ,the colors of sandstone are dependent usually upon iron oxids4 ,especially is this true of the red1 brown1 and yellow colors4 ,in some of the light grey varieties1 the color is that of the minerals comprising the stone4 ,some of the darker colored sandstones contain organic matter4 ,illustration3 ,,fig4 #g4 ,microscopic ,structure of ,sandstone4 ,the rocks of the argillaceous group are composed essentially of a hydrous silicate of alumina1 which is the basis of common clay1 and varying amounts of free silica1 oxids of iron and manganese1 carbonates of lime and magnesia1 and small quantities of organic matter4 ,they may have originated in situ from the decomposition of feldspars or as deposits of fine mud or silt at the bottom of large bodies of water4 ,the older formations of these rocks are known as shales1 argillites1 and slates and the fissile structure which enables this to be split into thin sheets is probably due to the conditions under which they have been formed and not to any properties of the clays themselves4 ,one of the purest forms of this rock is kaolin1 which is almost a pure hydrous silicate of alumina formed from the decomposition of feldspathic rocks from which the alkalies1 iron oxids and other soluble constituents have been removed by water4 ,under the volcanic group are included the materials ejected from volcanic vents in a more or less finely comminuted condition and which through the drifting power of atmospheric currents may be scattered over many miles of territory4 ,various names are applied to such products1 names dependent in large part upon their state of subdivision4 ,volcanic dust and sand1 or ashes1 includes the finer dust-like or sand-like materials1 and lapilli1 or rapilli the coarser4 ,the general name tuff includes the more or less compacted and stratified beds of this material1 while trass1 peperino1 and pozzuolano are local varietal names given to similar materials occurring in ,european volcanic regions4 ,the second division1 namely sedimentary rocks composed of the dbris of plant and animal life includes many forms of great agricultural importance4 ,the first subdivision of this group is the infusorial or diatomaceous earth4 ,it forms a fine white or yellowish pulverulent rock composed mainly of minute shells1 or tests of diatoms1 and is often so soft and pliable as to crumble readily between the thumb and fingers4 ,according to ,whitney the beds are of comparatively limited extent and for this reason are of little agricultural value1 although the weathering of this diatomaceous material gives rise to a light yellow clay forming very fertile agricultural lands4 ,the second subdivision of this group includes the rocks of a calcareous nature derived from animal life2 that is to say1 what are properly called limestones4 ,they vary in color1 structure1 and texture almost indefinitely1 and include all possible grades of materials from those which can be used only as a flux1 or for lime burning1 through ordinary building materials to the finest marbles4 ,these rocks are world-wide in their distribution and limited to no one particular geologic horizon1 but are found in stratified beds among rocks of all ages from the most ancient to the most recent4 ,owing to the fact that their chief constituent1 carbonate of lime1 is soluble in ordinary meteoric waters1 the rocks have undergone extensive decomposition1 their lime being removed1 while their less soluble constituents or impurities remain to form soil4 ,a single ton of residual soil represents not infrequently a loss of #ajj tons of original rock matter4 ,as this mass of lime carbonate is removed by solution the residual soil settles1 and as the limestone rocks are more soluble than the adjacent rock formations limestone formations usually form valley lands with ridges on either side4 ,caves are frequently found in such formations4 ,furthermore1 as the lime is almost all in the form of the easily soluble lime carbonate it can be very completely removed and the fertile 8limestone soils0 are often very deficient in lime and respond readily to an application of burnt lime1 which1 not infrequently1 is quarried from the same field4 ,from an agricultural standpoint this group is of very great interest and importance4 ,the third subdivision of this group1 namely1 that of vegetable origin1 includes peat1 lignite1 coals1 etc4 ,rocks of this group are made up of more or less fragmental remains of plants4 ,in many of them1 as the peats and lignites1 the traces of plant structure are still apparent4 ,in others1 as the anthracite coals1 these structures have been wholly obliterated by metamorphisms4 ,plants when decomposing on the surface of the ground give off their carbon to the atmosphere in the shape of carbon dioxid gas leaving only the strictly inorganic or mineral matter behind4 ,when1 however1 they are protected from the oxidizing influence of the air1 by water or by other plant growth1 decomposition is greatly retarded1 and a large portion of the carbonaceous and volatile matters is retained1 and by this means together with pressure from the overlying mass1 the material becomes slowly converted into coal4 ,when this process goes on near the surface of the earth1 and without much pressure1 peat or muck is the product4 ,the fourth subdivision of this group1 the phosphatic1 forms a class of rocks limited in extent but of the greatest economic importance4 ,guano1 coprolites1 and phosphatic rocks 7the phosphorites7 come under this head4 #cd4 ,aeolian ,rocks4--,this class of rocks is of less importance than the others1 either geologically or agriculturally4 ,it is formed from materials drifted by the winds and this material has various degrees of compactness4 ,usually the components of these drifts form rocks or deposits of a friable texture and of a fragmental nature4 ,the very extensive deposits of loess in ,china1 forming their most fertile lands1 are admitted now to have been formed in this way1 but it is now generally admitted that similar deposits in this country are of subaqueous origin4 ,chief among these rocks1 are the volcanic ashes which are often carried to a long distance by the wind before they are deposited and consolidated into rock masses4 ,many loose soils may be carried to great distances by the wind1 the deposits forming new aggregates4 ,this is particularly the case in arid regions4 #ce4 ,metamorphic ,rocks4--,this class of rocks includes all sedimentary or eruptive rocks1 which1 after their deposition and agglomeration1 have been changed in their nature through the action of heat1 pressure1 or by chemical means4 ,sometimes these changes are so complete that no indication of the character of the original rocks remains4 ,at other times the changes may be found in all the stages of progress1 so that they can be traced from the original fragmental or irruptive to the completely metamorphosed deposit4 ,this is especially true of rocks containing large quantities of lime4 ,in those containing silica1 the changes are less readily traced4 ,illustration3 ,,fig4 #h4 ,,microstructure ,,of ,,crystalline ,,limestone4 7,west ,rutland1 ,vermont47 ,the metamorphic rocks may be divided into two subclasses1 namely1 stratified or bedded1 and foliated or schistose4 ,the rocks of the first class are represented by the crystalline limestones and dolomites4 ,the microstructure of a crystalline limestone is shown in ,fig4 #h4be ,when lime and magnesia occur together in combination with carbon dioxid1 the substance is known as dolomite4 ,the chemical nature of these rocks and their soil-forming properties are the same as those of the ordinary1 non-metamorphosed limestones and dolomites to which reference has already been made4 ,the subject need not1 therefore1 be further dwelt upon here4 ,illustration3 ,,fig4 #i4 ,,microstructure ,,of ,,gneiss4 7,west ,andover1 ,massachusetts47 ,at a a are shown plagioclase crystals broken and rounded by the sheering force producing the foliation4 ,the second variety of metamorphic rocks is represented by the gneisses and crystalline schists4 ,gneiss has essentially the same composition as granite and can frequently hardly be distinguished from it1 except by a microscopic study of its sections1 and even thus it is sometimes difficult to determine4 ,frequently a number of new minerals is formed in the metamorphic changes4 ,the microstructure of a gneiss is shown in ,fig4 #i4bf ,the schists include an extremely variable class of rocks1 of which quartz is the prevailing constituent1 and which1 as a rule1 are deficient in potash and other important ingredients4 #cf4 ,rocks ,formed ,through ,igneous ,agencies1 or ,eruptive ,rocks4--,this group includes all those rocks1 which1 having been at some time in a state of igneous fusion1 have been solidified into their present form by a process of cooling4 ,it may be stated1 as a general principle1 that the greater the pressure under which a rock solidifies and the slower and more gradual the cooling the more perfect will be found the crystalline structure4 ,hence1 it follows that the older and more deep-seated rocks which are forced up in the form of dikes1 bosses1 or intrusive sheets1 into the overlying masses1 and which have become exposed only through erosion and removal of the overlying rocks1 are the more highly crystalline4 ,the eruptive rocks are divided into two main groups1 viz43 7a7 ,intrusive or plutonic rocks1 and 7b7 ,effusive or volcanic rocks4 ,among the more important of the first division of the plutonic form1 from an agricultural point of view1 are the granites4 ,the essential constituents of granite are quartz1 potash feldspar1 and plagioclase4 ,one or more minerals of the mica1 amphibole or pyroxene groups are also commonly present1 and in microscopic proportions apatite and particles of magnetic iron4 ,the more valuable constituents1 from an agricultural standpoint1 are the minerals potash feldspar1 and apatite1 which furnish by their decomposition the essential potash and phosphoric acid4 ,in addition to the granites1 which have already been mentioned1 the group includes the syenites1 the nepheline syenites1 the diorites1 the gabbros1 the diabases1 the theralites1 the peridotites1 and the pyroxenites4 ,the second group1 the effusive or volcanic rocks1 includes those igneous rocks1 which1 like the first group1 have been forced up through the overlying rocks1 but which were brought to the surface1 flowing out as lavas4 ,these1 therefore1 represent1 in many cases1 only the upper or surface portions of the first group1 differing from them structurally1 because they have cooled under little pressure more rapidly1 and hence are not so distinctly crystalline4 ,these comprise the following groups3 7a7 ,quartz porphyries4 7b7 ,liparites4 7c7 ,quartz-free porphyries4 7d7 ,trachytes4 7e7 ,phonolites4 7f7 ,porphyrites4 7g7 ,andesites4 7h7 ,melaphyrs and augite porphyrites4 7i7 ,basalts4 7j7 ,tephrites and ,basanites4 7k7 ,picrite porphyrites4 7l7 ,limburgites and augitites4 7m7 ,leucite rocks4 7n7 ,nepheline rocks4 7o7 ,melilite rocks4 ,it is1 in most cases1 impossible to state which of the above classes is of most importance from an agricultural standpoint1 since1 in the process of soil formation1 both chemical and physical processes are involved1 whereby the character of the resultant soil is so modified as to but remotely resemble its parent rock4 ,in most soils1 the prevailing constituent is but the least soluble one of the rock mass from which it was derived4 ,thus a limestone soil may contain upwards of ninety per cent of silica and alumina1 while the original limestone itself may not have carried more than one or two per cent of these substances4 ,of course1 if a rock mass contains none of the constituents essential to plant growth1 its resultant soil must by itself alone be quite barren4 ,it does not absolutely follow1 however1 that those rocks containing the highest percentages of valuable constituents will yield the most fertile soils1 since much depends on the manner in which they have been formed1 the amount of leaching1 etc41 they may have undergone4 ,nevertheless1 the study of the composition of the rocks in their relation to soils1 is an extremely interesting and by no means unimportant one4 ,a comparative table of rock compositions is here given4 ,it will be observed that there is a considerable range of variation even among rocks of the same class1 a fact due to the varying abundance of their mineral constituents4 ,the figures given are not those of actual analyses on any one particular rock1 but are selected from a number of comparatively typical cases2 and1 it is thought1 fairly well represent the composition of the class of rocks indicated4 ,,composition ,,of ,,rocks4--,,the ,,figures ,,indicate ,,parts ,,per ,,hundred4 ,si,o4 ,al,o4 ,fe,o4 ,mg,o4 ,fe,o4 ,granite ,quartz poryhyries #fc-gh #aj-ae #b-c #j4c-j4e ,liparite ,syenite ,orthoclase porphyries #ee-gc #ab-af #e-g #b-f ,trachyte ,nepheline syenites #ed-ef #af-bb #d-f #j4d-j4hh ,phonolites ,diorites ,porphyrites #eb-fe #af-bj #g-aj #e-g ,andesites ,gabbros ,norites #dh-ee #ab-bj #h-ae #b-g ,melaphyrs ,theralites ,tephrites #dc-dg #ae-bc #i-ah #a-f ,basanites ,peridotites ,picrite porphyrites #bc-dc #a-aj #aj-ae #ae-de ,limburgites ,pyroxenites #ej-ee #j4e-d #d-aj #bj-be ,augitites ,leucite rocks #dh-ej #ae-bj #g-aj #a-b ,nepheline rocks #dj-de #h-bj #aj-bj #a-ac ,ca,o4 ,na,o4 ,k,o4 ,p,o4 ,granite ,quartz poryhyries #a-b #b-c #d-e #j4je-j4ae ,liparite ,syenite ,orthoclase porphyries #c-e #b-f #d-g trace4 ,trachyte ,nepheline syenites #b-d #c-g #d-f #j4ae ,phonolites ,diorites ,porphyrites #e-g #b-d #a-b #j4a-j4c ,andesites ,gabbros ,norites #f-aj #b-d #j4e-b #j4a-j4cc ,melaphyrs ,theralites ,tephrites #f-aj #e-g #b-d trace4 ,basanites ,peridotites ,picrite porphyrites #a-d #j-d trace4 #j4j ,limburgites ,pyroxenites #h-ae ,augitites ,leucite rocks #e-aj #c-e #e-g #j4e-b ,nepheline rocks #d-aj #d-h #a-c #j4b #cg4 ,origin of ,soils4--,the soils in which crops grow and which form the subject of the analytical processes to be hereinafter described have been formed under the combined influences of rock decay and plant and organic growth4 ,the mineral matters of soils have had their origin in the decay of rocks1 while the humic and other organic constituents have been derived from living bodies4 ,it is not the object of this treatise to discuss in detail the processes of soil formation1 but only to give such general outlines as may bear particularly on the proper conceptions of the principles of soil investigation4 #ch4 ,the ,decay of ,rocks4--,the origin and composition of rocks are fully set forth in works on geology and mineralogy4 ,only a brief summary of those points of interest to agriculture has been given in the preceding pages4 ,the soil analyst should be acquainted with these principles1 but for practical purposes he has only to understand the chief factors active in securing the decay of rocks and in preparing the dbris for plant growth4 ,the following outline is based on the generally accepted theories respecting the formation of soils4#g ,the forces ordinarily concerned in the decay of rocks are3 #a4 ,changes of temperature1 including the ordinary daily and monthly changes1 and the conditions of freezing and thawing4 #b4 ,moving water or ice4 #c4 ,chemical action of water and air4 #d4 ,influence of vegetable and animal life3 7a7 ,shades the rock or soil surface4 7b7 ,penetrates the rock or soil material with its roots1 thus admitting air4 7c7 ,solvent action of roots4 7d7 ,chemical action of decaying organic matter4 #e4 ,earth worms4 #f4 ,bacteria4 #ci4 ,the ,action of ,freezing and ,thawing4--,in those parts of a rock stratum exposed near the surface of the earth the processes of freezing and thawing have perhaps had considerable influence in rock decay4 ,the expansive force of freezing water is well known4 ,ice occupies a larger volume than the water from which it was formed4 ,the force with which this expansion takes place is almost irresistible4 ,the phenomenon of bursted water pipes which have been exposed to a freezing temperature is not an uncommon one4 ,while the increase in volume is not large1 yet it is entirely sufficient to produce serious results4 ,the way in which freezing affects exposed rock is easily understood4 ,the effect is unnoticeable if the rock be dry4 ,if1 on the other hand1 it be saturated with water1 the disintegrating effect of a freeze must be of considerable magnitude4 ,this effect becomes more pronounced if the intervals of freezing and thawing be of short duration4 ,the whole affected portion of the rock may thus become thoroughly decayed4 ,but even in the most favorable conditions this form of disintegration must be confined to a thin superficial area4 ,even in very cold climates the frost only penetrates a few feet below the surface1 and therefore the action of ice cannot in any way be connected with those changes at great depths1 to which attention has already been called4 ,nevertheless1 certain building stones seem very sensitive to this sort of weathering1 and the crumbling of the stone in the ,houses of ,parliament is due chiefly to this cause4 ,on the whole it appears that the action of ice in producing rock decay has been somewhat overrated1 although its power must not by any means be denied4 ,but on the other hand a freeze extending over a long time tends to preserve the rocks1 and it therefore appears that the entire absence of frost would promote the process of rock decay4 ,at best it must be admitted that frost has affected the earth's crust only to an insignificant depth1 but its influence in modifying the arable part of the soil is of the utmost importance to agriculture4 #dj4 ,the ,action of ,glaciers4--,the action of ice in soil formation is not confined alone to the processes just described4 ,at a period not very remote geologically1 a great part of our ,northern ,states was covered with a vast field of moving ice4 ,these seas of ice crept down upon us from more northern latitudes and swept before them every vestige of animal and vegetable life4 ,in their movement they leveled and destroyed the crests of hills and filled the valleys with the dbris4 ,they crushed and comminuted the strata of rocks which opposed their flow and carried huge boulders of granite hundreds of miles from their homes4 ,on melting they left vast moraines of rocks and pebbles which will mark for all time the termini of these empires of ice4 ,when the ice of these vast glaciers finally melted the surface which they had leveled presented the appearance of an extended plain4 ,no estimate can be made of the enormous quantities of rock material which were ground to finest powder by these glaciers4 ,this rock powder forms to-day no inconsiderable part of those fertile soils which are composed of glacial drift4 ,the rich materials of these soils probably bear a more intimate relation to the rocks from which they were formed than of any other kinds of soil in the world4 ,the rocks were literally ground into a fine powder1 and this powder was intimately mixed with the soils which had already been formed in situ4 ,the melting ice also left exposed to disintegrating forces large surfaces of unprotected rocks in which decay would go on much more rapidly than when covered with the dbris which protected them before the advent of the ice4 ,the area of glacial action extended over nearly all of ,new ,england and over the whole area of the northern tier of ,states4 ,it extended southward almost to the ,ohio river1 and in some places crossed it4 ,the effect of the ice age in producing and modifying our soil must never be forgotten in a study of soil genesis4 ,it is not a part of our purpose here to study the causes which produced the age of ice4 ,even a brief reference to some of the more probable ones might be entirely out of place4 ,before the glacial period it is certain that a tropical climate extended almost1 if not quite1 to the ,north ,pole4 ,the fossil remains of tropical plants and animals which have been found in high northern latitudes are abundant proofs of this fact4 ,in the opinion of ,sterry ,hunt1#bg rock decay has taken place largely in preglacial and pretertiary times4 ,the decay of crystalline rocks is a process of great antiquity4 ,it is also a universal phenomenon4 ,the fact that the rocks of the southern part of this country seem to be covered with a deeper dbris than those further north is probably due to the mechanical translation of the eroded particles towards the south4 ,the decay and softening of the material were processes necessarily preceding the erosion by aqueous and glacial action4 ,it is possible that a climate may have existed in the earlier geologic ages more favorable to the decay of rocks than that of the present time4 #da4 ,progress of ,decay as ,affected by ,latitude4--,extensive investigations carried on along the ,atlantic side of the country show wide differences in the rate of decay in the same kind of rocks in different latitudes4 ,in general1 the progress of decay is more marked toward the south4 ,the same fact is observed in the great interior valleys of the country2 at least1 everywhere except in the arid and semi-arid regions4 ,wherever there is a deficiency of water the processes of decay have been arrested4 ,where the rock strata have been displaced from a horizontal position the progress of decay has been more rapid4 ,this is easily understood4 ,the percolation of water is more easy as the displacement approaches a vertical position4 ,a most remarkable example of this is seen in the rocks of ,north ,carolina4#bh ,a kind of rock known as trap is found in layers called dikes in the ,newark system of rocks in that ,state4 ,these dikes have been so completely displaced from the horizontal position they at first occupied as to have an almost vertical dip4 ,the edges thus exposed vary from a few feet to nearly #ajj feet in thickness4 ,the trap rock in those localities is composed almost exclusively of the mineral dolerite1 which is so hard and elastic in a fresh state as to ring like a piece of metal when struck with a hammer4 ,in building a railroad through this region these dikes were in some places uncovered to a depth of forty feet and more4 ,at this depth they were found completely decomposed and with no indications of having reached the lower limit of disintegration4 ,the original hard bluish dolerite has been transformed into a yellowish clay-like mass that can be molded in the fingers and cut like putty4 ,similar geologic formations in ,new ,jersey and further ,north do not exhibit anything like so great a degree of decomposition1 thus illustrating in a marked degree the fact that freezing weather for a part of the year is a protection against rock decay4 ,the ice of winter at least protects the rocks from surface infiltration1 although it can not stop the subterranean solution which must go on continuously4 ,other things being equal1 therefore1 it appears that as the region of winter frost is passed the decay of the rocks has been more rapid than in the ,north1 because the chief disintegrating forces act more constantly4 #db4 ,the ,solvent ,action of ,water4--,the water of springs and wells is not pure4 ,it contains in solution mineral matters and often a trace of organic matter4 ,the organic matter comes from contact with vegetable matter and other organic materials near the surface of the earth4 ,the mineral matter is derived from the solvent action of the water and its contents on the soil and rocks4 ,the expressions 8hard0 and 8soft0 applied to water indicate that it has much or little mineral matter in suspension1 as the case may be4 ,when surface and spring waters are collected into streams and rivers they still contain in solution the greater part of the mineral matters which they at first carried4 ,when well or spring waters have more than forty grains of mineral matter per gallon they are not suitable for drinking waters4 ,mineral waters1 so called1 are those which carry large quantities of mineral matter1 or which contain certain comparatively rare mineral substances which are valued for their medicinal effects4 ,the analysis of spring1 well1 or river waters will always give some indication of the character of the rocks over which they have passed4#bi ,the vast quantities of mineral matters carried into oceans and seas are gradually deposited as the water is evaporated4 ,if1 however1 these matters be very soluble1 such as common salt1 sulfate of magnesia1 etc41 they become concentrated1 as is seen with common salt in sea waters4 ,in small bodies of waters1 such as inland seas1 which have no outlet1 this concentration may proceed to a much greater extent than in the ocean4 ,as an instance of this1 it may be noted that the waters of the ,dead ,sea and ,great ,salt ,lake are impregnated to a far greater degree with soluble salts than the water of the ocean4 ,the solvent action of water on rocks is greatly increased by the traces of organic or carbonic acids which it may contain4 ,when surface water comes in contact with vegetable matter it may become partially charged with the organic acids which the growing vegetable may contain or decaying vegetable matter produce4 ,such acids coming in contact with limestone under pressure will set free carbon dioxid4 ,water charged with carbon dioxid acts vigorously on limestone and other mineral aggregates4 ,if such solutions penetrate deeply below the surface of the earth their activity as solvents may be greatly increased by the higher temperature to which they are subjected4 ,hence1 all these forces combine to disintegrate the rocks1 and through such agencies vast deposits of original and secondary rocks have been completely decomposed4 ,the gradual passing of the firm rock into an arable soil is beautifully shown in ,fig4 #aj1 a print from a negative taken by ,mr4 ,geo4 ,p4 ,merrill1 near ,washington1 ,d4 ,c4 ,illustration3 ,,figure #aj4 ,view on the ,broad ,branch of ,rock ,creek1 ,washington1 ,d4 ,c4 ,the fresh but badly decomposed granitic rock is shown passing upward into material more and more decomposed until it becomes sufficiently pulverulent and soluble to support plant life4 ,the roots showing in the upper part of the picture formerly penetrated the decomposed rock1 but have been exposed through quarrying operations4 ,photograph by ,george ,p4 ,merrill1 #ahia4 #dc4 ,action ,of ,vegetable ,life4--,the preliminary condition to vegetation is the formation of soil1 but once started1 vegetation aids greatly in the decomposition of rocks4 ,some forms of vegetation1 as the lichens1 have apparently the faculty of growing on the bare surface of rocks1 but the higher order requires at least a little soil4 ,the vegetation acts by shading the surface and thus rendering the action of water more effective1 by mechanically separating the rock particles by means of its penetrating roots and by the positive solvent action of the root juices4 ,the rootlets of plants in contact with limestone or marble dissolve large portions of these substances1 and while their action on more refractory rocks is slower1 it must be of considerable importance4 ,the organic matter introduced into the soil by vegetation also promotes decay still further both directly and by the formation of acids of the humic series4 ,this matter also furnishes a considerable portion of carbon dioxid which is carried by the water to assist in its solvent action4 #dd4 ,action of ,earth-,worms4--,of animal organisms those most active in the formation of soil are earth-worms4 ,the work of earth-worms has been exhaustively studied by ,darwin4#cj ,the worms not only modify the soil by bringing to the surface portions of the subsoil1 but also influence its physical state by making it more porous and pulverulent4 ,according to ,darwin the intestinal content of worms has an acid reaction1 and this has an effect on those portions of the soil passing through their alimentary canal4 ,the acids1 which are formed in the upper part of the digestive canal are neutralized by the carbonate of lime secreted by the calciferous glands of the worms thus neutralizing the free acid and changing the reaction to alkaline in the lower part of the canal4 ,there is a fair presumption that the acids of the worm are of a humic nature4 ,the worms further modify the composition of the soil by drawing leaves and other organic matter into their holes1 and leaving therein a portion of such matter which is gradually converted into humus4 ,stockbridge#ca gives a striking illustration of this process due to an experiment by von ,hensen4 ,darwin estimates that about eleven tons of organic matter per acre are annually added to the soil in regions where worms abound4 ,a considerable portion of the ammonia in the soil at any given time may also be due to the action of worms1 as much as #j4ah per cent of this substance having been found in their excrement4 ,it is probable that nearly the whole of the vegetable matter in the soil passes sooner or later through the alimentary canals of these ceaseless soil builders1 and is converted into the form of humus4 #de4 ,action of ,bacteria4--,the intimate relations which have been found to subsist between certain minute organisms and the chemical reactions which take place in the soil is a sufficient excuse for noting the effect of other similar organisms in the formation of soils4 ,in addition to the usual forces active in decomposing rocks ,mntz#cb has described the effects of a nitrifying bacillus contributing to the same purpose4 ,according to him the bare rock usually furnishes a purely mineral environment where organisms cannot be developed unless they are able to draw their nourishment directly from the air4 ,some nitrifying organisms belong to this class4 ,it has been shown that these bodies can be developed by absorbing from the ambient atmosphere carbonate of ammonia and vapors of alcohol1 the presence of which has been determined in the air4 ,according to the observations of ,winogradsky1 they assimilate even the carbon of the carbon dioxid just as vegetables do which contain chlorophyl4 ,thus even in the denuded rocks of high mountains the conditions for the development of all these inferior organisms exist4 ,in examining the particles produced by attrition1 it is easily established that they are uniformly covered by a layer of organic matter evidently formed by microscopic vegetations4 ,thus we see1 in the very first products of attrition1 appearing upon the rocky particles the characteristic element of vegetable soil1 viz41 humus1 the proportion of which increases rapidly with the products of disaggregation collected at the foot of declivities until finally they become covered with chlorophyliferous plants4 ,in a similar manner the presence of nitrifying organisms has been noted upon rocky particles received in sterilized tubes1 and cultivated in an appropriate environment where they soon produce nitrification4 ,the naked rocks of the ,alps1 the ,pyrenees1 the ,auvergnes and the ,vosges1 comprise mineralogical types of the most varied nature1 viz41 granite1 porphyry1 gneiss1 micaschist volcanic rocks and limestones and all these have shown themselves to be covered with the nitrifying ferment4 ,it is known that below a certain temperature these organisms are not active2 their action upon the rock is1 therefore1 limited to the summer period4 ,during the cold season their life is suspended but they do not perish1 inasmuch as they have been found living and ready to resume all their activity after an indefinite sleep on the ice of the glaciers where the temperature is never elevated above zero4 ,the nitrifying ferment is exercised on a much larger scale in the normal conditions of the lower levels where the rock is covered with earth4 ,this activity is not limited to the mass of rock but is continued upon the fragments of the most diverse size scattered through the soil and it gradually reduces them to a state of fine particles4 ,it is therefore a phenomenon of the widest extension4 ,the action of these micro-organisms according to ,mntz is not confined to the surface but extends to the most interior particles of the rocky mass4 ,where1 however1 there is nothing of a nitrogenous nature1 to nitrify such an organism must live in a state of suspended animation4 ,when the extreme minuteness of these phenomena is considered there may be a tendency to despise their importance1 but their continuity and their generality in the opinion of ,mntz place them among the geologic causes to which the crust of the earth owes a part of its actual physiognomy and which particularly have contributed to the formation of the deposits of the comminuted elements constituting arable soil4 ,the general action of nitrifying organisms in the soil1 the nature of these bodies1 and the method of isolating and identifying them will be fully discussed in another part of this work4 #df4 ,action of the ,air4--,the air itself takes an active part in rock decay4 ,wherever rocks are exposed to decay1 there air is found or1 at least1 the active principle of air1 viz41 oxygen4 ,the air not only penetrates to a great depth in the earth1 but is also carried to much greater depths by water which always holds a greater or less quantity of air in solution4 ,the oxygen of the air is thus brought into intimate contact with the disintegrating materials and in a condition to assist wherever possible in the decomposing processes4 ,the oxygen acts vigorously on the lower oxids of iron1 converting them into peroxids1 and thus tends to produce decay4 ,there are other constituents of rocks which oxygen affects injuriously and thus helps to their final breaking up4 ,it is true that1 as a rule1 the constituents of rocks are already oxidized to nearly as high a degree as possible1 and on these constituents of course the air would have no effect4 ,but on others1 especially when helped by water with the other substances it carries in solution1 the air may greatly help in the work of destruction4 ,in a general view1 the action of the air in soil formation may be regarded as of secondary importance1 and to depend chiefly on the oxidation of the lower to the higher basic forms4 ,these processes1 while they seem of little value1 have1 nevertheless1 been of considerable importance in the production of that residue of rock disintegration which constitutes the soil4 #dg4 ,classification of ,soils ,according to ,deposition4--,in regard to their deposition soils are divided into five classes3 #a4 ,those which are formed from the decomposition of crystalline or sedimentary rocks or of unconsolidated sedimentary material in situ4 #b4 ,those which have been moved by water from the place of their original formation and deposited by subsidence 7bottom lands1 alluvial soils1 lacustrine deposits1 etc474 #c4 ,those which have been deposited as dbris from moving masses of ice 7glacial drift74 #d4 ,soils formed from volcanic ashes or from materials moved by the wind and deposited in low places or in hills or ridges4 #e4 ,those formed chiefly from the decay of vegetable matter1 7tule1 peat1 muck74 #dh4 ,qualities of ,soils4--,in respect of quality1 soils have been arbitrarily divided into many kinds4 ,some of the more important of these divisions are as follows3 #a4 ,sand4 ,soils consisting almost exclusively of sand4 #b4 ,sandy ,loams4 ,soils containing some humus and clay but an excess of sand4 #c4 ,loams4 ,soils inclining neither to sand nor clay and containing some considerable portions of vegetable mold1 being very pulverulent and easily broken up into loose and porous masses4 #d4 ,clays4 ,stiff soils in which the silicate of alumina and other fine mineral particles are present in large quantity4 #e4 ,marls4 ,deposits containing an unusual proportion of carbonate of lime1 with often some potash or phosphoric acid resulting from the remains of sea-animals and plants4 #f4 ,alkaline4 ,soils containing carbonate and sulfate of soda1 or an excess of these alkaline and other soluble mineral substances4 #g4 ,adobe4 ,a fine grained porous earth of peculiar properties hereinafter described4 #h4 ,vegetable4 ,soils containing much vegetable dbris in an advanced state of decomposition4 ,when such matter predominates or exists in large proportion in a soil the term tule1 peat or muck is applied to it4 ,with the exception of numbers six1 seven and eight these types of soil are so well-known as to require no further description for analytical purposes4 ,the alkaline1 adobe and vegetable soils on the contrary demand further study4 #di4 ,alkaline ,soils4--,the importance of a more extended notice of this class of soils for analytical purposes is emphasized by their large extent in the ,united ,states4 ,chiefly through the researches of ,hilgard attention has been called to the true character of these soils which are found throughout a large part of the ,western ,united ,states and which are known by the common name of alkali4 ,the following description of the origin of these soils is compiled chiefly from ,hilgard's papers on this subject4 ,wherever the rain-fall is scanty1 and especially where the rains do not come at any one time with sufficient force to thoroughly saturate the soil and carry down through the subsoil and off through the drainage waters the alkali contained therein1 favorable conditions exist for the production of the alkaline soil mentioned above4 ,the peculiar characteristic of this soil is the efflorescence which occurs upon its surface and which is due to the raising of soluble salts in the soil by the water rising through capillary attraction and evaporating from the surface1 leaving the salts as an efflorescence4 ,soils which contain a large amount of alkali are usually very rich in mineral plant food1 and if the excess of soluble salt could be removed1 these lands under favorable conditions of moisture would produce large crops4 ,the formation of the alkali may be briefly described as follows3 ,by the decomposition of the native rocks1 certain salts soluble in water are formed4 ,these salts in the present matter are chiefly sodium and potassium sulfates1 chlorids and carbonates4 ,the salts of potash together with those of lime are more tenaciously held by the soil than the soluble salts of soda1 and the result of this natural affinity of the soil for soluble potash1 lime and magnesian salts is seen in the formation at the surface of the earth1 by the process of evaporation above described1 of a crust of alkaline material which is chiefly composed of the soluble salts of soda4 ,in countries which have a sufficient amount of rain-fall1 these soluble salts are carried away either by the surface drainage or by the percolation of water through the soil1 and the sodium chlorid is accumulated in this way in the waters of the ocean4 ,but where a sufficient amount of rain-fall does not occur1 these soluble salts carried down by each shower only to a certain depth rise again on the evaporation of the water1 reinforced by any additional soluble material which may be found in the soil itself4 ,the three most important ingredients of the alkali of the lands referred to are sodium chlorid1 sulfate1 and carbonate4 ,when the latter salt1 namely1 sodium carbonate1 is present in predominant quantity1 it gives rise to what is popularly known as black alkali4 ,this black color is due to the dark colored solution which sodium carbonate makes with the organic matters or humus of the soil4 ,the black alkali is far more injurious to growing vegetation than the white alkali composed chiefly of sodium sulfate and chlorid4 ,this black alkali has been very successfully treated by ,hilgard#cc by the application of gypsum which reacting with the sodium carbonate produces calcium carbonate and sodium sulfate1 thus converting the black into the white alkali and adding an ingredient in the shape of lime carbonate to stiff soils which tends to make them more pulverulent and easy of tillage4 ,this method of treatment1 however1 as can be easily seen1 is only palliative1 the whole amount of the alkaline substances being still left in the soil1 only in a less injurious form4 ,the only perfect remedy for alkaline soils1 as has been pointed out by ,hilgard1 is in the introduction of underdrainage in connection with irrigation4 ,the partial irrigation of alkaline soils1 affording enough moisture to carry the alkali down to and perhaps partially through the subsoil1 can produce only a temporary alleviation of the difficulties produced by the alkali4 ,subsequent evaporation may thus increase the amount of surface incrustation4 ,for this reason in many cases the practice of irrigation without underdrainage may completely ruin an otherwise fertile soil by slowly increasing the amount of alkali in the soil by the total amount of the alkaline material added in the waters of irrigation4 ,as ,hilgard has pointed out1 if a soil can be practically freed from alkali by underdrainage connected with a thorough saturation by irrigation1 it may be centuries before the alkali will accumulate in that soil again when ordinary irrigation only is practiced4 ,it may thus become possible to reclaim large extents of alkaline soil little by little by treating them with an excess of irrigation water in connection with thorough underdrainage4 ,the composition of the alkali on the surface of the soil due to the causes above set forth is thoroughly illustrated by the analyses of ,hilgard and ,weber1 which follow3 ,,table ,,showing ,,composition ,,of ,,alkali ,,salts ,,in ,,san ,,joaquin ,,valley4 ,,fresno ,,county4 ,sections #ac and #bd ,t4 #ad ,s4 ,r4 #ai ,e41 #d miles ,s4 ,w4 from ,fresno4 ,alkali ,alkali ,spot1 #ahhi4 soil1 #ahhh4 #a inch #ah #bf #db surface4 inches inches inches bel4 bel4 hardpan4 surface4surface4 ,soluble salts #j4gf #j4bj #j4ah #j4af in #ajj parts soil ,potassium sulfate ,d,potassium nitrate ,potassium carbonate 7,saleratus7 ,sodium large small small very very sulfate slight slight 7,glauber's salt7 ,sodium very large small large large carbonate slight 7,sal-soda7 ,sodium chiefly moderatechiefly moderatemoderate chlorid 7,common salt7 ,d,sodium phosphate ,calcium moderate small very very very sulfate slight slight slight 7,gypsum7 ,magnesium sulfate 7,epsom salt7 ,organic matter ,,fresno ,,county4 ,miss ,austin's ,n4,w4 ,cor4 ,n ,easton4,emigr'nt ,ranch1 ,central ,sec4 #bj ,t4 #ad ,s4 ,ditch4 ,colony4 ,r4 #ba ,e4 ,surface,surface ,surface,surface soil1 soil1 soil4 soil4 ,no4 #a4 ,no4 #b4 ,soluble salts #c4ed #a4ij #a4bj #b4fi in #ajj parts soil ,potassium small moderate sulfate ,d,potassium small nitrate ,potassium carbonate 7,saleratus7 ,sodium large large much moderate large sulfate 7,glauber's salt7 ,sodium small chiefly small small chiefly carbonate 7,sal-soda7 ,sodium chiefly large chieflychiefly large little chlorid 7,common salt7 ,d,sodium phosphate ,calcium small moderate small small much sulfate 7,gypsum7 ,magnesium small much sulfate 7,epsom salt7 ,organic matter ,footnote ,d3 ,very generally present1 but not always in quantities sufficient for determination4 ,,tulare ,,county4 ,goshen ,peopl's ,near ,visalia,lemoore ,tulare ,ditch ,lake ,exp't ,tulare ,station ,surf'ce,alkali ,surf'ce ,surf'ce ,alkali ,alkali soil crust soil soil crust crust ,soluble salts in #ajj #a4dj #j4hc #a4bf parts soil ,potassium sulfate small ,e,potassium nitrate small ,potassium carbonate #ah4hj 7,saleratus7 ,sodium sulfate #dd4bd #a4bbca4cj;,f #ac4d;chiefly #cb4h 7,glauber's salt7 ,sodium carbonate #cb4ih #hh4ji #ah4b #de4c #cf4af 7,sal-soda7 ,sodium chlorid #af4gd #a4jj #d4d little #ca4af 7,common salt7 ,e,sodium phosphate #a4ig #j4bb #aj4d ,calcium sulfate little 7,gypsum7 ,magnesium sulfate #h4amoderate 7,epsom salt7 ,organic matter #a4ei #i4ba #g4e #e4cg ,,kern ,,county4 ,alkali crusts from the ,smyrna artesian belt4 ,townships #be and #bf ,r4 #bc ,e4 ,w4 ,s4 ,w4 from ,delano1 ,s4 ,p4 ,r4 ,r4 ,no4 #a ,no4 #b ,no4 #c ,no4 #d ,no4 #e,no4 #f,no4 #g,no4 #h ,soluble salts in #ajj parts soil ,potassium sulfate ,e,potassium nitrate ,potassium carbonate 7,saleratus7 ,sodium smallmoderatemoderatemoderatelargesmalls mallsmall sulfate 7,glauber's salt7 ,sodium carbonate 7,sal-soda7 ,sodium largemoderate large large smalllargesmalllarge chlorid 7,common salt7 ,e,sodium phosphate ,calcium small small small small smallsmallsmallsmall sulfate 7,gypsum7 ,magnesium small small small small smallsmallsmallsmall sulfate 7,epsom salt7 ,organic matter ,,kern ,,county4 ,summer4 ,kern ,island ,alkali ,alkali crust crust ,soluble salts in #ajj parts soil ,potassium #d4gb sulfate ,e,potassium nitrate ,potassium carbonate 7,saleratus7 ,sodium #ai4bj #gj4fa sulfate 7,glauber's salt7 ,sodium #ad4hb carbonate 7,sal-soda7 ,sodium #cg4ad #d4ac chlorid 7,common salt7 ,e,sodium phosphate ,calcium #j4if #j4jh sulfate 7,gypsum7 ,magnesium #ah4ca sulfate 7,epsom salt7 ,organic #bj4hg matter ,footnote ,f3 ,common and ,glauber's salts4 #ej4 ,adobe ,soils4--,in many parts of the arid regions of this country which can be recovered for agricultural purposes by irrigation the soil has peculiar characteristics4 ,the name adobe as commonly used applies to both the sundried bricks of the arid regions of the ,west and ,southwest1 and to the materials of which they are composed4 ,the material is described by ,russell#cd as a fine grained porous earth1 varying in color through many shades of gray and yellow1 which crumbles between the fingers1 but separates most readily in a vertical direction4 ,the coherency of the material is so great that vertical scarps will stand for many years without forming a noticeable talus slope4 ,distribution4--,the area over which adobe forms a large part of the surface has not been accurately mapped1 but enough is known to indicate that it is essentially co-extensive with the more arid portions of this country4 ,in a very general way it may be considered as being limited to the region in which the mean annual rain-fall is less than twenty inches4 ,it forms the surface over large portions of ,colorado1 ,new ,mexico1 ,western ,texas1 ,arizona1 ,southern ,california1 ,nevada1 ,utah1 ,southern ,oregon1 ,southern ,idaho1 and ,wyoming4 ,adobe occurs also in ,mexico and may there reach a greater development than in the ,united ,states1 but observations concerning it south of the ,rio ,grande are wanting4 ,in the ,united ,states it occurs from near the sea-level in ,arizona1 and even below the sea-level in ,southern ,california1 up to an elevation of at least six or eight thousand feet1 along the eastern border of the ,rocky ,mountains1 and in the elevated valleys of ,new ,mexico1 ,colorado1 and ,wyoming4 ,it occupies depressions of all sizes up to valleys having an area of hundreds of square miles4 ,although occurring throughout the arid region1 it can be studied to best advantage in the drainless and lakeless basins in ,nevada1 ,utah1 and ,arizona4 ,composition4--,when examined under the microscope1 the adobe is seen to be composed of irregular1 unassorted flakes and grains1 principally quartz1 but fragments of other minerals are also present4 ,an exhaustive microscopic study has not been made1 but the samples examined from widely-separated localities were very similar4 ,the principal characteristics observed were the extreme angularity of the particles composing the deposit and the undecomposed condition of the various minerals entering into its composition4 ,it is to be inferred from this that the material was not exposed even to a very moderate degree of friction1 and had not undergone subaerial decay before being deposited4 ,adobe collected1 at typical localities is so fine in texture that no grit can be felt when it is rubbed between the fingers2 in other instances it contains angular rock fragments of appreciable size4 ,the composition of the material is illustrated by the following analyses3 ,,analyses ,,of ,,adobe4 ,,by ,l4 ,g4 ,,eakins4 ,constituents4 ,no4 #a4 ,no4 #b4 ,no4 #c4 ,no4 #d4 ,sante ,fe1 ,new ,fort ,wingate1 ,humboldt1 ,salt ,lake ,mexico4 ,new ,mexico4 ,nevada4 ,city1 ,utah4 ,si,o #ff4fi #bf4fg #dd4fd #ai4bd ,al,o #ad4af #j4ia #ac4ai #c4bf ,fe,o #d4ch #j4fd #e4ab #a4ji ,mn,o #j4ji trace #j4ac trace ,ca,o #b4di #cf4dj #ac4ia #ch4id ,mg,o #a4bh #j4ea #b4if #b4ge ,k,o #a4ba trace #a4ga trace ,na,o #j4fg trace #j4ei trace ,,co #j4gg #be4hd #h4ee #bi4eg ,p,o #j4bi #j4ge #j4id #j4bc ,,so #j4da #j4hb #j4fd #j4ec ,cl #j4cd #j4jg #j4ad #j4aa ,h,o #d4id #b4bf #c4hd #a4fg ,organic matter #b4jj #e4aj #c4dc #b4if ---------- ---------- ---------- ------------ #ii4gb #ii4ig #ii4hd #ajj4ce #ea4 ,vegetable ,soils4--,the heavy soils whose origin has been described are essentially of a mineral nature4 ,the quantity of organic matter in such soils may vary from a mere trace to a few per cent1 but they never lose their mineral predominance4 ,when a soil on the other hand is composed almost exclusively of vegetable mold it belongs to quite another type4 ,such soils are called tule1 peat or muck4 ,in this country there are thousands of acres of peat or muck soils2 the largest contiguous deposits being found in ,southern ,florida4 ,the origin of these soils is easily understood4 ,whenever rank vegetation grows in such a location as to secure for the organic matter formed a slow decay there is a tendency to the accumulation of vegetable mold in shallow water or on marshy ground and where conditions are favorable to such accumulations4 ,in ,florida the muck soils have been accumulated about the margins of lakes4 ,during the rainy season the marshes bordering these are partly covered with water1 but the vegetation is very luxuriant4 ,the water protects the vegetable matter from being destroyed by fire4 ,it therefore accumulates from year to year and is gradually compacted into quite a uniform mass of vegetable mold4 ,the composition of the muck is illustrated in the following table which shows the character of the layers at one1 two and three feet in depth3#ce ,carbon4 ,hydrogen4 ,nitrogen4 ,volatile matter4 #a foot #eg4fg per cent #d4dh per cent #b4bd per cent #ij4fj per cent #b feet #dg4jg #e4ae #a4dj #gb4jj #c feet #h4eb #j4ec #j4ca #ae4jj ,in this sample1 ,no4 #c1 the muck was only three feet deep1 resting on pure sand4 ,as the bottom of the deposit is approached the admixture of sand becomes greater and the percentage of organic matter less4 ,no reliable estimate of the time which has been required to form these deposits can be given1 but in the ,okeechobee region in ,florida the deposit of vegetable mold in some places exceeds ten feet in depth4 ,the purest muck or peat soils contain only small quantities of potash and phosphoric acid1 and especially is this true of the ,florida mucks which have been formed of vegetable growth containing very little mineral matter4 ,it is not at all probable that the flora now growing on any particular area of virgin peat contains all the plants that have contributed to its formation4 ,the principal vegetable growths now going to make up the muck soils of ,florida are the following3 ,common names4 ,botanical names4 ,saw grass ,cladium effusum ,yellow pond lily ,nymphea flava ,maiden cane grass ,panicum ,curtisii ,alligator ,wampee ,pontederia cordata ,sedge ,cyperus species ,fern brake ,osmunda ,mallow ,malva ,broom sedge ,andropogon ,arrow weed ,sagittaria ,the above are only the plants growing in the greatest profusion and do not include all which are now contributing to increase the store of vegetable dbris4 #eb4 ,humus4--,the active principle of vegetable mold is called humus1 a term used to designate in general the products of the decomposition of vegetable matter as they are found in soils4 ,in peat and muck are found a mixture of humus with undecomposed or partially decomposed vegetation4 ,according to ,kostytchoff#cf vegetable matter decays under the influence of molds and bacteria4 ,molds alone produce the dark colored matters which give soils rich in vegetable matter1 their color4 ,one chief characteristic of humus is its richness in nitrogen4 ,black ,russian soil contains from #d to #f4fe per cent of nitrogen4 ,this soil is estimated to contain sixty million organisms per gram and much of the nitrogen which it holds must be in the form of proteids4 ,the first development in decaying vegetable matter is of bacteria and there is a tendency of the decaying matter to become acid4 ,this causes a decay of the bacteria and the ammonia produced by this neutralizes the acid4 ,the various kinds of mold grow when the reaction becomes neutral4 ,afterwards the bacteria and the molds develop together4 ,this statement of ,kostytchoff is not a very satisfactory explanation of even our limited knowledge of the decomposition of organic matters in the soil4 ,ammonia and ammonia salts are formed not by the decay of some forms of bacteria but by the activities of other forms4 ,warington found that in nitrification there were three distinct forms of bacteria concerned in the final products of ammonia1 nitrites1 and nitrates4 ,humus always contains easily decomposable matter and consequently the rate of decay at any observed periods is nearly the same4 ,in humus which is produced above the water-level ,kostytchoff states that all trace of the vegetable structure is destroyed by the leaves being gnawed and passed through the bodies of caterpillars and wire-worms4 ,under the water-level the vegetable structure is preserved and peat results4 ,the decay of humus is most rapid in drained and open soils4 ,for this reason the presence of clay in a soil promotes the accumulation of humus4 ,inferior organisms are the means of diffusing organic matter through the soil4 ,the mycelia of fungi grow on a dead root for instance1 ramify laterally and thus carry organic matter outward and succeeding organisms extend this action and the soil becomes darkened in proportion4 ,humic acid in black soil is almost exclusively in combination with lime4 ,a more common view of the difference between the formation of humus above and below the water-level is that above the water-level there is a very free access of air and even the harder parts of the leaf skeleton can be oxidized through the agency of bacteria1 while under the water-level there is a very limited supply of air and this oxidation cannot proceed as rapidly4 ,the harder parts of the leaf skeleton are preserved1 and from the freer access of air humus is oxidized more readily in drained and open soils1 and accumulates in clay soils where there is less circulation of air4 ,the real composition of humus is a matter which has never been definitely determined4 ,composed of many different but closely related substances it has been difficult to isolate and determine them4 ,stockbridge#cg gives the following composition of the bodies which form the larger part of humus3 ,ulmin and ,ulmic ,acid4 ,carbon #fg4a per cent ,corresponding to ,c,h,o ,h,o4 ,hydrogen #d4b ,oxygen #h4g ,humin and ,humic ,acid4 ,carbon #fd4d per cent ,corresponding to ,c,h,o #c;,h,o ,hydrogen #d4c ,oxygen #ca4c ,crenic ,acid4 ,carbon #dd4j per cent ,corresponding to ,c,h,o8 ,hydrogen #e4e ,nitrogen #c4i ,oxygen #df4f ,apocrenic ,acid4 ,carbon #cd4d per cent ,corresponding to ,c,h,o8 ,hydrogen #c4e ,nitrogen #c4j ,oxygen #ci4a ,he further states that there are1 aside from these humus compounds1 others still less known and the action of which is not yet understood2 among them xylic acid1 ,c,h,o1 saccharic acid1 ,c,h,o1 glucinic acid1 ,c,h,o1 besides a brown humus acid containing carbon1 #fe4h per cent1 and hydrogen1 #f4be per cent1 and a black humus acid yielding carbon1 #ga4e per cent1 and hydrogen1 #e4h per cent4 ,according to ,mulder humic acid has the following composition1 ,c,h,o1 while ,thenard#ch ascribes to it the formula1 ,c,h,o4 ,at the present time we can only regard the various forms of humus bodies as mixtures of many substances mostly of an acid nature and resulting from a gradual decomposition of organic matter under conditions which partially exclude free access of oxygen4 ,for analytical purposes it is only necessary to separate these bodies by the best approved processes4 ,a further knowledge of their composition can then be derived by determining the percentages of carbon dioxid and water which they yield on combustion4 #ec4 ,soil and ,subsoil4--,many subdivisions have been made of the above varieties of soil1 but they have little value for analytical purposes4 ,for convenience in description for agricultural purposes1 the soil1 however1 is further divided into soil and subsoil4 ,in this sense the soil comprises that portion of the surface of the ground1 usually from four to nine inches deep1 containing most of the organic remains of plants and animals and in which air circulates more or less freely for the proper humification of the organic matter1 which usually gives a darker color to the soil than to the subsoil4 ,the subsoil proper lies below this1 and has usually more characteristic properties1 especially in respect of color and texture1 as it has been less influenced by artificial conditions of cultivation and the remains of vegetation4 ,the subsoil extends to an indefinite depth and is limited usually by deposits of undecomposed or partly decomposed rock matter1 or by layers of clay1 sand or gravel4 ,inasmuch1 however1 as the influence of the subsoil on growing crops is of little importance below the depth of eighteen inches the analysis of samples from a greater depth has more of a geologic than agricultural value4 ,hilgard regards as subsoil whatever lies beneath the line of change1 or below the minimum depth of six inches4 ,but should the change of color occur at a greater depth than twelve inches1 the soil specimen should nevertheless be taken to the depth of twelve inches only1 which is the limit of ordinary tillage2 then another specimen from that depth down to the line of change1 and then the subsoil specimens beneath that line4 ,the depth to which the last should be taken will depend upon circumstances4 ,it is always desirable to know what constitutes the foundation of a soil to the depth of three feet at least1 since the question of drainage1 resistance to drought1 etc41 will depend essentially upon the nature of the substratum4 ,but in ordinary cases ten or twelve inches of subsoil will be sufficient4 ,the sample should be taken in other respects precisely like that of the surface soil1 while that of the material underlying this subsoil may be taken with less exactness1 perhaps at some ditch or other easily accessible point1 and should not be broken up like the other specimens4 ,in the method of soil sampling adopted by the ,royal ,agricultural ,college of ,england1 the soil is regarded as that portion of the surface of the ground which is reached by ordinary tillage operations1 generally being from six to nine inches deep2 the subsoil is that portion which is ordinarily not touched in plowing4 ,,authorities ,,cited ,,in ,,part ,,first4 ,footnote #a3 ,comptes rendus1 ,tome #aaj1 p4 #abga4 ,footnote #b3 ,wyatt1 ,phosphates of ,america1 p4 #ff4 ,footnote #c3 ,engineering and ,mining ,journal1 ,august #bc1 #ahij4 ,footnote #d3 ,american ,journal of ,science1 ,vol4 #da1 ,february1 #ahia4 ,footnote #e3 ,preliminary ,sketch of ,florida ,phosphates1 ,author's edition1 pp4 #ah1 et seq4 ,footnote #f3 ,journal fr praktische ,chemie1 #ast series1 ,band #ch1 ,s4 #chh4 ,footnote #g3 ,annual ,report ,connecticut ,experiment ,station1 #ahij1 p4 #gb4 ,footnote #h3 ,annual ,report ,massachusetts ,experiment ,station1 #ahhg1 p4 #bcc4 ,footnote #i3 ,bulletin #ba1 ,rhode ,island ,experiment ,station1 #ahic4 ,footnote #aj3 ,chemical ,composition of ,food-,fishes4 ,report of ,u4 ,s4 ,commissioner of ,fish and ,fisheries1 #ahhh1 pp4 #fgi et seq4 ,footnote #aa3 ,g4 ,brown ,goode1 ,american ,naturalist1 ,vol4 #ad1 ,july1 #ahij4 ,footnote #ab3 ,comptes rendus1 ,tome #aja1 #ahhe1 pp4 #fe1 et seq4 ,footnote #ac3 ,royal ,agricultural ,society ,journal1 ,vol4 #ac1 #aheb1 pp4 #cdi et seq4 ,footnote #ad3 ,gtes ,mineraux1 par ,fuchs et ,de,launy1 ,tome #a1 p4 #dbe4 ,footnote #ae3 ,el ,salitre de ,chile2 ,ren ,f4 ,le,feuvre y ,artro ,dagnino1 #ahic1 p4 #ab4 ,footnote #af3 ,crampton1 ,american ,chemical ,journal1 ,vol4 ,,ii1 #ahij1 p4 #bbg4 ,footnote #ag3 ,potash1 pamphlet of ,german ,kali ,works1 pp4 #c1 #d4 ,footnote #ah3 ,gtes ,mineraux1 p4 #dbi4 ,footnote #ai3 ,bulletin of the ,philosophical ,society of ,washington1 ,vol4 ,,ii1 p4 #adb4 ,footnote #bj3 ,handbook for the ,department of ,geology of the ,u4 ,s4 ,national ,museum1 by ,geo4 ,p4 ,merrill4 ,footnote #ba3 ,vid4 supra1 p4 #ejf4 ,footnote #bb3 ,vid4 supra1 ,plate #abj4 ,footnote #bc3 ,merrill1 op4 cit4 p4 #eba4 ,footnote #bd3 ,merrill1 op4 cit4 p4 #ecf4 ,footnote #be3 ,merrill1 op4 cit4 p4 #ede4 ,footnote #bf3 ,merrill1 op4 cit4 p4 #edg4 ,footnote #bg3 ,mineral ,physiology and ,physiography1 p4 #bea4 ,footnote #bh3 ,bulletin ,no4 #eb1 ,united ,states ,geological ,survey1 p4 #af4 ,footnote #bi3 bis 7p4 #dh71 ,vid4 supra1 p4 #ch4 ,footnote #cj3 ,the ,formation of ,vegetable ,mold through the ,action of ,worms4 ,footnote #ca3 ,rocks and ,soils1 pp4 #aca-b4 ,footnote #cb3 ,comptes rendus1 ,tome #aaj1 p4 #acgj4 ,footnote #cc3 ,bulletin ,no4 #hc1 ,california ,experiment ,station4 ,footnote #cd3 ,geological ,magazine1 ,vol4 #g1 ,no4 #f1 pp4 #bia-ib4 ,footnote #ce3 ,wiley1 ,agricultural ,science1 #ahic1 pp4 #ajf et seq4 ,footnote #cf3 ,travaux de la ,socit des ,naturalistes ,st4 ,petersburg1 ,tome #bj1 #ahhi4 ,footnote #cg3 ,rocks and ,soils1 p4 #acd4 ,footnote #ch3 ,beilstein's ,handbuch der ,organischen ,chemie1 ,band ,i1 ,ss4 #hia-b4 ,,part ,,second4 ,,taking ,,samples ,,of ,,soil ,,for ,,analysis4 #ed4 ,general ,principles4--,it would be unwise to attempt to give any single method of taking soil samples as the only one to be practiced in all circumstances4 ,in the methods which follow it is believed will be found directions for every probable case4 ,the particular method to be followed will in each case have to be determined by circumstances4 ,the sole object in taking a sample of soil should be to have it representative of the type of soils to which it belongs4 ,every precaution should be observed to have each sample measure up to that standard4 ,the physical and chemical analyses of soils are long and tedious processes and are entirely too costly to be applied to samples which represent nothing but themselves4 ,the particular place selected for taking the samples as well as the method employed are also largely determined by the point of view of the investigations4 ,the collection of samples to illustrate the geologic or mineralogical relations of soils is quite a different matter from gathering portions to represent their agricultural possibilities4 ,in a given area the sum of plant food in the soil would only be determined by the analyses of samples from that particular field1 while samples illustrating geologic relations could or should be taken at widely distant points4 ,again the chemist is content with a sample of a few grams in weight while the physicist would require a much larger quantity4 ,much popular ignorance exists respecting the importance of the collection of soil samples4 ,as an illustration of this may be cited a recent instance in which a sample of soil was received by the author with a request for a complete analysis and a statement of the kinds of crops it was suited to grow4 ,no data relating to the locality in which the sample was taken accompanied this request4 ,the sample itself1 which weighed a little less than #c4f grams1 was not a soil at all in an agricultural sense but a highly ferruginous sand4 ,the collector of samples who understands the purpose for which he is working will find among the approved methods which follow some one or some combination of methods1 by means of which his work can be made successful4 ,in these cases it is the collector rather than the method on which reliance must be placed to secure properly representative samples4 #ee4 ,general ,directions for ,sampling4--,the locality having been selected which presents as nearly as possible the mean composition of the field a square hole is dug with a sharp spade to the depth of eighteen inches4 ,the walls of this hole should be smooth and perpendicular4 ,the soil to the depth of six to nine inches is then removed from the sides of the hole in a slice about four inches thick2 or the sample of soil may be taken to the depth indicated by a change of color4 ,any particles which fall into the bottom of the hole are carefully collected and added to the parts adhering to the spade4 ,the whole is thrown into a suitable vessel for removal to the laboratory4 ,the sample of soil having been thus secured1 the subsoil is taken in the same way4 ,to insure uniformity in the samples1 it is well to take several of them from the same field4 ,where more than one sample is taken it is advisable to mix all the sub-samples in the field1 remove large sticks1 stones1 roots1 etc41 and take a general sample of from three to five kilograms4 ,the character of the dbris1 etc41 removed should be carefully noted4 ,it is sometimes desirable to take samples of the subsoil to a greater depth than eighteen inches4 ,a post-hole auger or large wood auger will be found very useful for this purpose4 ,it is rarely necessary to take samples of subsoil to a greater depth than six feet4 ,in taking samples the geologic formation and the general topography of the field should be noted1 also the character of the previous crops1 kind and amount of fertilizers employed1 character of drainage and any other data of a nature to give a more accurate idea of the forces which have determined the physical and chemical properties of the sample4 #ef4 ,method ,of ,hilgard4--,hilgard#ci recommends that samples should not be taken indiscriminately from any locality you may chance to be interested in1 but that you should consider what are the two or three chief varieties of soil which1 with their intermixtures1 make up the cultivable area of your region1 and carefully sample these first of all4 ,as a rule1 and whenever possible1 samples should be taken only from spots that have not been cultivated1 or are otherwise likely to have been changed from their original condition of virgin soils and not from ground frequently trodden over such as roadsides1 cattle paths1 or small pastures1 squirrel holes1 stumps1 or even the foot of trees1 or spots that have been washed by rains or streams1 so as to have experienced a noticeable change1 and not be a fair representative of their kind4 ,he further suggests that the normal vegetation1 trees1 herbs1 grass1 etc41 should be carefully observed and recorded1 and spots showing unusual growth be avoided whether in kind or quality1 as such are likely to have received some animal manure or other outside addition4 ,specimens should be taken from more than one spot judged to be a fair representative of the soil intended to be examined as an additional guarantee of a fair average4 ,after selecting a proper spot pull up the plants growing on it1 and scrape off the surface lightly with a sharp tool to remove half-decayed vegetable matter not forming part of the soil4 ,dig a vertical hole1 like a post-hole1 at least #bj inches deep4 ,scrape the sides clean so as to see at what depth the change of tint occurs which marks the downward limit of the surface soil1 and record it4 ,take at least half a bushel of the earth above this limit1 and on a cloth 7jute bagging should not be used for this purpose1 as its fibers1 etc41 become intermixed with the soil7 or paper break it up and mix thoroughly1 and put up at least a pint of it in a sack or package for examination4 ,this specimen will1 ordinarily1 constitute the soil4 ,should the change of color occur at a less depth than six inches the fact should be noted1 but the specimen taken to that depth nevertheless1 since it is the least to which rational cultures can be supposed to reach4 ,in case the difference in the character of a shallow surface soil and its subsoil should be unusually great1 as may be the case in tule or other alluvial lands or in rocky districts1 a separate example of that surface soil should be taken1 besides the one to the depth of six inches4 ,specimens of salty or alkali soils should1 as a rule1 be taken only toward the end of the dry season1 when they will contain the maximum amount of the injurious ingredients which it may be necessary to neutralize4 ,whatever lies beneath the line of change1 or below the minimum depth of six inches1 will constitute the subsoil4 ,should the change of color occur at a greater depth than twelve inches the soil specimen should nevertheless be taken to the depth of twelve inches only1 which is the limit of ordinary tillage2 then another specimen from that depth down to the line of change1 and then the subsoil specimen beneath that line4 ,hilgard justly calls attention to the fact that all peculiarities of the soil and subsoil1 their behavior in wet and dry seasons1 their location1 position and every circumstance in fact1 which can throw any light on their agricultural qualities or peculiarities should be carefully noted and the notes sent with the samples4 ,unless accompanied by such information1 samples can not ordinarily be considered as justifying the amount of labor involved in their examination4 #eg4 ,whitney#dj suggests that a geologic map of the region to be sampled should always be at hand and that all samples should be rejected from spots showing local discrepancies1 washings or other disturbances4 ,the kind of analyses to which a sample is to be subjected also largely determines the method to be pursued in selecting it3 ,for instance1 a sample to be used for determining the size of the particles therein1 may be taken in quite a different manner from that designed only for the determination of moisture4 #eh4 ,in the directions collated by ,richards#da and which have been largely followed by the correspondents of the ,department of ,agriculture1 it is recommended to select in a field1 four or five places1 at least1 per acre1 taking care that these places have an homogeneous aspect1 and represent as far as possible the general character of the whole ground4 ,if the field1 however1 present notable differences1 either in regard to its aspect or its fertility1 the samples gathered from the different parts must be kept separate4 ,the sampling of arable soil should be made only after the raising of the crop and before it has received any new manure4 ,in other soils the sample should be taken only from spots that have not been cultivated4 #ei4 ,in the method of soil sampling adopted by the ,german ,experiment ,stations#db it is directed that the samples of soil should be taken according to the extent of the surface to be sampled1 in three1 five1 nine1 twelve or more places at equal distances from each other4 ,they should be taken in perpendicular sections to the depth turned by the plow2 and for some studies of the subsoil to a depth of sixty to ninety centimeters4 ,the single samples can be either examined separately or carefully mixed and an average portion of the mixture taken4 #fj4 ,method of the ,official ,french ,commission4--,the official ,french commission#dc emphasizes the fact that the sample of soil taken for analysis1 should represent a layer of equal thickness through the total depth of its arable part4 ,an analysis of the subsoil taken in the same way1 will often be useful to complete the data of the soil study4 ,first of all1 according to this authority1 it is necessary to determine the point of view from which the sample is to be taken4 ,if the object is a general study1 having for its aim the determination of the general composition of the soils of a definite geologic formation1 the sample should be taken in such a way that the different characteristics of the soil alone should enter into consideration without paying any attention to its accidental components1 which have been determined by local causes1 such as are produced by continued high cultivation1 the application of abundant fertilizers1 or the practice of a particular line of agriculture4 ,the samples of soil therefore1 with such an object in view1 should be taken on parts of the earth which are beyond the reach of the causes mentioned above and which tend to modify the nature of the primitive soil4 ,in such a case it is the soil which has not been modified1 or better still1 virgin soil1 such as is found in the woodlands and prairies1 which should be taken for a sample1 choosing those places in which the geologic formation is most perfectly characterized4 ,in such a case a soil taken in one spot corresponding to the conditions before mentioned1 would be the best for the purposes in view4 ,the sample would thus represent a true type to be studied1 not one of a mean composition got by taking samples from different localities and mixing them into a homogeneous parcel4 ,this last method of proceeding could introduce into the sample earth modified by culture or by influences purely accidental4 ,however1 it would be wise1 in a region characterized by the same geologic formation1 to take a certain number of samples in different localities1 and examine singly each one of them in order to be assured that there is a uniformity of composition in the whole of the soils4 ,if1 on the contrary1 it is the purpose of the investigation to furnish information to the cultivator concerning the fields which are worked1 it is necessary to approach the problem from a different point of view4 ,in this case the earth which is under cultivation should be first of all considered with all the modifications which nature causes or practical culture has caused1 in it4 ,but it often happens that upon the same farm the natural soil is variable1 caused either by the washings from the adjacent soils1 by the accumulation at certain points of deposits formed from standing water1 or from other reasons4 ,in such a case it would be necessary to take samples from every part of the field which exhibited any variation from the general type1 in order to get a complete mean sample of the whole4 ,it is necessary to be on guard against making a mixture of these different lots which would neither represent the different soils constituting the farm nor their mean composition4 ,it would be better to examine each of these samples alone and then from those parts which appear to have a similar composition1 to take a general sample for the mean analysis4 ,most often it is necessary to confine our studies to the really important part of the farm the composition of which would have a practical interest4 ,the aspect of the spontaneous vegetation in such a case1 will often serve as a guide to determine the parts of the farms which are similar in nature4 ,the sample should represent the arable layer1 properly so-called1 that is1 that part of it which is stirred by the agricultural implements in use and in which the root system of the plant takes its greatest development and which is the true reservoir of the fertilizing materials4 ,when a trench is dug in the soil it is easy to distinguish the arable layer from the subsoil4 ,in the first place1 its color is different1 generally being modified by vegetable dbris which forms the supply of humus4 ,the depth of the arable layer is variable1 but it is most frequently between #bjj and #cjj millimeters4 ,in the analysis the depth and layers should be indicated since the chemical composition of the earth varies according as the sample is taken to a greater or less depth4 ,as an example of this it may be said that the quantity of nitrogen decreases in general in proportion as the depth of the layer is increased4 ,the sample1 therefore1 should be limited exactly to the arable layer of soil4 #fa4 ,caldwell#dd advises that according to the purpose of the analysis samples be taken3 a1 from one or from several spots in the field1 in order to subject each sample to a separate analysis2 or b1 for an average representation of the soil of the whole field2 in this case1 several portions of earth are taken from points distributed in a regular manner over the field1 all of which are most carefully mixed together1 and #d-f kilograms of the mixture1 free from any large stones1 are preserved as the average sample4 ,an excavation in the soil #cj-ej centimeters deep1 or through to the subsoil1 and #cj-ej centimeters square1 with one side as nearly vertical as possible is made and a slice taken from this side of uniform thickness throughout1 weighing #d-e kilograms4 ,if the subsoil is to be examined1 a sample of it should be taken out in the same manner as directed for the upper soil1 to the depth of about #fj centimeters4 ,if the character of the soil varies materially in different parts of the field1 samples from several spots should be analyzed separately4 ,a small portion of the sample should be put at once in a well-stoppered bottle2 the remainder may be allowed to become air-dried1 by exposing it in a thin layer1 in summer1 to the common temperature in the shade1 or1 in winter1 to that of a warm room1 or a moderately warm drying-chamber1 heated to #cj-dj2 in either case it should be carefully protected from dust4 ,at the time of taking the sample of the soil1 observations should be made in regard to the following points3 a4 ,the geognostic origin of the soil4 b4 ,the nature of the underlying strata1 to the depth of #a-b meters1 if practicable4 c4 ,the meteorology of the locality1 by consulting meteorological records1 if possible2 otherwise1 by the general opinion of the neighborhood2 in this connection1 the height of the locality above the level of the sea should be noted also4 d4 ,the management and rotation of crops in previous years4 e4 ,the character of the customary manuring4 f4 ,the amount of the crops removed in the preceding year1 and1 if possible1 the average amount of each of the more important crops yielded by the field4 g4 ,the practical judgment of neighboring farmers in regard to the field4 ,caldwel's method is practically identical with that of ,wolff#de which was one of the earliest of the systematic schemes for taking soil samples4 #fb4 ,wahnschaffe#df insists on rather a fuller preliminary statement to accompany soil samples but gives essentially the method of ,wolff with some unimportant variations which add little to the value of the process4 #fc4 ,method ,of ,peligot4--,according to ,peligot#dg the taking of samples of soil of which the physical and chemical properties are to be determined is a delicate operation4 ,these samples should represent as nearly as possible both the good and bad qualities of a soil4 ,in the field selected are chosen a certain number of places at least four or five per hectare4 ,the spots selected should have a homogeneous appearance--resembling as nearly as possible the general aspect of the field4 ,by means of a spade a few kilograms of earth are removed to the depth of the subsoil being careful to include in the sample no accidental detritus which the upper part of the soil especially may contain4 ,the samples should be taken immediately after the crop is harvested and before any fresh fertilizer is applied4 ,the samples are carefully mixed and placed in a glass bottle or flask4 ,the sample of subsoil is obtained in the same manner4 ,if the field presents notable differences in surface or fertility all the samples taken should be examined separately4 #fd4 ,method of ,whitney4#dh--;,an ordinary wood auger1 #b inches in diameter is so arranged as to admit of additions to the stem to enable the operator to take samples at different depths4 ,it may be fitted with a short piece of gas pipe for a handle and the several pieces of which it is composed may be taken apart and carried in a knapsack4 ,in taking a soil sample the boring is continued until a change in color shows that the subsoil has been reached4 ,the auger cuts a very clean sample save in excessively sandy soil4 ,after the soil sample is secured the hole is cleaned out and the sample of subsoil taken by the same instrument4 ,the soil is conveniently preserved in heavy cloth bags of which the usual size is #f by #h inches4 ,where larger samples are required the size of the bag is correspondingly increased4 ,each bag is to be tagged or labeled to correspond with the entry in the note book4 ,samples to determine the amount of empty space in a soil are taken as follows3 ,the sampler is a piece of brass cylinder about nine inches long and about #a inches in diameter4 ,a piece of clock spring is soldered in one end and sharpened to give a good cutting edge4 ,this arrangement permits the sample to pass into the cylinder without much friction4 ,the area enclosed by the clock spring is accurately determined and a mark is placed in the cylinder six inches from the cutting edge4 ,the cylinder is driven into the soil to a depth of six inches1 a steel cap being used to prevent the hammer from injuring the cylinder4 ,the earth is next removed from about the cylinder with a trowel1 and the separated cylinder of earth is cut smoothly off by a sharp knife and removed together with its brass envelope4 ,the sample is taken to the laboratory in a cloth bag1 dried and weighed4 #fe4 ,taking ,samples for ,moisture ,determination4--,a number of brass tubes is provided nine inches long and inch in diameter and with a mark six inches from the bottom4 ,the tube is pushed down into the soil to the mark and the sample of soil removed with the tube4 ,there is but little danger of the sample dropping out of the tube even in sandy soils4 ,when the tube is withdrawn each end is capped with a rubber finger tip making a perfectly air tight joint4 ,the tubes containing the samples can be kept several days with no fear of losing moisture4 ,this method is especially useful in having samples taken by observers in different localities who can enclose the tubes in a cloth sack and send them to the laboratory by mail daily or at stated intervals4 ,a tube of the size given holds about fifty grams of soil4 #ff4 ,taking ,samples to ,determine the ,permeability of ,soil to ,water or ,air4--,whitney#di determines the permeability of soil or subsoil to water or air in the following manner3 ,an excavation two feet square and eighteen inches deep is made in the soil4 ,on one side of this hole the sample of soil or subsoil is taken by means of a narrow saw blade and a sharp carving knife4 ,the sample of soil taken should be two inches square and #c to #d inches long4 ,it is placed in a brass cylinder three inches long and #c inches in diameter4 ,the open space in the cylinder is filled with paraffin heated just to its melting point4 ,as the paraffin cools the upper surface should be kept stirred to prevent the mass when set from receding from the square column of soil4 ,care must be taken to keep the paraffin from the ends of the soil columns and these should be left1 as far as possible in their natural condition4 ,the rate of percolation of the water may be determined at the time the sample is taken4 ,for this purpose an additional section of brass tube two inches deep is secured to the one holding the sample by a rubber band4 ,an iron rod is driven into the earth carrying a retort stand ring supporting a funnel filled with fine gravel4 ,the lower end of the soil column in the brass cylinder is placed on this gravel4 ,water is next carefully poured upon the top of the sample of soil being careful not to disturb the surface4 ,the surface of the sample may be protected with a little fine sand4 ,the water should be poured on the paraffin thus affording an additional protection to the soil surface4 ,when the water begins to drop from the funnel a graduated glass is set under it and the time required for a given volume to pass through under an initial pressure of two inches is noted4 ,the volume required represents one inch in depth over the four square inches of soil surface1 viz43 four cubic inches4 #fg4 ,sampling of ,soil for ,staple ,crops4--,some variations from the usual methods are recommended by ,whitney when the samples are taken from fields growing staple crops4 ,the immediate object of the work1 for which these samples are desired1 is to make a thorough study of the physical and chemical properties of a number of typical soils adapted to the different staple crops1 such as grass1 wheat1 truck1 and the different types of tobacco4 ,they should be taken for a careful study of the texture of the soils1 the relative amount and arrangement of sand and clay1 the relation of the soils to moisture and heat1 and the ease with which they can maintain a proper water supply for the different staple crops under existing climatic and cultural conditions4 ,the ultimate object of such a study is to see how these conditions can be changed so as to make the soils more productive1 and make them yield a better quality of crop1 or to change the conditions in other soils1 which differ from these1 so that the culture of the different staple crops can be extended over wider areas by improved methods of cultivation and manuring4 ,the soil selected for sampling for these investigations should be typical1 should represent fairly well a considerable area of land4 ,it should represent either the very best type of land for the staple crop or crops of the locality1 or the very poorest lands for these same crops4 ,both of these extremes are desired for contrast4 ,for example1 if the staple crop of the locality is wheat or a certain type of tobacco1 select the soil best adapted to this staple crop1 and another soil1 if possible1 in the same locality1 representing considerable area of land upon which this staple crop cannot be successfully grown on account of the inferior yield1 quality1 or the time of ripening of the crop4 ,the soil sampled should be1 or should recently have been1 under actual cultivation in the crop or crops best adapted to it1 so that the real agricultural value of the land can be accurately known4 ,the samples should be taken inside the field1 some distance away from fences1 roads1 or trees4 ,if there are plants growing in the field1 the sample should be taken about midway between two plants4 ,the samples should be taken where they will typify fairly well the average soil of the field and of the large area of land which they are to represent4 ,the samples are taken in some one of the ways described herein4 ,each sample should be carefully labelled at the time of taking4 ,the following blank form will be found convenient for this purpose3 ,locality3 ,,laboratory ,no43 ,no4 of sack3 ,description3 7virgin or cultivated74 7a7 ,natural herbage3 7b7 ,crops best adapted to land 7grass1 wheat1 tobacco1 truck1 barren74 ------------------------ ,date3 ------------------------ ,collector3 ---------------------------------------- -------- ,depth of sample3 7,soil or ,subsoil87 ,geologic formation3 444 in4 to 444 inches4 #fh4 ,method of the ,royal ,agricultural ,society4#ej--;,have a wooden box made1 six inches long and wide1 and from nine to twelve inches deep1 according to the depth of soil and subsoil in the field4 ,at one of the selected places mark out a space of twelve inches square2 dig around it in a slanting direction a trench1 so as to leave undisturbed a block of soil1 with its subsoil1 from nine to twelve inches deep2 trim this block to make it fit into the wooden box1 invert the open box over it1 press down firmly1 then pass a spade under the box and lift it up and gently turn it over4 ,in the case of very light1 sandy1 and porous soils1 the wooden box may be at once inverted over the soil and forced down by pressure1 and then dug out4 ,proceed in the same way for collecting the samples from all the selected places in the field1 taking care that the subsoil is not mixed with the surface soil4 ,the former should be sampled separately4 ,in preparing the plot for the gathering of the sample1 take care to have it lightly scraped so as to remove any dbris which may be accidentally found there4 ,the different samples thus procured are emptied on a clean1 boarded surface1 and thoroughly mixed1 so as to incorporate the different samples of the same field together4 ,the heap is then divided into four divisions1 and the opposite quarters are put aside1 taking care to leave the two remaining ones undisturbed2 these are thoroughly mixed together1 the heap divided into quarters1 and the opposite ones taken away as before4 ,this operation of mixing1 dividing into quarters and taking away the opposite quarter is continued until a sample is left weighing about ten or twelve pounds4 ,thus is obtained the average sample of the soil4 ,of course where only a single sample is taken from the field this method of quartering is not resorted to1 but the bottom of the box is nailed directly on and sent to the laboratory1 where the soil is to be analyzed4 #fi4 ,grandeau#ea suggests that in taking soil samples there are two cases to be considered2 first a homogeneous soil and second1 a soil variable in its appearance and composition4 ,first1 if the soil is homogeneous1 being of the same geologic formation it will be sufficient to take a mean sample in accordance with the following directions3 ,the field is first divided by diagonals or by transverse lines the direction of which need not be fixed in advance but as inspection of the form and configuration of the field may indicate4 ,in the ordinary conditions1 of homogeniety 7marly1 granite1 argillaceous or silicious soils7 it will be sufficient to select about five points per hectare from which the samples are to be taken4 ,these points having been determined the surface is cleaned in such a way as to remove from it the detritus which may accidentally cover it2 such as dry leaves1 fragments of wood1 foreign bodies1 etc4 ,the surface having been prepared1 7five to six square meters7 a hole is dug four-tenths of a meter long and as wide as the spade employed4 ,the sides should be as nearly vertical as possible4 ,as to depth it varies with the usage of the country in regard to tillage4 ,the layer of arable earth is what in effect properly constitutes the soil4 ,it ought not to be mixed with any fragments of the subsoil4 ,when the hole is properly cleaned the samples are secured with a spade from the sides of the excavations4 ,about five kilograms are taken4 ,the soil is placed in a proper receptacle as it is removed from the hole4 ,this operation is repeated on as many points as may be necessary to obtain a mean sample of the soil of the whole field4 ,all the samples are now collected on a table sufficiently large1 and intimately mixed together4 ,two samples1 each of about five kilograms1 are then taken from the mixed material4 ,one sample is immediately placed in bottles and carefully stoppered and sealed2 the other is dried in the sun or on the hearth of a furnace4 ,when sufficiently dry the second sample is also placed in bottles and well stoppered4 ,while mixing the samples1 pebbles1 etc41 of the size of a nut and larger are removed1 the weight of the rejected matter being determined4 ,the nature of the pebbles should also be noted2 whether silicates1 limestone1 etc4 ,the sample of subsoil is taken in exactly the same manner1 using the same holes from which the samples of soil were taken4 ,the nature1 the arrangement and the appearance of the strata will indicate the depth to which the subsoil should be taken4 ,in general1 a depth equal to that of the sample of soil will be sufficient4 ,the depth to which the roots of cultivated plants reach is also a good indication in taking a sample of the subsoil4 ,in forests the sample of subsoil should be taken from four to five-tenths of a meter below the surface4 ,if the soil in respect of its geologic formation1 its fertility or its physical aspect presents great differences1 special samples should be taken in each part in accordance with the directions given above4 #gj4 ,method of the ,official ,agricultural ,chemists4--,in the directions given by the ,association of ,official ,agricultural ,chemists#eb it is stated that the soil selected should be as far as possible in its natural condition1 not modified by recent applications of manure1 or changed by the transporting action of water or wind4 ,surface accumulations of decaying leaves1 etc41 should be removed before taking the sample4 ,to eliminate accidental variations in the soil1 select specimens from five or six places in the field which seem to be fair averages of the soil1 remove two or three pounds of the soil1 taking it down to the depth of nine or ten inches#ec so as to include the whole depth4 ,mix these soils intimately1 remove any stones1 shake out all roots and foreign matter1 and dry the soil until it-becomes friable4#ed ,break down any lumps in a mortar with a wooden pestle1 but avoid pulverizing any mineral fragments2 pass eight to ten pounds of the soil through a sieve1 having circular perforations one twenty-fifth of an inch in diameter1 rejecting all pebbles and materials too coarse to pass through the sieve4 ,once more mix intimately the sifted soil4 ,expose in thin layers in a warm room till thoroughly air dry 7or dry it in an air-bath at a temperature of #dj71 place six to eight pounds in a clean bottle1 with label of locality and date1 and cork the bottle containing the soil1 for analysis4 ,the soil is rapidly dried to arrest nitrification2 it is not heated above #dj lest there should be dissipation of ammonia compounds1 or a change in solubility4 ,the normal limit to which the soil may be heated in place by the sun's rays should not be exceeded in preparing a sample for an agricultural chemical analysis4 ,the relative amount of fragments too coarse to pass through the sieve should be made a matter of record4 ,they are soil material1 but not yet soil1 so far as agricultural purposes are concerned4 #ga4 ,method of ,lawes4--,in a late method of sampling proposed by ,sir ,j4 ,b4 ,lawes#ee a steel frame ten by twelve inches1 and nine inches deep open at top and bottom is driven into the earth until its upper edge is level with the surface of the soil4 ,all above-ground vegetation is then cut off as closely as possible with scissors4 ,the soil within the frame is then removed exactly to the depth of the frame1 and immediately weighed4 ,it is then partially dried1 and mechanically separated by a series of sieves1 all visible vegetable matter being at the same time picked out4 ,the stones and roots and the remaining soil are thus separated1 and the determinations of dry matter1 nitrogen1 etc41 are made in the separated soil after being finely powdered4 ,the loss of water at each stage of preparation and on drying the samples as analyzed is also carefully determined4 ,this method1 which requires the soil to be taken to an arbitrary depth of nine inches1 could not be used when samples of strictly arable soil are to be taken4 #gb4 ,in taking a sample by the ,french commission#ef method it is necessary to remove from the surface1 the living and dead vegetation which covers the soil4 ,with a spade a square hole is then dug to the depth of about #ejj millimeters2 in other words1 to a depth considerably exceeding that of the arable layer4 ,afterwards on each of the four sides of the hole there is removed by the spade1 a prismatic layer of the arable portion of a thickness equal to its depth4 ,the samples thus obtained are united together and carefully mixed for the purpose of forming a sample for analysis4 ,if there are large stones they are removed by hand and their proportion by weight determined4 ,in all cases it would prove useful to take a sample of the subsoil which is far from playing a secondary rle4 ,the rootlets bury themselves deeply in it and seek there a part of their nourishment4 ,the subsoil1 therefore1 furnishes an important addition to the alimentation of the plants4 ,for taking a sample of the subsoil a ditch is dug of sufficient depth1 say one meter1 and the arable soil carefully removed from the top portion4 ,afterwards pieces are taken from the four sides of the hole at variable depths1 which should always be indicated1 and which should extend in general1 from six to eight-tenths of a meter below the arable soil since it is demonstrated that the roots of nearly all plants go at least to this depth4 ,the analysis of the subsoil1 however1 is less important than that of the soil1 properly so-called1 because the agronomist does not act directly upon it and takes no thought of modifying it and enriching it as he does the layer of arable soil4 ,but the composition of the subsoil is a source of information capable of explaining certain cultural results and capable sometimes1 of leading to the correct way of improving the soil1 as in cases where the subsoil can be advantageously mixed with the superficial layer4 #gc4 ,wolff#eg suggests that a hole thirty centimeters square be dug perpendicularly and a section from one of the sides taken for the sample4 ,to the depth of thirty centimeters the sample shall be taken as soil and to the additional depth of thirty centimeters as subsoil4 ,the thickness of the section taken may vary according to the quantity of the sample desired4 ,for analytical purposes1 five kilograms will usually be sufficient4 ,when culture experiments are also contemplated a larger quantity will be required4 #gd4 ,method of ,wahnschaffe4--,the method of sampling advised by ,wahnschaffe#eh is but little different from that of ,wolff already mentioned4 ,a square sample hole is dug with a spade having its sides perpendicular to the horizon4 ,the soil which is removed is thrown on a cloth and carefully mixed4 ,from the whole mass a convenient amount is next removed care being taken not to include any roots4 ,in a similar manner it is directed to proceed for the sample of subsoil4 ,at first the subsoil should be removed to a depth of two to three decimeters4 ,the number and depth of subsequent samples will depend chiefly upon the character of the soil4 ,where samples are taken to the depth of two meters the use of a post-hole auger is recommended4 ,the samples taken should not be too small4 ,in general from two to three kilograms should remain after all preliminary sampling is finished4 #ge4 ,method of ,knig4--,the directions given by ,knig#ei for taking soil samples are almost identical with those prescribed by ,wahnschaffe and do not require any further illustration4 #gf4 ,special ,instruments ,employed in ,taking ,samples4--,in general a sharp spade or post-hole auger is quite sufficient for all ordinary sampling but for certain special purposes other apparatus may be used4 ,the instrument which is used by ,king#fj consists of a thin metal tube of a size and length suited to the special object in view1 provided with a point which enables it to cut a core of soil smaller than the internal bore of the tube and at the same time make a hole in the ground larger than its outside diameter4 ,its construction is shown in figure #aa1 in which ,a ,b represent a soil tube intended to take samples down to a depth of four feet4 ,a is a cross-section of the cutting end of the tube1 which is made by soldering a heavy tin collar1 about three inches wide1 to the outside of a large tube allowing its lower end to project about one-half an inch4 ,into this collar a second one is soldered with one edge projecting about one-quarter of an inch and the other abutting directly against the end of the soil tube4 ,still inside of this collar is a third about one-half an inch wide which projects beyond the second and forms the cutting edge of the instrument4 ,illustration3 ,,figure #aa4 ,the construction of the head of the tube is shown at ,b4 ,it is formed by turning a flange on the upper end of the tube and then wrapping it closely with thick wire for a distance of about three inches1 the wire being securely fixed by soldering4 ,the soil tube should be of as light weight as possible not to buckle when being forced into the ground1 and the cutting edge thin4 ,the brass tubing used by gas fitters in covering their pipes has been found very satisfactory for ordinary sampling4 ,with a one inch soil tube four feet long it is possible to get a clear continuous sample of soil to that depth by simply forcing the tube into the ground with the hand and withdrawing it1 or the sample may be taken in sections of any intermediate length4 ,later in the season when the soil becomes dryer it is necessary to use a heavy wooden mallet to force the tube1 and this should be done with light blows4 ,the closeness with which it is possible to duplicate the samples in weight by this method will be seen below1 where from each of four localities three samples were taken from the surface to a depth of four feet4 ,,showing ,,variations ,,in ,,the ,,dry ,,weight ,,of ,,triplicate ,,samples ,,of ,,soil4 ,a4 ,b4 ,c4 ,i4 ,surface to four feet#gaf4f gms4#gae4e gms4#gaj4c gms4 ,,ii4 ,surface to four feet#gae4d gms4#fhg4a gms4#gca4b gms4 ,,iii4 ,surface to four feet#fed4j gms4#fhh4c gms4#gji4j gms4 ,,iv4 ,surface to four feet#gad4j gms4#fhg4h gms4#gai4c gms4 ,these four series of samples were taken at the four corners of a square twelve feet on a side and serve to show how much samples may vary in that distance4 ,the large difference shown in ,,iii1 ,a is due to the fact that the soil tube penetrated a hole left by the decay of a rather large root as shown by the bark in the sample4 #gg4 ,auger for ,taking ,samples4--,it has already been said that the ordinary auger used for boring fence post-holes may be used to advantage in taking soil samples4 ,large wood augers can also be used to advantage for the same purpose4 ,for special purposes1 however1 other forms of augers may be used4 ,norwacki and ,borchardt#fa have described a new auger for taking samples of soil for analytical purposes4 ,illustration3 ,,figure #ab4 ,in figure #ab1 ,a1 ,b and ,c show the general exterior and interior form of the instrument4 ,the handle is hollow and made of iron gas pipe covered with leather4 ,on the inside of this1 in the middle1 is fixed a wooden plug a1 which leaves two compartments1 one in each end for holding the brass plug bb1' and the wicker lubricating wad cc4' ,the stem of the auger a1 is heavy and made of eight-sided steel and the under end is strengthened with a heavy casting fitting into the auger guide g g4 ,the end of the auger ,i ,i is triangular and hardened4 ,the auger guide g g1 is made out of a single piece of drawn steel tubing4 ,above it is strengthened by a ring-shaped piece of iron or copper and its lower end is furnished with saw teeth as shown in ,k and is hardened4 ,the fixing key e1 is bent in the form of a hook and can be passed through the two holes o o1 of the auger stem and through the one hole o in the strengthened part of the auger guide4 ,it permits the auger guide to be fixed upon the auger stem in two different positions1 higher and lower4 ,on one end it is cut squarely across and on the other provided with a conical hole drilled into it4 ,it fits on the one hand exactly in the auger guide and on the other loosely plays in the cavity of the handle at b1 designed to hold it when not in use4 ,the cap d is made of heavy sheet brass and is fastened upon the end of the handle at c c after the manner of a bayonet4 ,the wicker cartridge is made of rolled and sewed wicker-work4 ,at the upper end it is provided with a metallic button and before use it is saturated with paraffin oil4 ,it fits on the one side firmly in the auger guide and on the other in the cavity1 of the handle c where it is kept when not in use4 ,the union h is made of a brass tube which below is closed with a piece of solid brass upon the inside of which a hole is bored4 ,in this hole rests the end of the auger stem when the union is placed firmly upon the auger guide4 ,the auger is placed together as is shown in ,a ,b1 the union h is taken off and it is driven with gentle blows1 turning it back and forth1 to the proper depth into the soil4 ,after the key is loosened the auger is lifted high enough so that the second hole appears and then it is fixed in position by the key4 ,then the boring is continued1 turning the auger to the right1 by which the auger1 eating its way with its saw teeth1 presses deeper into the ground and withdraws the material for analysis4 ,after the auger guide has been filled through any desired length1 say five to ten centimeters with the sample of soil1 the whole auger is drawn out of the soil1 the key removed1 the auger stem withdrawn from the auger guide1 the apparatus opened by turning the bayonet fastening of the stopper on the handle1 the brass plug placed in the end and then with the smooth part forward1 from above1 it is allowed to fall into the auger guide until it reaches the soil4 ,the auger stem is then put back1 the point of it fitting into the hole of the plug and the sample of soil shoved out of the auger guide4 ,the auger guide is again fixed on the auger stem by the key and then the apparatus is ready for a second operation4 ,when the borings cease the wicker cartridge is drawn out of the handle and shoved1 the soft end forward1 from above1 into the auger guide and the brass plug after it and pushed through with the auger stem4 ,by this process the wicker cartridge gives up a sufficient amount of paraffin oil to completely grease the inside of the auger guide and to protect it from rust4 ,after use the instrument should be cleaned on the outside by means of a cloth1 the plug and wicker wad replaced in their proper positions1 the cap fixed on the handle and the union on the point of the instrument4 ,the length of the whole apparatus may reach one meter or more2 the internal diameter sixteen millimeters4 ,the apparatus weighs with a length of one meter1 together with all its belongings1 about two kilograms4 ,for the investigation of peat and muck soils as well as sand1 instead of the steel auger guide one of brass or copper can be used4 ,for this purpose the length of the apparatus may reach three to four meters4 ,in comparison with other apparatus which are used for taking samples1 it appears without doubt that with the one just described a better and less mixed portion of the soil can be obtained at great depths4 ,the apparatus is said to have many advantages over a similar one known as ,fraenkel's1 and is much more easy to clean4 ,the advantages of the apparatus are said to be the following3 ,the farmer with this piece of apparatus in a short time can go over his whole farm taking samples to the depth of ninety centimeters since a single boring does not take more than one minute4 ,geologists and others interested in the soil at greater depths can use an apparatus three to four meters in length and obtain unmixed samples from these lower depths4 ,these are also interesting from a bacteriologic point of view4 ,the entire apparatus is especially valuable for the investigation of the lower parts of peat and muck soils4 ,the apparatus has been tried in the collection of samples for the laboratory of the ,department of ,agriculture and is too complicated to be recommended for ordinary use4 ,when however samples are to be taken at great depths as in peat soils it is highly satisfactory4 #gh4 ,soil ,sampling depends for its success more on the judgment and knowledge of the collector than on the method employed and the apparatus used4 ,one skilled in the art and having correct knowledge of the purpose of the work will be able to get a fair sample with a splinter or a jack-knife while another with the most elaborate outfit might fail entirely in collecting anything of representative value4 ,there are some special kinds of soil sampling1 however1 which cannot be left to the method of the individual and it is believed that with the descriptions given above nearly all purposes for which samples are desired may be served4 ,for the study of nitrifying organisms1 however1 special precautions are required and these will be noted in a more appropriate place4 ,in taking samples for moisture determinations the method of ,whitney is recommended as the best4 ,for the general physical and chemical analytical work the standard methods are all essentially the same4 ,the principles laid down by ,hilgard will be found a sufficient guide in most cases4 ,,treatment ,,of ,,sample ,,in ,,the ,,laboratory4 #gi4 ,the ,sample1 or mixed sample1 taken by one of the methods above described1 is placed on a hard smooth board1 broken up by gentle pressure into as fine particles as possible and all pieces of stone and gravel carefully removed and weighed2 all roots1 particles of vegetable matter1 worms1 etc41 are also to be weighed and thrown out4 ,this can be done very well by using a sieve of from one to two millimeter mesh4 ,care should be taken that the soil be made to pass through1 which can be accomplished by subjecting the lumps to renewed pressure with a rubber-tipped pestle4 ,in the above operation the soil should be dry enough to prevent sticking4 ,the relative weights of the pebbles1 roots1 etc41 and the soil should be determined4 #hj4 ,order of ,preliminary ,examination4--,hilgard#fb commences the examination of a soil sample by washing about ten grams of it into a beaker with a water current of definite velocity1 stirring meanwhile actively the part carried into the vessel4 ,the residue not carried by the current is examined macro- and microscopically to determine the minerals which may be present1 and the condition in which the fragments exist--whether sharp or rounded edges1 etc4 ,this examination will give some general idea of the parent rocks from which the sample has been derived and of the distance the particles have been transported4 ,next follows the hand test1 viz41 rubbing the soil between the thumb and fingers first in the dry state and afterwards kneading it with water and observing its plasticity4 ,following this should come a test of the relations of the sample to water1 viz41 its capacity for absorbing and retaining moisture4 ,finally the separation of the soil into particles of definite hydraulic value and a chemical examination of the different classes of soil concludes the analytical work4 #ha4 ,air ,drying4--,the sifted soil should be thoroughly mixed and about one kilogram spread on paper and left for several days exposed in a room with free circulation of air and without artificial heat4 ,the part of the sample to be used for the determination of nitrates should be dried more quickly as described in another place4 ,the sample is then placed in a clean1 dry glass bottle1 corked1 sealed1 and labeled4 ,the label or note book should indicate the locality where the sample was taken1 the kind of soil1 the number of places sampled1 and other information necessary to proper description and identification4 #hb4 ,caldwell#fc directs that having taken the sample to the laboratory1 the stones and larger pebbles should be separated from the finer parts by the hand1 or by sifting with a very coarse sieve1 and examined with reference to their mineralogical character1 weight and size1 making note1 in this last respect1 of the number that are as large as the fist or larger1 the number as large as an egg1 a walnut1 hazel-nut1 and pea1 or give the percentage of each by weight4 ,pulverize the air-dried soil in a mortar with a wooden pestle1 and separate the fine earth by a sieve with meshes three millimeters wide2 this sieve should have a tightly fitting cover of sheepskin stretched over a loop1 and it should be covered in the same manner underneath1 so that no dust can escape during the process of sifting4 ,wash the pebbles and vegetable fibers remaining on the sieve with water1 dry and weigh the residue2 the water with which this gravel was washed should be evaporated to dryness at a temperature not exceeding #ej towards the close of the evaporation1 and the residue mixed with what passed through the dry sieve4 ,the sifted fine earth is reserved for all the processes hereinafter described1 and is kept in well-stoppered bottles1 marked air-dried fine earth4 ,the sieve mentioned above is too coarse for the more modern methods of analysis4 #hc4 ,wolff#fd directs that the air-dried earth 7in summer dried in thin layers at room temperature1 in winter in ovens at #cj to #ej7 be freed from all stones1 the latter washed1 dried1 and weighed4 ,the soil is next passed through a three millimeter mesh sieve1 the residual pebbles and fiber washed1 dried and weighed4 ,the fine earth passing the sieve is used for all subsequent examinations4 ,it is air-dried at moderate temperatures and preserved in stoppered glass vessels4 #hd4 ,the ,french#fe commission calls especial attention to the method of subsampling1 and prescribes that the sample of earth which has been taken in the manner indicated1 and of which the weight should be greater as the material is less homogeneous should not be analyzed as a whole4 ,it should be divided into two parts4 ,the first includes the finer particles constituting the earth1 properly so-called1 with the elements which alone enter into play in vegetable nutrition and on which it is necessary to carry out the analysis4 ,the second embraces the coarser particles to which only a superficial examination should be given and which may have a certain importance from a physical point of view but which cannot take any part from a chemical point of view1 in the nutrition of plants4 ,it is1 however1 useful to examine its mineralogical constitution and to look for the useful elements such as lime1 potash1 etc41 which it may be able to furnish to the earth1 and in proportion as it is decomposed1 finer particles which may be useful in plant nutrition4 ,how are we to distinguish between the fine and coarse elements8 ,all grades of fineness are observed in the soil1 from the particles of hydrated silica so small that with the largest magnifying power of the microscope it is scarcely possible to distinguish them1 up to grains of sand which are of palpable size and visible to the naked eye1 and extending to pebbles of varying sizes4 ,all intermediate stages are found between these and if it should be asked what is the precise limit at which it is necessary to stop in distinguishing the fine from the coarse elements of the soil1 the answer is that this can only be determined by a common understanding among analysts4 ,in general1 it may be said1 that the mark of distinction should be the separation which can be secured with a sieve having ten meshes per centimeter4 #he4 ,loose ,soils4--,having agreed upon a sieve of the above size1 the process of separation in loose soils is as follows3 ,the earth is exposed to the air and when the touch shows that it is sufficiently dry the conglomerated particles should be simply divided without breaking the rocky material which exists in a state of undivided fragments4 ,there are some special precautions to be taken4 ,rubbing in a mortar must be forbidden since it reduces the earth to particles which are unnatural in size1 by securing the breaking up of the fragments consisting of the dbris of rocks4 ,when it is possible the earth should be rubbed simply in the hand and after having separated that which passes the sieve1 the large particles which have not passed should be again rubbed with the hand1 until all the particles which can be loosened by this simple treatment have passed the sieve4 ,the separation should be as complete as possible in order that a sample of the particles passing the sieve should represent as nearly as possible1 a correct sample of the fine particles of the soil4 ,in regard to the pebbles1 they should be washed with water upon the sieve in order to carry through the last of the particles of earth adhering to them4 ,they are then dried and their weight taken4 ,the fine part of the earth is also weighed4 ,on an aliquot part1 say #ajj grams1 the moisture is determined and then by simple calculation the whole sample of the air-dry soil can be calculated to the dry state4 ,the sample is then placed in a glass flask4 ,the pebbles are examined with a view of determining their mineralogical constitution2 as for instance1 on being touched with a little hydrochloric acid it can be determined whether or not they are carbonate of lime4 ,the nature of the rock from which they have been derived is often to be determined by a simple inspection4 #hf4 ,compact ,soils4--,if the soils are not sufficiently loose to be treated as before described1 it is necessary to have recourse to other means of division1 which should not1 however1 be sufficiently energetic to reduce the rocky elements to fine particles4 ,for this purpose the earth may be broken by means of a wooden mallet1 striking it lightly and separating the fine elements from time to time by sifting4 ,a wooden roller may also be used with a little pressure1 for breaking up the particles or a roller made out of a large glass bottle4 ,these methods will permit of a sufficiently fine division of the soil without breaking up any of the pebbles4 ,sometimes1 however1 a soil can not be broken up by such treatment4 ,it is then necessary to have recourse to the following process3 ,the soil is thoroughly moistened and afterwards rubbed up with water4 ,the paste which is thus formed1 is poured upon the sieve and washed with a stream of water until all the fine particles are removed4 ,the wash water and the fine particles are left standing until the silt is thoroughly deposited when the supernatant water is poured off and the deposited moist earth is transferred into a large dish and dried on a sand or water-bath4 ,in this way a firm paste is formed which can be worked up with the hand until rendered homogeneous and afterwards an aliquot portion be taken to determine moisture4 #hg4 ,method of ,peligot4--,the method recommended by ,peligot#ff for the preparatory treatment of the sample is essentially that already described4 ,the sample is at first dried in the air and then in an oven at #abj4 ,when dry and friable #ajj grams are placed in a mortar and rubbed with a wooden pestle4 ,it is then passed through a sieve of ten meshes per centimeter4 ,the largest particles which remain in the sieve should have about the dimensions of a pin's head4 ,the stones are separated by hand4 ,they should be shaken with water in order to detach any pulverulent particles adhering thereto4 ,the turbid water resulting from this treatment is added to that which is used in separating the sand from the impalpable part of the soil4 #hh4 ,wahnschaffe prescribes#fg in the further preparation of the sample for analysis that the coarse pieces up to the size of a walnut be separated in the field where the sample is taken and their relative weight and mineralogical character determined4 ,the soil sample is then to be placed in linen or strong paper bags and carefully labelled4 ,in order to avoid any danger of loss of label the description or number of the sample should be put on the cloth or paper directly4 ,the sample when brought to the laboratory should be spread out to dry1 in a room free of dust4 ,in the winter the room should be heated to the usual temperature4 ,the air drying should continue until there is no sensible loss of weight4 ,the samples then are to be placed in dry1 glass-stoppered glass bottles where they are kept until ready for examination4 ,this method of keeping the samples avoids contact with ammonia or acid fumes with which a laboratory is often contaminated4 #hi4 ,the ,swedish chemists#fh direct that samples which are to be used for chemical examination in the manner described below1 are most conveniently brought to such a condition of looseness and humidity that the soil feels moist when pressed between the fingers without1 however1 sticking to the skin4 ,to prepare the sample in this manner1 spread it in a large porcelain dish or on a glass plate in a place where it is not reached by the laboratory atmosphere2 stir it frequently till it assumes the mentioned humidity 7if the sample when sent is too dry1 moisten it with distilled water till its condition is as indicated72 then pulverize carefully between the fingers and finally sift through a sieve with five millimeter holes4 ,in this way free the sample from stones1 undecayed roots and similar parts of plants1 pieces of wood1 and other matter strange to the soil1 which remain on the sieve2 mix the sample carefully and put it into a glass bottle provided with a stopper well ground in2 keep it in a cool place4 ,samples prepared in this way will usually contain #bj-cj per cent moisture2 boggy soils #fj-hj per cent and peat soils #ej per cent4 #ij4 ,petermann#fi follows the method below in preparing samples of soil for analysis4 ,the soil is gently broken up by a soft pestle and all dbris if of organic nature1 cut fine with scissors4 ,about #bejj grams of this soil are passed through a one millimeter mesh sieve4 ,the organic dbris is removed by forceps1 washed free of adhering earth dried at #abj and weighed4 ,the nature of the organic dbris should be noted as carefully as possible4 ,the pebbles and mineral dbris not passing the sieve are worked in a large quantity of water by decantation4 ,they are also dried at #abj and weighed4 ,this dbris is examined mineralogically and thus some idea of the origin of the soil obtained4 #ia4 ,the various methods for the preliminary treatment as practiced by the best authorities have been somewhat fully set forth in the foregoing rsum4 ,the common object of all these procedures is to get the soil into a proper shape for further physical and chemical examination and to determine the comparative weights of foreign bodies contained therein4 ,the essential conditions to be observed are the proper sifting of the material and avoidance of mechanical communition of the solid particles too large to pass the meshes of the sieve4 ,if possible the material should be passed through a sieve of one millimeter mesh4 ,in cases where this is impracticable a larger mesh may be used1 but as small as will secure the necessary separation4 ,before final chemical analysis a half millimeter mesh sieve should be employed if the soil be of a nature which will permit its use4 ,over-heating of the sample should be avoided4 ,rapid drying is advisable when the samples are to be examined for nitrates4 ,the method recommended by the ,french commissions seems well adapted to the general treatment of samples1 but the analyst must be guided by circumstances in any particular soil4 ,,authorities ,,cited ,,in ,,part ,,second4 ,footnote #ci3 ,bulletin #ch1 pp4 #fa-b4 ,footnote #dj3 ,ms4 communication to author4 ,footnote #da3 ,bulletin ,no4 #aj4 ,footnote #db3 ,landwirtschaftliche ,versuchs-,stationen1 ,band #ch1 ,ss4 #cji et seq4 ,footnote #dc3 ,annales de la ,science ,agronomique1 ,tome #a1 ,part #b1 p4 #bdj4 ,footnote #dd3 ,agricultural ,chemical ,analysis1 p4 #aff4 ,footnote #de3 ,zeitschrift fr analytische ,chemie1 ,band #c1 ,s4 #hg4 ,footnote #df3 ,anleitung zur ,wissenschaftlichen ,bodenuntersuchung1 ,s4 #ag4 ,footnote #dg3 ,trait de ,chimie ,analytique1 p4 #adi4 ,footnote #dh3 ,bulletin #ce1 p4 #ajh4 ,footnote #di3 ,op4 cit4 ,footnote #ej3 ,bulletin #aj1 p4 #cc4 ,footnote #ea3 ,analyse des ,matires ,agricoles1 p4 #aca4 ,footnote #eb3 ,bulletin #ch1 p4 #bjj4 ,footnote #ec3 ,this in some instances would include a part of the subsoil4 ,footnote #ed3 ,all soils do not become friable on drying4 ,footnote #ee3 ,journal of the ,royal ,agricultural ,society1 7#b71 ,vol4 #be1 p4 #ab4 ,footnote #ef3 ,annales de la ,science ,agronomique1 ,tome #a1 ,part ,second1 pp4 #bdj et seq4 ,the personnel of the commission is as follows3 ,,mm4 ,risler1 ,grandeau1 ,joulie1 ,schloesing1 and ,mntz4 ,footnote #eg3 ,vid4 #g4 ,footnote #eh3 ,anleitung zur ,wissenschaftlichen ,bodenuntersuchung1 ,s4 #ag4 ,footnote #ei3 ,untersuchung ,landwirtschaftlich und ,gewerblich ,wichtiger ,stoffe1 ,s4 #e4 ,footnote #fj3 ,seventh ,annual ,report of the ,wisconsin ,agricultural ,experiment ,station1 p4 #afa4 ,footnote #fa3 ,deutsche ,landwirtschaftliche ,presse1 ,band #ai1 ,no4 #ce1 ,ss4 #chc-d4 ,footnote #fb3 ,journal ,american ,chemical ,society1 ,vol4 #af1 p4 #cf4 ,footnote #fc3 ,agricultural ,chemical ,analysis1 p4 #afh4 ,footnote #fd3 ,vid4 #g4 ,footnote #fe3 ,vid4 #af4 ,footnote #ff3 ,vid4 #i4 ,footnote #fg3 ,vid4 #h1 p4 #ai4 ,footnote #fh3 ,methods of ,analysis of ,soils1 ,fertilizers1 etc41 adopted by the ,swedish ,agricultural ,chemists1 translated for the author by ,f4 ,w4 ,woll4 ,footnote #fi3 ,l',analyse du ,sol1 p4 #ad4 ,,part ,,third4 ,,physical ,,properties ,,of ,,soils4 #ib4 ,the ,soil as a ,mass4--,the soil constituted as indicated in the preceding pages1 is now brought to the analyst for investigation4 ,the properties with which he first becomes acquainted are those which impress his senses as mass characteristics4 ,there is a perception of color1 consistence1 weight and other features which the soil possesses as a whole4 ,the several constituents of the soil must first be considered as molecular and mole aggregates4 ,in other words1 the soil in its natural state is a mechanical mixture of particles which must first be considered as a whole4 ,the physical properties of the soil1 therefore1 should engage the attention of the analyst before he proceeds to the investigation of the properties of its several constituents as classified by the relative size or hydraulic value of the particles of which they are composed1 or to a chemical determination of the compounds or elements therein contained4 ,,determination ,,of ,,physical ,,properties4 #ic4 ,color4--,the color of a soil depends chiefly upon the proportion of organic matter and iron compounds which it contains and the state of subdivision of its particles4 ,when a soil contains a large amount of organic matter1 especially when this organic matter is in an advanced state of decay1 it assumes more or less a black color when moist4 ,this black color is to be distinguished from the black alkali tint which is produced by the action of carbonate of soda on organic matter4 ,the naturally black color of a soil containing a large amount of organic matter depends1 however1 either upon the action of mineral matters upon this organic matter1 as in the case of the black alkali mentioned1 or upon the blackish color of carbon resulting from the slow combustion of the organic matter during the period of decay4 ,the presence of a large amount of ferric oxid in soil gives the well-known red color so well-marked in the soils of southwestern ,kentucky and other portions of the ,united ,states4 ,the preponderance of sand in a soil tends to produce a light yellow or whitish tint1 while certain kinds of clay have a bluish tint probably due to the presence of ferrous salts4 ,the influence of the color of the soil upon the color of the vegetation is also well-marked1 the black soils as a rule producing a much deeper green tint of foliage than the light colored soils4 ,this effect should not be attributed to color alone for as a matter of fact highly colored soils are usually very close and very retentive of moisture1 which is one reason1 probably1 for their not being more highly oxidized4 ,such soils will produce a more vigorous and ranker growth of vegetation1 but it is the texture of the soil and the more moist condition which it maintains1 rather than the color1 which produce the deeper green tint of foliage4 ,the color of a soil is also used as an index of its fertility1 the black and red soils being usually the most fertile4 ,it may be well to add here the probable reason as given by ,whitney for this1 viz41 that the deeper color shows that the oxids of iron and the organic compounds have less oxygen and indicate that the soils are quite retentive of moisture and rather tend to the exclusion of air1 so that part of the oxygen of the iron compounds and of the organic matters has been used up in the oxidation processes within the soil4 ,it is known1 for example1 that wood oxidizes much more rapidly around a rusty nail than where it is simply exposed to the air1 the iron oxid acting as a carrier between the oxygen of the air and the organic matter4 ,in a sandy soil1 on the contrary1 where there is usually less moisture and much freer circulation of air1 the iron compounds have more oxygen and usually have a light yellow color4 ,if this sand is heated1 however1 with the exclusion of air1 and especially in the presence of organic matters1 part of this oxygen will be given off and there will be the same red color as in the heavier clay soils4 ,it is frequently noticed1 also1 in compact clays that where air gains access through cracks or root-holes1 the color is altogether modified4 #id4 ,determination of ,color4--,there is no process which will give experimentally and accurately the color of a soil sample4 ,the changes which the color of a soil undergoes in passing from a saturated to an anhydrous state are well-marked4 ,the analyst will have to be content with giving as nearly as possible a description of the color of the sample when taken and the changes which it undergoes in air drying or on heating in a bath to #ajj-aaj1 or in heating to redness with or without exclusion of the air4 ,these changes in color will give some indication of the character of the organic and mineral matters present4 #ie4 ,odoriferous ,matters in ,soil4--,it is known that the soil emits a peculiar odor which is not disagreeable except when it has been recently wet1 for instance1 after a short rain4 ,several attempts have been made to discover the nature of this odor4 ,these researches have established the fact that the essential principle of this odor resides in an organic compound of a neutral nature of the aromatic family and which is carried by the vapor of water after the manner of a body possessing a feeble tension4 ,the odor is penetrating1 almost piquant1 and analogous to that of camphorated and quite distinct from other known substances4 ,in regard to the quantity of this substance1 it is extremely minute and can be regarded as being only a few millionths of a per cent4 ,according to ,berthelot and ,andr#gj this new principle is neither an acid nor an alkali nor even a normal aldehyd4 ,it is1 in a concentrated aqueous solution1 precipitable by potassium carbonate with the production of a resinous substance4 ,heated with potash it develops a sharp odor similar to the aldehyde resin4 ,it does not reduce the ammoniacal nitrate of silver4 ,treated with potash and iodin it gives an abundant formation of iodoform1 which1 however1 is a property common to a great number of substances4 ,for the qualitative and quantitative estimation of the odoriferous matter the following process is employed3 ,about three kilograms of the soil are mixed with sand containing a small amount of carbonate of lime and some humic substance2 after having freed it from all organic dbris which is visible1 it is placed in a glass alembic4 ,the soil should contain from ten to twelve per cent of water at least4 ,the alembic is placed in a sand bath and is kept at #fj for several hours4 ,the water evaporated is condensed until about seventy-five cubic centimeters are distilled over4 ,this distilled water is again rectified so as to obtain in all about twenty cubic centimeters4 ,the odoriferous matter appears to be nearly all contained in this twenty cubic centimeters4 ,the liquid thus obtained shows an alkaline reaction2 it contains some ammonia and reduces ammoniacal silver nitrate4 ,this last reaction is due to some pyridic alkali or analogue thereof1 and is cause for it to be distilled anew with a trace of sulfuric acid which gives a neutral liquor deprived of all reducing action but which preserves the odor peculiar to the soil4 ,the twenty cubic centimeters obtained as before are subjected to two additional distillations and in the final one only one cubic centimeter of liquid is distilled over4 ,the peculiar odor is intensified proportionately as the volume of the liquid is decreased4 ,to this one cubic centimeter1 is added some pure crystallized potassium carbonate4 ,the liquor is immediately troubled and some hours are required for it to become clear again4 ,meanwhile there is formed upon its surface a resinous ring almost invisible1 amounting at most to from ten to twenty milligrams of a matter which has not been identified with any known principle4 ,the reactions described above1 however1 permit of its general character being known4 ,this resinous matter contains the odoriferous principle1 the composition of which is not yet definitely known4 #if4 ,specific ,gravity4--,the density of a soil depends on its composition1 the fineness of its particles and upon the packing which it has received4 ,it has in other words an apparent and a real specific gravity4 ,it is easy to see that a soil in good tilth would weigh less per cubic foot than one which had been pressed closely together1 as in a road or well-pastured field4 ,ordinary soils in good tilth have an apparent specific gravity of about #a4b1 and when entirely free from air1 a real specific gravity of about #b4e4 ,if the apparent specific gravity of a soil sample were #a4b and the air were removed1 leaving a vacuum in the interstices of the soil1 the apparent specific gravity would not be sensibly increased4 ,the figure #a4b is the apparent specific gravity of a mixture of soil material which is about #b times heavier than water1 and of an extremely small proportion by weight of air which is about #ajjj times lighter than water4 ,the figure #b4e is about the true specific gravity of the real soil material1 and shows that this material is about #b times heavier than an equal volume of water4 ,the weights of a cubic foot of different kinds of soil as given by ,schbler#ga are as follows2 ,pounds4 ,sand #aaj ,sand and clay #if ,common arable soil #hj to #ij ,heavy clay #ge ,vegetable mold #gh ,peat #cj to #ej ,in general the specific gravity of soil decreases inversely as its content of humus4 #ig4 ,determination of ,specific ,gravity4--,the ordinary method of proceeding to determine the true specific gravity is by means of a pyknometer4 ,the pyknometer should have a capacity of from twenty-five to fifty cubic centimeters4 ,from ten to fifteen grams of earth dried to constant weight at #ajj are taken1 boiled for a time with a few cubic centimeters of water to remove air and poured into the pyknometer4 ,all soil particles are washed out of the vessel in which the boiling took place into the pyknometer with freshly boiled distilled water and after cooling to the temperature at which the calibration took place1 the pyknometer is filled with distilled water at the given temperature and weighed4 ,if the soil contain materials soluble in water1 alcohol of definitely known specific gravity may be employed and the number thus obtained calculated to a water basis4 ,the calculations when water is used are made as follows3 ,grams4 ,weight of pyknometer #ac4dghi pyknometer full of distilled water at #bj #fb4hicd water in pyknometer #di4dade dry soil taken #aj4jjjj pyknometer dry soil filled with water at #bj #fg4ihcd soil and water #ed4ejde water #dd4ejde water displaced by ten grams soil #d4iajj ,then specific gravity #aj4jjj #d4iajj #b4jd4 #ih4 ,specific ,gravity of ,undried ,soils4--,it is often desirable to determine the specific gravity of an undried portion of the soil4 ,for this purpose a portion of the sample is dried at #ajj to determine its percentage of moisture4 ,the specific gravity is then determined on a ten gram sample of the undried soil as just given4 ,the actual weight of soil taken is calculated from the percentage of moisture obtained in the first instance4 ,in the case given if the percentage of moisture at #ajj be ten then the actual weight of dry soil taken is nine grams4 ,this number is therefore used in making the calculations4 ,in all statements of specific gravity taken in the manner described the temperature at which the pyknometer is calibrated should be stated and all weighings where water is involved made at that degree4 #ii4 ,volume of ,soil4--,if it be desired to calculate the volume occupied by a soil it is easily done by dividing the weight of water displaced by the weight of one cubic centimeter of water of the temperature at which the determination took place4 ,in the case given one cubic centimeter of water at #bj weighs #j4iihbei4 ,then #d4iajj #j4iihbei #d4iahf cubic centimeters volume occupied by ten grams of dry soil excluding interstitial spaces between particles4 #ajj4 ,volumetric ,methods4--,the water displaced by a given weight of soil may also be measured volumetrically by the method of ,knop4#gb ,place #bjj grams of the soil in a flask of from three to five hundred cubic centimeters capacity4 ,add a measured quantity of water1 and shake thoroughly to eliminate air1 and fill up to the mark from a burette4 ,the quantity of water required to complete the volume subtracted from the number expressing the volume of the flask will give the volume of water displaced by the earth4 ,another method consists in thoroughly shaking about thirty grams of the soil in a graduated cylinder with fifty cubic centimeters of water containing a little ammonium chlorid and after twenty-four hours recording the volume occupied by the whole4 ,the increase in volume over fifty cubic centimeters shows the quantity of water displaced4 ,this method may also be used to determine the volume occupied by a soil when saturated with water4 ,the above methods are only to be used when approximately correct results are all that are desired4 #aja4 ,apparent ,specific ,gravity4--,the apparent specific gravity of a soil is obtained by dividing its volume1 interstitial spaces included1 by the weight of an equal volume of water4 ,the real and apparent specific gravities of six samples of soil are given below4#gc ,real specific gravity #b4edde1 #b4fcae1 #b4fejh1 #b4fdjj1 #b4gcbe1 #b4ffjc ,apparent specific gravity of air-dried soil #a4jidj1 #a4agaj1 #a4cegj1 #a4bhaj1 #a4djfj1 #a4bgcj ,apparent specific gravity of soil dried at #abe #a4jiij1 #a4aggj1 #a4cgej1 #a4biaj1 #a4dfdj1 #a4bhej ,it is to be noted that in computing the apparent specific gravity of a soil dried at #abe the volume occupied by the water is assumed to occupy the same space as if it existed in a free state4 ,the volume of this water is therefore to be subtracted from the contents of the flask before proceeding with the computations4 #ajb4 ,determination of ,apparent ,specific ,gravity4--,place in small quantity portions of the air-dried sample properly prepared1 into an open glass cylinder1 holding one liter1 and about #agj millimeters high 7if the height is exactly the mentioned one1 the diameter of the cylinder will be #hf4f millimeters72 pack the sample by striking the bottom of the cylinder hard against the palm of the hand after each new filling2 close the cylinder thus filled by a glass plate and weigh on a balance sensitive to #j4a gram2 deduct the weight of the cylinder and glass plate1 and the weight of one liter of soil in approximately similar conditions as it is found on the dry land prepared for cultivation1 is thus ascertained4 ,the weight of one liter of the soil in grams multiplied by #bjjj will give in kilograms the weight of the surface soil from a hectare 7#b4dg acres7 of the field from which the sample is taken when the depth of this is calculated at twenty centimeters4#gd ,,relation ,,of ,,the ,,soil ,,to ,,heat4 #ajc4 ,sources of ,soil ,heat4--,the heat of the soil comes from three sources1 viz43 solar heat1 as the sun's rays1 heat of chemical and vital action within the soil1 and the original heat of the earth's interior4 ,the latter is sensibly a constant quantity1 and of great value to plants4 ,the heat of chemical and vital action is not great in amount except in a few special cases but is often1 as in germination1 of the greatest importance to plant growth4 ,the sun1 therefore1 remains the greatest source of heat of practical importance in relation to the production of crops4 ,dark-colored soils1 absorbing most and radiating the fewest rays1 must attain the highest temperature4 ,schbler's classical researches on soil temperatures1 show that there is at times a difference of over #g in temperature between white and black soils1 all other conditions being alike4 ,schbler's researches1 being made on dry soils in the laboratory1 do not1 however1 apply wholly to conditions in the field4 #ajd4 ,influence of ,specific ,heat4--,the heat which a soil receives and retains is largely due to the specific heat of the soil4 ,the specific heat of a body is expressed by a number which shows the amount of heat necessary to raise a given weight of the body #a of temperature1 as compared with the amount necessary to raise the same weight of water #a4 ,the specific heat of the soil is usually between #j4bj and #j4be1 while that of water taken as the standard is unity4 #aje4 ,influence of ,moisture4--,the moisture of the soil possesses great influence on the soil temperature1 so much so that a dry1 light-colored soil may attain a greater degree of warmth than a moist1 dark-colored one4 ,the action of water in reducing soil temperature is easily explained4 ,in our latitude1 we see the water in all its forms1 solid1 liquid1 and gaseous1 and we know that these forms are the direct result of temperature4 ,the changing of water from the solid to the liquid or gaseous form is performed at the expense of heat2 the more water evaporated from the soil the more heat must be used for the evaporation4 ,therefore1 the more water contained in the soil at any given time the lower must be its temperature during subsequent exposure to sun heat because of the greater evaporation4 ,the experiments of ,liebenberg1 ,pattner1 ,schbler and ,dickenson have practically settled all the questions of soil temperatures4 ,the radiation of heat from the soil1 and the consequent cooling propensity of the latter1 are directly proportional to the absorptive power of the soil4 ,two soils of like absorptive power towards heat possess1 as a rule1 equal radiating power4 ,in a general way1 it can be said the greater the heating capacity and conductivity of a soil the more readily and rapidly does it give off its heat and become cooled4 #ajf4 ,absorption of ,solar ,heat4--,the quantity of heat absorbed from the sun by the earth is an important factor in the growth of vegetation4 ,as has been established in the physics of heat1 a black surface1 other things being equal1 will absorb a larger amount of heat than one of any other color2 so1 other things being equal in the physical and chemical composition of a soil1 variations in the amount of organic matter producing greater or less black coloration will affect the heat absorption4 ,thus1 black soils1 in the conditions above mentioned1 will absorb more heat than lighter colored soils4 ,as a result1 the vegetation in such soils gets an earlier start in the ,spring and matures more rapidly4 ,as an illustration of this it may be noted that the black prairie soils of ,iowa produce uniformly crops of maize which are matured before the early frosts1 while crops grown on lighter soils much farther ,south often suffer injury from that source4 ,,determination ,,of ,,specific ,,heat4 #ajg4 ,general ,principles4--,the quantity of heat stored in any given weight of soil is capable of being measured and compared with the quantity stored in an equal weight of water at the same temperature4 ,the ease1 however1 with which disturbing influences operate during the determination makes the manipulation somewhat difficult4 ,the specific heat of the containing vessels must be carefully determined4 ,fortunately this has been done for most materials and the data thus obtained are recorded in standard works on physics4 ,the material operated on must be protected from thermal influences from sources not controlled by the experiment and even the heat of the operator's body may often disturb the conduct of the work4 ,the general conditions which should control the experiment as well as the details thereof are given in the following method which1 however1 the ingenious analyst may profitably simplify4 #ajh4 ,method of ,pfaundler4--,the process of estimating the specific heat of soils by the method of mixture1 is essentially that of ,regnault and is described as follows by ,pfaundler#ge4 ,the apparatus used is illustrated in ,fig4 #ac4 ,a and ,a show the heating apparatus4 ,it consists of a vessel of sheet iron in which a test tube ,e is fixed by means of a cork4 ,the test tube holds the soil whose specific heat is to be determined4 ,the apparatus contains water1 which is brought to the boiling point by means of a lamp1 and the excess of steam is conducted away1 as indicated in the figure1 through one of the axes of the apparatus2 the opposite axis is1 of course1 closed4 ,it requires about thirty-five minutes boiling to bring the contents of the test tube to the temperature of the aqueous vapor4 ,the exact temperature at which the water boils is determined by observing the barometer at the time and consulting a table of the boiling temperature of water at different barometric pressures4 ,the calorimeter is shown in the figures ,b and ,b4 ,it consists of a wooden box closed on one side by a glass plate ,g and on the other to the heighth ,f by a small board on which a calorimeter of ordinary construction is placed4 ,the cylinder of the calorimeter is seventy millimeters high and forty-seven millimeters in diameter4 ,illustration3 ,,figure #ac4 ,,regnault',s ,,apparatus ,,for ,,determining ,,the ,,specific ,,heat ,,of ,,soils4 ,this part of the apparatus is supported by triangular pieces of cork4 ,a delicate thermometer is fastened to the top of the box of the calorimeter and the value of the degrees is so arranged that about twelve of them correspond to about one degree ,c4 ,the scale of the instrument can be arbitrarily fixed and the temperature of any part of it determined by comparison with a delicately graduated thermometer4 ,near the thermometer in the calorimeter is a stirrer made of a very thin copper disk with a bent rim4 ,this stirrer is operated by means of a silk cord moved by appropriate machinery4 ,the reading of the thermometer is made through a glass plate and this should be protected from the heat of the body of the observer by a paper screen4 ,the test tube ,e is first filled with the substance1 whose specific heat is to be determined1 and weighed4 ,it is then placed in the water bath until constant weight is reached4 ,after constant weight has been obtained the apparatus is again dried and the exact weight of the moisture lost thus determined4 ,the test tube is then placed in the apparatus ,a closed with a well-fitted cork1 the top covered with cotton and heated in the aqueous vapor for about one hour4 ,the heating apparatus should be far removed from the calorimeter so that the temperature of the latter cannot be influenced thereby4 ,meanwhile the calorimeter is filled with water which has stood in the room for a long time until it has acquired1 as nearly as possible1 the room temperature4 ,the quantity of water is such that the water value of the whole of the calorimeter together with the immersed portions of the thermometer and stirrer shall amount to exactly #ajj grams4 ,a few minutes before bringing the substance into the calorimeter1 the stirring apparatus is put in motion and the temperature observations are commenced4 ,these should be at intervals of twenty seconds and should be continued until ten observations have been made4 ,meanwhile the height of the barometer is also read4 ,a few seconds before the tenth interval the apparatus ,a is brought quickly to the calorimeter and its contents emptied into it at the moment of the tenth interval4 ,the apparatus ,a should be removed as quickly as possible after its contents are emptied4 ,after the introduction of the substance and its thorough incorporation with the water of the calorimeter by the stirring apparatus1 the thermometer is again read1 at intervals of twenty seconds1 until its maximum has been reached and as much longer thereafter as may be necessary to show that an appreciable fall of temperature has taken place4 ,the test tube1 in which the substance was heated is weighed and the exact quantity of the added substance thus determined4 ,in order that the sample of soil may be easily removed from the test tube in which it is heated1 it is best to have it molded into appropriate forms before being placed in the heating tube4 ,this is easily accomplished by pressing it into molds of convenient shape and of a size so that six or eight pieces 7best of cylindrical shape7 will be necessary to give the quantity sufficient for the experiment4 ,since some soils will not retain their shape after molding1 the molds may be made of zinc foil whose water values in the calorimeter are previously determined and they can be placed with their contents in the calorimeter thus securing the total immersion of all the particles of soil in the water4 ,with very dusty materials1 it is necessary that these little cylinders should be closed with pieces of foil at the ends in order to prevent the particles of dust from escaping and rising to the surface of the water4 ,another source of error consists in the solution of the soluble salts which the soil may contain4 ,this is avoided by the use of turpentine instead of water4 ,if the cylinder containing the soil be made water-tight1 this danger from the solubility of the salts in water is avoided4 ,another method of correcting these errors is in making a blank experiment in which a quantity of the earth taken is kept at the temperature of the water in the calorimeter until both are of the same temperature4 ,the earth is then mixed with the water and the change of temperature produced noted4 ,in this way the corrections made necessary by the solution of the salts in water and other causes are determined4 #aji4 ,method of ,calculating ,results4--,let t represent the mean temperature of the beginning period of the experiment1 and v equal the loss in heat per interval4 ,let t and v represent the same values for the end period4 ,let 1 1 1 etc41 represent the temperature at the end of the first1 second and third intervals of the middle period and the temperature at the beginning of the middle period and the end temperature of of the middle period4 ,let 1 1 1 444 1 represent the mean temperature of the single intervals2 then 7 7_/7#b72 7 7_/7#b71 and 7n-#a 7_/7#b74 ,the constant ,c represents the correction which must be applied in order to determine the true increase of temperature in the calorimetric system4 ,the expression ,c represents the true temperature increase of the calorimetric system which we may represent by and ,c represents the true maximum1 that is1 the end temperature1 which by exclusion of external influences is reached4 ,the correction ,c1 as already indicated1 is to be added to when it is positive and is to be subtracted therefrom when it is negative4 ,the numerical value of ,c is usually very small1 and1 in the experiments indicated1 varied between zero and one division of the thermometer employed1 that is it seldom exceeded one degree4 #aaj4 ,illustration4--,the method of determining value of specific heat is best illustrated by an example3 ,in one determination the water value of the calorimetric system1 including stirrer and thermometer was #b4ej grams1 the weight of water added was #ig4ej grams and the total water value of the system #ajj grams4 ,the substance was dried at #ajj and weighed in five envelopes3 ,total weight #ca4dbc grams4 ,the envelopes alone weighed #aj4fed ,weight of the soil taken #bj4gfi ,the envelopes holding the soil were made of brass with zinc ends1 the specific heat of which is #j4jici and the water value of the whole of the envelopes was #a4jjjd grams4 ,since1 however1 the ends were soldered on with zinc the true water value was somewhat smaller being equal to #j4hfib gram4 ,the data of the observations were as follows3 ,corrected height of barometer #fii4f millimeters4 ,intervals between the observations #bj seconds4 ,no4 of ,temperature on the ,observations4 arbitrary scale of the thermometer4 ,first ,period #j #afb4f #aj #afb4i 7,moment of immersion47 ,second ,period #aa #ahe4j #ab #bjj4j #ac #bjf4a #ad #bji4e #ae #baj4g #af #baa4c #ag #baa4e ,differences4 #ah #baa4e #j #ai #baa4e #j #bj #baa4e #j #ba #baa4e #j #bb #baa4d -#j4a -#j4a -#j4a ,third ,period #bc #baa4c #bd #baa4b -#j4a #be #baa4a -#j4a #bf #baa4j -#j4a #bg #baj4i -#j4a #bh #baj4h -#j4a #bi #baj4f -#j4b #cj #baj4e -#j4a ,from the twenty-second interval1 the regular fall of temperature begins and #baa4d is therefore taken as 4 ,the mean temperature of the beginning period is therefore 7#afb4f #afb4i7_/7b7 #afb4ge t4 ,the value of v is 7#afb4f #afb4i7_/7aj7 -#j4jc4 ,for the end period the value of t is 7#baa4d #baj4e7_/7b7 #baj4ie and the value of v is 7#baa4d #baj4e7_/7h7 #j4aa4 ,then the sum of the observations from eleven to twenty-one inclusive n-#a #bbhj4a 7 7_/7#b7 #ahg4ae ,the sum #bdfg4be nt #aiec4jj ,difference #ead4be ,this difference multiplied by v v #j4ad gives a product equal to #ga4iie ,this product divided by t t #dh4bj gives a quotient equal to #a4di nv -#j4cf ,the sum #a4ac ,c ,then ,c #baa4d #afb4i #a4ac #di4fc4 ,the true end temperature ,c #bab4ec4 ,the zero point of the thermometer #bd4gj1 and the actual rise of temperature #ahg4hc4 ,the rise of temperature due to the proximity of the warming apparatus at the beginning was found by experiment to be equal to #j4a of the division of the scale4 ,on comparing the thermometer used with a standard centigrade scale it was found that one division of the calorimetric thermometer was equal to #j4jheh4 ,converting these numbers into expressions of the centigrade scale we have the following summary3 ,the true rise of temperature1 #d4be ,the true end temperature1 ,c #af4aj ,the temperature of the steam1 as determined by the height of the barometer1 was equal to #ig4gj ,from these data the specific heat is calculated according to the following formula3 #a_/bj4gfi 77#ajj #d4be7_/7ig4gj #af4aj7 #j4hfib7 #j4bjhi4 ,from this formula the following rule for calculating specific heat is deduced3 ,multiply the water value of the calorimetric system by the true rise in temperature in degrees ,celsius and divide the product by the difference between the temperature of boiling water under the conditions of the experiment and the true end temperature4 ,from the quotient subtract the water value of the envelopes holding the soil sample4 ,divide the remainder by the weight of soil taken4 #aaa4 ,variations in ,specific ,heat4--,different soils deport themselves very differently in respect of specific heat4 ,in a large number of soils examined by ,pfaundler1 the specific heats were found to vary from #j4ai to #j4ea4 ,the highest specific heat was observed in the case of a peaty soil4 ,next to peaty soils came those soils which were highest in humus1 and in general it was found that the specific heat varied directly with the humus content4 ,,soil ,,thermometry4 #aab4 ,general ,principles4--,the measurement of the temperature of the soil at stated depths is often of use in analytical processes connected with agricultural chemistry and physics4 ,the general principles on which the process rests1 depend on bringing the bulb of the thermometer into as intimate contact as possible with the particles of soil at the depth required1 disturbing as little as possible the normal state of the soil particles4 ,in the thermometer chiefly used for this purpose in this country1 the stem is strong and carries the degrees figured on the glass4 ,the whole is inclosed in a wooden case which is cut away to expose the face of the scale4 ,the scale is about eleven inches long4 ,the part which enters the soil is of varying lengths1 according to the depth at which the temperature is desired4 #aac4 ,method of ,procedure4--,an excellent method of determining soil temperatures and of recording results is well illustrated by ,frear4#gf ,the thermometers are set in niches cut in a trench1 the earth being afterwards carefully tamped about the bulbs to secure a good contact1 the trench being filled at the same time4 ,the surface of the soil is freed from vegetation and kept in good tilth4 ,the depths at which observations are made are at the surface and one1 three1 six1 twelve1 and twenty-four inches4 ,the soil tested was moderately dark and loamy to a depth of seven inches and below that a stiff clay4 ,solid rock existed at from five to seven feet below the surface4 ,readings were made three times a day4 #aad4 ,method of ,stating ,results4--,the individual readings of the thermometers should be entered at the time they are made4 ,at the end of each month the mean of the readings should be determined1 together with the maxima and minima1 and a comparison made between the mean readings of the temperature of the air and maxima and minima4 ,as a sample of the method of stating these mean results the data are given for the month of ,may1 #ahia1 for the atmosphere1 surface1 and for the depths mentioned above3 ,,may4 ,t ,fahrenheit4 ,,atmosphere4 ,monthly mean #eg4a ,maximum #he4j ,minimum #ca4j ,mean daily range #bb4e ,greatest daily range #cb4j ,least daily range #h4j ,,surface4 ,monthly mean #ef4g ,extremes4 ,maximum 7#ajth of month7 #gg4j ,minimum 7#eth7 #cf4j ,mean maximum #fe4b ,mean minimum #di4i ,range4 ,monthly #da4j ,mean daily #ad4i ,greatest daily 7#aith7 #be4j ,least daily 7#bast7 #d4j ,,one ,,inch4 ,monthly mean #ef4h ,extremes4 ,maximum 7#ajth7 #gd4e ,minimum 7#eth7 #cf4e ,mean maximum #fb4i ,mean minimum #di4e ,range4 ,monthly #ch4j ,mean daily #aa4i ,greatest daily 7#aj and #ai7 #bj4j ,least daily 7#bcrd7 #a4j ,,three ,,inches4 ,monthly mean #ef4g ,extremes4 ,maximum 7#cast7 #ga4j ,minimum 7#fth7 #dj4j ,mean maximum #fj4i ,mean minimum #di4g ,range4 ,monthly #ca4j ,mean daily #i4c ,greatest daily 7#aith7 #ae4e ,least daily 7#bcrd7 #a4e ,,six ,,inches4 ,monthly mean #ef4c ,extremes4 ,maximum 7#cast7 #ff4j ,minimum 7#fth and #gth7 #dc4j ,mean maximum #ef4g ,mean minimum #ec4b ,range4 ,monthly #bc4j ,mean daily #d4fe ,greatest daily 7#h and #ai7 #h4e ,least ,daily 7#eth7 #a4j ,,twelve ,,inches4 ,monthly mean #ee4f ,extremes4 ,maximum 7#cast7 #fd4j ,minimum 7#fth and #gth7 #df4j ,mean maximum #ef4f ,mean minimum #ed4d ,range4 ,monthly #ah4j ,mean daily #b4ah ,greatest daily 7#hth7 #d4e ,least daily 7#crd and #bjth7 #j4j ,,twenty-,,four ,,inches4 ,monthly mean #ec4a ,extremes4 ,maximum 7#cast7 #eh4j ,minimum 7#fth and #hth7 #dh4j ,mean maximum #ec4d ,mean minimum #eb4h ,range4 ,monthly #aj4j ,mean daily #j4dh ,greatest daily 7#bcrd7 #b4j ,least daily 7on #ab days7 #j4j ,illustration3 ,,fig4 #ad4 ,,soil ,,thermometer--,whitney and ,marvin4 #aae4 ,method of ,whitney and ,marvin4#gg--,the thermometer devised by ,whitney and ,marvin is shown in ,fig4 #ad4 ,the principle on which this modification depends is as follows3 ,a mercurial thermometer of the ordinary construction is liable to give wrong indications of the temperature because it is difficult to determine the temperature of the column of mercury from the bulb to the surface of the ground4 ,to avoid this source of error the thermometer figured was constructed4 ,the bulb of the thermometer is made quite small and a slender portion of the stem extends into its spherical portion4 ,the top portion of the thermometer stem does not differ in any essential respect from the stem of an ordinary thermometer4 ,the bulb is almost wholly filled with alcohol1 which acts as the principal thermometric fluid and has the advantages of a high coefficient of expansion4 ,the thermometer bulb and the stem of the thermometer up to a point convenient for graduation1 are filled with mercury4 ,in the drawing the mercury is represented by the heavy black marking in and just above the small bulb4 ,the peculiar construction at this point is for the purpose of retaining the mercury about the point of the slender capillary stem inside the bulb and preventing the entrance of alcohol into the stem when the thermometer is horizontal4 ,in order to register the maximum and minimum temperatures a short column of alcohol is placed in the upper portion of the stem1 above the mercury1 and within this are arranged two small steel indexes1 so constructed that they will not slide in the tube of their own weight1 but are easily pushed upward by the mercury column or pulled downward by the top meniscus of the alcohol column4 ,the indexes are set by means of a small magnet1 the one being drawn down upon the top of the mercurial column and the other raised up against the meniscus of the alcohol column4 ,the rise of the mercury carries its index upward1 leaving it to register the highest point reached1 while the alcohol meniscus withdraws the other index and leaves it at a point representing the minimum temperature4 ,it remains only to mention that the graduations are fixed in the usual way1 having reference only to the positions of the mercurial column4 ,beyond the highest point supposed to be reached by the mercury1 say about #abj1 the graduations are extended in an arbitrary manner4 ,the scale numbers represent temperatures by the mercurial column and are continued in regular sequence beyond the #abj4 ,on this plan the readings for minimum temperatures are on a purely arbitrary scale and are converted into true degrees of temperature by use of a table prepared for each thermometer1 which table embodies as well all the corrections for instrumental error4 ,the arrangement of the alcohol columns above the mercurial column and the indexes are shown enlarged at one side of the illustration4 ,the readings of the maximum temperature are made from the bottom end of the index next to the mercurial column4 ,the minimum temperature is the reading of the top of the uppermost index4 ,thus in the figure the maximum temperature indicated is #gf4e1 and the minimum #abe4g1 which1 by reference to the table of correction for this thermometer1 ,no4 #aj1 is found to be #ec4c4 ,the use of mercury in the stem of the thermometer not only admits of the use of the index for registering the maximum temperature1 but possesses the additional advantage of reducing the error due to uncertain temperature of the stem to about one-sixth what it would be if alcohol were used4 ,moreover1 if necessary1 as in the case with thermometers for greater depths than that figured1 the ungraduated portion of the stem can be made of very much finer bore than the graduated portion1 the effect of which is to diminish the objectionable error to a comparatively unimportant quantity4 ,the chief objection to thermometers of this construction is the liability of alcohol getting from the bulb into the stem during the processes of construction1 graduation and subsequent handling1 and the difficulty of safely shipping them4 ,when once set up1 however1 there seems to be little or no possibility of derangement and the error common to mercurial thermometers due to rise of the freezing point with age does not apply owing to the high coefficient of expansion of the alcohol used in the bulb4 ,,applications ,,of ,,soil ,,thermometry4 #aaf4 ,estimation of the ,absorption of ,heat by ,soils4--,a cubical zinc box1 six centimeters square1 is filled with the sifted air dried soil4 ,the box1 one side of which is left open1 is encased snugly in a wooden cover1 exposing only the open end1 and placed for a few hours in the direct rays of the sun4 ,the temperature is then taken at a given depth4 ,the box may be provided with thermometers at different depths1 the bulbs thereof extending to the center4 ,in this case the box should be covered with thick felt instead of wood4 ,the temperature of the layers of soils of different depths can thus be read off directly4 ,the air temperature directly above the box should be accurately noted while the experiment continues4 ,any other kind of box well protected against all heat save the direct sunlight on the open surface of the soil will answer as well as the one described4 ,to determine the action of moist earth in similar conditions the soil may be previously moistened2 the per cent of moisture being determined in a separate portion of the soil or the amount of water added to the air-dried soil being noted4 #aag4 ,estimation of the ,conductivity of ,soils for ,heat4--,the bulb of a thermometer is placed in the middle of a mass of fine earth which is then exposed1 best in a metallic box painted with lamp black1 in a warm place4 ,the time required for the thermometer to reach a certain degree is noted4 ,by reversing the experiment and placing the mass of earth heated to a given degree in a cool place the conductivity can be determined by the time required for the mercury in the thermometer to fall to any given point4 ,the experiment may also be made by packing the soil by gently jolting it in a glass tube six to eight centimeters in diameter4 ,one end of the tube is closed with a piece of metal or fine wire gauze painted with lamp black and is exposed to the source of heat4 ,the bulb of a thermometer is placed at a given distance from the end of the tube and the time for the mercury to be affected observed4 ,,cohesion ,,and ,,adhesion ,,of ,,soils4 #aah4 ,behavior of ,soil ,after ,wetting4--,the deportment of a soil when thoroughly wet in respect of its physical state on drying out is a matter of great practical concern to the agronomist4 ,some soils on becoming dry fall into a pulverulent state and are easily brought into proper tilth2 others become hard and tenacious1 breaking into clods and resisting ordinary methods of pulverization4 ,the physical laws which determine these conditions depend largely on the principles of flocculation soon to be described4 ,the present task is to describe briefly some of the methods of estimating the force of cohesion and adhesion4 #aai4 ,general ,method4--,the fine earth1 air-dried1 is mixed with enough water to make a paste and molded into forms suitable for trial in a machine for testing strength of cement1 etc4 ,the forms most used are cakes three to five centimeters in length and one to two centimeters thick4 ,these are used for determining crushing power4 ,for longitudinal adhesion the paste may be molded in prismatic or cylindrical shape4#gh ,the prisms should show one to two centimeters in cross section or the cylinder be one to two centimeters in diameter4 ,before use they are to be exposed for several days until thoroughly air-dried4 ,the force required to separate or crush these prepared pieces will measure the adhesive or cohesive property of the sample4 ,a great number of trials should be made and the mean taken4 #abj4 ,method of ,heinrich4#gi--,this process consists in mixing the air-dried earth with water until its aqueous content is fifty per cent of the highest water capacity determined by experiment4 ,the sample is next placed between two pieces of sheet iron of ten centimeters square1 each of which in its middle point is provided with a hook4 ,the thickness of the layer between the two pieces of iron should be about five to ten centimeters4 ,the exuding particles of soil are cut off with a knife4 ,the upper piece of sheet iron is next suspended by a cord in such a way that the iron piece occupies a horizontal position4 ,a small basket is attached to the lower surface and sand added thereto1 little by little1 until the column of earth is separated4 ,the sand basket and iron plate are weighed1 and the total weight gives the power necessary to separate a column of soil ten centimeters square in cross section4 ,the iron plates may be roughened so that the adhesion thereto of the soil is greater than its cohesive force4 #aba4 ,adhesion of ,soil to ,wood1 ,iron1 ,etc4--,the adhesive power of moist soil for wood1 iron1 etc41 is measured by ,heinrich#hj in the following way3 ,the soil is mixed with water1 as above1 until it contains just fifty per cent of its total water-holding content4 ,it is then placed in a large vessel and the upper surface made as smooth as possible4 ,a plate of wood1 iron1 etc41 of ten centimeters square is then pressed on the surface until a complete contact is secured4 ,this plate1 by means of a hook and cord passing over a pulley1 is then subjected to stress by weighting the cord which carries a basket for that purpose4 ,the basket should be of the same weight as the plate in contact with the soil4 ,the weight added to the basket necessary to separate the plate from the soil is taken to represent the cohesive force4 ,the author of the method appears to take no account of the pressure of the air on the plate caused by the exclusion of the air from its under surface4 ,,the ,,absorptive ,,power ,,of ,,soils ,,for ,,salts ,,in ,,solution4 #abb4 ,general ,principles4#ha--;,it is a fact of every-day observation that soils have a particular property of absorbing certain materials with which they come in contact4 ,if it were not for this property all our wells would soon become unwholesome from the reception of decayed animal and vegetable matter carried to them in the drainage water from the surface4 ,it is also a well-known fact that burying dead bodies prevents the gaseous products of decomposition from reaching and vitiating the atmosphere4 ,besides this well-known power of soils to absorb the decomposition products of animal and vegetable matter1 they also possess a property which is of far greater importance in plant economy2 that is1 the power of withdrawing and retaining certain mineral constituents from their solutions4 ,as far back as the sixteenth century mention is made by ,lord ,bacon of a process for obtaining pure water on the seashore by simply digging a hole in the sand and allowing it to fill with filtered sea water1 which by this means is deprived of its salt4 ,although certain facts were observed by some of the earlier writers in regard to soil absorption1 no systematic researches were conducted with a view of demonstrating the extent and cause of this power until within a comparatively few years4 ,in #ahej ,prof4 ,way published in the ,journal of the ,royal ,agricultural ,society of ,england1 the results of a thorough and most excellent investigation of the subject4 ,since then many distinguished chemists1 such as ,henneberg1 ,stohmann1 ,peters1 ,heiden1 ,knop1 ,ullik1 ,pillitz1 ,biedermann1 ,tuxen1 and others have given their attention to this matter4 #abc4 ,summary of ,data4--,if a solution of a soluble sulfate1 chloride or nitrate of an alkali or an alkaline-earth metal be placed in contact with a soil1 the result is that the soil takes up a part of the base but none of the acid4 ,this absorption of base is attended with the liberation of some other base from the soil which combines with the acid of the solution4 ,any alkali or alkaline earth base has the power of replacing any other such base4 ,however1 if soluble phosphates and silicates of these bases be placed in contact with the soil both the base and the acid are removed from the solution4 ,peters#hb has shown that the amount of absorption depends upon the concentration of the solution1 the relation between the quantity of solution and the soil and the kind of salt used4 ,he treated #ajj grams of earth with #bej cubic centimeters of solutions of different potash salts with the following results3 ,strength of solution4 ,normal4 ,normal4 ,grams ,grams ,salt ,used ,k,o absorbed4 ,k,o absorbed4 ,k,cl #j4cabd #j4aiij ,k,,so #j4ccfb #j4bjih ,k,,co #j4egdg #j4caed ,biedermann#hc proves that1 for phosphoric acid at least1 the absorption increases with the temperature4 ,it has also been found that the amount of absorption depends upon the time of contact between the soil and solution4 ,way found that the absorption of ammonia was complete in half an hour1 while ,henneberg and ,stohmann#hd noticed that the phosphoric acid continued to be fixed after the expiration of twenty-four hours4 ,it is a very important fact that the absorption of a base is never complete2 no matter how dilute the solution it will still carry a small portion of the base with it4 ,peters states that it requires about #bh1jjj parts of water to remove one part of absorbed potash and ,stohmann found that it required about #aj1jjj parts of water to remove one part of absorbed ammonia4 ,with phosphoric acid1 the resulting compound seems to be much more insoluble4 ,according to ,tuxen#he the presence of salts of soda and potash in solution decreases the power of a soil to absorb ammonia compounds and the presence of sodium salts decreases the power of a soil to absorb potash4 ,on the other hand the presence of potassium compounds considerably increases the absorption of phosphoric acid4 ,he further affirms that the compounds of potash1 phosphoric acid1 etc41 formed in the soil1 are decidedly more soluble in sodium salts than in pure water4 #abd4 ,cause of ,absorption4--,the withdrawing and fixing of phosphoric acid from solutions by the soil is not very difficult to understand as this acid forms insoluble compounds of iron1 lime1 and magnesium1 some or all of which are present in all soils4 ,as to the absorption of the alkalies1 the explanation is far more difficult as nearly all of their ordinary compounds are readily soluble in water4 ,as lime is usually found combined with the acid part of an alkali salt1 from which the base has been absorbed by the soil1 it might naturally be supposed that the absorptive power of the soil would depend upon the amount of lime present4 ,way found1 however1 that the addition of chalk in no way influenced the absorption of ammonia by a soil which contained but a small amount of lime4 ,this fact was also confirmed by ,knop#hf who found that chalk exerted no influence on the absorption of ammonia salts4 ,these facts would seem to point to the conclusion that lime was present in sufficient quantity in these experiments1 or that it is not essential to the phenomena of absorption4 ,however1 as any alkali or alkaline-earth base can replace any other such base1 the presence of lime in the filtrate is probably more of an accidental occurrence1 owing to the comparatively large amount of that substance in most soils1 than a necessary condition1 as any other base would doubtless answer in the absence of lime4 #abe4 ,warington#hg has shown that hydrated oxides of iron and aluminum1 and especially the former1 are capable of absorbing potash and ammonia1 and as more or less of these hydrates exist in nearly all soils1 a part1 at least1 of absorptive phenomena is to be ascribed to them4 #abf4 ,way tried to determine which of the constituents of a soil exercised chiefly the absorptive power4 ,he passed a solution of ammonia through tubes containing pure sand and found that it came through apparently unaltered from the first1 while a soil treated in the same way removed the ammonia for a considerable time4 ,he concluded from this that the absorptive power does not exist in the sand4 ,he next oxidized the organic matter in a soil with nitric acid and then treated it with ammonia in the same way4 ,the first portions of the filtrate showed no ammonia in any form1 hence he concluded that organic matter is not essential to the act of absorption4 ,he further showed that clay alone is capable of causing absorption phenomena1 by treating powdered clay tobacco pipes with ammonia4 ,having shown that clay was the main constituent in a soil which caused the absorption of alkalies1 he tried next to trace out the particular compound which caused the absorption4 ,having tried various natural silicates he at last succeeded in producing a hydrated silicate of aluminum and soda which exhibited displacement and absorptive properties very similar to those shown by the soil4 ,as ,way had succeeded in producing an artificial hydrated silicate possessing absorptive properties1 ,eichorn#hh thought of trying natural hydrated silicates or zeolites and found that they exhibited the same power as ,way's artificial preparation4 ,it has also been shown by ,biedermann1#hi ,rautlenberg1#ij and ,heiden#ia that the absorptive power bears a close relation to the amount of soluble silicates present4 ,in view of these facts it is now generally accepted that the absorption of salts of the alkalies1 accompanied by the change of base1 is due chiefly to the presence of decomposed zeolite minerals in the soil4 ,besides the purely chemical absorption of salts by the soil1 we have a physical absorption of various substances similar to the action of charcoal when used as a filter4 #abg4 ,conclusions of ,armsby4--,the data connected with the absorption of bases by a soil have also been reviewed by ,armsby4#ib ,he shows that the absorption is accompanied by a chemical reaction between the salt whose base is absorbed and some constituent of the soil1 and this change seems to be due particularly to certain zeolitic silicates1 although ,liebig and others were disposed to credit this absorption largely to physical causes4 ,knop advances the idea that the soil has the power of disintegrating salts in the presence of some substances like calcium carbonate which can unite with the acid4 ,in experiments made with hydrous silicates it was shown that the absorption resembled in all cases like phenomena in the soil2 hence the supposition already advanced in regard to the influence of such silicates is doubtless true4 ,in respect of absorption in general1 the following conclusions were reached3 #a4 ,the absorption of combined bases by the soil consists in an exchange of bases between the salt and the hydrous silicates of the soil4 #b4 ,this exchange1 which is primarily chemical1 is only partial1 its extent varying 7a7 with the concentration of the solution1 and 7b7 with the ratio between the volume of the solution and the quality of soil used4 #c4 ,the cause of these variations is probably the action of mass or the tendency of resulting compounds to re-form the original bodies1 the absorption actually found in any case marking the point where the two forces are in equilibrium4 #abh4 ,selective ,absorption of ,potash4--,as a rule more potash is absorbed from the sulfate than from the chlorid4 ,this fact would seem to point to the advisability of using sulfate as a fertilizer in preference to chlorid4 ,however1 as with the exception of nitrates1 the absorptive power of a soil1 for the salts used as fertilizers1 is many times greater than it is ever called upon to exert in fixing applied fertilizers1 we need not trouble ourselves in regard to the absorption of phosphoric acid1 potash or ammonia1 in so far as the practical side of the matter is concerned4 ,for example1 an acre of soil to the depth of nine inches weighs about #ijj tons4 ,now it has been found by ,huston1#ic that #ajj parts of a soil experimented upon absorbed over #j4be part of ,p,o1 hence #ijj parts would absorb over #b4be parts of ,p,o2 or an acre of this soil to the depth of nine inches would absorb over two and one-fourth tons of phosphoric acid4 #ejj pounds per acre is a large dressing of a phosphatic fertilizer for field crops and #ejj pounds of a high grade fertilizer would contain about #ajj pounds of ,p,o2 hence the power of such a soil to absorb phosphoric acid is more than forty-five times as great as it is ever likely to be called upon to exert in fixing the phosphoric acid added to it as a fertilizer4 ,huston has further shown that an acre of soil nine inches deep will absorb more than #b4g tons of potash 7,k,o7 from potassium chlorid from which salt less potash is absorbed than from the sulfate4 ,now one-tenth ton of potassium chlorid per acre would be a large dressing of potash1 hence this soil possesses the power of absorbing more than twenty-seven times as much potash as is ever likely to be applied as a fertilizer4 ,in like manner it may be shown that the power of an acre of soil nine inches deep to absorb ammonia from ammonium sulfate is more than thirty-two times as great as it would be called upon to exert in fixing the ammonia from a dressing of one-quarter ton of ammonium sulfate per acre4 ,with sodium nitrate1 however1 there is no absorption2 hence great care is necessary in the application of nitrogen as a nitrate1 for1 if it be put on in large quantities1 at a season when the plant is not prepared to assimilate it1 or during a period of heavy rains1 there must unavoidably result loss from drainage4 ,the best time to apply a nitrate is evidently during the active growing season4 #abi4 ,whitney#id places great emphasis on the surface area of soil particles in respect to their power to absorb solutions of salts4 ,the approximate surface area of a cubic foot of each of the different typical soils of ,maryland is as follows3 ,pine barrens #bc1idj square feet4 ,truck lands #gd1acj ,tobacco lands #hd1hej ,wheat lands #id1edj ,river terrace #ajf1bfj ,limestone subsoil #bjb1fjj ,it will be seen that there are about #bd1jjj square feet of surface area in a cubic foot of the subsoil of the pine barrens1 no less then #ajj1jjj square feet or two and three-tenths acres of surface area in a cubic foot of the subsoil of the river terrace1 and #bjj1jjj square feet of surface area in a cubic foot of the limestone subsoil4 ,these figures seem vast1 but they are probably below rather than above the true values1 on account of the wide range of the diameters of the clay group4 ,this great extent of surface and of surface attraction1 which has been described as potential1 gives the soil great power to absorb moisture from the air1 and to absorb and hold back mineral matters from solution4 ,a smooth surface of glass will attract and hold1 by this surface attraction1 an appreciable amount of moisture from the surrounding air4 ,a cubic foot of soil1 having #ajj1jjj square feet of surface1 should be able to attract and hold a considerably larger amount of moisture4 ,it might have been added that if the potential of the surface1 separating the solution from the soil1 be greater than the potential in the interior of the liquid mass1 there will be a tendency to concentrate the liquid on this surface of separation4 ,it has been shown that certain fluids have greater density on a surface separating the fluid from a solid4 ,on the other hand1 if the potential were low there might be no tendency for this concentration1 and even the reverse conditions would prevail and the soluble substance could be readily washed out of the soil4 #acj4 ,removal of ,organic ,matters4--,it is probably largely due to this straining power that organic matters are removed from solutions in percolating through the soil4 ,whitney#ie has observed that the organic matter may be coagulated and precipitated from solution by the soil constituents1 and held in the soil in loose flocculent masses1 while the liquid passes through nearly free of organic matter4 #aca4 ,importance of ,soil ,absorption4--,the importance of the absorptive power of the soil can hardly be overestimated4 ,by means of this power those mineral ingredients of plant food1 of which most soils contain but little1 are held too closely to allow of rapid loss by drainage1 and still sufficiently available to answer the needs of vegetation1 provided the store is large enough4 ,the only important plant food liable to be deficient in the soil which does not come under the influence of absorption is nitrogen in the form of salts of nitric acid1 and nature has made a wide provision for this element by binding it in the form of organic bodies which nitrify but slowly1 and by supplying each year a small quantity from the atmosphere4 ,by means of the absorptive power of soils the farmer1 if he puts on an excess of potash or phosphoric acid as a fertilizer1 does not lose it but is able to reap some benefits from it in the next and even in succeeding crops4 ,if it were not for this power the best method for applying fertilizers would be a much more complicated problem than it is at present2 and it would be necessary to apply them at just the proper season and in nicely regulated amounts to insure against loss4 #acb4 ,method of ,determining ,absorption of ,chemical ,salts4--,the soil which is to be used for this experiment should be treated as has been indicated and passed through a sieve the meshes of which do not exceed half a millimeter in size4 ,from twenty-five to fifty grams of the fine earth may be used for each experiment4 ,the fine earth should be placed in a flask with #ajj to #bjj cubic centimeters of the one-tenth to one-hundredth normal solution of the substance to be absorbed4 ,the flask should be well shaken and allowed to stand with frequent shaking twenty-four to forty-eight hours at ordinary temperatures4 ,the whole is then to be thrown upon a folded filter and an aliquot part of the filtrate taken for the estimation4 ,the methods of determining the quantities of the substances used will be found in other parts of this manual4 ,it is recommended to conduct a blank experiment with water under the same conditions in order to determine the amount of the material under consideration abstracted from the soil by the water alone4 ,the difference in the strength of the solution as filtered from the soil1 corrected by the amount indicated by the blank experiment1 and the original solution will give the absorptive power of the soil for the particular substance under consideration4 ,if it should be desired to determine the absorptive power of the soil for all the ordinary chemical fertilizing materials at the same time1 a larger quantity of the sample should be taken corresponding to the increased amount of the standard solutions used4 ,about #ejj cubic centimeters of the mixed salt solution should be shaken with #abe grams of the earth and the process carried on in general as indicated above4 ,the absorption coefficient of an earth for any given salt according to ,fesca1#if is the quantity of the absorbed material expressed in milligrams calculated to a unit of #ajj grams of the soil4 #acc4 ,method of ,pillitz and ,zalomanoff4--,it is recommended by ,pillitz and ,zalomanoff#be to reject the old method1 viz41 shaking the soil with the solution in a flask1 and substitute the filtration method both because it gives a more natural process and because the results are more constant4 ,the apparatus is shown in ,fig4 #ae4 ,illustration3 ,,figure #ae4 ,,zalomanoff',s ,,apparatus ,,for ,,determining ,,absorption ,,of ,,salts ,,by ,,soils4 ,two cylinders are placed vertically1 one over the other4 ,the lower cylinder is graduated in cubic centimeters1 the upper cylinder is closed at each end by perforated rubber stoppers ,a and ,b through the openings of which the glass tubes c and d pass4 ,within the cylinder ,a the opening of the small tube d is closed with a disk of ,swedish filter paper4 ,the lower part of the small tube is d connected by means of a rubber tube carrying a pinch-cock ,c1 with another small tube e which passes through the stopper f4 ,in carrying out the process the weighed quantity of soil is placed in the upper cylinder and afterwards the measured quantity of the solution1 the whole thoroughly mixed and the cylinder closed4 ,the valve ,c is then opened1 a given quantity of the solution1 but not all1 is made to drop into the lower cylinder and the valve ,c is then closed4 ,the liquid which has passed into the lower cylinder as well as that which remains in the upper cylinder1 is thoroughly stirred and the quantity of the material remaining in both liquids determined and the absorbing power of the soil estimated from their difference4 ,it does not appear that this method of estimation of the absorption power possesses any special advantages over the old and far simpler method of shaking in a flask4 ,illustration3 ,,figure #af4 ,m,,ller',s ,,apparatus ,,to ,,show ,,absorption ,,of ,,salts ,,by ,,soils4 #acd4 ,method of ,mller4--,the method of ,mller#ig for illustrating absorption is carried out by means of the apparatus shown in ,fig4 #af4 ,a glass cylinder ,a about #gej centimeters long and four to five centimeters wide is closed at each end with rubber stoppers with a single perforation4 ,the cylinder ,a is for the reception of the soil with which the experiment is to be made4 ,before using1 the lower part of it is filled with glass pearls or broken glass and above this a layer of glass wool is placed about one centimeter thick4 ,the object of this is to prevent the soil from passing into the small tube below4 ,as soon as the soil has all been placed in the cylinder ,a the upper part of the tube is also filled with glass wool4 ,the cylinder ,a is connected with the pressure bottle ,b by means of a rubber tube and the small glass bulb tube shown in the figure4 ,the bottle ,b should have a content of about two liters4 ,it is filled with the standard solution of the material of which the absorption coefficient is to be determined4 ,at c the rubber tube is connected with a glass ,t one arm of which is provided with a piece of rubber tubing which can be closed by means of a pinch-cock4 ,at c a screw pinch-cock is placed which can be used to regulate the flow of the solution from ,b to ,a4 ,by opening the pinch-cock at e on the short arm of the ,t piece1 a sample of the original liquid can be taken and this can be compared with the part which runs to b4 ,if it is desired for instance1 to show that potassium carbonate has been absorbed by the soil the two bulbs shown on the small glass tubes connecting with ,a can be filled with red litmus paper4 ,this paper will at once be turned blue in the lower bulb while in the upper one it will retain its original color because the liquid in passing through the soil will have lost its alkaline reaction4 ,the solutions used should be very dilute4 ,the apparatus is designed for lecture experiments and not for quantitative determinations4 #ace4 ,method of ,knop4--,for rapid determination of the absorption coefficient of the soil ,knop's method may be used4#ih ,the fine earth which is employed is that which passes a sieve with meshes of half a millimeter4 ,from #ej to #ajj grams of this soil are mixed with from five to ten grams of powdered chalk and with about twice the weight of ammonium chlorid solution of known strength1 viz41 from #ajj to #bjj cubic centimeters4 ,the ammonia solution should be of such a concentration that the ammonia by its decomposition for each cubic centimeter of the liquid evolves exactly one cubic centimeter of nitrogen4 ,this solution is prepared by dissolving in #bjh cubic centimeters of water one gram of ammonium chlorid4 ,with frequent shaking the solution is allowed to stand in contact with the soil for forty-eight hours4 ,the whole is now allowed to settle and the supernatant clear liquid is poured through a dry filter4 ,from the filtrate twenty to forty cubic centimeters are removed by a pipette1 and evaporated to dryness in a small porcelain dish1 with the addition of a drop of pure hydrochloric acid4 ,the ammonium chlorid remaining in the porcelain dish is washed with ten cubic centimeters of water into one of the compartments of the evolution flask of the ,knop-,wagner azotometer4 ,it is decomposed with fifty cubic centimeters of bromin lye and the nitrogen estimated volumetrically4 ,the difference between the amount of nitrogen in this material and that of the original material will give the amount of absorption exercised by the fine earth4 ,this number1 without any further calculation1 can be taken as the coefficient of absorption4 #acf4 ,method of ,huston4--,the salt solutions recommended by ,huston#ii are sodium phosphate 7,na,,hpo71 potassium chlorid1 potassium sulfate1 ammonium sulfate and sodium nitrate4 ,the solutions should be approximately tenth normal1 the actual strength in each case being determined by analysis4 ,the phosphorus is determined as magnesium pyrophosphate in the usual way1 the potash as potassium platinochlorid1 the ammonia by collecting the distillate from soda in half normal hydrochloric acid and titrating with standard alkali1 and the nitrate by ,warington's modification of ,schlsing's method for gas analysis4 ,the details of these methods of determination will be given later4 ,one hundred grams of the sifted1 air-dried soil are placed in a rubber stopped bottle and treated with #bej cubic centimeters of the solution to be tested4 ,the digestion is continued for forty-eight hours in each case1 the bottles being thoroughly shaken at the end of twenty-four hours4 ,at the end of the treatment the solutions are filtered and the salts determined in aliquot portions4 ,the details of this method are essentially those already described4 #acg4 ,statement of ,results4--,duplicate analyses should be made and the tabulation of the data is illustrated in the following analyses by ,huston3 ,na,,hpo cubic ,weight of ,weight of ,p,o ,salt centimeters ,mg,p,o in ,mg,p,o in absorbed removed filtrate taken4 twenty-five filtrate4 by #ajj per cubic grams cent4 centimeters of soil4 the solution4 7a7 #be #j4acfh gram #j4jifb gram 7b7 #be #j4jifc #j4behi #bi4f gram ------------ ,mean #j4jifc ,k,cl cubic ,weight of ,weight of ,k,o ,salt centimeters ,k,pt,cl in ,k,pt,cl4 absorbed removed filtrate taken4 twenty-five by #ajj per cubic grams cent4 centimeters of soil4 solution4 7a7 #be #j4faed gram #j4deje gram 7b7 #be #j4dedj #j4cafa #bf4e gram ------------ ,mean #j4debc ,k,,so cubic ,weight of ,weight of ,k,o ,salt centimeters ,k,pt,cl in ,k,pt,cl4 absorbed removed filtrate taken4 twenty-five by #ajj per cubic grams cent4 centimeters of soil4 solution4 7a7 #be #j4faac gram #j4ddbf gram 7b7 #be #j4dcga #j4ccbd #bh4j gram ------------ ,mean #j4dcii 7,,nh7,,so cubic ,number cubic ,half normal acid ,n absorbed ,salt centimeters centimeters neutralized4 by #ajj absorbed filtrate taken4 one-half normal grams per acid neutralized soil4 cent4 by fifty cubic centimeters of solution4 7a7 #ej #aj4jj #g4be grams 7b7 #ej #g4be #j4jifd #bg4e gram -------- ,mean #g4be ,na,n,o cubic ,number cubic ,cubic centimeter ,n absorbed ,salt centimeters centimeters ,n,o ,n,o at #j and by #ajj absorbed filtrate taken4 afforded by ten #ajjj grams per cubic millimeters4 soil4 cent4 centimeters of solution at #j and #ajjj millimeters pressure4 7a7 #aj #af4fc #af4gg grams 7b7 #aj #af4gj none #jj4jj ---------- ,mean #af4gc ,upon comparing the figures it will be found that the absorption1 passing from the greatest to the least1 is as follows3 phosphoric acid 7,p,o71 potassium sulfate1 ammonium sulfate1 potassium chlorid and sodium nitrate4 ,it will be seen that there was no absorption in the case of the nitrate1 while with each of the other salts there was quite a marked absorption4 ,it will also be noticed that the percentages of absorption are not very different1 and especially is this true of the potassium and ammonium salts1 the ,p,o being somewhat higher4 ,whether this fact is merely an accidental occurrence or is due to the law of combination by equivalents could hardly be predicted from the single soil experimented upon2 but taking into consideration the possibility of difference in solubility of the resulting compounds in the saline solutions used1 and of other varying conditions1 the percentages are evidently not far enough apart to exclude the possibility of the bases uniting in equivalent proportions4 #ach4 ,preparation of ,salts for ,absorption4--,the salts employed in the foregoing determinations are conveniently prepared1 in fractional normal strength4 ,in grams per liter the following quantities in grams are recommended1 viz41 #e4ce g ,,nh,cl2 #aj4aa g ,,kno2 #af4dj g ,ca7,,no72 #bd4fj g ,mg,s,o #g;,h,o2 #bc4d g ,ca,h7,,po71 etc4 ,the ammonium chlorid1 potassium nitrate and magnesium sulfate can be weighed as chemically pure salts and the standard solution be directly made up4 ,calcium nitrate is so hygroscopic that a stronger solution must be made up1 the calcium determined and the proper volume taken and diluted to one liter4 ,monocalcium phosphate is prepared as follows3 ,a solution of sodium phosphate is treated with glacial acetic acid and precipitated with a solution of calcium chlorid4 ,it is then washed with water until all chlorin is removed4 ,the fresh precipitate is saturated with pure1 cold phosphoric acid of known strength4 ,after filtering the solution is placed in a warm room and left for two or three weeks until crystallization takes place4 ,the crystals are pressed between blotting papers and finally dried over sulfuric acid and washed with water-free ether1 and again dried4 ,since this salt is decomposed in strong solutions it should be used only in one hundredth normal strength1 viz41 #b4cd grams per liter4 ,,porosity ,,and ,,its ,,relations ,,to ,,moisture4 #aci4 ,porosity4--,the porosity of a soil depends upon the state of divisibility and arrangement of its particles1 and upon the amount of interstitial space within the soil4 ,if a soil be cemented together into a homogeneous mass1 its porosity sinks to a minimum2 if it be composed1 however1 of numerous fine particles1 each preserving its own physical condition1 the porosity of the soil will rise to a maximum4 ,the porosity of a soil may be judged very closely by the percentage of fine particles it yields by the process of silt analysis to be described further on4 ,in general1 the more finely divided the particles of a soil1 the greater its fertility4 ,this arises from various causes2 in the first place1 such a soil has a high capacity for absorbing moisture and holding it2 thus the dangers of excessive rain-falls are diminished1 and the evil effects of prolonged drought mitigated4 ,in the second place1 a porous soil permits a freer circulation of the gases found in the soil4 ,the influence of lime in securing the proper degree of porosity of a soil is very great1 especially in alluvial deposits and other stiff soils4 ,it prevents the impaction which will necessarily follow in a soil which is too finely divided4 ,in general1 the porosity of the soil may be said to depend on three factors1 viz43 #a4 ,upon the state of divisibility or the number of particles per unit volume2 #b4 ,upon the nature and arrangement of these particles2 #c4 ,upon how much interstitial space there is in the soil4 #adj4 ,influence of ,drainage4--,good underdrainage increases the porosity of a soil by removing the excess of water during wet seasons and rendering the soil more suitable to capillary attraction which will supply moisture during dry seasons4 ,the influence of tile drainage on the production of floods has been carefully studied by ,kedzie1#ajj who shows that surface ditching in conjunction with deforesting may increase floods and contribute to droughts1 and that tile-draining may increase flood at the break-up in spring1 when the water accumulated in the surface soil by the joint action of frost and soil capillarity during the winter1 and the surface accumulations in the form of snow are suddenly set free by a rapid thaw4 ,he also points out that during the warm months tile-draining tends to prevent flood by enabling the soil to take up the excessive rain-fall and hold it in capillary form1 keeping back the sudden flow that would pass over the surface of the soil if not absorbed by it1 and it mitigates summer drought by increased capacity of the soil to hold water in capillary form and to draw upon the subsoil water supply4 #ada4 ,soil ,moisture4--,the capacity of a soil to absorb moisture and retain it depends on its porosity and is an important characteristic in relation to its agricultural value4 ,the following general principles relating to soil moisture are adapted from ,stockbridge3#aja ,during dry weather plants require a soil which is absorptive and retentive of atmospheric moisture4 ,the amount of this retention is generally in direct ratio to two factors1 viz41 the amount of organic matter and its state of division4 ,the capillary water of the soil is very closely related to its percolating power1 since all waters in the soil are governed in their movements by what is known as capillary force4 ,liebenberg has shown that this movement may be either upwards or downwards1 according as the atmosphere is dry or supplies soil-saturating rain4 ,the water absorbed by the roots passes into the plant circulation1 and the greater part is evaporated from the leaves4 ,where the supply of water is insufficient1 the plant wilts1 and if the evaporation long continue in excess of the supply obtained from the soil1 the plant must die4 ,the experiments of ,hellriegel have shown that any soil can supply plants with all the water they need1 and as fast as they need it1 so long as the moisture within the soil is not reduced below one-third of the whole amount that it can hold4 ,the quantity of water required and evaporated by different agricultural plants during the period of growth has been found to be as follows3 ,one acre of wheat exhales #dji1hcb pounds of water4 clover #a1jif1bcd sunflowers #ab1ehe1iid cabbage #e1jdi1aid grape-vines #gcj1gcc hops #d1dde1jba ,dietrich estimates the amount of water exhaled by the foliage of plants to be from #bej to #djj times the weight of dry organic matter formed during the same time4 ,cultivation conserves soil moisture4 ,it must be remembered that this water contains soil ingredients in solution4 ,hoffmann has estimated that the quantity of matter dissolved from the soil by water varies from #j4bdb to #j4jbje per cent of the dried earth4 ,the experiments of ,humphrey and ,abbott have shown that about one-sixth of the total sediment of the ,mississippi river is soluble in water4 #adb4 ,determination of the ,porosity of the ,soil4--,the porosity of the soil is fixed by the relative volume of the solid particles as compared with the interstitial space4 ,it is most easily determined by dividing the apparent by the real specific gravity4 ,let the real specific gravity of a soil be #b4edde and the apparent specific gravity of the same soil be #a4jiij4 ,the porosity is then calculated according to the following ratios1 viz43 #b4edde 3 #a4jii #ajj 3 ,x ,whence ,x #dc4b per cent volume occupied by the solid particles of the soil4 ,the per cent volume occupied by the interstitial space is therefore #ef4h4 #adc4 ,method of ,whitney4--,the total volume of interstitial space within the soil1 in which water and air can enter1 is best determined by calculation from the specific gravity and the weight of a known volume of soil4 ,to determine this in the soil in its natural position in the field1 a sample is taken in the following way3 ,a brass tube1 about two inches in diameter and nine inches long1 has a clock spring securely soldered into one end1 and this end turned off in a lathe to give a good cutting edge of steel4 ,the area enclosed by this steel edge is accurately determined1 and a mark is placed on the side of the tube exactly six inches from the cutting edge4 ,a steel cap fits on top of the brass cylinder to receive the blows of a heavy hammer or wooden mallet4 ,the cylinder is driven into the ground until the six-inch mark is just level with the surface4 ,the whole is then dug out1 care being taken to slip a broad piece of steel under the cylinder before it is removed1 so as to prevent the soil which it contains from falling out4 ,the cylinder is then carefully laid over on its side1 and the soil is cut off flush with the cutting edge of steel4 ,the soil is then removed from the cylinder1 carried to the laboratory and properly dried and weighed4 ,the object of the steel inserted in one end of the cylinder is to reduce the friction on the inside of the tube to a minimum1 and thus prevent the soil inside the cylinder being forced down below the level of the surrounding earth4 ,the volume of the soil removed with this sampler can readily be determined by calculation1 as the area of the end of the tube is known and the sample is six inches deep4 ,in a sampler1 such as described here1 this volume is about #cjj cubic centimeters4 ,from the weight of soil and the volume of the sample1 the volume of interstitial space may be found by the following formula3 ,s 7,v ,w_/ #ajj7_/,v ,s is the per cent by volume of interstitial space1 ,v is the volume of the tube in cubic centimeters1 ,w is the weight of soil in grams1 and is the specific gravity of the soil4 ,the specific gravity can be determined for each soil1 or the factor #b4fe can be used1 which is sufficiently accurate for most work4 ,the per cent by volume of interstitial space in the undisturbed subsoil is found to range from about thirty-five for sandy land1 to sixty-five or seventy for stiff clay lands4 ,for the determination of the amount of water an air-dried soil will hold1 if all the space within it is completely filled with water1 an eight-inch straight argand lamp chimney1 with a diameter of about two inches1 can be conveniently used4 ,a mark is placed on the side of the tube1 six inches from one end1 and the volume of the tube up to this mark is found by covering the end with a piece of thin rubber cloth1 or by pressing the chimney down firmly on a glass plate1 and making a water-tight joint with paraffin or wax4 ,water is then poured into the tube up to the six-inch mark1 and the weight or volume of water determined4 ,the tube can then be dried1 a piece of muslin tied tightly over the top and the whole then weighed4 ,soil is carefully poured in and the tube gently tapped on a soft support until the soil is six inches deep in the tube1 and has the desired degree of compactness4 ,the weight and volume of the soil can thus be determined1 and the volume of the interstitial space from the formula already given4 ,this can also be determined directly by introducing water from above1 or by immersing the cylinder of soil up to the six-inch mark in water1 and allowing the water to enter the soil from below4 ,with such a short depth of soil1 very little water will flow out when the cylinder is suspended in the air4 ,the amount which will flow out when the cylinder is thus suspended1 will depend both upon the texture and the depth of soil4 ,it is impossible1 however1 by this method1 to completely remove the air or to completely fill the space within the soil with water2 for as the water enters the soil1 a considerable amount of air becomes entangled in the capillary spaces1 and this could not be removed except by boiling and vigorous stirring1 which would altogether change the texture of the soil4 ,the amount of water held by the soil1 or the amount of space within the soil into which water and air can enter1 will evidently depend upon the compactness of the soil1 and this is best expressed in per cent by volume of space4 #add4 ,capacity of the ,fine ,soil for ,holding ,moisture4--,the soil1 as it is taken from the field1 may have quite a different water coefficient from the same soil after it has been passed through a fine sieve or been dried at air temperatures or at #ajj or #aaj4 ,the method of determination which depends upon adding excess of water to a given weight of fine earth1 and afterwards eliminating the excess by percolation or filtration1 is apt to give misleading results4 ,if1 however1 the results are obtained by working on the same weight of soil1 and in the same conditions1 they may have value in a comparative way4 ,the comparison between soils must be made with equal weights1 in like apparatus and with the same manipulation1 to have any value4 ,these determinations1 however1 cannot have the same practical value as those made in the samples in a natural condition as has just been described4 #ade4 ,method of ,wolff ,modified by ,wahnschaffe4#ajb--;,a cylindrical zinc tube 7,fig4 #ag71 sixteen centimeters long and four centimeters internal diameter1 is used1 the cubical capacity of which is #bjj cubic centimeters4 ,the cylinder is graduated by placing the moist linen disk on the gauze and tying a piece of rubber cloth over the bottom4 ,water is now poured in until the level is even with the gauze bottom4 ,add then exactly #bjj cubic centimeters of water1 mark its surface on the zinc1 throw out the water1 and file the zinc down to the mark4 ,the bottom of the tube is closed with a fine nickel-wire gauze4 ,below this a piece of zinc tubing1 of the size of the main tube1 is soldered2 pierced laterally with a number of holes4 ,before using1 the gauze bottom of the cylinder is covered with a moist1 close fitting linen disk1 and the whole apparatus weighed4 ,it is then filled with the fine earth1 little by little1 jolting the cylinder on a soft substance after each addition of soil to secure an even filling4 ,when filled even full the whole is weighed1 the increase in weight giving the weight of soil taken4 ,illustration3 ,,figure #ag4 ,,capacity ,,of ,,the ,,fine ,,soil ,,for ,,holding ,,moisture4 ,,method ,,of ,,wolff ,,modified ,,by ,,wahnschaffe4 ,a large number of cylinders can be filled at once and placed in a large glass crystallizing dish containing water and covered with a bell jar 7,fig4 #ag74 ,the water should cover the gauze bottoms of the cylinders to the depth of five to ten millimeters4 ,more water should be added from time to time as absorption takes place4 ,the cylinders should be left in the water until when weighed at intervals of an hour no appreciable increase in weight takes place4 ,the temperature and barometer reading should be noted in connection with each determination4 ,with increasing temperature the water coefficient is diminished4 ,the method of ,wolff1 as practiced in the laboratory of the ,chemical ,division of the ,u4 ,s4 ,department of ,agriculture1 has given very concordant results4 ,five determinations were made on a sample of vegetable soil with the ,wolff cylinders1 which were weighed at intervals of ten1 twenty1 and thirty days1 with the following results3 ,no4 #a4 ,water absorbed after ten days #ajf4be per cent #b4 #aje4fh #c4 #aje4hf #d4 #ajf4aa #e4 #aje4hc ------------ ,mean #aje4ie ,no4 #a4 ,water absorbed after twenty days #ajf4dd per cent #b4 #aje4ih #c4 #ajf4ef #d4 #ajf4eb #e4 #ajf4ch ------------ ,mean #ajf4ch ,no4 #a4 ,water absorbed after thirty days #ajh4ce per cent #b4 #ajg4fj #c4 #ajh4cb #d4 #ajg4hf #e4 #ajg4hg ------------ ,mean #ajh4jj ,the data obtained show that there was a very slight increase in the amount of moisture absorbed after the tenth day4 ,as will be seen1 however1 from the following data1 the soil within the cylinder does not contain in all parts the same percentage of moisture1 the lower portions of the cylinder containing notably larger proportions than the upper parts4 ,the cylindrical soil column was divided into four equal parts and the moisture determined in each part4 ,beginning with the top quarter the percentages of moisture were as follows3 ,first quarter #ig4eb per cent ,second #aje4ia ,third #aab4hc ,fourth #aaf4dh #adf4 ,method of ,petermann4#ajc--,the method of ,wolff as practiced by the ,belgian ,experiment ,station1 at ,gembloux1 is essentially the same as described above4 ,petermann recommends the use of tared cylinders twenty to twenty-five centimeters long and six to eight centimeters in diameter4 ,the cylinder is to be filled with the fine earth1 little by little1 with gentle tapping after each addition4 ,the bottom of the cylinder is closed with a perforated rubber stopper on which is spread a moistened disk of linen4 ,the cylinder1 thus prepared and filled1 is weighed and afterwards placed in a vessel containing distilled water1 to such a depth as to secure a water level about two centimeters above the lower surface of the soil in the cylinder4 ,the level of the water is kept constant as the contents of the cylinder are moistened by capillarity4 ,when the earth appears to be thoroughly moistened1 as can be told by the appearance of the upper surface1 maintain the contact with water for about five or six hours4 ,the cylinder is then removed1 the upper surface covered to avoid evaporation1 allowed to drain for a few hours1 wiped and weighed4 ,the cylinder is again placed in water to see if any increase in weight takes place4 ,the weight of the fine earth and of the absorbed water being known1 the percentage of absorption is easily calculated4 #adg4 ,method of ,a4 ,mayer4#ajd--;,a glass tube1 one and seven-tenths centimeters in diameter1 composed of two pieces1 seventy-five centimeters and twenty-five centimeters in length1 is united by a piece of rubber tubing4 ,the lower free end of the seventy-five centimeter piece is closed with a piece of linen4 ,the tube is filled1 with gentle jolting1 to the depth of one meter with fine earth1 the earth column thus extending twenty-five centimeters above the point of union of the two pieces4 ,thus prepared1 a quantity of water is poured into the upper tube sufficient to temporarily saturate the whole of the soil4 ,during the sinking of the water in the tube there is thus effected a moistening of the material before it is wholly filled with water4 ,after waiting until the water poured on top has disappeared the tube is separated at the rubber tube connection and a sample of the moist soil taken at that point4 ,this is at once weighed and then dried at #ajj4 ,the loss in weight gives the water absorbed4 ,the number thus obtained is calculated to the standard by volume1 by use of the number representing the apparent specific gravity of the fine earth4 ,for sand of different degrees of fineness the following numbers were found3 ,degree of fineness #b #c #d ,per cent water absorbed #g4j #ac4g #dd4f ,the numbers thus obtained are taken to represent the absolute water capacity of a mineral substance in powder4 ,the full water capacity1 i4 e41 the power of holding water when the powder is immersed in water1 the excess of which is then allowed to flow away is much greater than the absolute number4 ,this difference is shown in the following data3 ,quartz1 size three4 ,clay1 size three4 ,full water capacity #di4j per cent #df4h per cent ,absolute water capacity #ac4g #bd4e ,in general the absolute is markedly inferior to the full water capacity4 ,only in the finest dust do the two numbers approach each other4 #adh4 ,volumetric ,determination4--,a convenient apparatus for this determination has been devised by ,mr4 ,j4 ,l4 ,fuelling1 of the ,chemical ,division1 ,department of ,agriculture4 ,it is shown in ,fig4 #ah4 ,it consists of an ordinary percolator the diameter of which decreases slightly towards the lower end1 a thick-wall rubber tube and an ordinary burette1 divided in tenths4 ,a rubber stopper is fitted to the mouth of the percolator and perforated twice--in the middle and at the side1 the former for a small tube provided with pinch-cock and the latter for the neck of a small funnel4 ,the whole is supported on a convenient stand1 the clamp holding the percolator being placed above that supporting the burette1 both clamps arranged to slide on the stand-rod4 ,illustration3 ,,figure #ah4 ,,fuelling',s ,,apparatus4 ,the method is as follows3 ,a mark is placed upon the projecting tube at the lower end of the percolator1 and the tube at this point may be drawn out sufficiently to decrease the width of meniscus to one-eighth inch4 ,into the percolator is first introduced a small disk of wire gauze or perforated porcelain1 with heavy wire pendant in the tube4 ,through the rubber stopper a small glass tube is passed and its lower end pressed firmly upon the wire or porcelain disk1 its upper end being curved and supplied with a pinch-cock4 ,into the percolator is now poured one inch of fine shot 7,no4 #bj7 and then one inch of fine sand which has been previously digested with hydrochloric acid and well cleaned of dust by washing4 ,the zero4--,after the shot and sand have been shaken even1 the burette is filled with water and raised above the level of the sand1 wetting the percolator for four inches of its length4 ,the burette is lowered and the shot and sand bed allowed to drain by opening the pinch-cock of the inner tube4 ,the burette is raised and the shot-sand flooded repeatedly until1 by lowering the burette until the zero mark of the percolator tube is reached1 a uniform reading on the burette is secured4 ,thus the shot-sand bed is completely charged with water4 ,the water level is now made zero on the percolator stem1 the burette filled to its zero mark and the apparatus is prepared for introduction of the soil4 ,the ,determination4--,from #ajj to #bjj grams of soil1 previously dried free of moisture1 are weighed1 the burette raised until the water level is three inches above the sand1 and the soil gently dropped through a funnel into the water4 ,when the soil has been introduced and wetted completely the water level is raised above the soil and allowed to remain thus two hours4 ,the burette is then lowered and the water allowed to drain from the wetted soil4 ,four to six hours are usually given the draining1 the reading taken on the burette after establishing the zero on the percolator stem1 the volume of absorbed water thus ascertained and divided by the weight of soil multiplied by #ajj2 the result expresses the water absorbed per hundred of soil4 ,example3 ,water required to saturate disk1 etc4 #j4ej cubic centimeter4 ,weight of air-dried soil taken #bj4jj grams4 ,moisture at #aje therein #ad4be per cent4 ,weight water in soil #b4he grams4 ,reading of burette after saturation #aj4ge cubic centimeters4 ,less water required for disk1 etc #i4be ,temperature #bj4jj ,weight of #i4be cubic centimeters ,h,o at #bj #i4bb grams4 ,total weight of water retained by soil #ab4jg ,per cent water retained by soil #fj4ce per cent4 ,for general analytical work the correction for variations in the weight of water for different temperatures is of no practical importance4 #adi4 ,accuracy of ,results4--,a sample of soil from the beet sugar station1 in ,nebraska1 gave the following duplicate results3 ,first trial #de4ge per cent water4 ,second trial #dd4he ,muck soils from ,florida1 containing varying proportions of sand1 gave the following numbers3 ,soil number one1 #add4he per cent1 and #ade4dc per cent2 soil number two1 #aji4ac per cent1 and #ajg4ic per cent2 soil number three 7very sandy71 #df4hf per cent1 and #df4ea per cent4 #aej4 ,method of ,wollny4#aje--;,a zinc tube1 ninety centimeters long and four centimeters internal diameter1 carries at each end1 at right angles to the axis1 a flattened rim #a4e centimeters broad4 ,the lower end of the tube is closed with a strong piece of coarse linen4 ,the soil to be examined is then filled in little by little1 with gentle tamping4 ,on the upper end two glass tubes are placed1 each ten centimeters long and four centimeters internal diameter4 ,these tubes are furnished at each end with cemented brass cylinders which are expanded to a circular1 evenly ground rim1 #a4e centimeters wide1 also at right angles to the axis of the main tube4 ,these rims are greased and placed together1 one on the other1 and held together by wooden clamps4 ,the glass tube in immediate connection with the zinc tube is also firmly filled with the soil sample1 while the second tube is only partly filled1 so that any settling which may take place in the soil on the addition of water may still find the first glass tube full of the sample4 ,the empty part of the upper glass tube is now filled with water and additional quantities of water are added from time to time until the soil is saturated4 ,in order to be able to observe when this takes place there is a slit at the lower end of the zinc tube which is closed with a piece of glass4 ,this slit should be about two centimeters broad and ten centimeters long4 ,the lower end of the zinc tube is set on a glass plate to prevent evaporation4 ,as soon as the water shows itself at the lower end of the zinc tube1 the excess of water in the upper glass tube is at once removed by a pipette and a stopper inserted through which a glass tube passes drawn out into a fine point above4 ,the object of this is to avoid evaporation on the upper surface4 ,the apparatus is then left at rest for thirty-six hours4 ,at the end of this time the clamps are removed and the column of moist earth cut with a piece of platinum foil1 and the two ends of the glass tube1 next to the zinc tube1 covered with glass plates4 ,it is then weighed and the weight of moist earth determined by deducting the weight of the tube and its glass covers4 ,the moist earth is carefully removed to a large porcelain dish and dried at #ajj4 ,before weighing it is allowed to stand twenty-four hours in the air4 ,the data obtained are used to calculate the water content to volume per cent4 ,the volume of the glass tubes should be determined by careful calibration4 #aea4 ,method of ,heinrich4#ajf--,the soil to the depth turned by the plow is dug out and in the hole a lead vessel without bottom1 twenty centimeters in diameter and forty centimeters high1 is placed4 ,the soil is then thrown back around and outside the lead vessel until the latter appears buried in the fragments4 ,the rest of the soil is passed into the lead vessel1 through a sieve having four meshes to the centimeter1 using for this purpose enough water to thoroughly moisten it4 ,care should be taken not to use enough water to cause any separation of the fine from the coarse particles4 ,by this process all coarse stones1 sticks1 etc41 are separated4 ,in sandy soils the flask is left for a few hours while in clay soils a much longer time is necessary4 ,when the excess of water has disappeared the lead cylinder is removed1 and a piece cut out of the center of it placed in a weighed drying flask and dried at #ajj4 #aeb4 ,effect of ,pressure on ,water ,capacity4#ajg--,the increasing capacity of soil to hold water developed by shaking or pressure1 is determined by ,henrici in the following way3 ,into a glass cylinder of twenty millimeters internal diameter are poured twenty cubic centimeters of water4 ,a given quantity of soil is next added1 and after standing until thoroughly saturated1 the residual water is measured by pouring off1 or better1 by graduations on the side of the tube4 ,the increase in the volume of the clear water is also measured1 after shaking1 in the same way4 ,the data of a determination made as above described follow3 ,water in cylinder #cj cubic centimeters4 ,water and saturated soil #dj ,volume of unsaturated soil e #aj ,volume of saturated soil e w #bj4e ,water contained therein w #aj4e ,by repeated shaking the volume of e w1 the content of w therein1 and the relative values of e_/w were found to be as follows3 ,cubic ,cubic ,cubic ,cubic centimeters4 centimeters4 centimeters4 centimeters4 e w #bj4e #af4j #ae4g #ae4j w #aj4e #f4j #e4g #e4j w_/e #a4je #j4fj #j4eg #j4ej ,if e represent the volume of the saturated soil then e e w1 and this gives the relation to the volume of dry earth represented by the equation e_/e #a w_/e4 ,this indicates that the relative volume of the saturated soil is equal to unity increased by the relative content of water4 #aec4 ,coefficient of ,evaporation4--,at an ordinary room temperature in the shade1 samples of soil1 if they are subjected to experiment in tolerably thin layers have nearly an equal coefficient of evaporation4 ,that is1 the absolute quantity of water evaporated in a given time is almost entirely conditioned upon the magnitude of the surface exposed and the temperature of the surrounding air4 ,only when exposed in conditions as nearly as possible natural in thin layers to the action of the sunlight and shade do the soils show their peculiarities in respect of the evaporation of moisture4 ,in order to see these peculiarities1 samples of soil which have been previously examined must be subjected to examination at the same time with the soil whose properties are to be determined4 ,the zinc box1 before described1 should be protected with a well fitting cover of thick paper1 and the different samples of soil which are to be tested placed therein4 ,this should now be placed in a wooden box1 the top of which is exactly even with the top of the zinc vessel4 ,this box containing the vessel should be exposed to the sunlight4 ,after twenty-four hours the zinc boxes can be taken away from position and their loss in moisture determined1 and these weighings1 according to the condition of the atmosphere1 can be continued from fourteen days to three weeks1 the temperature of the air of course being carefully determined at each time4 ,at first1 all the different soils being saturated with moisture1 it will be observed that the loss of moisture is proportionately the same for all4 ,soon1 however1 the rapidity of the evaporation in the samples of soil rich in humus and clay will be decreased as compared with the sandy soils1 and in general1 those which possess a high capillary power capable of bringing the moisture rapidly from the deeper layers to the surface4 ,there soon comes a point when the difference in evaporation is at its greatest2 and then there will be a gradual diminution until the samples lose no further moisture4 ,this point1 for the different soils1 can be determined by frequent weighings of the vessel4 #aed4 ,determination of ,capillary ,attraction4--,long glass tubes graduated in centimeters may be used for this determination1 or plain tubes so arranged as to admit of easy measurements with a rule4 ,the tubes may be from one to two centimeters internal diameter and about one meter long4 ,the fine earth should be evenly filled in little by little1 with gentle jolting4 ,the lower end of each tube1 before filling1 is closed with a piece of linen4 ,the tubes1 after filling1 are supported in an upright position by a frame ,,ae1 ,fig4 #ai1 in a vessel ,b containing water in which the linen covered ends ,d dip to the depth of two centimeters4 ,the height of the water in the several tubes should be read or measured at stated intervals4 ,the water contained in the supply vessel should be kept at a constant height by a ,mariotte bottle4 ,illustration3 ,,figure #ai4 ,,apparatus ,,to ,,show ,,capillary ,,attraction ,,of ,,soils ,,for ,,water4 ,the observations may be discontinued after one hundred and twenty hours1 but even then the water will not have reached its maximum height4 ,it is recommended by some experimenters to cut the tubes1 after the above determination is completed1 into pieces ten centimeters in length1 and to determine the per cent of water in each portion4 #aee4 ,statement of ,results4--,the following table illustrates a convenient method of tabulating the observed data as given by ,knig4#ajh ,number of sample #a #b #c #d #e #f ,height of #bd hours4 #bg4c #ch4j #af4g #cf4d #h4j #bh4h centimeters4 moisture column after3 #dh #ce4i #ej4h #bd4e #di4b #aa4i #dj4e #gb #da4e #ei4e #cj4j #eg4i #ae4b #di4a #if #dd4d #ff4b #cc4e #fc4h #ag4e #ee4b #abj #df4g #gj4j #cf4c #fh4e #ai4b #fj4e #aef4 ,inverse ,capillarity4--,in tubes filled with fine earth1 as described in paragraph #aed1 water is quickly poured1 the same quantity into each tube of the same diameter1 or such quantities in tubes of different diameters as would form a water column of the same depth over the surface of the sample4 ,the rate at which the water column descends in each tube1 the time of the disappearance of the water at the surface and the final depth to which it reaches1 are the data to be entered4 #aeg4 ,statement of ,results4--,the points to be observed in the determination of inverse capillarity are the number of hours required for the total absorption of a column of water of a given height1 the depth of the moisture column at that moment1 and the total depth to which the moisture column finally reaches4 ,the data of observations with six samples with a water column four centimeters high are given by ,knig#aji as follows3 ,number of sample #a #b #c #d #e #f ,number of hours required for water to disappear #d4c #a4h #aj4c #c4j #ba4j #d4c ,depth of moisture at time of disappearance of water #aa4j #ab4j #aa4d #ac4c #aa4g #ab4j centimeters4 ,total depth of moisture #ac4j #ah4a #ac4j #ai4j #ab4j #af4e #aeh4 ,determination of the ,coefficient of ,evaporation4--,the coefficient of evaporation is the number of milligrams of water evaporated from a square centimeter of soil surface in a given unit of time4 ,it is evident that this number will vary with the physical state of the soil1 the velocity of the wind1 the saturation of the air with aqueous vapor and the temperature4 ,in all statements of analyses these factors should appear4 ,the process may be carried on first 7a7 with soil samples kept continually saturated with water and 7b7 with samples in which the water is allowed to gradually dry out4 ,method a4--,the determination may be made in the shade or sunlight4 ,in the ,shade4--,a zinc cylinder 7,z ,fig4 #bj71 fifteen centimeters in diameter and #g4e centimeters high1 with a rim one centimeter wide and one centimeter from top1 is covered at one end with linen or cotton cloth and filled with fine earth1 with gentle jolting1 until even with the top4 ,it is then placed in a zinc holder ,h1 into the circular opening of which it snugly fits as in ,a4 ,this holder is twenty centimeters in diameter and #g4e centimeters deep4 ,it has an opening at ,o through which water can be added until it is filled so as to wet the bottom of ,z when in place4 ,as the water is absorbed by the soil more is added and1 the top being covered1 the apparatus is allowed to stand for twenty-four hours4 ,at the end of this time the soil in the zinc cylinder is saturated with water to the fullest capillary extent4 ,the whole apparatus1 after putting a stopper in ,o1 is now weighed on a large analytical balance and placed in an open room1 with free-air circulation1 for twenty-four hours4 ,at the end of this time it is again weighed and the loss of weight calculated to milligrams per square centimeter4 ,where large and delicate balances can not be had1 the apparatus can be constructed on a smaller scale suitable for use with a balance of the ordinary size4 ,in the ,sunlight4--,the apparatus described above is enclosed in a wooden box having a circular opening the size of the soil-zinc cylinder4 ,in the determination of the rate of evaporation1 the apparatus1 charged and weighed as above described1 is exposed to the sun for a given period of time1 say one hour4 ,on the second weighing the loss represents the water evaporated4 ,the time of year1 time of day1 velocity of wind and temperature1 and degree of saturation of the air with aqueous vapor1 should be noted4 ,the data obtained can then be calculated to milligrams of water per square centimeter of surface for the unit of time4 ,method b4--,as in method a the determination may be made in the shade or in the sunlight4 ,the rate of evaporation is1 in this method1 a diminishing one and depends largely on the reserve store of water in the sample at any given moment4 ,the same piece of apparatus may be used as in the determinations just described4 ,after charging the sample with moisture all excess of water in the outer zinc vessel is removed and the rate of evaporation determined by exposure in an open room or in the sunlight1 as is done in the operations already described4 ,alternate ,method4--,the zinc cylinders used in determining saturation coefficient1 paragraph #ade1 may also be employed in determining the rate of evaporation4 ,each cylinder should be wrapped with heavy paper or placed in a thick cardboard receptacle1 and all placed in a wooden box1 the cover of which is provided with circular perforations1 just admitting the tops of the cylinders1 which should be flush with the upper surface of the cover4 ,arranged in this way the cylinders previously weighed are exposed in the shade or to direct sunlight and reweighed after a stated interval4 ,on account of the small surface here exposed in comparison with the total quantity of soil and moisture it is recommended to weigh the cylinders once only in twenty-four hours4 ,the weighings may be continued for a fortnight or even a month4 ,in soils fully saturated with water the rate of evaporation is at first nearly the same on account of the surface being practically that of water alone4 ,as the evaporation continues1 however1 the rate changes markedly with the character of the soil4 #aei4 ,rapid ,method of ,wolff4--,in order to expose a larger surface to evaporation and to secure the results in a shorter period of time1 ,wolff#aaj fills square boxes1 having wire-gauze bottoms1 with fine earth1 and after saturating with moisture weighs and suspends them in the open air4 ,the wire-gauze bottoms are previously covered with filter paper to prevent loss of soil4 ,illustration3 ,,figure #bj4 ,,apparatus ,,for ,,determining ,,coefficient ,,of ,,evaporation4 #afj4 ,estimation of ,water ,given up in a ,water-,free ,atmosphere4--,the air-dried sample1 in quantities of from five to ten grams in a thin layer on glass1 is placed over a vessel containing strong sulfuric acid4 ,it is then placed on a ground glass plate and covered with a bell jar4 ,the sample is weighed at intervals of five days until the weight is practically constant4 ,this method is valuable in giving the actual hygroscopic power of a soil depending on its structure alone4 #afa4 ,estimation of the ,porosity of the ,soil for the ,passage of ,gases4--,some further notion of the physical state of the soil known as porosity1 may also be derived by a study of the rate at which it will admit of the transmission of gases4 ,a method for estimating this has been devised by ,ammon4#aaa ,air is compressed in two gas holders by means of a column of water of proper height to give the pressure required4 ,the tubes through which the air passes out of the gas holders are each furnished with a stop-cock and united with a glass tube having a side tube set in at right angles for carrying off the air4 ,the use of two holders makes it possible to carry on the experiment as long as may be desired1 one holder being filled with air while the other is emptying4 ,the common conducting tube is joined with a meter which is capable of measuring1 to #j4ja1 the volume of air passing through it4 ,the pressure is regulated by means of the stop-cocks4 ,the air passing from the meter is received in a drying tube filled with calcium chlorid4 ,from the drying tube the air enters a drying flask filled below with concentrated sulfuric acid and above with pumice stone saturated therewith4 ,next the dried air passes through a worm1 eight meters long1 surrounded with water at a given temperature4 ,the dried air of known temperature next enters the experimental tube4 ,this tube is made of sheet zinc #abe centimeters in length and five centimeters in internal diameter4 ,it is placed in an upright position1 and about six centimeters from its upper end carries a small tube at right angles to the main one for connection with a water-filled manometer4 ,the upper and lower ends of the tube are closed with perforated rubber stoppers carrying tubes for the entrance and exit of the air4 ,in the inside of the zinc tube are found two close-fitting but movable disks1 of the finest brass wire gauze1 between which the material to be experimented upon is held4 ,the layer of fine soil is held between these disks and may be of such a depth as is required for the proper progress of the experiment4 ,with soils of firm texture opposing a great resistance to the passage of the air the column of earth tested should be shorter than with light and very permeable soils4 ,the experimental tube is surrounded with a water jacket1 which may also be made of sheet zinc1 carrying small tubes directed upwards for holding thermometers4 ,the water jacket should be kept at the same temperature as the air which is used in the experiment4 ,the process of filling the tube1 the amount of pressure to be used and the air and soil temperature1 will naturally vary in different determinations4 ,the volume of air at a given pressure and temperature which passes a column of soil of a given length in a unit of time will give the coefficient of permeability4 #afb4 ,determination of ,permeability in the ,open ,field4--,a method for determining the rate of transmission of a gas through the soil in the field has been devised by ,heinrich4#aab ,a box ,c 7,fig4 #ba7 is made of strong sheet iron and has an opening below1 ten centimeters square1 and a height of about twenty centimeters4 ,at exactly ten centimeters from the bottom1 the box has a rim at right angles to its length so that it can be placed only ten centimeters deep in the soil4 ,the box holds a volume of earth equal to #a1jjj cubic centimeters4 ,illustration3 ,,figure #ba4 ,,method ,,of ,,heinrich4 ,the part of the box above ground is connected with the bottle ,b by a glass tube as indicated in the figure4 ,the bottle ,b should have a capacity of about ten liters4 ,the air in ,b is forced out through ,c by water running in from the supply ,a and the pressure in ,b is recorded by the manometer ,d4 ,the experiment should be tried on a soil thoroughly moist4 ,in measuring the pressure in ,b the water pressure should be cut off by the pinch-cock between ,a and ,b1 and the pressure on the manometer observed after the lapse of one to two minutes4 ,,movement ,,of ,,water ,,through ,,soils3 ,,lysimetry4 #afc4 ,porosity in ,relation to ,water ,movement4--,the intimate relation which water movement in a soil bears to fertility makes highly important the analytical study of this feature of porosity4 ,a soil deficient in plant food1 in so far as chemical analysis is concerned1 will produce far better crops when the flow of moisture is favorable than a highly fertile soil in which the water may be in deficiency or excess4 ,aside from the actual rain-fall the texture of the soil1 in other words its porosity1 is the most important factor in determining the proper supply of moisture to the rootlets of plants4 ,even where the rain-fall is little1 a properly porous soil in contact with a moist subsoil will furnish the moisture necessary to plant growth4 ,this fact is well illustrated by the beet fields in ,chino ,valley1 ,california4 ,in this locality most excellent crops of sugar beets are produced without irrigation and almost without rain4 #afd4 ,methods of ,water ,movement--,the translocation of soil water is occasioned in at least two ways2 namely1 #a4 ,by changing the porosity of a given stratum of soil4 #b4 ,by changing the amount of water a given stratum contains4 ,the following experiment by ,king#aac illustrates a convenient method of studying this movement of water3 ,on a rich fallow ground of light clay soil1 underlaid at a depth of eighteen inches by a medium-grained sand1 water1 to the amount of two pounds per square foot on an area of eight by eight feet1 was slowly added with a sprinkler1 samples of soil having been previously taken in six-inch sections down to a depth of three feet4 ,the samples were taken along a diagonal of the square under experiment and one foot apart4 ,the middle sample of the line being from the center of the area4 ,the sampling and wetting occurred between one and three ,p4 ,m41 on ,july #bb1 and on the evening of the #bc a corresponding series of samples was taken along a line parallel to the first but eight inches distant4 ,the changes in the percentages of water in the soil are given in the following table1 showing the translocation of water in soil due to wetting the surface3 ,,per ,,cent ,,of ,,water4 ,,difference4 ,inches4 ,before ,after ,in per cent4 ,in pounds per wetting4 wetting4 cu4 ft4 #j-f #ad4jj #bb4bc #h4bc #b4hgc #f-ab #ae4ad #ae4ga #j4eg #j4aii #ab-ah #af4bc #ae4ge -#j4dh -#j4bac #ah-bd #ag4gj #af4ib -#j4gh -#j4cdg #bd-cj #af4gf #ad4da -#b4ce -#a4jcb #cj-cf #ae4ea #ae4ba -#j4cj -#j4acb ,the figures given in the last column of the table are computed from the absolute dry weights of the upper three feet of soil as determined in a locality some rods from the place of experiment1 and are therefore only approximations1 but the error due to this cause is certainly small4 ,it will be seen that while only two pounds of water to the square foot were added to the surface1 the upper six inches contained #b4hg pounds per square foot more than before the water was added1 and the second six inches contained #j4aii pound more1 and this too in the face of the fact that the evaporation per square foot from a tray sitting on a pair of scales close by1 was #j4dbh pound during the interval under consideration4 ,similar experiments were made by taking the samples of soil at #e4cj ,p4 ,m4 in one-foot sections down to four feet1 at four equally distant places along the diagonal of a square1 six by six feet1 and having the ground sprinkled4 ,at the same time four similar sets of samples were taken on lines vertical to each of the sides of the square but four feet distant from them4 ,the amount of water the soil contained was then determined1 and at #aa4cj ,a4 ,m41 nineteen hours later1 another series of samples was taken at points about four inches distant from the last and the amount of water determined with the result given below4 ,,translation ,,of ,,water ,,occasioned ,,by ,,wetting ,,the ,,surface4 ,depth of samples4 ,,wet ,,area4 ,before wetting4 ,after wetting4 ,pounds of ,pounds of ,per cent of water per ,per cent of water per water4 cubic foot4 water4 cubic foot4 #j-ab inches #af4hf #aa4gh #bj4ae #ad4jf #ab-bd #ag4gf #ae4gi #ai4ga #ag4eb #bd-cf #af4gf #ad4gc #ag4gb #ae4eh #cf-dh #ae4ja #ad4jc #af4dg #ae4dj ,averages #af4ei #ad4jh #ah4ea #ae4fd ,total amount of water #ef4cc #fb4ef ,amount of change #f4bc ,depth of samples4 ,,area ,,not ,,wet4 ,first samples4 ,second samples4 ,pounds of ,pounds of ,per cent of water per ,per cent of water per water4 cubic foot4 water4 cubic foot4 #j-ab inches #ag4gb #ab4ch #ah4bg #ab4ge #ab-bd #ai4ah #ag4je #ai4id #ag4gb #bd-cf #af4ig #ad4ib #ag4eb #ae4dj #cf-dh #ae4di #ad4dh #ae4af #ad4ag ,averages #ag4cd #ad4ga #ag4ga #ae4ja ,total amount of water #eh4hc #fj4jd ,amount of change #a4ba ,the above data show sufficiently well the method of investigation to be pursued in studies of this kind4 #afe4 ,capillary ,movement of ,water4--,the method of investigation proposed by ,king#aad consists in taking samples of soil at intervals of one1 two1 three1 or four feet in depth1 and determining the amount of moisture in each in connection with the amount of rain-fall during the period4 ,the quantity of water contained in a given soil1 at various depths and on different dates1 is shown in the following table3 ,depth in ,date4 ,per cent ,pounds per ,increase or decrease4 feet4 water4 cubic foot4 ,pounds per cubic foot4 #a ,march #hth #bd4cc #af4ih #a ,april #ahth #bb4cg #ae4fa -#a4cg #b ,march #hth #ae4hj #ad4je #b ,april #ahth #ba4fd #ai4bd #e4ai #c ,march #hth #aa4af #i4ha #c ,april #ahth #af4bd #ad4bg #d4df #d ,march #hth #g4hg #g4cf #d ,april #ahth #aa4ai #aj4df #c4aj ,the rain-fall during the interval was #d4ah inches1 equal to #ba4gg pounds per square foot4 #aff4 ,lateral ,capillary ,flow4--,to determine the lateral capillary flow of water in a soil the following method1 used by ,king#aae may be employed3 ,a zinc lined tray1 six by six feet in area and eight inches deep1 is filled with a soil well packed4 ,in one corner of this tray a section of five inches of unglazed drainage tile1 having its lower end broken and jagged1 is set and the dirt well filled in round it4 ,by means of a ,mariotte bottle water is constantly maintained in the bottom of this tile1 three-quarters of an inch deep1 so that it will flow laterally by capillary action into the adjacent soil1 the object being to determine the extent and rate of capillary flow laterally4 ,the water content of the soil is determined at the time of starting the experiment1 on the circumferences of circles described with the tile as a center1 the distance between the circles being one foot4 ,at stated periods1 usually at intervals of one day1 the content of moisture is again determined at the same points4 ,the investigations show that the lateral movement of water in the soil is not rapid enough to extend much beyond three feet in thirty-one days1 for beyond that distance the soil was found to be drier than at the beginning of the experiment4 ,a record is to be kept of the amount of water delivered to the soil by weighing the supply bottle at intervals1 and the rates given at which the soil takes up the water in grams per hour and pounds per day4 ,also the amount of flow per square foot of soil section together with the mean daily evaporation should be noted4 ,the mean flow per foot of soil section is computed on the assumption that the outer face of the zone of completely saturated soil is the delivering surface4 ,in ,king's work this point1 as nearly as could be determined1 was twelve inches from the corner of the tray and hence the figures at best can only be regarded as approximations4 ,the method of stating results is shown in the following table3 ,,showing ,,the ,,rate ,,of ,,lateral ,,capillary ,,flow ,,of ,,water ,,in ,,clay ,,loam4 ,date4 ,no4 ,total mean1 ,total mean1 ,mean daily flow ,mean daily of hourly flow1 daily flow1 per square evaporation1 days4 grams4 pounds4 foot1 pounds4 pounds4 ,jan4 #bh to #e #gj4gj #c4gc #b4ch ,feb4 #b ,feb4 #b-g #e #he4ih #d4ed #b4ia ,feb4 #g-ab #e #gi4cc #d4ai #b4fd ,feb4 #ab-ag #e #gi4da #d4ai #b4fd #j4eih ,feb4 #ag-bb #e #gj4gi #c4gd #b4ch #j4ecd ,feb4 #bb-bh #f #ei4hi #c4af #b4ja #j4dea ,feb4 #bh to #f #fj4gd #c4ba #b4jd #j4deh ,march #f ,mar4 #f-ac #g #fj4cg #c4ad #b4jj #j4ddh ,means #b4ch #j4dih ,from this table it will be seen that the flow of water in the soil varied in rate1 being slower during the first five days than in the succeeding fifteen days4 ,after twenty days the flow dropped again to the beginning rate and then fell below1 but remained quite constant during the following nineteen days4 ,for the sake of uniformity in units of measure the daily quantity of flow should be given in kilograms when the hourly flow is given in grams4 #afg4 ,causes of ,water ,movement in the ,soil4--,the movement of water in a soil as explained by ,whitney#aaf is due to two forces1 viz41 gravitation and surface tension4 ,the force of gravitation in a given locality is always uniform1 both in direction and magnitude per unit volume of water4 ,surface tension is the tendency of any exposed water surface to pull itself together4 ,it may act in any direction1 according to circumstances1 and may thus sometimes help and sometimes antagonize the force of gravitation4 ,according to the law of surface tension any particle of moisture tends to assume the smallest possible area4 ,this tendency is a constant definite force per unit of surface at a given temperature4 ,in the soil this constant strain on the free surface of water particles serves1 in a high degree1 to move them from place to place1 in harmony with the requirements of the different portions of the field4 ,when a soil is only slightly moist the water clings to its grains in the form of a thin film4 ,when these soil particles are brought together the films of water surrounding them unite1 one surface being in contact with the soil particles and the other exposed to the air4 ,if more water enter the soil the film thickens until finally1 when the point of saturation is reached1 all the space between the soil particles becomes filled with water1 and surface tension within the soil is thus reduced to zero4 ,gravity then alone acts on the water and with a maximum force4 ,in a cubic foot of ordinary soil the total surface of the soil particles will be at least #ej1jjj square feet4 ,it follows that when the soil is only slightly moist the exposed water surface of the films surrounding the soil particles approximates that of the particles themselves4 ,if such a mass of slightly moist soil be brought in contact with a like mass saturated with water1 the films of water at the point of contact will begin to thicken in the nearly dry soil at the expense of the water content of the saturated mass4 ,the water will thus be moved in any direction4 ,during evaporation the surface tension near the surface of the soil is increased1 and water is thus drawn from below4 ,in like manner1 when rain falls on a somewhat dry soil1 the surface tension is diminished and the greater surface tension below pulls the moisture down even when gravitation would not be sufficient for that purpose4 ,certain fertilizers have the faculty of modifying surface tension and thus change the power of the soil in its attraction for moisture4 ,in this way such fertilizers act favorably on plant growth1 both by providing plant food and by supplying needed moisture4 #afh4 ,surface ,tension of ,fertilizers4--,whitney gives the following data in respect of the surface tension of aqueous solutions of some of the more common fertilizing materials4 ,it is expressed in gram meters per square meter1 i4 e41 on a square meter of liquid surface there is sufficient energy to lift the given number of grams to the height of one meter4 ,,surface ,,tension ,,of ,,various ,,fertilizing ,,solutions4 ,solution of-- ,specific gravity4 ,gram meters per square meter4 ,salt #a4jgj #g4ige ,kainite #a4jec #g4ijj ,lime #a4jjb #g4fif ,water #a4jjj #g4ffh ,acid phosphate #a4jje #g4fef ,plaster #a4jjj #g4fch ,ammonia #j4ifj #f4hfi ,urine #a4jbf #f4fae ,magnesium chlorid #a4ajjj #g4ifd ,basic slag #a4jjab #g4hij ,marl #a4jjac #g4hee ,potassium chlorid #a4ajjj #g4hec ,ammonium sulfate #a4ajjj #g4hcd ,dried blood #a4jjja #g4gfd ,ground bone #a4jjjg #g4gdi ,sodium nitrate #a4ajjj #g4gcj ,sodium sulfate #a4ajjj #g4gcj ,wood ashes #a4jjch #g4fgd ,potassium nitrate #a4ajjj #g4ffa ,potassium sulfate #a4jhcj #g4feh ,ammonium nitrate #a4ajjj #g4fef ,dried fish #a4jjbf #g4eid ,stable manure #a4jjac #g4dfd ,cotton-seed meal #a4jjed #f4ecd ,tankage #a4jafi #d4hdd ,cotton seed #a4jjgj #d4ghh ,,surface ,,tension ,,of ,,soil ,,extracts4 ,kind of ,soil4 ,specific gravity4 ,surface tension4 ,kentucky blue grass #a4jjj #g4bdd ,triassic red sandstone #a4jjj #g4bdd ,wheat soil #a4jjj #g4jih ,garden soil #a4jjj #g4jhi #afi4 ,method of ,estimating ,surface ,tension4--,the determination of surface tension is made by measuring the rise of the liquid in a capillary tube4 ,a short piece of thermometer tubing is used1 the diameter of the bore being determined by careful microscopic measurements with a micrometer eyepiece4 ,the diameter of the tube should be about #j4eegh millimeter4 ,the tube is very thoroughly cleaned after each observation1 or set of observations1 with a strong caustic potash solution1 and1 after washing1 is allowed to stand for some time in a saturated solution of potassium bichromate in strong sulfuric acid4 ,the height of the rise in the capillary tube is measured with a cathetometer4 ,the following formula is used for the calculation of the results3 ,t 7h d 7_/7#d cos4 a7 ,where ,t is the surface tension1 d is the diameter of the tube in centimeters2 h the height to which the liquid rises in the capillary tube in centimeters2 is the specific gravity of the solution2 and #d cos4 a refers to the angle of the liquid with the sides of the glass tube4 ,for a tube of the size given above1 #e #bd is the value of this edge angle4 ,in regard to saline solutions1 ,quincke#aag says1 that the edge angle appears to increase a little with augmenting concentration of the saline solution1 but otherwise to differ only inconsiderably from the edge angle of pure water4 #agj4 ,effect of the ,solutions on ,surface ,tension4--,the mineral fertilizers1 as a rule1 increase the surface tension of water1 while organic matters in solution decrease it4 ,but it must not be forgotten in this connection that but little of the organic matter in the fertilizers employed for the experiment passes into solution4 ,moreover1 with these substances1 the accuracy of the work is impaired somewhat by the increased viscosity4 ,in general1 the results of the experiment are in harmony with the well-known effect of magnesium1 sodium1 and potassium chlorids1 and sodium nitrate1 to make the soil more moist in dry weather1 and the opposite effect produced by the application of organic matter4 #aga4 ,method of ,preparing ,soil ,extracts4--,the soil extracts used in determining the surface tension1 as given in the above table1 are prepared as follows3 ,ten grams of the soil are rubbed up with fifteen to twenty cubic centimeters of distilled water and allowed to stand for twenty-four hours with frequent stirring4 ,any fine particles not removable by a filter are neglected1 although they may give a turbid appearance to the solution4 #agb4 ,lysimetry4--,the process of measuring the capacity of a soil to permit the passage of water and of collecting and determining the amount of flow and determining soluble matters therein is known as lysimetry4 ,in general1 the rate at which water will pass through a soil depends on the fineness and approximation of its particles4 ,water will pass through coarse sand almost as rapidly as through a tube1 while a fine clay may be almost impervious4 ,the study of the phenomena of filtration through soil1 and the methods of quantitatively estimating them1 are therefore closely related to porosity4 ,two cases are to be considered1 viz43 ,first1 percolation through samples of soil prepared for analysis1 and second1 the passage of the water through soil in situ1 whether it be virgin or cultivated4 ,the determination of the rate of flow through a soil in laboratory samples1 gives valuable information in respect of its physical properties1 while the same determination made on the soil in situ1 has practical relations to the supply of moisture1 to growing plants1 and the waste of valuable plant food in the drainage waters4 ,the determination of the rate of flow of water through a small sample1 disturbed as little as possible in its natural condition1 is classed with the first divisions of the work1 inasmuch as the removal of a sample of soil from a field1 and its transfer to the laboratory1 subjects it to artificial conditions1 even if its texture be but little disturbed by the removal4 #agc4 ,calculation of the ,relative ,rate of ,flow of ,water ,through ,soils4--,there will evidently be one space1 or opening1 into the soil for every surface grain1 as pointed out by ,whitney1#aah and the approximate number of grains1 or of openings1 on a unit area of surface may be found by the following formula3 ,n 777,m ,w7_/7,v77 where ,n is the number of grains1 or openings1 on one square centimeter of surface1 ,m is the approximate number of grains in one gram of soil1 ,w is the weight of soil1 ,v is the total volume of the soil grains and the empty space4 ,if the grains are assumed to be symmetrically arranged and the spaces between them cylindrical in form1 the radii of the spaces can be found by the following formula3 r 7,v7_/7,,nl7 where r is the radius of a single space1 ,v is the total volume of the empty space1 ,n is the number of grains or spaces on one square centimeter of surface1 and ,l is the depth of the soil4 ,if the space within the soil is completely filled with water the relative rate of flow of water through the soil will be according to the fourth power of the radius of a single space multiplied by the number of spaces on the unit area of surface1 as shown by the following formula3 ,t 7,n7r7,t7_/7,n7r77 where ,n-,n are the numbers of spaces1 and r-r are the radii of single spaces in the respective soils1 and ,t-,t the times required for a unit volume of water to flow through the soils under the same head or pressure4 ,the space within the soil is rarely filled with water in agricultural lands1 and the most favorable amount of water for the soil to hold1 as ,hellriegel and others have shown1 is from thirty to fifty per cent of the total amount of water the soil can hold if all the space within it were filled4 ,if the space within the soil be only partly filled with water1 as in most arable lands1 the water will move in a thin film surrounding the soil grains and according to the fourth power of the thickness of the film4 ,the mean thickness of the film surrounding the soil grains may be theoretically determined by the following formula1 which is based on the conception that the film is cylindrical and of uniform size throughout3 t r7#a 7s7_/7s p77 where s is the per cent by weight of water which the soil will hold when the empty space is filled with water1 p the per cent of water actually contained in the soil1 r the radius of a single space1 and t the mean thickness of the film surrounding the soil grains4 ,the relative rate of flow of water through the soils will then be according to the following formula3 ,t 7,n7t7,t7_/7,n7t777 ,it must be remembered that these formul give only approximate and comparative values for comparing one soil with another4 ,the structure of the soil is altogether too intricate to expect ever to obtain absolute values4 ,if the observed rate of flow varies widely from the relative rate calculated from the mechanical analysis1 it will indicate a difference in the arrangement of the soil grains1 or in the amount or condition of the organic matter in the soils4 ,in the older agricultural regions of the ,united ,states1 south of the influence of the glacial action1 the great soil areas appear to have sensibly similar arrangements of the soil grains1 and sensibly uniform conditions of organic matter1 save where these have been modified by local conditions4 #agd4 ,measurement of ,rate of ,percolation in a ,soil ,sample4--,in order to measure the power of the soil for permitting the passage of water1 a box1 about twenty-five centimeters high and having a cross section of about three centimeters square1 is used4 ,below1 this box has a funnel-shaped end with a narrow outlet tube1 which at its lower end is closed with cotton1 in such a way that a portion of the cotton extends through the stem of the funnel4 ,a little coarse quartz sand is scattered over the cotton and afterwards the funnel part of the apparatus filled with it4 ,the sand and the cotton are saturated with water and the apparatus weighed4 ,the box is then filled with the fine sample of earth1 with light tapping1 until the depth of earth has reached about sixteen centimeters4 ,the apparatus1 after the addition of the air-dried earth1 is again weighed to determine the amount of earth added1 and the soil is then saturated by the careful addition of water4 ,after the excess of water has run down the funnel1 the total quantity of absorbed water is determined by reweighing the apparatus and the total water-holding power of the soil is determined4 ,there is carefully added1 without stirring up the surface of the soil1 a column of water eight centimeters high1 making in all from sixty to seventy grams4 ,the time is observed until the water ceases to drip from the funnel4 ,the dripping begins immediately after the water is poured on and ceases as soon as the liquid on the surface of the soil has completely disappeared4 ,on the repetition of this operation a longer time for the passage of the water is almost always required than at the first time4 ,the experiment1 therefore1 must be tried three or four times and the mean taken4 #age4 ,method of ,welitschowsky4#aai--,the soil is placed in the vessel a1 ,fig4 #bb1 which is cylindrical in shape and five centimeters in diameter4 ,the lower end of the cylinder is closed with a fine wire-gauze disk and the upper end is provided with an enlargement for the reception of the tube b1 which is connected to a with a wide rubber band4 ,the lower end of the tube b is also closed with a wire-gauze disk4 ,these tubes may be conveniently made of sheet zinc4 ,the tube b carries on the side1 at distances of ten centimeters1 small tubes of fifteen millimeters diameter4 ,on the opposite side it is provided with a glass tube set into a side tube near the bottom for the purpose of showing the height of the water4 ,the side tube carrying the water meter is provided with a stop-cock as shown in the figure4 ,illustration3 ,,figure #bb4 ,,method ,,of ,,welitschowsky4 ,in conducting the experiment1 after the apparatus has been arranged as described1 the small lateral tubes are1 with one exception1 closed with stoppers4 ,on the open one1 d1 a rubber tube is fixed for the purpose of removing the water4 ,the required water pressure is secured by taking the lateral opening corresponding to the pressure required4 ,water is introduced into the apparatus slowly through the glass tube f4 ,the water rises to d and then any excess flows off through e4 ,by a proper regulation of the water supply the pressure is kept constant at d4 ,the water flowing off through a is collected by the funnel and delivered to graduated flasks where its quantity can be measured for any given unit of time4 ,since the rate of flow at first shows variations1 the measurement should not be commenced until after the flow becomes constant4 ,in general1 the experiments should last ten hours1 and1 beginning with a water pressure of #ajj centimeters1 be repeated successively with pressures of eighty1 sixty1 forty1 and twenty1 centimeters1 etc4 ,in coarse soils1 or with sand1 one hour is long enough for the experiment4 #agf4 ,statement ,of ,results4--,in the following tables the results for ninety centimeters1 seventy centimeters1 etc41 are calculated from the analytical data obtained for #ajj centimeters1 eighty centimeters1 etc4 ,,material--,,quartz ,,sand4 ,,liters ,,of ,,water ,,passing ,,in ,,ten ,,hours4 ,no4 ,diameter of of sand ,exp4 particles ,water in pressure in ,thickness of ,soil ,layer4 mm4 cm4 #aj cm4 #bj cm4 #cj cm4 #a4 #j4ja-j4ga #aj #j4bdd #j4ahg #j4aea #bj #j4bhb #j4aih #j4aed #cj #j4cbj #j4bji #j4aeh #dj #j4ceh #j4bbj #j4afa #ej #j4cif #j4bca #j4afe #fj #j4dcd #j4bdb #j4afh #gj #j4dgb #j4bec #j4agb #hj #j4eaj #j4bfd #j4age #ij #j4edh #j4bge #j4agi #ajj #j4ehf #j4bhf #j4ahb #b4 #j4jga-j4aad #aj #b4aid #a4gbd #a4dbe #bj #b4hih #b4jab #a4egh #cj #c4fjb #b4cjj #a4gca #dj #d4cjf #b4ehh #a4hhd #ej #e4jaj #b4hgf #b4jcg #fj #e4gad #c4afd #b4aij #gj #f4dah #c4deb #b4cdc #hj #g4abb #c4gdj #b4dif #ij #g4hbf #d4jbh #b4fdi #ajj #h4ecj #d4caf #b4hjb ,similar sets of data have been collected with powdered limestone1 clay and humus4 ,the general conclusions from the experiments are as follows3 #a4 ,clay 7kaolin7 and humus 7peat7 are almost impermeable for water1 and fine quartz and limestone dust are also very impermeable4 #b4 ,the permeability of a soil for water increases as the particles of the soil increase in size1 and when particles of different sizes are mixed together the permeability approaches that of the finer particles4 #c4 ,the quantity of water passing through a given thickness of soil increases with the water pressure but is not proportional thereto1 increasing less rapidly than the pressure4 #d4 ,the quantity of water passing under a given pressure is inversely proportional to the thickness of the soil layer when the particles are very fine and the pressure high4 #agg4 ,method of ,whitney4--,to determine the permeability of the soil or subsoil to water or air1 in its natural position in the field1 the following method1 due to ,whitney1 can be recommended3 ,a hole should be dug1 and the soil and subsoil on one side removed to the depth at which the observation is to be made4 ,a column of the soil or subsoil1 two inches or more square1 and four or five inches deep1 is then to be carved out with a broad bladed knife1 or a small saw can be conveniently used for cutting this out4 ,a glass or metal frame1 a little larger than the sample and three or four inches deep1 is slipped over the column of soil1 and melted paraffin is run in slowly to fill up the space between the soil and the frame4 ,the soil is then struck off even with the top and bottom of the frame1 preferably with a saw1 or at any rate taking care not to smooth it over with a knife1 which would disturb the surface and affect the rate of flow4 ,the frame is then placed upon some coarse sand or gravel1 contained in a funnel1 to prevent the soil from falling out and to provide good drainage for the water to pass through4 ,another similar frame can then be placed on top and secured by a wide rubber band4 ,a little coarse sand1 which has been thoroughly washed and dried1 is then placed on the soil1 and water carefully poured on until it is level with the top of the frame4 ,when the water begins to drop from the funnel more water must be added to the top1 so as to have the initial depth of water over the soil the same in all the experiments4 ,a graduated glass is then pushed under the funnel1 and the time noted which is required for a quantity of water to pass through the soil4 ,the quantity usually taken for measurement is equivalent to one inch in depth over the soil surface4 ,in taking the sample1 root and worm-holes are to be avoided1 and these are particularly troublesome in clay lands4 #agh4 ,measurement of ,percolation through the ,soil in ,situ4--,if lateral translocation could be prevented1 the measurement of the quantity of water descending in the soil through a given area would be a matter of simplicity4 ,but to secure accurate results all lateral communication of a given body of soil with adjacent portions must be cut off4 ,various devices have been adopted to secure this result4 ,an elaborate system of lysimetric measurements is illustrated by the apparatus erected by the ,agricultural ,experiment ,station1 of ,indiana4 ,the plan and section of the apparatus are shown in ,fig4 #bc4 ,each lysimeter box1 when finished1 resembles somewhat a hogshead with one head out4 ,the sides1 however1 are perfectly straight inside1 having a slight thickening in the center1 on the outside1 for making them stronger4 ,the sides and bottom of the apparatus are constructed of oak and lined with sheet copper carefully soldered so as to be water-tight4 ,six inches above1 and parallel to the bottom of each of the boxes1 is a perforated copper tube1 which extends entirely across the lysimeter1 and passing through one of the sides connects the box with an underground vault in which the observations are taken4 ,these tubes give an outlet to the drainage water1 as described further on4 ,the lysimeters are made of any required depth1 the two which are shown in section being three and two-thirds and six and two-thirds feet deep1 respectively4 ,the following method is employed for filling them with soil3 ,there are first placed in the bottom of each lysimeter six inches of fine sand1 sifted and washed1 which fills them up to the level of the drainage tubes4 ,the lysimeters are then filled with fine1 sifted surface soil1 to the depth of three and six feet1 respectively1 making a complete pair of lysimeters1 and leaving two inches of the lysimeter boxes projecting above the surface of the soil so that each one will receive exactly its proper share of the rain-fall4 ,the lysimeters of the other pair1 which are the same size as the first1 are filled in a different way4 ,the lysimeters are first constructed and placed over vertical columns of soil in situ1 which are obtained by digging away all the surrounding soil and leaving the columns standing4 ,the shorter lysimeter is sunk in this way to within two inches of its entire length4 ,it is then tipped over carrying the column of soil with it4 ,six inches of the subsoil are then removed1 when the drainage tube and sand are put in1 as in the first pair1 and the bottom of the tube soldered in place4 ,the lysimeter is thus filled with the natural soil in place4 ,the longer box is in the same way filled1 as far as possible1 with the soil in place1 but a gravelly nature of the soil may render it impossible to do the filling with a single column unbroken1 so the gravel and sand from the lower portion of the soil are to be filled in separately4 ,the drainage tube and bottom of sand are placed in the longer lysimeter in the same way as in the shorter4 ,illustration3 ,,figure #bc4 ,,ground ,,plan ,,and ,,vertical ,,section ,,of ,,lysimeters ,,and ,,vaults ,,showing ,,position ,,of ,,the ,,apparatus4 #a1 #a1 #a1 #a1 ,lysimeters4 #b1 #b1 #b1 #b1 ,receiving bottles4 #c1 #c1 ,supplying apparatus4 #d1 #d1 ,skylights4 #e1 #e1 #e1 #e1 ,wall of vault4 #f1 #f1 ,brick walls4 #g1 ,entrance ,steps4 #h1 ,vault4 ,the purpose of placing sand at the bottom of each lysimeter is to offer a porous stratum in which free water may collect and rise to the level of the perforated copper tube1 which would prevent any further rise by conveying the surplus above into the vault as drainage water4 ,the soil above the tube will therefore be constantly drained and the sand below constantly saturated1 unless the water be drawn up by the capillary action of the soil as the result of evaporation from the surface4 ,by means of a proper arrangement within the vault1 of a kind of ,mariotte's bottle1 the water may be caused to flow back through the drainage tube into the lysimeter to take the place of that lost by evaporation1 and thus maintain the level of free water just below the drainage tube4 ,the water flowing back to the lysimeter1 and the amount of drainage water1 are carefully measured by a system of graduated tubes4 ,the lysimeters thus constructed represent tile-drained land2 in one case the tile being three feet below the surface and in the other six feet below4 ,the drainage waters collected in the receiving bottles can be measured and analyzed from time to time1 as occasion may require1 to determine the amount of plant food which is removed4 #agi4 ,improved ,method of ,deherain4#abj--;,deherain's earlier experiments were made in pots containing about sixty kilos of soil4 ,these vases serve very well for some kinds of plants1 but there are other kinds which do not grow at all normally when their roots are imprisoned4 ,for instance1 in pots1 even of the largest size1 wheat is always poor1 beets irregular1 maize never acquires its full development1 and the conclusions which can be drawn from the experiments can not be predicated of the action of the plant under conditions entirely normal4 ,it is necessary therefore to carry on the work in an entirely different way1 and to construct boxes so large as to make the conditions of growth entirely normal4 ,the arrangement of these boxes is shown in ,fig4 #bd4 ,they are placed in a large trench1 two meters wide1 one meter deep1 and forty meters long4 ,there are twenty boxes in this trench1 the upper surface of each containing four square meters area4 ,the boxes are one meter deep1 and therefore can contain four cubic meters of soil4 ,the sides and bottoms of the boxes are made of iron lattice work1 covered with a cement which renders them impervious to water4 ,the bottom inclines from the sides towards the middle1 and from the back to the front1 thus forming a gutter which permits of the easy collection of the drainage4 ,the drainage water is conveyed1 by means of a pipe and a funnel1 into a demijohn placed in the ditch in front of the apparatus1 as shown in the figure4 ,these receptacles stand in niches under the front of the cases1 and are separated by the brick foundations4 ,access to them is gained by means of the inclined plane shown in the figure1 and this plane permits the demijohns in which the drainage water is collected1 to be removed with a wheelbarrow for the purpose of weighing4 ,this apparatus is especially suitable for a study of the distribution of the nitrogen to the crop1 the soil and the drainage waters4 ,the loss in drainage waters of potash and phosphoric acid is insignificant in comparison with the loss in nitrogen4 ,the cases having been placed in position they are filled with the natural soil1 which is taken to the depth of one meter1 in such a way that the relative positions of the soil and subsoil are not changed4 ,while the soil is transferring to the cases it is carefully sampled in order to have a portion representing accurately the composition of both the soil and subsoil4 ,these samples are subjected to analysis and the quantities of nitrogen1 phosphoric acid1 and potash contained therein carefully noted4 ,one or two cases should be left without crop or fertilizer to determine the relations of the soil and subsoil to the rain-fall4 ,three or four cases should be kept free of vegetation and receive treatment with different fertilizer1 in order to determine the influences of these on the deportment of the soil to rain-fall4 ,the rest of the cases should be seeded with plants representing the predominant field culture of the locality1 and some of them should be fertilized with the usual manures used in farm culture4 ,illustration3 ,,figure #bd4 ,,deherain',s ,,apparatus ,,for ,,collecting ,,drainage ,,water4 ,,authorities ,,cited ,,in ,,part ,,third4 ,footnote #gj3 ,comptes rendus1 ,tome #aab1 p4 #eih4 ,footnote #ga3 ,stockbridge1 ,rocks and ,soils1 p4 #aec4 ,footnote #gb3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #h1 ,s4 #dj4 ,footnote #gc3 ,knig1 ,untersuchung ,landwirtschaftlich und ,gewerblich ,wichtiger ,stoffe1 ,s4 #dh4 ,footnote #gd3 ,methods of ,swedish ,agricultural ,chemists1 translated for author by ,f4 ,w4 ,woll4 ,footnote #ge3 ,poggendorff's ,annalen1 ,fifth ,series1 ,band #i1 ,ss4 #ajb1 et seq4 ,footnote #gf3 ,pennsylvania ,agricultural ,experiment ,station ,report1 for #ahia1 pp4 #aid1 et seq4 ,footnote #gg3 ,agricultural ,science1 ,vol4 #h1 pp4 #bh1 et seq4 7,correction4 ,for ,fig4 #ac1 second line from bottom of page #aab1 read ,fig4 #ad47 ,footnote #gh3 ,haberland4 ,forschungen auf der ,gebiete der ,agricultur-,physik1 #ahgh1 ,s4 #adh4 ,footnote #gi3 ,grundlagen zur ,beurteilung der ,ackerkrume1 ,weimar1 #ahhb4 ,footnote #hj3 ,vid4 supra1 #aj4 ,footnote #ha3 ,these general principles are taken chiefly from a rsum of the subject by ,prof4 ,h4 ,a4 ,huston4 ,indiana ,agricultural ,experiment ,station1 ,bulletin #cc1 pp4 #df1 et seq4 ,footnote #hb3 ,knop's ,agricultur ,chemie1 ,abteil ,,ii4 ,footnote #hc3 ,beitrge zur ,frage der ,bodenabsorption4 ,footnote #hd3 ,henneberg's ,journal1 #ahei1 ,s4 #ce4 ,footnote #he3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #bg1 ,s4 #ajg4 ,footnote #hf3 ,die ,bonitirung der ,ackererde1 ,s4 #di4 ,footnote #hg3 ,journal ,chemical ,society of ,london1 #ahfh4 ,footnote #hh3 ,landw4 ,central-,blatt1 ,band #aa1 ,s4 #afi4 ,footnote #hi3 bis ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #ab1 ,ss4 #ba-ej4 ,footnote #ij3 ,jour4 f4 ,landw41 #ahfb1 ,band #c1 ,ss4 #di-fg4 ,footnote #ia3 ,ann4 d4 ,landw41 ,band #cd1 ,s4 #cai4 ,footnote #ib3 ,american ,journal of ,science1 ,vol4 #ad1 p4 #be4 ,footnote #ic3 bis 7p4 #abb74 ,ms4 communication to author4 ,footnote #id3 ,maryland ,agricultural ,experiment ,station1 ,fourth ,annual ,report1 p4 #bhb4 ,footnote #ie3 ,bulletin ,no4 #d1 ,u4 ,s4 ,weather ,bureau1 p4 #hj4 ,footnote #if3 bis 7p4 #abe71 ,beitrge zur ,agronomische ,bodenuntersuchung1 ,s4 #ca4 ,footnote #ig3 ,zeitschrift fr angewandte ,chemie1 #ahhi1 ,s4 #eja4 ,footnote #ih3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #ag1 ,s4 #he4 ,footnote #ii3 ,ms4 communication to author4 ,footnote #ajj3 ,proceedings of the ,ninth ,meeting of the ,society for the ,promotion of ,agricultural ,science1 p4 #ea4 ,footnote #aja3 ,rocks and ,soils1 pp4 #aee et4 seq4 ,footnote #ajb3 ,anleitung zur ,wissenschaftlichen ,bodenuntersuchung1 ,s4 #acg4 ,footnote #ajc3 ,analyse du ,sol1 p4 #ac4 ,footnote #ajd3 ,landwirtschaftliche ,jahrbcher1 ,band #c1 ,ss4 #gga4 ,footnote #aje3 ,forschungen auf dem ,gebiete der ,agricultur-,physik1 #ahhe1 ,ss4 #agg1 et seq4 ,footnote #ajf3 ,vid4 supra1 ,s4 #bei4 ,footnote #ajg3 ,poggendorf1 ,annalen1 ,band #abi1 ,ss4 #dcg1 et seq4 ,footnote #ajh3 ,knig1 ,untersuchung ,landwirtschaftlich und ,gewerblich ,wichtiger ,stoffe1 ,s4 #ei4 ,footnote #aji3 ,vid4 #cg1 ,s4 #fj4 ,footnote #aaj3 ,landwirtschaftliche ,jahrbcher1 ,band #b1 ,s4 #chc4 ,footnote #aaa3 ,forschungen auf dem ,gebiete der ,agricultur-,physik1 #ahhj1 ,s4 #bah4 ,footnote #aab3 ,beurteilung der ,ackerkrume1 ,s4 #bbb4 ,footnote #aac3 ,wisconsin ,agricultural ,experiment ,station1 ,seventh ,annual ,report1 pp4 #acd1 et seq4 ,footnote #aad3 ,vid4 supra1 pp4 #aci1 et seq4 ,footnote #aae3 ,wisconsin ,agricultural ,experiment ,station1 ,seventh ,annual ,report1 p4 #ade4 ,footnote #aaf3 ,bulletin ,no4 #d1 ,weather ,bureau1 pp4 #ac1 et seq4 ,footnote #aag3 ,philosophical ,magazine1 #ahgh4 ,footnote #aah3 ,weather ,bureau1 ,bulletin ,no4 #d4 ,footnote #aai3 ,forschungen auf dem ,gebiete der ,agricultur-,physik1 #ahia1 ,s4 #aa4 ,footnote #abj3 ,annales ,agronomiques1 ,tome #af1 p4 #ccg2 ,tome #ag1 p4 #di2 ,tome #ah1 p4 #bcg2 ,tome #ai1 p4 #fi4 ,,part ,,fourth4 ,,mechanical ,,analysis ,,of ,,soils4 ,,the ,,flocculation ,,of ,,soil ,,particles4 #ahj4 ,relation of ,flocculation to ,mechanical ,analysis4--,the tendency of the fine particles of silt to form aggregates1 which act as distinct particles of matter1 is the chief difficulty connected with the separation of the soil into portions of equal hydraulic value by the silt method of analysis4 ,this tendency has been discussed fully by ,johnson#aba and ,hilgard4#abb #aha4 ,illustration of ,flocculation4--,a sediment1 consisting of particles of a hydraulic value1 equal to one millimeter per second1 is introduced into an ordinary conical elutriating tube placed vertically1 in which the current of water entering below performs all the stirring which the particles receive4 ,a current of water corresponding to a velocity below one millimeter per second will1 of course1 not carry any of the particles out at the top of the cylindrical tube1 but will keep them moving through the conical portion of the tube4 ,if now the current be increased until its velocity is greater than one millimeter per second after having run at the slower velocity for fifteen or twenty minutes1 very little of the sediment will pass over1 although theoretically the whole of it should4 ,even at a velocity of five millimeters per second1 much of the sediment will remain in the tube4 ,this1 of course1 is due to the coagulation of the particles into molecular aggregates having a higher hydraulic value even than five millimeters per second4 ,these aggregates can be broken up by violent stirring or moderate boiling1 and the sediment reduced again to its proper value4 ,the conclusions which ,hilgard derives from a study of the above phenomena are as follows3 #a4 ,the tendency to coagulation is1 roughly1 in an inverse ratio to the size of the particles4 ,with quartz grains it practically ceases when their diameter exceeds about two-tenths of a millimeter having a hydraulic value of eight millimeters per second4 ,the size of the aggregates formed follows practically the same law as above4 ,sediment of #j4be millimeter hydraulic value will sometimes form large masses like snow-flakes on the sides of the elutriator tube4 #b4 ,the degree of agitation which will resolve the aggregates into single grains is inversely as the size of the particles2 or1 more properly perhaps1 inversely as their hydraulic value4 #c4 ,the tendency to flocculation varies inversely as the temperature4 ,so much so is this the case that ,hilgard at one time contemplated the use of water at the boiling point in the mechanical analysis of soils1 in place of mechanical stirring4 #d4 ,the presence of alcohol1 ether1 and of caustic or carbonated alkalies1 diminishes the tendency to flocculation1 while the presence of acids and neutral salts increases it4 #e4 ,as between sediments of equal hydraulic value1 but different densities1 the tendency to flocculation seems to be greater with the less dense particles4 ,in regard to the mechanical actions which take place between the particles1 ,hilgard considers them as irregular spheroids1 each of which can at best come in contact at three points with any other particle4 ,the cause of aggregation cannot therefore be mere surface adhesion independent of the liquid1 and the particles being submerged there is no meniscus to create an adhesive tension4 ,since experiment shows that the flocculative tendency is measurably increased by the cohesion coefficient of the liquid1 it seems necessary to assume that capillary films of the latter interposed between the surfaces of solids create a considerable adhesive tension even in the absence of a meniscus4 #ahb4 ,effect of ,potential of ,surface ,particles4--,whitney suggests that this is due to the potential of the surface particles of solids and liquids4#abc ,the potential of a single water particle is the work which would be required to pull it away from the surrounding water particles and remove it beyond their sphere of attraction4 ,for simplicity1 it may be described as the total force of attraction between a single particle and all other particles which surround it4 ,with this definition1 it will be seen that the potential of a particle on an exposed surface of water is only one-half of the potential in the interior of the mass1 as half of the particles which formerly surrounded and attracted it were removed when the other exposed surface of water was separated from it4 ,a particle on an exposed surface of water1 being under a low potential1 will therefore tend to move toward the center of the mass where the potential1 i4 e41 the total attraction1 is greater1 and the surface will tend to contract so as to leave the fewest possible number of particles on the surface4 ,this is surface tension4 ,if1 instead of air1 there is a solid substance in contact with the water1 the potential will be greater than on an exposed surface of the liquid1 for the much greater number of solid particles will have a greater attraction for the water particles than the air particles had4 ,they may have so great an attraction that the water particle on this surface1 separating the solid and liquid1 may be under greater potential than prevails in the interior of the liquid mass4 ,then the surface will tend to expand as much as possible1 for the particles in the interior of the mass of liquid will try to get out on the surface4 ,this is the reverse of surface tension4 ,it is surface pressure1 which may exist on a surface separating a solid and liquid4 ,muddy water may remain turbid for an indefinite time1 but if a trace of lime or salt be added to the water the grains of clay flocculate1 that is1 they come together in loose1 light flocks1 like curdled milk1 and settle quickly to the bottom1 leaving the liquid above them clear4 ,ammonia and some other substances tend to prevent this and to keep the grains apart if flocculation has already taken place4 ,if two small grains of clay1 suspended in water1 come close together they may be attracted to each other or not1 according to the potential of the water particles on the surface of the clay4 ,if the potential of the surface particle of water is less than that of the particle in the interior of the mass of liquid1 there will be surface tension1 and the two grains will come together and be held with some force1 as their close contact will diminish the number of surface particles in the liquid4 ,if1 on the other hand1 the potential of the particle on the surface of the liquid is greater than of the particle in the interior of the mass1 the water surface around the grains will tend to enlarge1 as there will be greater attraction for the water particles there than in the interior of the mass of liquid1 and the grains of clay will not come close together and will even be held apart1 as their close contact would diminish the number of surface particles in the liquid around them4 #ahc4 ,influence of ,surface ,tension4--,hilgard supposes that the surface tension which is assumed to exist between two liquid surfaces must exert a corresponding influence between the surfaces of solids and liquids1 apart from any meniscal action4 ,it is then to be expected that the adhesion of the particles constituting one of these floccules will be very materially increased whenever the formation of menisci between them becomes possible by the removal of the general liquid mass4 ,suppose one of the floccules to be stranded1 it will1 in the first place1 remain immersed in a sensibly spherical drop of liquid4 ,as this liquid evaporates1 the spherical surface will become pitted with menisci forming between the single projecting particles1 and as these menisci diminish their radius by still further evaporation1 the force with which they hold the particles together will increase until it reaches a maximum4 ,as the evaporation progresses beyond this point of maximum1 the adhesion of the constituent particles must diminish by reason of the disappearance of the smaller menisci1 and when finally the point is reached when liquid water ceases to exist between the surfaces1 the slightest touch1 or sometimes even the weight of the particles themselves1 will cause a complete dissolution of the floccule1 which then flattens down into a pile of single granules4 ,in regard to natural deposits from water1 ,hilgard supposes that they are always precipitated in a flocculated state4 ,the particles of less than two-tenths millimeter diameter are carried down with those of a larger diameter having much higher hydraulic value4 ,thus the deposition of a pure clay can take place under only very exceptionable circumstances4 ,whitney1 on the other hand1 suggests that grains of sand and clay carry down mechanically the particles of fine silt and clay as they settle in a turbid liquid in a beaker2 and it is often difficult to wash out a trace of fine material from a large amount of coarse particles1 for this reason1 although there may be no trace whatever of flocculation4 #ahd4 ,destruction of ,floccules4--,the destruction of the natural floccules is seen in the ordinary process of puddling earth or clay4 ,it is also the result of violent agitation of water or of kneading or boiling1 or1 finally1 to a certain extent1 of freezing4 ,all these agencies are employed by the workers in clay for the purpose of increasing the plasticity which depends essentially upon the finest possible condition of the material to be worked4 ,as an illustration of this1 ,hilgard cites the fact that any clay or soil which is worked into a plastic paste with water1 and dried1 will form a mass of almost stony hardness4 ,if1 however1 to such a substance one-half per cent of caustic lime be added1 a substance which possesses in an eminent degree the property of coagulating clay1 the diminution of plasticity will be obvious at once1 even when in a wet condition4 ,if now the mass be dried1 as in the previous case1 it is easily pulverized4 ,this is an illustration of the effect of lime upon stiff lands1 rendering them more readily pulverulent and tillable4 ,the conversion of the lime into a carbonate in the above experiment by passing bubbles of carbonic acid through the mass while still suspended in water does not restore the original plasticity1 thus illustrating experimentally the fact known to all farmers that the effect of lime on stiff soil lasts for many years1 although the whole of the lime in that time has been converted into carbonate4 #ahe4 ,practical ,applications4--,the practical application of this is1 according to ,hilgard1 that the loosely flocculated aggregation of the soil particles is what constitutes good tilth4 ,for this reason the perfect rest of a soil1 if it is protected from the tamping influence of rains and the tramping of cattle1 may produce a condition of tilth which cannot be secured by any mechanical cultivation4 ,as an illustration of this1 the pulverulent condition of virgin soils protected in a forest by the heavy coating of leaves may be cited4 ,on the contrary1 as pointed out by ,hilgard1 there are some kinds of soil in which a condition of rest may produce the same effect as tamping4 ,these are soils which consist of siliceous silt without enough clay to maintain them in position after drying4 ,in such a case1 the masses of floccules collapse by their own weight or by the least shaking1 and fall closely together1 producing an impaction of the soil4 ,this takes place in some river sediment soils in which the curious phenomenon is presented of injurious effects produced by plowing when too dry1 which is the direct opposite of soils containing a sufficient amount of clay and which are injured by plowing too wet4 ,it is further observed that the longer a soil has been maintained in good tilth1 the less it is injured by wet plowing4 ,this is doubtless1 according to ,hilgard1 due to the gradual cementation of the floccules by the soil water which fixes them more or less permanently4 ,whitney believes that the arrangement of the grains1 or the condition of flocculation in the soil1 or the distance apart of the soil grains1 is determined1 to a large extent1 by the potential on the surface of the grains2 and he suggests that by changing this the exceedingly fine grains of silt and clay can be pulled together or can be pushed further apart1 and so alter the whole texture of the land4 ,the action of alkaline carbonates in preventing flocculation1 and thus rendering tillage difficult or impossible1 is pointed out by ,hilgard in the case of certain alkali soils of ,california4 ,the soils which are impregnated with alkaline carbonates are recognized by their extreme compactness4 ,the suggestion of ,hilgard to use gypsum on such soils has been followed by the happiest results4 ,this gypsum renders any phosphates present insoluble1 and thus prevents loss by drainage1 and yet leaves the plant food in a sufficiently fine state as to be perfectly available for vegetation4 #ahf4 ,suspension of ,clay in ,water4--,the suspension of clay in water and the methods of producing or retarding flocculation and precipitation have also been studied by ,durham4#abd ,his experiment is made as follows3 ,in a number of tall glass jars fine clay is stirred with water1 and the results of precipitation watched4 ,in all cases it will be noticed that the clay rapidly separates into two portions1 the greater part quickly settling down to the bottom of the jars1 and the smaller part remaining suspended for a greater or less length of time4 ,the power which water possesses of sustaining clay is gradually destroyed by the addition of an acid or salt2 a very small quantity1 for instance1 of sulfuric acid1 is sufficient to precipitate the clay with great rapidity4 ,in solutions of sulfuric acid and sodium chlorid of varying strengths1 suspended clay is precipitated in the order of the specific gravity of the solutions1 the densest solutions being the last to clear up4 ,this may be due to the greater viscosity of the denser liquids4 ,the power which water possesses of sustaining clay is gradually decreased by the addition of small quantities of certain salts and of lime4 #ahg4 ,effect of ,chemical ,action--,brewer#abe emphasizes the importance of chemical action in the flocculation of clays4 ,as expressed by him the chemical aspects of the phenomena of sedimentation have either been lightly considered or entirely ignored4 ,brewer is led to believe that the action of clay thus suspended is analogous to that of a colloidal body4 ,like a colloid1 when diffused in water1 the bulk of the mass is very great1 shrinking enormously on drying4 ,he therefore concludes that clays probably exist in suspension as a series of hydrous silicates feebly holding different proportions of water in combination and having different properties so far as their behavior to water is concerned4 ,some of them he supposes swell up in water much as boiled starch does1 and are diffusible in it with different degrees of facility1 and that the strata observed on long standing of jars of suspended clay represent different members of this series of chemical compounds which hold their different proportions of combined water very feebly and are stable under a very limited range of conditions4 ,these compounds are probably destroyed or changed in the presence of acids1 salts and various other substances1 and are stable only under certain conditions of temperature1 those which exist at one temperature being destroyed or changed to other compounds at a different temperature4 #ahh4 ,theory of ,barus4--,brewer's hypothesis1 however1 is not in harmony with the demonstration of ,barus1 who proves that a given particle of clay has the same density in ether as in water4 ,the physical and mathematical aspects of sedimentation have also been carefully studied by ,barus4#abf ,the mathematical conditions of a fine particle suspended in a liquid and free from the influences of flocculation are described by ,barus in the following equations4 ,if ,p be the resistance encountered by a solid spherule of radius r1 moving through a viscous liquid at the rate x1 and if k be the frictional coefficient1 then ,p #fkrx4 ,again1 the effective part of the weight of the particle is ,p r 7-7g1 where g is the acceleration of gravity and and the density of solid particle and liquid1 respectively4 ,in case of uniform motion ,p ,p4 ,hence x #b_/ikr 7-7g 444 7#a74 ,in any given case of thoroughly triturated material the particles vary in size from a very small to a relatively large value2 but by far the greater number approach a certain mean figure and dimension4 ,an example of this condition of things may be formulated4 ,to avoid mathematical entanglement let y ,axe-x 444 7#b7 where y is the probable occurrence of the rate of subsidence x4 ,if now the turbidity of the liquid 7avoiding optical considerations7 be defined as proportional to the mass of solid material particles suspended in unit of volume of liquid1 then the degree of turbidity which the given ydx particles add to the liquid is1 caeteris paribus1 proportional to rydx1 where r is the mean radius4 ,hence the turbidity1 ,t1 at the outset of the experiment 7immediately after shaking71 is ,t ,trydx ,t1 where equations 7#a7 and 7#b7 have been incorporated4 ,if the plane at a depth d below the surface of the liquid be regarded1 then at a time after shaking the residual turbidity is 7#c7 444 ,td ,td_/trydx ,t7#a 7#a 7d_/t e-d_/t77 ,the equation describes the observed occurrences fairly well4 ,the phenomena of stratification observed by ,brewer are explained by ,barus from the above formula3 ,in proportion as the time of subsidence is greater1 the tube shows opacity at the bottom1 shading off gradually upward1 through translucency1 into clearness at the top4 ,if1 instead of equation 7#b71 there be introduced the condition of a more abrupt maximum1 if1 in other words1 the particles be very nearly of the same size1 then subsidence must take place in unbroken column capped by a plane surface which at the time zero coincided with the free surface of the liquid4 ,again1 suppose one-half of the particles of this column differ in some way uniformly from the other half4 ,then at the outset there are two continuous columns coinciding1 or1 as it were1 interpenetrating throughout their extent4 ,but the rate of subsidence of these two columns is necessarily different1 since the particles1 each for each1 differ in density1 radius and frictional qualities1 by given fixed amounts4 ,hence the two surfaces of demarcation at the time zero coincided with the free surface4 ,in general1 if there be n groups of particles uniformly distributed1 then at the time zero n continuous columns interpenetrate and coincide throughout their extent4 ,at the time t1 the free surface will be represented by n consecutive surfaces of demarcation below it1 each of which caps a column1 the particles of which form a distinct group4 ,from a further discussion of the mathematical condition under which the subsidence of the particles takes place1 ,barus is of the opinion that ,durham's theory of suspension being only a lower limit of solution is rapidly gaining ground1 yet without being attended with concise experimental evidence which will account for the differences in the rate of subsidence4 ,on the contrary1 ,brewer's hypothesis of colloidal hydrates is more easily subjected to experimental proof4 ,the test shows that the particles retain their normal density1 no matter how they are suspended or circumstanced4 ,further1 in the explanation of the phenomenon of sedimentation1 the following principle may be regarded as determined2 namely1 if particles of a comminuted solid are shaken up in a liquid1 the distribution of parts after shaking will tend to take place in such a way that the potential energy of the system of solid particles and liquid1 at every stage of subsidence1 is the minimum compatible with the given conditions4 ,according to ,barus it is necessary1 in order to pass judgment on the validity of any of the given hypotheses1 to have in hand better statistics of the size of the particles relatively to the water molecule1 than are now available4 ,inasmuch as the particles in pure water are individualized and granular1 it is apparently at once permissible to infer the size of the particles from the observed rates of subsidence4 ,his observations show that the said rate decreases in marked degree with the turbidity of the mixture4 ,hence the known formul for single particles are not rigorously applicable1 though it cannot be asserted whether the cause of discrepancy is physical or mathematical in kind4 ,it follows that special deductions must be made for the subsidence of stated groups of particles before an estimate of their mean size can fairly be obtained4 ,rowland#abg reaches a closer approximation for the fall of a single particle by showing that the liquid1 even at a large distance from the particle1 is not at rest4 ,in the case of water1 however1 it is noticed that despite the large surface energy of the liquid1 subsidence takes place in such a way that for a given mass of suspended sediment the surfaces of separation are a maximum4 ,on the other hand1 in case of subsidence in ether or in salt solutions1 the solid particles behave much like the capillary spherules of a heavy liquid shaken up in a lighter liquid with which it does not mix4 ,in other words1 the tendency here is to reduce surfaces of separation to the least possible value1 large particles growing in mass and bulk mechanically at the expense of smaller particles2 in other words1 exhibiting the phenomenon of flocculation4 #ahi4 ,physical ,explanation of ,subsidence4--,whitney#abh thinks that the phenomena of the suspension of clay in water may be explained on purely physical principles1 and that neither the partial solution nor hydration hypotheses are necessary1 or will explain the suspension of clay in water1 for the solution1 or hydrated substance1 would still have a higher specific gravity than the surrounding liquid4 ,he calls attention in the first place to the fact1 that in a turbid liquid1 which has been standing for weeks and which is only faintly opalescent1 the grains in suspension are still of measurable size1 if properly stained as in bacteriological examinations and viewed through an oil emersion objective4 ,he gives a value of #j4jjja millimeter1 as the lower limit of the diameters of these particles of 8clay10 which are usually met with in agricultural soils4 ,he refers to the fact that fine dust and ashes1 and even filings of metals1 may remain in suspension in the air for days and even months in very apparent clouds1 or haze1 although they may be a thousand times heavier than the surrounding air4 ,particles of clay1 no smaller than the limits which have been assigned1 should remain in suspension in the much heavier fluid1 water1 for an indefinite time1 for the volume or weight of the particles 777r7 decreases so much more rapidly in proportion than the surface 7#dr71 that there is1 relatively1 a larger amount of surface area in these fine clay particles1 and a great deal of surface friction in their movement through a medium1 and they would settle very slowly4 ,under ordinary conditions1 however1 the mean daily range of temperature is about twenty degrees1 the mean monthly range is fifty degrees1 and the yearly range #ajj ,f41 and the ordinary convection currents1 induced by the normal change of temperature1 would be sufficient of itself to keep these fine particles in suspension in the liquid for an indefinite time1 as it is known that currents of air keep fine particles of dust and ashes in suspension4 ,if the volume or weight of a fine gravel1 having a diameter of one and five-tenth millimeters1 be taken as unity1 then for a particle1 having a diameter of #j4jjbee millimeter1 which is the mean diameter for ,whitney's clay group1 the volume decreases in the ratio #a3j4jjjjjjjjdhec1 and the surface decreases only in the ratio #a3j4jjjbhf4 #aij4 ,practical ,applications4--,the action of mineral substances in promoting flocculence has been taken advantage of in later times in the construction of filters for purifying waters holding silt in solution4 ,in these filters the introduction of a small quantity of alum1 or some similar substance1 into the water usually precedes the mechanical separation of the flocculent material4 ,in the same way the action of iron and other salts on sewage waters has been made use of in their purification and in the collection of the sewage material for fertilizing purposes4 #aia4 ,separation of the ,soil ,into ,particles of ,standard ,size4--,the agronomic value of a soil depends largely on the relative size of the particles composing it4 ,the finer the particles1 within a certain limit1 the better the soil4 ,the size of the particles may be estimated in three ways3 7#a7 by passing through sieves of different degrees of fineness2 7#b7 by allowing them to subside for a given time in water at rest2 7#c7 by separating them in water moving at a given rate of speed4 ,the first method is a crude one and is used to prepare in a rough way1 the material for the second and third processes4 #aib4 ,separation in a ,sieve4--,the soil should be dry enough to avoid sticking to the fingers or to prevent agglutination into masses when subjected to pressure4 ,it should not1 however1 be too dry to prevent the easy separation of any agglutinated particles under the pressure of the thumb or of a rubber pestle4 ,the sieve should have circular holes punched in a sheet of metal of convenient thickness to give it the requisite degree of strength4 ,sieves made of wire gauze are not so desirable but it is difficult to get the finer meshes as circular perforations4 ,such sieves cannot give a uniform product on account of the greater diagonal diameter of the meshes and the ease with which the separating wires can be displaced4 ,it is convenient to have the sieves arranged en batterie2 say in sets of three4 ,such a set should have the holes in the three sieves of the following dimensions2 viz41 #ast sieve #b millimeters diameter4 #bnd #a millimeter #crd #j4e ,coarser single sieves may be used to separate the fragments above two millimeters diameter if such a further classification be desired4 ,each sieve fits into the next finer one and the separation of a sample into three classes of particles may be effected by a single operation4 ,in most cases1 however1 it is better to conduct each operation separately in order to promote the passage of agglutinated particles by gentle pressure with the thumb or with a rubber pestle4 ,in no case should a hard pestle be used and the pressure should never be violent enough to disintegrate mineral particles4 ,there is much difference of opinion concerning the smallest size of particles which should be obtained by the sieve4 ,most analytical processes prescribe particles passing a sieve of one millimeter mesh 7 inch74 ,there is little doubt1 however1 of the fact that a finer particle would be better fitted for subsequent analysis by the hydraulic method4 ,for this purpose a sieve of #j4e millimeter circular mesh is preferred4 #aic4 ,sifting with ,water4--,in soils where the particles adhere firmly the sifting should be done with the help of water4 ,in such cases the soil is gently rubbed with a soft steple or the finger in water4 ,it is then transferred to the sieve or battery of sieves which are held in the water1 and rubbed through each of the sieves successively until the separation is complete4 ,after the filtrate has stood for a few minutes the supernatant muddy liquor is poured off1 the part remaining on the sieve is added to it and the process repeated until only clean particles larger than #j4e millimeter are left on the sieve4 ,these particles can be dried and weighed and entered on the note book as sand4 ,the filtrate should be evaporated to dryness at a gentle temperature and when sufficiently dry be rubbed up into a homogeneous mass by a rubber pestle4 ,the sieve recommended by the ,association of ,official ,agricultural ,chemists#abi for the preparation of fine earth for chemical analysis has circular openings inch 7one millimeter7 in diameter4 ,wahnschaffe#acj directs that a sieve of two millimeters mesh be used in preparing the sample for silt analysis and that the residue after the silt analysis is finished1 which has not been carried over by a velocity of twenty-five millimeters per second1 be separated in sieves of one millimeter and #j4e millimeter meshes respectively4 ,hilgard objects to leaving this coarse material in the sample during the process of churn elutriation on account of the attrition which it exerts and therefore directs that it be separated by sieve analysis before the elutriation begins4 #aid4 ,method of the ,german ,experiment ,stations4#aca--;,in the method recommended for the ,german ,agricultural ,stations an attempt is made to secure even a finer sieve separation than that already mentioned4 ,sieves having the following dimensions are employed2 sieve ,no4 #a1 square meshes #j4ji millimeter in size1 diagonal measure #j4aa millimeter2 sieve ,no4 #b1 square meshes #j4ad to #j4ag millimeter in diameter1 diagonal measure #j4bb to #j4bd millimeter2 sieve ,no4 #c1 square meshes #j4ce to #j4ci millimeter in diameter1 diagonal measure #j4de to #j4ej millimeter2 finally a series of sieves one1 two and three millimeters circular perforations4 ,five hundred grams of the soil 7in the ,halle ,station only #bej7 are placed in a porcelain dish with about one liter of water and allowed to stand for some time with frequent stirring1 on a water bath4 ,after about two hours1 when the soil is sufficiently softened so that with the help of a pestle it can be washed through the sieves1 the process of sifting is undertaken in the following manner3 ,sieve ,no4 #c is placed over a dish containing water1 the moistened soil placed therein and the sieve depressed a few centimeters under the water and the soil stirred by means of a pestle until particles no longer pass through4 ,after the operation is ended the residue in the sieve is washed with pure water and dried4 ,the part passing the sieve is thoroughly stirred and then washed with water into sieve ,no4 #b and treated as before4 ,the product obtained in this way is brought into sieve ,no4 #a and carefully washed4 ,all the products remaining on each of the sieves are dried at #ajj and weighed4 ,the portion passing sieve ,no4 #a is either dried with its wash water or estimated by loss by deducting from the total weight taken1 the sum of the other weights obtained4 ,if a more perfect separation of the first sieve residue be desired it can be obtained by passing it through sieves of the last series which may have meshes varying in size1 viz43 one1 two1 or three millimeters in diameter4 ,each sieve of the same class should have holes uniformly of the same size4 ,the sieve products are characterized as follows3 ,the part passing a three millimeter sieve is called fine earth1 while the part remaining is called gravel4 ,the fine earth is separated into the following products3 ,the part that passes through the three millimeters opening and is left by the two millimeters opening is called steinkies4 ,the product from the two millimeters opening and the residue from the one millimeter opening is called grobkies4 ,the product from the one millimeter opening and the residue on the sieve ,no4 #c is called feinkies4 ,the product from the sieve ,no4 #c and the residue from the sieve ,no4 #b is called coarse sand4 ,the product from sieve ,no4 #b and the residue from sieve ,no4 #a is called fine sand4 ,the product from sieve ,no4 #a is called dust4 ,the dust can be further separated into sand1 dust1 and clay4 ,for the examination of the clay the ,khn silt cylinder as modified by ,wagner1 is recommended4 ,the cylinder has a diameter of eight centimeters and a height of thirty centimeters1 and is furnished with a movable exit tube reaching to its bottom4 #aie4 ,general ,classification of the ,soil by ,sieve ,analysis4--,the classification recommended by the ,german chemists is satisfactory but the following one is more simple4 ,all pebbles1 pieces of rock1 etc41 should first be separated by a two millimeters circular mesh sieve1 dried at #aje and weighed4 ,the result should be entered as pebbles and coarse sand4 ,the finer sand may be separated with a sieve of one millimeter circular openings4 ,the still finer sand is next separated with the sieve of #j4e millimeter circular openings as indicated above4 ,the sample may now be classified as follows3 #a4 ,coarse pebbles1 sticks1 roots1 etc41 separated by hand4 #b4 ,pebbles and coarse sand not passing a two millimeters sieve4 #c4 ,sand not passing a one millimeter sieve4 #d4 ,fine sand not passing a #j4e millimeter sieve4 #e4 ,fine earth passing a #j4e millimeter sieve4 #aif4 ,classification of ,orth4#acb--;,as fine silt are reckoned those particles which range from #j4jb to #j4je millimeter2 as fine sand the groups from #j4je to #j4b millimeter2 as medium sized sand those ranging from #j4b to #j4e millimeter and for large grained sand those particles ranging from #j4e to #b millimeters in diameter4 ,particles over two millimeters form the last classification4 ,,separation ,,of ,,the ,,earth ,,particles ,,by ,a ,,liquid4 #aig4 ,methods of ,silt ,analysis4--,the further classification of the particles of a soil passing a fine sieve can best be effected by separation in water4 ,the velocity with which the current moves or with which the particles subside will cause a separation of the particles into varying sizes4 ,the slower the velocity the smaller the particles which are separated4 ,there is1 however1 a large and important constituent of a soil which remains suspended in water1 or in a state of seeming solution4 ,this suspended matter would still be carried over by a current of water moving at a rate so slow as to make a subclassification of it impossible4 ,this suspended matter passing off at a given velocity may be classed as clay1 and it consists in fact chiefly of the hydrated silicate of alumina1 or other particles of equal fineness4 ,the laws which govern its deposit have already been discussed4 ,the apparatus which have been used for silt analysis may be grouped into four classes4 7#a7 ,apparatus depending on the rate of descent of the particles of a soil through water at rest4 ,the apparatus for decanting from a cylinder or a beaker belong to this class4 7#b7 ,apparatus which determine the rate of flow by passing the liquid through a vessel of conical shape4 ,the system of ,nbel is a good illustration of this kind of apparatus4 7#c7 ,apparatus in which the elutriating vessel is cylindrical and the rate of flow determined by a stop-cock or pressure feed apparatus4 ,the system of ,schne represents this type4 7#d7 ,apparatus in which the above system is combined with a device for mechanically separating the particles and bringing them in a free state into the elutriating current4 ,the system of ,hilgard is the type of this kind of apparatus4 ,in practice the use of cylindrical apparatus with or without mechanical stirring and the method by decantation have proved to be the most reliable and satisfactory procedures4 ,between the beaker and churn methods1 of separation there is little choice in regard to accuracy4 ,which is the superior method1 is a question on which the opinions of experienced analysts are divided4 ,the various processes will be described in the order already mentioned4 #aih4 ,methods ,depending on ,subsidence of ,soil ,particles4--,the simplest method of effecting the further separation of the soil particles is without doubt that process which permits them to fall freely in a liquid sensibly at rest4 ,the practical difficulties of this method consist in the trouble of securing a perfect separation of the particles1 in preventing flocculation after division and in avoiding currents in the liquid of separation4 ,for the separation of the soil particles for this method boiling and wet pestling are the only means employed4 ,the flocculation of the separated particles may be partially prevented by adding a little ammonia to the water employed4 ,the author has also tried dilute alcohol as the separating liquid but the results of this method are not yet sufficiently definite to find a place in this manual4 ,evidently the practical impossibility of avoiding convection currents prevents the use of water at a high temperature for this separation1 although the tendency to flocculation almost disappears as the temperature approaches #ajj4 ,the general method of avoiding the errors due to flocculation in the subsidence method consists in repestling the deposited particles and thus subjecting them as often as may be necessary to resedimentation4 ,these principles are well set forth by ,osborne1#acc who states that when a soil is completely suspended in water by vigorous agitation1 particles of all the sizes present are to be found throughout the entire mass of liquid4 ,when subsidence takes place1 the larger particles will go down more rapidly than the smaller ones1 but some of the small particles that are near the bottom will be deposited sooner than some of the larger ones which have a much greater distance to travel4 ,thus1 independently of the fact that the larger particles in their descent are somewhat impeded by the smaller1 the smaller being at the same time somewhat hastened by the larger1 the sediment that reaches the bottom at any moment is a more or less complex mixture of all the mechanical elements of the soil4 ,the liquid1 however1 above this sediment at the same moment will have completely deposited all particles exceeding certain dimensions of hydraulic value1 determined mainly by the time of subsidence4 ,if now the aforesaid first sediment be suspended in pure water1 and allowed to subside for the same time as before1 the larger part of it will be again deposited1 but some will remain in suspension1 consisting of a considerable part of the finer matter of the first sediment4 ,by pouring off these suspended particles with the water and agitating the sediment again with clear water as before1 another portion of fine particles will be suspended and may be decanted from it4 ,on continuing this process of repeated decantations it will soon be found that the soil has been separated into two grades4 ,it is evident that in this way a separation can be made1 but it is perhaps not so clear that such a separation would be sharp enough for the purposes of a mechanical soil analysis4 ,if1 for instance1 the separation is to be made at #j4je millimeter diameter1 it is evident that by repeated decantations all below #j4ja millimeter can be washed out of that above #j4je millimeter1 but it may not appear so probable that all below #j4jde millimeter can be removed without removing some above #j4jee millimeter4 ,such a result may be easily attained1 however1 if the following principle be adhered to3 ,make the duration of the subsidence such that the liquid decanted the first few times shall contain nothing larger than the desired diameter4 ,then decant into another vessel1 timing the subsidence so that the sediment shall contain nothing smaller than the chosen diameter4 ,this can not be done without decanting much that is larger than the chosen diameter1 but the greater part of the particles greater and less than the chosen diameter can be removed and an intermediate product obtained1 the diameters of whose particles are not very far from that desired4 ,if this intermediate portion be again subjected to the same process1 two fractions may be separated from it1 one containing particles larger than the chosen diameter and another containing particles smaller than this diameter1 while a new intermediate product will remain which is less in amount than that resulting from the first operation4 ,by frequent repetitions of this process this intermediate product can be reduced to a very small amount of substance the particles of which have diameters lying close to the chosen limit and may then be divided between the two fractions4 ,the principles of the separation described by ,osborne set forth with sufficient clearness the purposes to be achieved by the analysis4 ,the chief methods of manipulation practiced will be found below4 #aii4 ,khn's ,silt ,cylinder4--,a simple form of apparatus for the determination of silt by the sedimentation process is the one described by ,khn4#acd ,the cylinder should be about twenty-eight centimeters high with a diameter of #h4e centimeters4 ,at the lower end of the cylinder five centimeters from the bottom it carries a tube #a4e centimeter in diameter furnished with a pinch-cock and held in position by a rubber stopper4 ,in carrying out the process thirty grams of sifted soil 7two millimeters mesh sieve7 are boiled with water for an hour and after cooling the soil and water are washed into the separating cylinder4 ,the cylinder is then filled with water with constant shaking4 ,after standing for ten minutes the stop-cock is opened and the water with its suspended matter allowed to flow into a porcelain dish4 ,the cylinder is then again filled with water and the process is continued until the water drawn off is practically clear4 ,the fine particles having been separated in this way the next coarser grade of particles is separated by repeating the process at intervals of five minutes4 ,by these two operations it is considered that the clay is entirely removed4 ,the residue remaining in the cylinder is dried and weighed4 ,the relative proportions of clay and residue in the sample are thus determined4 ,the residue is then separated into two portions by sieves of one millimeter and #j4e millimeter mesh4 ,the soil is thus separated into the following parts3 #a4 ,by the first sifting coarse quartz larger than two millimeters diameter4 #b4 ,fine quartz two millimeters1 to one millimeter diameter4 #c4 ,coarse sand one millimeter1 to #j4e millimeter diameter4 #d4 ,fine sand finer than #j4e millimeter diameter4 #e4 ,silt1 clay1 humus1 etc41 separated by the water4 #bjj4 ,knop's ,silt ,cylinder4--,the cylinder recommended by ,knop#ace is essentially that of ,khn being furnished with four lateral tubes instead of one 7,fig4 #be74 ,illustration3 ,,figure #be4 ,,knop',s ,,silt ,,cylinder4 ,the sample of soil1 twenty-five to thirty grams1 after passing a two millimeters mesh sieve1 and long boiling1 is washed through a series of sieves of the following diameters of mesh respectively2 viz41 one millimeter1 #j4e millimeter1 #j4be millimeter1 and #j4a millimeter4 ,the part which passes the finest sieve is placed in a ,knop's cylinder1 the cylinder filled with water one decimeter above upper tube and well shaken4 ,the cylinder is allowed to rest for five minutes when the upper cock is opened and the water drawn off4 ,after five minutes more the next tube is opened and so on with equal intervals for the three upper tubes4 ,the operation is repeated with fresh water until the water drawn off is clear4 ,finally the lowest tube is opened and all the water poured off of the sandy residue4 ,the space between each tube is one decimeter4 ,the dust remaining is dried and weighed and the weight of material carried over as silt determined by difference4 #bja4 ,siphon ,silt ,cylinder4--,instead of the tubulated cylinder one furnished with a siphon can be employed#acf 7,fig4 #bf74 ,it should be about forty centimeters high and six centimeters internal diameter4 ,the cylinder first receives twenty-five to thirty grams of the well boiled fine earth and then water until there is but a small space between it and the stopper when the latter is inserted4 ,the cylinder is marked exactly #bjj millimeters below the surface of the water with a narrow strip of paper at a1 stoppered1 inverted and well shaken4 ,the cylinder being again placed in normal position the soil particles under the influence of gravity tend to sink with greater or less rapidity according to their size4 ,the siphon a b c is filled with water1 the cock at c closed and the opened end a placed in the cylinder ,a just at the mark #bjj millimeters below the surface of the water1 and the water thus transferred to ,b when desired4 ,if the suspended matter is allowed to stand for #ajj seconds the particles of more than two millimeters hydraulic value will have fallen below the open end of the siphon4 ,if allowed to stand #a1jjj seconds the silt value of the particles will be #j4b millimeter per second4 ,whatever the number of seconds may be1 the operation is continued until the water removed is practically clear4 ,the open end of the siphon a should be bent upwards so that no disturbing current may bring the particles below the line into the liquid discharged into ,b4 ,illustration3 ,,figure #bf4 ,,siphon ,,cylinder ,,for ,,silt ,,analysis4 ,while the results obtained by this method are satisfactory as compared with other similar processes it cannot be highly recommended because of the time and trouble required to get a complete separation and by reason of the difficulty of collecting the separated silt4 #bjb4 ,wolff's ,method4#acg--;,as modified by ,wolff the ,knop process is conducted as follows3 ,fifty grams of fine earth are boiled with water and then the entire mixture is passed through three sieves with openings of one millimeter1 #j4e millimeter1 and #j4be millimeter in diameter1 respectively4 ,the finest part is mixed with water to a height of eighteen centimeters in a bottle twenty centimeters high and having a capacity of one liter and thoroughly agitated1 after which it is left to rest1 and finally the turbid liquid is drawn off with a siphon1 the bottle refilled with water1 agitated1 and left to rest1 and the process repeated as long as the water carries any suspended matter after a definite time4 ,wolff proposes for the first three periods of rest one hour1 for the second three1 a half an hour1 for the third three1 a quarter of an hour1 and for the fourth three1 five minutes4 #bjc4 ,moore's ,modification of ,knop's ,method4#ach--,the sample of soil is first passed through a sieve having round perforations three millimeters in diameter4 ,the weight of the particles remaining on the sieve is then determined1 and likewise that of the portion passing through1 which is known as fine earth4 ,the last named portion constitutes the material for all subsequent operations of mechanical and chemical analysis4 ,thirty grams of the fine earth are boiled rapidly with water until the lumps are disintegrated and clayey portions separated from the sand4 ,the material is then successively washed through perforated metal sieves1 the holes of which are respectively #a1 #j4e1 and #j4be millimeter in diameter4 ,the portions retained on the sieves are severally dried1 ignited and weighed1 and the finest portion1 or that passing through the #j4be millimeter sieve1 is then submitted to the following process of separation3 ,the sediment and water passing through the #j4be millimeter sieve are placed in a glass cylinder fifty centimeters long and thirty-seven millimeters in internal diameter4 ,the cylinder is closed at the bottom and is provided with a lateral tube inserted six centimeters above the bottom4 ,three other lateral tubes are inserted at intervals of ten centimeters above the first tube1 and a ring is etched into the cylinder ten centimeters above the uppermost tube4 ,the lateral tubes are closed with rubber tubes compressed by spring clips4 ,the sediment being placed in the cylinder1 water is added to the mark or ring1 the cylinder closed with a rubber stopper1 and vigorously shaken until the contents are thoroughly mixed4 ,it is then placed upright1 the stopper removed1 and after standing undisturbed for five minutes the clip on the uppermost tube is opened and the water allowed to flow into a beaker4 ,after five minutes further standing1 the second clip is opened and the water drawn off into the same beaker2 in the same manner the water is drawn off from the other tubes at intervals of five minutes until the level of the lowest tube is reached4 ,the cylinder is then refilled with water to the mark1 thoroughly shaken after inserting the stopper and the water again drawn off at intervals of five minutes1 as before2 the operation being repeated until the water drawn off is almost free from turbidity4 ,the sediment remaining in the cylinder from this process of washing by subsidence is termed by ,knop1 fine sand1 the material flowing off in suspension in the wash waters1 dust1 and the process of separation by ,knop's original method ends here4 ,in order to remedy the imperfect separation into definite particles secured by the above method1 ,moore proposes the following device3 ,the fine sand from the first series of subsidences is placed in a separate vessel1 the washings are allowed to remain undisturbed for twelve hours1 the turbid liquid decanted and the sediment returned to the cylinder4 ,water is then added to the mark1 the whole shaken1 and the liquid drawn off at intervals of five minutes1 as in the first series4 ,the sediment from this operation is placed in a separate beaker1 the washings returned to the cylinder1 and again allowed to subside as before2 the sediment from this second subsidence is added to that from the preceding operation1 and the washings again returned to the cylinder1 the operation being repeated as long as any sediment can be obtained from renewed treatment of the washings2 the final washings are then placed in a separate vessel for subsequent microscopic measurements4 ,the collective sediments from the last series of operations are then returned to the cylinder and allowed to subside with fresh additions of water1 as in the case of the first series2 the fine sand thus obtained being added to that from the first series1 and the washings being collected in a large beaker4 ,the latter are left at rest for twelve hours1 and the sediment returned to the cylinder and treated as before until no further separation can be effected4 ,the fine sand resulting from all of these operations is then dried1 ignited and weighed2 the weight of the portion removed by the washing being determined by difference1 as it is1 owing to its excessively slow rate of subsidence1 found impracticable to collect it for direct weighing4 ,the size of the particles of fine sand is then determined by micrometric measurement4 ,similar measurements are made on the material obtained by long subsidence from the washings from the foregoing operations4 ,the average diameter of the largest particles should not exceed #j4ja millimeter4 #bjd4 ,statement of ,results4--,the results of the analyses on three soils from the localities indicated in the table1 and the method of stating them1 are given in the following table3 ,new ,milford1 ,clarksville1 ,granville1 ,conn41 per ,tenn41 per ,n4 ,c41 per cent4 cent4 cent4 ,particles larger in diameter #h4ee #j4cb #j4bc than #c4j millimeters ,particles of diameter from #c4j #d4if #j4de #ae4jd millimeters to #a4j millimeter ,particles of diameter from #a4j #d4dc #j4if #cc4dc millimeter to #j4e millimeter ,particles of diameter from #j4e #aa4hf #a4be #ah4hb millimeter to #j4be millimeter ,particles of diameter from #j4be #fj4ed #fa4eh #bc4ei millimeter to #j4ja millimeter ,particles smaller in diameter #i4ff #ce4dd #h4hi than #j4ja millimeter ,total #ajj4jj #ajj4jj #ajj4jj #bje4 ,method of ,bennigsen4--,the silt flasks recommended by ,bennigsen#aci are shown in ,fig4 #bg4 ,the glass flask b carries a long cylindrical neck a the upper part of which is graduated in cubic centimeters4 ,ten grams of the fine soil are shaken with water in the flask1 the neck of which is closed with a rubber stopper4 ,the flask is then inverted bringing the soil and water into the neck4 ,the flask is hung up and sedimentation is assisted by imparting a pendulous motion to the neck for ten minutes4 ,after an hour the soil particles have separated into a coarse layer below and a fine layer above4 ,the relative volumes of the two layers are then read off in cubic centimeters4 ,while this method may be useful in helping to form a speedy judgment concerning the character of a soil it can lay no claim to being an accurate method of silt separation4 ,illustration3 ,,figure #bg4 ,,bennigsen',s ,,silt ,,flasks4 #bjf4 ,method of ,gasparin4--,the method of ,gasparin only gives a very primitive separation of the various components of the earth according to their fineness4 ,it is conducted as follows3 ,ten grams of sifted earth are put into a beaker1 water is added and strongly agitated2 after five minutes the water is decanted into another vessel1 the first vessel is filled anew with water1 agitated1 decanted1 and this process is repeated until the liquid remains perfectly clear4 ,only two portions are weighed1 i4 e41 the pebbles which remain in the sieve and the coarse sand which remains in the beaker2 while the argillaceous portion drawn off with the water is determined by the difference4 #bjg4 ,the ,italian ,method4--,the following modification of ,gasparin's process is practiced by the ,italian chemists3#adj ,twenty grams of earth are passed through a sieve having openings of one millimeter in diameter1 then the sifted part is mixed with #ajj cubic centimeters of water in a #bjj cubic centimeters beaker and left to rest for some hours1 then strongly agitated and after ten seconds the turbid liquid is poured into another vessel of half a liter capacity4 ,this manipulation is repeated until the liquid is clear4 ,the decanted liquid is thoroughly agitated1 then left to stand until the movement shall be completely arrested1 after which the supernatant liquid is poured into another vessel holding two liters4 ,to the residuum is added more water2 it is agitated1 decanted1 and this process is repeated until the water is no longer turbid4 #bjh4 ,method of ,osborne4--,in the foregoing paragraphs the methods of silt separation by subsidence as practiced in different countries have been outlined4 ,the good points of the various methods are combined in the process as carried out by ,osborne4#ada ,the details of this method will be given with sufficient minuteness to make its practice possible by all analysts4 ,selecting the ,sample4--,several pounds of air-dried1 fine earth are secured by passing the soil through a sieve1 the holes of which are three millimeters in diameter4 ,sifting4--,thirty grams of the above fine earth are stirred with #cjj to #djj cubic centimeters of water and then thrown successively upon sieves with circular holes of #a1 #j4e1 and #j4be millimeter diameter respectively4 ,by means of successive additions of water and the use of a camel's hair brush1 all the fine material is made to pass through the sieves and these at the last are agitated under water in a shallow dish in such a way that the soil is immersed4 ,the finest sieve should be well wet with water on its lower surface just before using4 ,the finest particles which render the water turbid are easily washed through4 ,the turbid water is kept separated from the clear water which comes off with the last portions that pass the sieves4 ,the turbid water usually does not amount to more than one liter4 ,elutriation4--,the elutriation should be carried on so as to secure three grades of silt2 the diameters of the particles ranging in the first grades from #j4be to #j4je millimeter1 in the second grade from #j4je to #j4ja millimeter1 and in the third grade from #j4ja millimeter to the impalpable powder4 ,the term sand is applied to the first grade1 silt to the second1 and dust to the third4 ,after the turbid liquid from the sifting has stood a short time it is decanted from the sediment and after standing until a slight deposit is formed1 is again decanted and the sediment examined with a microscope4 ,if sand be present1 the subsidence of the turbid liquid is continued until no more sand is deposited4 ,as the sand subsides rapidly there is no difficulty in altogether freeing the liquid first decanted from this grade of particles4 ,the sediment thus obtained contains all the sand1 a part of the dust and much silt4 ,as only dust and the finest silt render the water turbid the sediment is stirred a few times with a fresh quantity of water and decanted after standing long enough to let all the sand settle4 ,when the water decanted is free from turbidity1 the last portions of the soil passing through the sieve with clear water are added to the sediment and the decantations continued so as to remove most of the silt4 ,when no more silt can be easily removed from the sediment without decanting sand1 the decantations are made into a different vessel and the subsidences so timed as to remove as much of the silt as possible4 ,by using a little care1 at least three-quarters of the sand are thus obtained free from silt4 ,the rest of the sand is mixed with the greater part of the silt which has been decanted into the second vessel4 ,the size of the smallest particles in this vessel is determined with the microscope1 to make sure that its contents are free from dust as they usually will be if1 after settling for a few moments1 they leave the water free from turbidity4 ,the soil is thus separated into three portions1 one containing sand1 one sand and silt1 and the other silt1 dust1 and clay4 ,the sand and silt are separated from each other by repeating the subsidences and decantations in the manner just described4 ,in this way there is removed from the sediment1 on the one hand1 a portion of silt free from sand and dust1 and on the other hand a portion of sand free from silt4 ,thus is obtained a second intermediate portion consisting of sand and silt1 but less in amount than the first and containing particles of diameters much more nearly approaching #j4je millimeter4 ,by repeating this process a few times1 this intermediate portion will be reduced to particles whose diameters are very near #j4je millimeter and which may be divided between sand and silt1 according to judgment4 ,the amount of this is usually very small4 ,as soon as portions are separated1 which the microscope shows to be pure sand or pure silt1 they are added to the chief portions of these grades already obtained4 ,the same process is applied to the separation of silt from dust4 ,when all the silt has been removed from the dust and clay1 the turbid water containing the dust and clay is set aside and allowed to settle in a cylindrical vessel for twenty-four hours4 ,the vessel is filled to a height of #bjj millimeters4 ,according to ,hilgard1 the separation of the dust from clay during a subsidence of twenty-four hours1 will give results of sufficient accuracy1 although the clay then remaining suspended will not be entirely free from measurable fine particles up to #j4jja or #j4jjb millimeter diameter4 ,small beakers and small quantities of distilled water are used at first for the decantations1 as thus the duration of subsidence is less and more decantations can be made in a given time than when larger quantities of water are employed4 ,beakers of about #ajj cubic centimeters capacity are convenient for the coarser grades1 but it is necessary to use larger vessels for the fine sediments from which turbid water accumulates that cannot be thrown away1 as may be done with the clear water1 from which the coarse sediments settle out completely in a short time4 ,it is best to keep the amount of water as small as possible in working out the dust since loss is incurred in using too large quantities4 ,it is also necessary in most cases to subject the various fractions obtained during elutriation1 to careful kneading with a soft rubber pestle so that the fine lumps of clay may be broken up and caused to remain suspended in the water4 ,this treatment with the pestle should be done in such a way as to avoid as far as possible all grinding of the particles1 the object being merely to pulverize the minute aggregations of clay and extremely fine particles which always form on drying a sample of soil after removing it from the ground4 ,measurement of the ,particles4--,to determine the size of particles in suspension1 a small glass tube is applied to the surface of the liquid in such a way as to take up a single drop which is transferred to a glass slide4 ,this drop will contain the smallest particles in the liquid4 ,to obtain a sample of the coarsest particles the liquid is allowed to stand long enough to form a very slight sediment and a portion of this sediment is collected with a glass tube4 ,to determine the diameter of the particles in a sediment it is stirred vigorously with a little water and the pipette at once applied to the surface of the water4 ,on decanting the greater part of the sediment1 the large particles remain at the bottom of the beaker and may be easily examined4 ,time4--,the time required to make the separations1 above described1 is about two hours for each1 so that an analysis including the sittings1 is made in five or six hours1 exclusive of the time necessary for collecting the dust and separating the clay1 for which a subsidence of twenty-four hours is allowed4 ,weighing the ,sediments4--,the sediments are prepared for weighing by allowing them to subside completely1 decanting the clear water as far as possible1 rinsing them into a weighed platinum dish and igniting4 ,the dish is cooled in a desiccator4 ,effect of ,boiling4--,the analyses show a very decided increase in the particles smaller than #j4ja millimeter diameter at the expense of coarser particles as the result of boiling4 ,the surfaces of the coarser particles are seen to be polished and of a lighter color than those not boiled4 ,the surfaces of the unboiled particles are coated with a film of fine material probably cemented to them by clay4 ,when these coarse particles which have not been boiled1 are violently stirred with water for a short time1 no fine particles are detached from them2 and a careful examination under the microscope fails to reveal in any of the sediments more than an occasional grain exceeding the #j4je millimeter limit by so much as #j4ja millimeter1 or the #j4ja limit by as much as #j4jje millimeter4 ,it would1 therefore1 appear that these small particles thus set free by long boiling are really a part of the larger ones and should be treated as such in a mechanical analysis of these soils4 #bji4 ,the ,french ,method4--,the ,schloesing method#adb as practiced by the ,french agricultural chemists#adc differs essentially from those already described in attempting to first free the silt from carbonates and organic matter4 ,it is conducted as follows3 ,one kilogram of the soil previously dried in the air1 is taken and passed through a sieve of which the meshes are five millimeters4 ,the agglomerated particles of earth are broken up by the hand4 ,the pebbles are also taken out and weighed4 ,the pebbles are then treated with hydrochloric acid until all effervescence is over4 ,the insoluble part is dried and again weighed4 ,the difference in weight gives the quantity of calcium carbonate contained on the external surface of the pebbles4 ,the earth which passes the sieve of five millimeters mesh is next passed through a sieve having ten meshes to the centimeter4 ,the masses on the sieve are broken up with the hand or with a pestle1 in such a manner as to separate the fine agglomerated particles4 ,the material which remains upon the sieve after being dried at #ajj1 is weighed4 ,this gives the coarse sand4 ,this is treated with hydrochloric acid as were the pebbles before1 washed and the residue dried and weighed4 ,the difference in weight gives the quantity of calcium carbonate adhering to the surface of the coarse sand4 ,the mechanical analysis is continued with the matter which has passed the sieve with ten meshes to the centimeter and which consists of the soil1 properly so-called4 ,ten grams of this are taken1 dried at #ajj until no further loss takes place and the moisture thus determined4 ,another ten grams are taken and placed in a capsule with a flat bottom1 and from nine to ten centimeters in diameter4 ,this is moistened with a small quantity of water in such a way as to make a paste4 ,this paste is rubbed with the finger in fifteen cubic centimeters of water4 ,ten seconds after the stirring is completed the supernatant liquid is poured into a precipitating jar of about #bej cubic centimeters capacity1 taking great care not to allow any particles to pass over which have been deposited during that time4 ,this operation is repeated in the same way waiting about ten seconds each time before decanting1 until the decanted liquor is almost perfectly clear4 ,in this way the particles of different fineness are separated4 ,the decanted portions contain the fine sand and clay4 ,the remaining portion contains the sand and particles of medium fineness4 ,this last part is dried1 being kept at #ajj until it has a constant weight4 ,it is afterwards treated with dilute nitric acid to dissolve the calcium carbonate4 ,when the carbonate is abundant1 it is sufficient to determine it by difference which is done by washing the material1 drying and weighing4 ,but when the proportion of carbonate is very small and in consequence when its exact determination acquires a greater importance1 it is better to determine the lime directly4 ,for this purpose the part soluble in dilute nitric acid is collected1 treated with ammonia and acetic acid and precipitated with ammonium oxalate4 ,details of this operation will be given in another part of this manual4 ,in regard to the matter which is insoluble in nitric acid1 it is composed chiefly of silica or silicates1 and sometimes also of vegetable dbris4 ,the vegetable matter is determined by the incineration of the material which has been previously dried4 ,the loss of weight gives the proportion of vegetable or organic dbris contained in the soil and of combined water4 ,the portion which has been decanted1 the volume of which should not exceed #ejj cubic centimeters1 is treated with nitric acid until effervescence ceases4 ,it is then left to digest for some time1 in order to permit the whole of the carbonate to dissolve4 ,it is next thrown upon a smooth filter about one decimeter in diameter4 ,after filtration it is washed to secure the complete elimination of the soluble lime salts4 ,the lime is determined in the filtered liquid4 ,the insoluble portion contains the fine sand1 the clay and humus bodies4 ,in order to separate the three elements the precipitate which was received upon the filter1 is rubbed with water1 the filter is broken and all its contents washed through4 ,the volume of wash water is made up to #bjj cubic centimeters2 two or three cubic centimeters of ammonia are added and the whole left to digest for two or three hours4 ,the volume of the liquid is then made up to one liter with distilled water1 vigorously shaking in such a way as to put all the matter in suspension4 ,it is then left to settle for twenty-four hours4 ,at the end of this time the supernatant liquid is decanted by the aid of a siphon4 ,to the residue are added two cubic centimeters of ammonia and one liter of water4 ,the matter is again brought into suspension and allowed to settle for twenty-four hours4 ,the supernatant liquid is again decanted with a siphon1 and added to the liquid previously removed4 ,for ordinary soils two decantations are generally sufficient but when the soils contain a large quantity of clay it is convenient to decant three or four times4 ,by an examination of the supernatant liquid it is easy to tell if the washings have been sufficiently prolonged4 ,the decanted liquors contain the organic matter and that which it is convenient to call clay1 which is constituted of very fine particles of sand and colloidal clay which play1 in arable soil1 a rle somewhat like that of cement4 ,these matters are estimated in the following manner3 ,the liquor is first treated with nitric acid and the clay and the humic matters are precipitated together4 ,they are collected upon a smooth filter one decimeter in diameter and washed with water4 ,by means of a washing bottle all the solid matters which have stuck to the sides of the filter are finally collected in the bottom of it4 ,since the last washings pass the filter very slowly1 they can be removed after the complete deposition of the matter they contain1 by means of a pipette4 ,when all the liquid is removed the filter is placed upon blotting paper1 great care being taken to avoid desiccation1 having in view only the elimination of the excess of humidity4 ,the folds in the filter are then carefully smoothed out with the finger4 ,the matter which has collected upon the filter is then removed completely with a washing bottle1 placed in a dish and dried at #ajj and weighed4 ,after weighing1 the mass is incinerated in a muffle in order to destroy the humic bodies4 ,the difference in weight before and after incineration1 gives the total weight of the humic bodies and since the diminution in weight comprises not only the weight of the humic bodies1 but also the weight of the combined water which is lost during the process of incineration1 there should be subtracted from the total loss of weight ten per cent of the weight of the residual mineral matter1 which represents the water of composition of the hydrated silicate4 #baj4 ,statement of the ,analysis4--,schloesing in his original paper#add recommends that the analysis be commenced with #a1jjj grams of soil4 ,the data of the analysis and the method of arrangement are illustrated by the following example4 ,the physical examination of the earth having been completed as above1 the results can be tabulated as follows3 taken1 #a1jjj grams of dry earth1 digested in water1 thoroughly worked by hand1 sifted1 and passed through the meshes of the sieve by a stream of water1 the meshes having a diameter of one millimeter4 ,dry residue1 fifty-five grams1 contains ,pebbles #ba grams4 ,gravel #cc ,organic dbris #a ,sifted earth by difference1 #ajjj #ee #ide -------- #ajjj grams4 ,humidity of the homogeneous paste1 twenty-seven per cent4 ,then #ide grams of the dry sifted earth correspond to 7#ide7_/7a4jj 4#bg7 #abid4e of paste4 ,the analysis1 therefore1 should be carried on upon this weight or some aliquot part say #j4ja thereof2 viz41 #ab4ide grams4 #ab4ide grams of the #ast4--,coarse sand dry ,noncalcareous #c4je grams4 paste after successivegiving by treatment sand kneadings and with acid and decantations furnish ignition4 dry3 ,calcareous #a4ai sand ,organic #j4jh dbris #bnd4--,fine elements decanted with the water1 their weight calculated by difference1 #i4de #d4cb #e4ac grams4 ,treatment of the ,fine ,elements4--,treated by nitric acid until a complete decomposition of the calcareous matter is secured1 filtered1 washed1 the residual matter collected upon a filter1 and the liquid received in a two-liter flask1 a little ammonia added1 allowed to digest1 the flask filled with distilled water1 left for twenty-four hours at repose1 and decanted3 ,the decantation furnishes#ast4--,a deposit of fine calcareous#c4ad grams4 sand weighing dry #bnd4--,clayey liquid giving after coagulation by acid1 filtration and drying #j4he grams of clay4 ,then3 ,total fine elements #e4ac grams4 ,fine elements determined ,fine calcareous sand #c4adc4ii directly4 ,clay #j4he -------- ,fine calcareous sand by difference #a4ad ,calculating these results to the original quantity of #a1jjj grams the following data are obtained3 ,r,,sum4 ,one thousand grams of dry earth contain3 ,pebbles #ba grams4 ,gravel #cc ,organic dbris #a gram4 ,fine earth #ide grams4 -------- ,total #ajjj #ide grams of ,coarse sand #dcb gms4 ,noncalcareous sand #cje gms4 fine earth contain3 ,calcareous sand #aai ,organic dbris #h ,fine elements #eac gms4,fine1 noncalcareous sand #cad gms4 ,clay #he ,fine calcareous sand #aad ---- ,total #ajjj ,there are counted as clay all the elements which have remained in suspension in the water after a period of repose of twenty-four hours4 ,in fact1 these elements comprise a notable proportion of very fine sand which is not deposited during that time4 ,in order that the liquid should become entirely freed from this sand it would be necessary to wait several weeks and even several months4 ,such a prolongation of the analysis is evidently inadmissible4 ,the period of twenty-four hours of repose therefore has been adopted4 ,this is merely conventional1 in the same way that the period of ten seconds adopted for the precipitation of the gravel is conventional4 ,but this convention is justified by the fact that the substance which is called clay presents1 when it has a proper degree of humidity and cohesion1 a plasticity entirely analogous to that property of natural clay4 ,moreover1 as has already been said1 that which is chiefly important in these analyses is the employment of processes always comparable among themselves in their results and generally followed4 #baa4 ,the ,belgian ,method4--,the method of estimating the percentage of sand and clay practiced at the ,gembloux ,station#ade is essentially that recommended by ,schloesing with a few minor modifications4 ,with the ball of the thumb or with the finger1 #ajj grams of fine earth are rubbed with water in a porcelain capsule or mortar with a capacity of about #bej cubic centimeters4 ,the suspended particles are poured off with the wash water and the process repeated five or six times1 using in all about #bjj cubic centimeters of water4 ,the water containing the sediment is rendered slightly acid 7hydrochloric acid7 adding the acid in minute particles with constant stirring for about an hour in order to dissolve all the carbonate and to separate the organic acids from the bases with which they are combined4 ,the liquid is allowed to remain at rest for five or six hours and a part of the liquor decanted to remove any supernatant particles of organic matter which may have passed the sieve in the original preparations of the sample4 ,filter through a smooth filter about twelve centimeters in diameter1 wash until the chlorin has disappeared1 and throw the filtrate away4 ,break the filter paper over the vessel in which the soil was treated with hydrochloric acid and wash all the contents of the filter into this vessel with as little water as possible 7about #ajj cubic centimeters71 add five cubic centimeters of strong ammonia water1 allow to stand for three hours1 shaking from time to time and with distilled water make the volume up to #bej cubic centimeters4 ,stir vigorously with a glass rod or spatula1 take this out and wash any adhering particles back1 leave at rest for twenty-four hours1 siphon the turbid liquid into a two-liter vessel4 ,make the volume up again to #bej cubic centimeters and treat as above described and repeat the operation until the water becomes clear after standing for twenty-four hours4 ,usually eight or ten washings are necessary4 ,wash the residual sand into a weighed dish1 evaporate to dryness1 ignite and weigh4 ,the weight obtained divided by the weight of the original sample gives the per cent of sand4 ,the sand is separated by sieves of varying fineness into coarse1 fine1 and pulverulent sand4 ,add to the ammoniacal liquor collected in the two-liter flask some powdered potassium chlorid 7five grams per liter7 to hasten the coagulation and rapid deposit of the clay4 ,after twenty-four hours siphon the clear liquor1 collect the deposited clay in a smaller vessel1 allow to remain at rest and decant as much of the clear liquor as possible4 ,pass through a plain tared filter about nine centimeters in diameter1 dry at #aej and weigh the clay4 #bab4 ,the ,italian ,method4--,schloesing's method as carried out by the ,italian chemists#adf is as follows3 ,a kilo of earth dried in the air is passed through a sieve the threads of which are separated a distance of five millimeters2 and with this the small pebbles are separated4 ,with another sieve having spaces of one millimeter1 the coarse sand is separated4 ,the pebbles and sand are dried1 weighed1 treated with hydrochloric acid and again weighed in order to find the quantity of calcareous matter contained in them4 ,in ten grams of this fine earth the humidity is determined by drying at #ajj4 ,ten grams are mixed in a capsule with fifteen to twenty cubic centimeters of water and after eight to ten seconds the supernatant liquid is poured into a beaker having a capacity of #bej cubic centimeters4 ,the same operation is repeated until there are contained in the beaker the fine sand and the clay1 while the coarser sand remains in the capsule4 ,this last is then dried and weighed and the quantity of calcium carbonate determined by treating it with diluted nitric acid4 ,by means of calcination the organic matter is determined4 ,the liquid decanted in the beaker1 the volume of which must not surpass #bjj to #bej cubic centimeters1 is treated with nitric acid1 filtered after some time1 washed and the calcium is directly determined by precipitating the solution with ammonium oxalate4 ,the part in the filter which contains the fine sand1 the clay1 and the humus material is mixed with water to a volume of about #bjj cubic centimeters2 there are then added to it two to three cubic centimeters of ammonia and after two or three hours it is diluted to a liter and strongly agitated4 ,after twenty-four hours of rest it is decanted and the residuum is treated a second time with diluted ammonia1 decanting after twenty-four hours4 ,ordinarily these two treatments suffice1 if1 however1 the earth is very argillaceous1 this operation should be repeated three and even four times4 ,the clay which is found in the liquid suspended in colloidal form coagulates and is precipitated by adding thirty to forty cubic centimeters of a saturated solution of potassium chlorid1 while the humus substance1 under the influence of the ammonia remains dissolved4 ,sestini found that the method of ,schloesing was the only one which indicated exactly the quantity of clay in the soil4 ,he modified this method by reducing the time of rest from twenty-four hours1 as proposed by ,schloesing1 to only twelve hours1 a reduction which in his opinion does not in the least impair the exactness of the method4 ,sestini also proposes twelve treatments instead of six4 ,,separation ,,of ,,the ,,soil ,,particles ,,by ,a ,,liquid ,,in ,,motion4 #bac4 ,general ,principles4--,the laws1 already discussed1 applying to the subsidence of a solid particle in a liquid1 are equally applicable to the separation of the particle by imparting a motion to the liquid at a given rate4 ,if a solid particle subside in a given liquid at the rate of one millimeter per second it follows that this particle will remain at rest if the liquid be set in motion upward with a like velocity4 ,if the velocity be greater the particle will be carried upward and eventually out of the containing vessel4 ,such a particle is said to have a hydraulic value of one millimeter per second4 ,if there be a perfect separation of a soil into its constituent particles and no subsequent flocculation1 all the particles of one millimeter hydraulic value and less will be separated by a current of the velocity mentioned4 ,the general principles on which the separation rests1 therefore1 are the securing of the proper granulation of the sample and the maintenance of a fixed velocity of the current until the separation is finished4 ,the separation must be commenced with a period of subsidence so as to remove first of all the suspended clay or impalpable particles4 ,the velocity can then be increased in a certain fixed ratio to secure a separation into particles of any required hydraulic value4 #bad4 ,nbel's ,apparatus4--,one of the earliest methods of separating the soil particles by a moving liquid is that of ,nbel4#adg ,the apparatus is shown in ,fig4 #bh4 ,the four separating vessels #a1 #b1 #c1 #d are of glass1 pear shaped1 and have a relative capacity of #a1 #b1 #c1 #d1 or #a 3 #h 3 #bg 3 #fd4 ,no4 #d has an outlet tube leading to the beaker ,b1 of such a capacity as to allow the passage of just nine liters of water in forty minutes1 constant pressure being maintained by means of a ,mariotte's bottle or of the constant level apparatus ,a1 a1 b1 which is connected with the main water supply through the tube a by means of a rubber hose4 ,the reservoir ,c should hold about ten liters4 ,the sample of soil to be separated should be previously boiled and passed through a sieve having circular openings one millimeter in diameter4 ,the flask in which the sample is boiled is allowed to stand for some time when the muddy supernatant liquid is poured into elutriator ,no4 #b and the remaining sediment washed into ,no4 #a4 ,no4 #a is filled with water by connecting it with the water supply and opening the pinch-cock p4 ,the water is carefully admitted until the air is all driven out and ,nos4 #a and #b connected4 ,the cock p is then opened and the vessels all filled1 and the water allowed to run into ,b for forty minutes1 the level being maintained uniformly at ,a4 ,illustration3 ,,figure #bh4 ,n,,bel',s ,,elutriator4 ,of the water used1 four liters are found in the elutriating vessels and nine liters in the receiving vessel ,no4 #e4 ,the apparatus is left standing for an hour until the liquid in the elutriators is clear and the portions in each vessel are received on weighed filters dried at #abe1 and the weight of each portion determined4 ,it is recommended that the loss on ignition of each part be also determined4 ,the separated particles thus secured are classified as follows3 ,no4 #a4 ,dbris and gravel4 ,no4 #b4 ,coarse sand4 ,no4 #c4 ,fine sand4 ,no4 #d4 ,clayey sand4 ,no4 #e4 ,finest parts or clay4 ,although the method of ,nbel has been much used1 the results which it gives are entirely misleading4 ,the convection currents produced in the conical vessels by the passing water and the flocculation of the soil particles prevent any sharp separation into classes of distinct hydraulic value4 ,the process may be useful for a qualitative test1 but its chief claim to a place in this manual is in its historic interest arising from its use in the first attempts at silt analysis4 #bae4 ,method of ,dietrich4#adh--,the difficulties attending the silt separation by the ,nbel method1 led ,dietrich to construct an apparatus in which the sides of the elutriating vessels were parallel1 but these vessels1 with the exception of the first1 were not set in an upright position4 ,illustration3 ,,figure #bi4 ,,dietrich',s ,,elutriator4 ,the apparatus 7,fig4 #bi7 consists of a series of cylindrical vessels connected by rubber tubing4 ,the elutriators are of the following dimensions3 ,no4 #a4 ,seventeen centimeters long1 #b4h centimeters in diameter1 position upright4 ,no4 #b4 ,thirty-four centimeters long1 four centimeters in diameter1 inclined #fg4e4 ,no4 #c4 ,fifty-one centimeters long1 #e4b centimeters in diameter1 inclined #de4 ,no4 #d4 ,sixty-eight centimeters long1 #f4d centimeters in diameter1 inclined #bb4e4 ,the rubber tubes passing from one vessel to the other are furnished with pinch-cocks so that each one of the elutriating vessels can be shut off from the others and independently removed from the circuit4 ,the stream of water is made to pass through the apparatus under a constant pressure of one meter4 ,only the fine earth1 boiled with water or hydrochloric acid1 is to be placed in the apparatus4 ,the part coming through a sieve with a mesh #j4fg millimeters is to be used and placed in ,no4 #a4 ,about thirty grams of soil1 are employed for each elutriation4 ,before adding the soil1 the air is completely removed from all parts of the apparatus by connecting it with the water supply and allowing it to be filled with water4 ,the rate of flow is controlled by the orifice of the last effluent tube and the analyst is directed to continue the operation until the effluent water collected in the beaker glass 7#e7 is clear4 ,the particles then remaining in each of the vessels are collected separately4 ,the author of the method claims that in respect of likeness of particles the results are especially gratifying and that duplicate analyses give results fully comparable4 ,the process1 however1 has not commended itself to analysts1 but it marks a distinct progress toward the principles of later investigators4 ,had each of the elutriating vessels been placed upright and the rate of flow determined1 the apparatus of ,dietrich would have served1 to a certain extent1 for the more rigid investigations of his successors4 #baf4 ,method of ,masure4--,the sifted earth1 from ten to fifteen grams1 is carefully mixed with #bjj cubic centimeters of water4 ,it is then introduced into a doubly conical elutriator ,b1 ,fig4 #cj1 of about #bej cubic centimeters capacity4 ,a current of distilled water is allowed to flow from a ,mariotte's bottle1 ,a1 which secures a regular and constant flow4 ,the bottle ,a is joined to the elutriator ,b by means of a rubber tube and the vertical glass tube ,d1 the top of which is expanded into a funnel for the purpose of receiving the water from the ,mariotte flask4 ,the current of water flowing upward through the elutriator ,b carries in suspension the most finely divided particles of clay1 and these are collected with the emergent water in the receiver ,c4 ,the sand and coarser particles of clay remain in the elutriator4 ,the water flows out by the tube ,f1 the diameter of which should be less than that of ,d4 ,when the emergent water becomes limpid the operation is terminated4 ,after the apparatus is disconnected1 the water is decanted from the sand in the elutriator1 and the whole residue is weighed after drying for two hours at #aaj4 ,illustration3 ,,figure #cj4 ,,masure',s ,,silt ,,apparatus4 ,the fine soil collected in ,c may also be separated and weighed1 for control1 after drying as above4 ,the pebbles and coarse sand separated by the sieves should also be weighed4 ,by this process the soil is separated into four portions2 viz41 7#a7 ,pebbles4 7#b7 ,coarse sand4 7#c7 ,fine sand and other materials not carried off by the current of water4 7#d7 ,fine soil1 carried into the receiver ,c4 #bag4 ,method of ,schne4--,the method of ,schne#adi is based on the combination of a cylindrical and conical separatory tube through which the flow of water is regulated by a piezometer4 ,if1 in the process of silt separation1 the water move perpendicularly upward with a given velocity1 e4g4 v the separation is dependent3 7#a7 ,on the volume of the silt particles1 7#b7 ,on their specific gravity1 and1 7#c7 ,on their state of disintegration4 ,if it be assumed that the silt particle is a sphere with a diameter d1 then according to ,newton's law of gravity1 the following formula would be applied3 d v 77#c,z7_/7#d;g 7,s #a7774 ,illustration3 ,,figure #ca4 ,,sch,,ne',s ,,elutriator4 ,in the above formula ,z a coefficient which depends on the condition of the surface against which the hydraulic pressure or resistance works1 in this case a sphere2 g the acceleration of gravity equivalent to #i4ha meter2 and ,s the specific gravity of the particle4 ,this expression signifies that in a given case1 the velocity of the current in the apparatus is just sufficient to counteract the tendency of a given particle to sink4 ,all particles of a smaller diameter1 in such a case1 will be carried on by the current1 while all of a greater diameter would separate by sedimentation4 ,these theoretical conditions are not met with in practice where silt particles of all shapes and degrees of aggregation abound4 ,these particles1 whatever their shape1 may be said to have the same hydraulic value when carried by the same current4 ,it is necessary1 therefore1 to secure some uniform standard of expression to assume a normal form of particle and a normal specific gravity4 ,for the form1 a sphere is evidently the normal which must be considered and for specific gravity that of quartz is taken2 viz41 #b4fe4 ,the mean coefficient for ,z may also be placed at #j4ee1 although slightly different values are ascribed to it4 ,substituting these values in the formula1 it is reduced to the expression2 d v #j4jjjjbee millimeters4 ,it can1 therefore1 be said that by this or that velocity of the current1 silt particles will be removed of this or that diameter1 it being understood that all particles of equal hydraulic value to spherules of quartz of the given diameter are included in each class4 ,in order to have the theoretical formula agree with the results of analysis it is necessary to modify it empirically to read d v #j4jcad millimeters4 ,this formula is found to agree well with the results obtained for all velocities between #j4a millimeter and twelve millimeters per second1 the ordinary limits of silt separation4 ,the ,apparatus4--,the conic-cylindrical elutriating vessel ,a1 ,b1 ,c1 ,d1 ,e1 ,f1 ,g1 ,fig4 #ca1 is of glass4 ,the part ,b1 ,c1 is cylindrical1 ten centimeters in length and as nearly as possible five centimeters in diameter4 ,the conical part ,c1 ,d1 is fifty centimeters in length4 ,its inner diameter at ,d must not be greater than five centimeters nor smaller than four centimeters4 ,the bend1 ,d1 ,e1 ,f1 should have the same diameter2 viz41 four to five centimeters4 ,the part ,a1 ,b1 ,c1 ,d1 and ,d1 ,e1 ,f1 ,g1 may be made of separate parts and joined by a rubber tube4 ,outflow ,tube and ,piezometer4--,the outflow tube and piezometer1 ,h1 ,j1 ,k1 ,l1 is constructed as shown in ,fig4 #cb4 ,it should be made of barometer tubing having an internal diameter of about three millimeters4 ,the tube is bent at ,j at an angle of forty to forty-five degrees4 ,the knee ,j must be as acute as possible not to interfere with the inner diameter4 ,the form and especially the magnitude of the outlet are of great importance4 ,it must be circular and nearly #a4e millimeter in diameter4 ,it must not be larger than #a4fg millimeter nor smaller than #a4e millimeter4 ,the opening should be so made as to direct the stream of outflowing liquid in the direction shown by the arrow4 ,illustration3 ,,figure #cb4 ,,sch,,ne',s ,,elutriator1 ,,outflow ,,tube4 ,the piezometer ,l1 ,k is parallel to the arm ,h1 ,j1 of the delivery tube4 ,its graduation has its zero point in the center of the outlet ,k4 ,it commences with the one centimeter mark4 ,from one to five centimeters it is divided into millimeters1 from five to ten centimeters into one-fourth centimeter1 from ten to fifty centimeters into one-half centimeter1 and from fifty to #ajj centimeters into centimeters4 ,the dimensions given are those required for ordinary soils and for velocities ranging from two-tenths millimeter to four millimeters per second4 ,for greater velocities1 a delivery tube with a larger outlet must be used and the piezometer must be of greater internal diameter than indicated4 ,illustration3 ,,figure #cc4 ,,sch,,ne',s ,,elutriator1 ,,arrangement ,,of ,,apparatus4 ,arrangement of the ,apparatus4--,the apparatus is conveniently mounted as shown in ,fig4 #cc1 giving front and side views of all parts of apparatus in position ready for use4 ,when numerous analyses are to be made much time is saved by having a number of apparatus arranged en batterie4 ,the ,sieve4--,the soil1 before being subjected to elutriation1 should be passed through a sieve of which the meshes are #j4b millimeter square4 ,the ,process4--,to measure the diameter of the cylinder1 two marks are made with a diamond upon the glass which are distant from each other a certain space1 for instance1 h centimeters4 ,the space between these two marks is filled with water exactly measured4 ,suppose that a cubic centimeters were used1 then the diameter is determined by the formula3 ,d 7#d;a7_/7h7 centimeters4 ,in order to determine that the elutriating cylinder is strictly comparable in all its parts this measurement should be made upon several parts thereof4 ,the apparatus should now be tested in regard to the quantity of liquid which it will deliver under a given pressure in the piezometer4 ,by means of the stop-cock ,h the flow of water is so regulated that the outflow at c can be measured at a given height of the water in the piezometer4 ,suppose that a cubic centimeters of water flow in t seconds1 then the quantity which would flow in one second is determined by the formula1 ,q a_/t cubic centimeters4 ,since according to the law of hydraulic outflow the quantities are proportional to the square root of the height of the column it is easy to compute from any given height the quantity which will flow from any other one desired4 ,for the retardation due to capillary attraction1 it is sufficient1 in general1 to take it in a constant quantity2 if this constant quantity be represented by ,c1 the observed height of the water in the piezometer by h1 and the quantity of water flowing out by ,q1 the data required for any given velocity can be calculated from the following proportion3 7h ,c7 3 7h ,c7 ,q 3 ,q4 ,it is necessary to compute the magnitude of this constant ,c which is to be subtracted4 ,this is accomplished by measuring the quantity of water which flows out at two different heights of the column in the piezometer4 ,from the foregoing proportion1 the value of ,c is as follows3 ,c 7,q h ,q h7_/7,q7 ,q7 centimeters4 ,the value of ,c can be the more exactly determined as h is greater and h smaller4 ,it is best to choose the lowest height from which an exact reading can be made2 that is1 by which the regular rise and fall of the level of the water in the piezometer 7in consequence of the formation of drops7 just begins to disappear4 ,this usually takes place when h #a4e centimeter to #a4g centimeter4 ,for the higher value h it is best to take about #ajj centimeters4 ,suppose1 for example1 the following results are obtained3 ,height of column to be ,observed height4 ,observed quantity of subtracted outflow4 due to capillary attraction4 h h ,q cubic ,q cubic centimeters4 centimeters4 centimeters4 centimeters4 centimeters4 #hj #a4f #e4ec #j4djf #a4ba #ajj #a4f #f4ac #j4dhd #a4ag #hj #a4h #e4ec #j4djf #a4ai #ajj #a4h #f4ac #j4dhd #a4ai ,the same quantity of water which flows out in a unit of time passes also at the same time over a cross section of the elutriating cylinder4 ,the diameter of this cylinder being ,d the equation is derived v ,q7#d7_/7;,d7 centimeters4 ,since the velocity in the elutriating cylinder v is directly as the quantity of water overflowing so is v 3 v 7h ,c7 3 7h ,c72 then v 7h ,c7 7v7_/77h ,c77 and h v77h ,c7_/7v7 ,c4 ,the constant 7h ,c7_/7v7 is obtained from the means of a number of estimations2 for example as illustrated in the following data3 ,observed ,corresponding velocity quantity of in elutriating cylinder ,constant4 ,observed height1 outflow1 cubic of #d4dhi centimeters 7h centimeters4 centimeters4 diameter1 millimeters4 ,c7_/7#b7 #a4f #j4djf #j4jbeg #fba #a4h #j4dhd #j4jcjf #feb #hj4j #e4ecj #j4cdij #fdg #ajj4j #f4acj #j4chgj #ffj ------ ,mean #fde ,then are obtained the following values of h and v3 h #fde7,v7 #a4ai centimeters4 and v 7h #a4ai7 #j4jcid centimeters4 ,in order to be able easily and rapidly to judge under what pressure the outflow has taken place in any particular instance1 a larger number of values are computed with the help of the formula given and placed together in tabular form4 ,as an example the following table may serve which was computed for one of the apparatus used4 ,usually it will be sufficient to test the apparatus for four different heights and then to interpolate the values for all the others4 ,the numbers marked with a star in the table are those which were determined by experiment2 the others were calculated4 ,height of column ,velocity in the elutriating ,corresponding diameter of in piezometer4 cylinder of #d4dhi silt particles4 d h centimeters diameter4 v v77#j4jcad millimeters4 centimeters4 ,observed1 ,calculated1 millimeters4 millimeters4 millimeters4 #a4e #j4bbb #j4bbj #j4jabj #a4f #j4beg99 #j4beb #j4jaca #a4g #j4bhd #j4bha #j4jadj #a4h #j4cjf99 #j4cjg #j4jadh #a4i #j4cbc #j4ccb #j4jaee #b4j #j4cdf #j4cee #j4jafb #b4e #j4dbg #j4dea #j4jahe #c4j #j4eca #j4ecj #j4jbaj #c4e #j4egg #j4eii #j4jbbg #d4j #j4fej #j4ffj #j4jbcf #d4e #j4fid #j4gag #j4jbed #e4j #j4gea #j4gfi #j4jbfe #f4j #j4hej #j4hfd #j4jbhf #g4j #j4idb #j4iej #j4jcjd #h4j #a4jej #a4jbh #j4jcbj #i4j #a4abj #a4aja #j4jccd #aj4j #a4agj #a4afi #j4jcdg #ae4j #a4dij #a4dfj #j4jdjj #bj4j #a4gcj #a4gaj #j4jdda #be4j #a4idj #a4ibj #j4jdgf #cj4j #b4ajj #b4aaj #j4jejf #ce4j #b4caj #b4bij #j4jecb #dj4j #b4dfj #b4dej #j4jeef #de4j #b4faj #b4faj #j4jegh #ej4j #b4ggj #b4gej #j4jeih #fj4j #c4jcj #c4jbj #j4jfce #gj4j #c4bij #c4bgj #j4jffg #hj4j #c4dij99 #c4ejj #j4jfig #ij4j #c4gaj #c4gaj #j4jgbd #ajj4j #c4hgj99 #c4ibj #j4jgdi ,suppose the problem is by means of the apparatus tested above1 to separate into a number of groups a mixture of silt particles1 whose hydraulic values are found between the following diameters3 #j4ja1 #j4jb1 #j4jc1 #j4jd1 #j4je1 #j4jf1 #j4jg millimeters4 ,the table will show at once under what pressure of water the piezometer must be placed in order to give the values2 viz41 #a4d1 #b4h1 #g4j1 #ae4j1 #bi4j1 #ec4j1 and #hc4j centimeters respectively4 ,the apparatus described above1 is adapted for velocities in the elutriating cylinder varying from two-tenths millimeter to four millimeters per second4 ,the largest silt particles which can be separated by the velocities given above1 have approximately a diameter of #j4jh millimeter4 ,for the separation of larger particles a sieve can take the place of the silt apparatus4 ,if1 however1 it be desired to subject larger particles to silt analysis1 the dimensions of the elutriating cylinder and of the outlet of the delivery tube must be changed accordingly4 ,preparation of ,sample4--,the conduct of silt analysis of natural soils must1 in certain cases1 be preceded by a special treatment of the sample4 ,if the latter be rich in humus the organic substance must previously be separated as completely as possible4 ,with sandy soils this can be accomplished by ignition4 ,with clayey soils1 on the contrary1 it is to be performed by boiling the soils at least one hour with water which contains from one to two per cent of free alkali4 ,soils which contain lime must also be subjected to treatment with dilute hydrochloric acid1 and the hydrochloric acid must be as carefully removed1 as possible before the sample is subjected to elutriation2 afterward follows the boiling of the sample in the ordinary way with water4 ,this1 of course1 can be omitted when it has already been treated with boiling dilute alkali4 ,it is also important to remove the larger particles by a sieve before the elutriation begins4 ,it is well to pass a sample through a sieve after it has been boiled1 by which all particles of a larger diameter than #j4b millimeter are removed4 ,this will usually require about one liter of water and this water should be allowed to rest from one to two hours and poured off with the suspended material which it contains4 ,only what subsides should be brought into the apparatus4 ,in rinsing the sample as much water must be used as will fill the apparatus up to its cylindrical portion4 ,after the sample has been placed in the apparatus1 the water is allowed slowly to enter1 being careful to avoid reaching more than the lowest required velocity1 until the outflow begins4 ,the water then is so regulated by the stop-cock as to bring it to the desired height in the piezometer4 ,this being accomplished1 the different velocities which have been decided upon for separating the particles of silt are used one after the other1 as soon as all the silt which can be removed at each given velocity1 has been secured4 ,from three to five liters of water will be required for the separation of each class of particles4 ,sometimes the reading of the height of the water in the piezometer is difficult2 as1 for instance1 when foam or bubbles accumulate therein4 ,these bubbles can be removed by simply blowing into the tube1 or dropping into it a little ether4 ,the outflow of water can be received in vessels1 beaker glasses1 or cylinders1 in which it is allowed to subside4 ,the finest particles which remain in suspension in the water are best determined by difference4 ,if it be desired to weigh them directly1 the water can be treated with ammonium bicarbonate until it contains from one to two per cent thereof4 ,the precipitation then takes place in a few hours4 ,the collection and weighing of silt particles are accomplished in the usual way4 ,that which finally remains in the elutriating vessel is taken out after the end of the operation by closing the stop-cock1 removing the stoppers with the piezometer tube1 pouring the contents of the elutriating vessel into a beaker glass and rinsing out carefully all adhering particles4 ,examples of the working of the apparatus follow3 ,the soil was taken from the ,imperial ,russian ,agricultural ,experimental ,institute at ,gorki4 ,it was a fine clay sand and was carefully treated with hydrochloric acid4 ,the results of the analysis are given in the following table3 ,velocities ,largest diameter of the ,percentage of silt product employed in collected particles in obtained in repeated millimeters4 millimeters4 elutriations4 #j4be #j4jab #ac4d #ab4f #aa4i #j4e #j4jbj #i4a #h4g #i4e #a #j4jcb #ba4j #ba4d #bj4h #b #j4jej #cj4d #bi4h #ca4g #c #j4jfc #af4g #af4a #ae4e #d #j4jgf #e4c #e4e #e4e ,residue #d4b #d4i #c4h ---------- -------- -------- ,total #ajj4j #ii4j #ih4g ,holthof modifies the apparatus of ,schne by putting into the lower mouth of the elutriator a little mercury so that the particles of earth are deposited upon its surface and are thus better agitated and washed by the current of water4 #bah4 ,mayer's ,modification of ,schne's ,method4--,an improvement of ,schne's apparatus in the direction of greater simplicity has been tested by ,mayer#aej with satisfactory results3 ,the apparatus1 7,fig4 #cd71 consists of a glass vessel having a glass stop-cock at the bottom for admitting the water4 ,for a distance of twenty centimeters the sides of the tube are parallel and the diameter about one centimeter4 ,next for a distance of fifty centimeters the tube is conical expanding at a regular rate until the internal diameter reaches five centimeters4 ,for a distance of ten centimeters the vessel is again strictly cylindrical and it is in this cylindrical portion that the separation of the different constituents takes place4 ,the vessel is then rapidly narrowed until it carries the stopper ,a two centimeters in diameter4 ,this stopper carries two glass tubes1 one ,f bent downward to conduct the overflow into the receiving vessels1 and one ,h for the purpose of regulating the rate of overflow by the height of the column of water therein4 ,the orifice of the overflow tube ,f should be so regulated that with a pressure of five centimeters water in ,h1 one liter shall pass over in ten minutes4 ,illustration3 ,,figure #cd4 ,,sch,,ne',s ,,apparatus ,,for ,,silt ,,analysis1 ,,modified ,,by ,,mayer4 ,if the separation be conducted in an apparatus thus mounted and graduated with a pressure of two centimeters in ,h all that portion of the soil which can properly be called clay will pass over4 ,the fine earth1 that is1 earth in which all coarse particles have been removed by proper sifting1 is used in ten-gram lots for each experiment4 ,the residue1 after the separation is complete1 consists of pure sand or at least pure sand mixed with humus4 ,before the fine earth is placed in the apparatus1 the calcium carbonate therein is removed with hydrochloric acid4 ,the treatment with hydrochloric acid1 however1 is not to be recommended in soil containing many undecomposed particles of calcium carbonate or dolomite for then large additions to the silt output might be made from these particles1 which could not be regarded as coming from the soil as it actually exists4 ,for alluvial soil1 however1 previous treatment with hydrochloric acid is recommended unconditionally4 #bai4 ,schne's ,method as ,practiced by ,osborne4--,the apparatus used by ,osborne#aea was obtained from ,germany and was similar to that described by ,schne in his original paper1 except that it was furnished with a second elutriating tube as suggested by ,orth4 ,the modification made by ,orth consists1 essentially1 of a second elutriating tube with straight sides into which the bulk of the soil is introduced1 only the final part being carried over into the ,schne's tube proper4 ,water is supplied to the apparatus under constant pressure by means of a ,mariotte's bottle4 ,the preliminary treatment recommended by ,schne is omitted1 as these steps have been shown to be undesirable1 on account of affecting the accuracy of the results4 ,twenty grams of the air-dried soil are passed1 under water1 through a sieve of one-fourth millimeter mesh4 ,that part of the soil which remains in suspension after being sifted is placed at once in the ,schne's tube of the apparatus1 the coarser portion being rinsed into the ,orth tube4 ,the current is regulated so that the largest particles of quartz carried off have an average diameter of #j4ja millimeter4 ,when all is carried off that can be removed at this rate the current is increased until the largest quartz grains passing off have a diameter of #j4je millimeter4 ,as noticed by ,hilgard with ,schulze's apparatus1 secondary currents are formed during the process of elutriation which descend along the walls of the conical portion of the ,schne's tube and some distance along the sides of the cylindrical portion4 ,the tendency of these currents is to produce globular aggregates of particles which fall to the bottom4 ,they are broken up from time to time by increasing the velocity of the current but even this method fails to disintegrate a considerable quantity of them4 #bbj4 ,statement ,of ,results4--,two samples of soil from the garden of the experiment station analyzed by ,schne's method gave the following proportions of sediment4 ,in the table the term clay is used to designate all that part of the soil which has diameters less than #j4ja millimeter and which remains suspended after twenty-four hours standing in water having a depth of #bjj millimeters4 ,,soil1 ,,from ,,garden ,,of ,,the ,,experiment ,,station4--,,not ,,boiled4 ,analyses with the ,schne-,orth ,elutriator4 ,a4 ,b4 ,c4 ,above #j4be millimeter #dh4hb #dh4hb #dh4hb #j4be-j4je #bg4cf #bi4id #bb4cg #j4je-j4ja millimeter #h4fc #f4jg #ac4gj #j4ja millimeter and less depos4 #g4cf #g4ca #g4bj ,clay 7by difference7 #a4jj #a4jc #a4jh ,loss on ignition #f4hc #f4hc #f4hc ------------ ------------ ------------ #ajj4jj #ajj4jj #ajj4jj ,the last column ,c represents the average of three direct beaker elutriations according to the method of ,osborne4 ,the differences which these figures show are found to be due to imperfect separation of the finer grades from the coarser and even when the various fractions separated by the ,schne method are subjected to beaker elutriation and the portions separated from them added to the grades to which they properly belong the ,schne elutriator was found to effect far less exact separations than the beaker method4 ,samples of prairie soil from ,mercer ,county1 ,ill41 not boiled1 were examined by the two methods with the following results3 ,schne-,orth ,beaker elutriation4 method4 ,above #j4be millimeter #j4gf #j4fb #j4be-j4je millimeter #aa4be #b4db #j4je-j4ja millimeter #eb4fe #dc4eh #j4ja millimeter and less deposited #ad4hd #ca4eh ,clay #d4dd #e4ha ,loss on ignition #ad4di #ad4di ---------- ---------- #ih4dc #ih4ej ,in this case it is seen that ,schne's method varies considerably from the beaker method and if the beaker method be regarded as correct the ,schne method is evidently less reliable4 ,in the next table are given the data of the examination of brick clay from ,north ,haven1 ,conn41 by the two methods4 ,,brick ,,clay ,,from ,,north ,,haven1 ,,conn4 ,schne-,orth elutriation4 ,beaker method4 ,above #j4be millimeter #a4jb #a4jb #j4be-j4je millimeter #c4ia #j4gf #j4je-j4ja millimeter #bi4fc #bj4ie #j4ja millimeter and less #eh4eh #ga4ja ,loss on ignition #f4fj #f4fj ---------- ------------ #ii4gd #ajj4cd ,the failure of the ,schne method to give the results obtained by the beaker method is ascribed to the fact that it is impossible for the current of the strength used to disintegrate the clay and further that the particles after they are once separated tend to coalesce by the currents produced by the elutriating process4 #bba4 ,the ,berlin-,schne ,method4--,osborne has also made a study of the ,schne method as modified by the ,bodenlaboratorium of ,berlin4 ,the directions for the analysis by this laboratory method are as follows3 ,five hundred grams of the soil are sifted through a sieve with circular holes two millimeters in diameter4 ,of the earth passing the sieve from #cj to #ajj grams are boiled in water with constant stirring from one-half to one hour or longer1 according to the character of the soil4 ,the finer the texture of the soil the smaller the quantity taken and the longer the time of boiling4 ,treatment with acids or alkalies is not practiced4 ,the finer portion of the soil remaining suspended in the water1 after boiling1 is poured into the ,schne tube1 the remaining coarse part is rinsed into the ,orth tube4 ,the clay1 together with the finest sand1 is collected in a separate vessel1 the water in which it is suspended is evaporated and the residue after drying in the air is weighed4 ,the rest of the operation is carried out as previously described except that the products of elutriation are not ignited but weighed air dried1 in order that they may be further examined1 chemically if desired4 ,by proceeding in this manner the following results were obtained3 ,,soil1 ,,from ,,garden ,,of ,,the ,,experiment ,,station1 ,,boiled ,,forty-,,five ,,minutes4 ,separations by the ,berlin-,schne method4 ,air-dried4 ,ignited4 ,above #j4je millimeter #gb4fc #ga4gf #j4je-j4ja millimeter #ad4ag #ab4ec #j4ja millimeter and less #ab4ig #i4ch ,loss on ignition #f4hc ---------- ---------- #ii4gg #ii4ej ,for the sake of comparing the mechanical separation attainable by this procedure with those yielded by other methods1 the air-dried products were ignited and again weighed and examined4 ,by subtracting from the ignited portion above #j4je millimeter1 #di4cg per cent1 the amount of this soil that remained on a #j4be millimeter sieve1 the fraction between #j4be millimeter and #j4je millimeter is found1 and the separations in this analysis may be compared with those previously obtained by the beaker method as follows3 ,,soil ,,from ,,garden ,,of ,,experiment ,,station4 ,beaker ,method4 ---------------------------------------- -------------------------------------- ,berlin-,schne1 ,boiled ,pestled1 not ,not boiled boiled twenty-three boiled4 nor pestled1 forty-five hours1 average average of minutes4 of four three analyses4 analyses4 ,above #j4be #di4cg #dg4gg #dh4hb #dh4hb millimeter #j4be-j4je #ba4ci #bj4ge #bb4dd #bb4cg millimeter #j4je-j4ja #ab4ec #aa4ah #ab4ee #ac4gj millimeter #j4ja clay #i4ch #ac4dg #i4cf #h4bh included ,loss on #f4hc #f4hc #f4hc #f4hc ignition #ii4ej #ajj4jj #ajj4jj #ajj4jj ,osborne concludes from the above facts that the ,berlin-,schne method1 while showing close agreement with the beaker method1 does not give results which are identical with that method4 ,on subjecting portions separated by the ,berlin-,schne method to the beaker analysis additional separations were secured4 ,in the case of heavy loams the inability of the ,berlin-,schne method to effect even a rough or approximate separation of the several grades becomes very conspicuous4 #bbb4 ,method of ,hilgard4--,two important principles lie at the foundation of this method2 viz41 #a1 the use only of separating vessels of true cylindrical shape and #b1 the employment of a mechanical stirrer to break up the floccules formed during the process of separation4 ,the points in the apparatus to be considered are uniformity of the cross section of the elutriator at every point1 exact perpendicularity of position1 careful control of the rate of flow and continuous operation of the mechanical stirrer4 ,according to ,hilgard's observations the stirring due to the current of water alone is not sufficient to break up the floccules unavoidably formed during the separation1 while any inclination of the sides of the elutriating vessel from the perpendicular due either to a conical shape or false position favors in the highest degree the formation of floccules due to reflex currents formed in the body of the liquid4 ,in order to carry out the idea suggested by ,trschmidt of substituting for the accidental and indefinite products usually appearing in the statements of silt analyses sediments of known and definite hydraulic value a constant head of water is used1 secured by means of a ,mariotte's bottle connecting with the tube delivering the current through a cock provided with an arm moving on a graduated arc4 ,according to ,hilgard the separation of sediments by the method of subsidence does not possess the analytical accuracy of the moving liquid method1 especially when the latter is combined with mechanical stirring4 ,the subsidence method requires close and continuous attention and in the case of fine sediments tending to flocculation the difficulties of the method are greatly increased4 ,the views of ,hilgard in respect of the laboriousness of the subsidence method lose1 however1 some of their force since the modifications of ,osborne have come into use4 ,the simplicity and cheapness of the apparatus required for subsidence give it at the start many advantages over the more elaborate process with a churn elutriator4 ,for rigid scientific investigation1 however1 the method of ,hilgard is commended as a standard of comparison in all cases4 ,illustration3 ,,figure #ce4 ,,hilgard',s ,,churn ,,elutriator4 #bbc4 ,the ,elutriator4--,the instrument devised by ,hilgard#aeb for the purpose of breaking up these flocculent aggregates is shown in figure #ce1 together with the simpler form1 a ,schne's elutriator1 figure #cf1 which can serve for grain sizes above eight millimeters hydraulic value4 ,the latter is conveniently selected so as to have half the cross-section of the former1 so that with the same position of the index lever the velocity will be just doubled4 ,the cylindrical glass tube1 of about forty-five millimeters inside diameter at its mouth1 and #bij to #cjj millimeters high1 has attached to its base a rotary churn consisting of a brass cup1 shaped like an egg with point down1 so as to slope rather steeply at base1 and triply perforated2 viz41 at the bottom for connection with the relay reservoir1 and at the sides for the passage of a horizontal axis bearing four grated wings4 ,this axis1 of course1 passes through stuffing boxes1 provided with good thick leather washers1 saturated with mutton tallow4 ,these washers1 if the axis runs true1 will bear a million or more revolutions without material leakage4 ,when a beginning is noted additional washers may be slipped on without emptying the instrument1 until the analysis is finished4 ,for the finest sediments1 from five to six hundred revolutions per minute is a proper velocity1 which may be secured by clock work1 turbine or electric power4 ,the driving pulley should not be directly connected with the axis1 both because it is liable to cause leakage1 and because it is necessary to be able to handle the elutriator quickly and independently4 ,this is accomplished by the use of 8dogs0 on the pulley and churn axis4 ,for the grain sizes of one to eight millimeters hydraulic value lower velocities are sufficient2 too low a velocity causes an indefinite duration of the operation and may be recognized by the increase of turbidity as the velocity is increased4 ,as the whirling agitation caused by the rotation of the dasher would gradually communicate itself to the whole column of water and cause irregularities1 a wire screen of #j4h millimeter aperture is cemented to the lower base of the cylinder4 ,the relay vessel should be a thick1 conical test glass with foot2 its object is to serve as a reservoir for the heavy sediments not concerned at the velocity used in the elutriator tube1 and whose presence in the latter or in its base1 the churn1 would only cause abrasion of the grains and changes of current velocity1 such as occur in the apparatus of ,schne1 and compel the current measurement of the water delivered4 ,it is connected above with the churn by a brass tube about ten millimeters in clear diameter1 so as to facilitate the descent of the superfluous sediments1 which the operator1 knowing the proportion of area between the connecting tube and elutriator1 can carry to any desired extent2 thus avoiding the disturbance of the gauged current velocities1 as well as all material abrasion4 ,illustration3 ,,figure #cf4 ,,improved ,,sch,,ne',s ,,apparatus ,,with ,,relay4 ,a glass delivery tube should extend quite half way down the sides of the relay vessel1 to insure a full stirring up of the coarse sediments when required4 ,by means of a rubber hose1 not less than twenty inches in length1 this delivery tube connects with the siphon carrying the water from near the bottom of the ,mariotte's bottle1 a ten-gallon acid carboy4 ,a stop-cock provided with a long1 stiff index lever1 moving on an empirically graduated arc1 regulates the delivery of water through the siphon4 ,knowing the area of the cross section of the elutriator tube1 the number of cubic centimeters of water which should pass through it in one minute1 at one millimeter velocity1 is easily calculated1 and from this the lever positions corresponding to other velocities are quickly determined and marked on the graduated arc4 ,the receiving bottle for the sediments1 also shown in the figure1 must be wide and tall1 so as to allow the sediment to settle while the water flows from the top into the waste pipe4 ,the receiving funnel tube must dip nearly to the bottom of the bottle4 ,thus arranged1 the instrument works very satisfactorily1 and by its aid soils and clays may readily be separated into sediments of any hydraulic value desired4 ,but in order to insure correct and concordant results1 it is necessary to observe some precautions2 viz41 7#a7 ,the tube of the instrument must be as nearly cylindrical as possible and must be placed and maintained in a truly vertical position4 ,a very slight variation from the vertical at once causes the formation of return currents1 and hence of molecular aggregates on the lower side4 7#b7 ,sunshine1 or the proximity of any other source of heat1 must be carefully excluded4 ,the currents formed when the instrument is exposed to sunshine will vitiate the results4 7#c7 ,the ,mariotte's bottle should be frequently cleansed1 and the water used be as free from foreign matters as possible4 ,for ordinary purposes it is scarcely necessary to use distilled water4 ,the quantities used are so large as to render it difficult to maintain an adequate supply1 and the errors resulting from the use of any water fit for drinking purposes are too slight to be perceptible1 so long as no considerable development of the animal and vegetable germs is allowed4 ,water containing the slimy filaments of fungoid growths and moss protonema1 algae1 vorticellae1 etc41 will not only cause errors by obstructing the stop-cock at low velocities1 but these organisms will cause a coalescence of sediments that defies any ordinary churning1 and completely vitiates the operation4 7#d7 ,the amount of sediment discharged at any time must not exceed that producing a moderate turbidity4 ,whenever the discharge becomes so copious as to render the moving column opaque1 the sediments assume a mixed character1 coarse grains being1 apparently1 upborne by the multitude of light ones whose hydraulic value lies considerably below the velocity used1 while the churner also fails to resolve the molecular aggregates which must be perpetually reforming where contact is so close and frequent4 ,this difficulty is especially apt to occur when too large a quantity of material has been used for analysis1 or when one sediment constitutes an unusually large portion of it4 ,within certain limits the smaller the quantity employed the more concordant are the results4 ,between ten and fifteen grams is the proper amount for an instrument of the dimensions given above4 #bbd4 ,preparation of the ,sample4#aec--;,in some cases simple sifting will be sufficient to prepare the air-dried soil for the elutriator4 ,in most cases1 however1 some mechanical aid must be invoked to secure particles of sufficient fineness4 ,nothing harder than a rubber pestle should be used and care must be taken not to break up any calcareous or ferruginous masses which the particles of fine soil may contain4 ,the use of water in this mechanical attrition should be avoided1 if possible1 but in some heavy clay and adobe soils wetting becomes necessary4 ,in this case the parts separated by the sieve are collected separately and the turbid mass removed by water and dried for further examination4 ,a sieve of #j4e millimeter mesh is recommended as the best because that is almost exactly the diameter of the particles passing off at the maximum velocity of sixty-four millimeters per second to which the elutriator is adapted4 ,the particles passing the #j4e millimeter mesh are called fine earth4 #bbe4 ,preparation by ,boiling4--,the method of preparation by boiling may be applied to all samples of fine earth4 ,the fact pointed out by ,osborne1 that diffusibility of some clays is diminished by long boiling1 renders it important to restrict the time of this operation as much as possible4 ,with most soils from eight to fifteen hours will be long enough1 occasionally extending to even twenty-four hours4 ,a thin long-necked flask of about one-liter capacity should be used2 filled three-quarters full with distilled water and the sample of soil added4 ,the flask is supported over the lamp on a piece of wire gauze at an angle of #de4 ,it carries a cork with a long condensing tube4 ,at first the boiling goes on smoothly1 but after a time violent bumping may supervene1 endangering the flask but promoting the object in view4 ,the contents of the flask are transferred to a beaker and diluted with distilled water to one and a half liters1 shaken and allowed to settle for a time necessary to allow all particles of #j4be millimeter hydraulic value to reach the bottom4 ,the supernatant turbid liquid is decanted and the process repeated with smaller quantities of water until no further turbidity is produced4 ,the united decantations1 of which there will be from four to eight liters1 are well shaken and a proper time allowed for the #j4be millimeter hydraulic value sediments to fall4 ,this last step is necessary to remove any such sediments which may have been carried over mechanically in the first separation4 ,the dilution being very great1 a fairly perfect separation is thus secured and the sediments are then ready for the elutriator4 #bbf4 ,separation of ,clay and ,finest ,silt4--,the property which pure clay possesses1 of remaining suspended almost indefinitely in pure water1 affords a ready means of separation from the silt particles of less than #j4be millimeter hydraulic value4 ,but the finest silt particles subside so slowly that this method of separation is too long to become practically applicable to secure a perfect demarcation between the finest silt and so-called colloidal clay4 ,hilgard recommends the following procedure3 ,the clay water from the previous separation is placed in a cylindrical vessel of such a diameter as to allow the column of water to be #bjj millimeters high where it is allowed to settle for twenty-four hours4 ,when the clay is very abundant a longer time may be allowed2 viz41 from forty to sixty hours4 ,the line of separation between the dark silt below and the translucent clay above is sharply defined4 ,finally the clay water is decanted and the remaining liquid poured off leaving the sediment as sharply defined as possible4 ,the sediment is rubbed with a rubber pestle and a few drops of ammonia water added4 ,distilled water is added1 the beaker well shaken or stirred to break up the floccules that may have formed and subsidence permitted as before4 ,this operation is repeated from six to nine times until the water remains quite clear after subsidence or the decanted turbid water fails to be precipitated by brine showing the suspended matter to be fine silt and not clay4 ,the diameter of the particles of silt thus obtained is from #j4jja to #j4jb millimeter1 and it is impossible to obtain it quite free from any admixture with clay4 #bbg4 ,estimation of the ,colloidal ,clay4--,the importance of the colloidal constituent of the clay is such as to make its direct determination desirable4 ,the volume of the clay waters at this stage of the analysis may amount to twenty liters4 ,one method of determination consists in evaporating an aliquot portion and this method will yield good results if the sample be free from soluble salts and the quantity taken be not too small4 ,at least #ejj cubic centimeters should be used for this purpose4 ,a better method consists in precipitating the clay by means of a saline solution4 ,a saturated solution of salt is recommended for this purpose of which fifty cubic centimeters are sufficient to precipitate the clay from one liter of the clay water4 ,the precipitation is hastened by heating4 ,each portion of the clay water should be precipitated as soon as obtained1 the total volume of the precipitate at the end of twenty-four hours is thus reduced to a minimum4 ,the clay water from the succeeding separations of the same analysis can be mixed with the precipitate which diffuses therein1 thus promoting the precipitation of the rest of the clay inasmuch as the separation takes place more readily where more clay is present4 ,when all the clay is thus collected it can be gathered on a tared filter and washed with weak brine4 ,pure water may not be used because of the diffusibility of clay therein4 ,after drying at #ajj and weighing it is washed with a weak solution of ammonium chlorid until all sodium is removed4 ,the filtrate is evaporated to dryness1 ignited at low redness1 and weighed4 ,the weight of the sodium chlorid thus obtained plus the weight of the filter deducted from the total weight gives the weight of the clay precipitate4 ,whenever the clay collected as above will not diffuse in water it may be washed with water and its weight directly obtained4 ,an excess of iron in clay will usually allow of the above treatment4 #bbh4 ,properties of ,pure ,clay4--,the percentage of pure clay as obtained by the procedure described is about seventy-five in the finest natural clays1 forty-five in heavy clay soils1 and fifteen in ordinary loamy soils4 ,when freshly precipitated by brine it is gelatinous resembling a mixed precipitate of iron and aluminum oxids4 ,its volume greatly contracts on drying1 clinging tenaciously to the filter1 from which it may be freed by moistening4 ,on drying1 it becomes hard1 infriable1 and often resonant4 ,it usually possesses a dark brown tint due to iron oxid4 ,under the action of water it swells up like glue1 the more slowly as the percentage of iron is greater4 ,in the dry state it adheres to the tongue with great tenacity4 ,according to ,whitney the finest particles of colloidal clay have a diameter of #j4jjja millimeter4 ,with a magnifying power of #cej diameters1 however1 ,hilgard states that no particles can be discerned4 #bbi4 ,chemical ,nature of the ,fine ,clay4--,the fine particles separated as above consist essentially of hydrous aluminum silicate or kaolinite4 ,it doubtless contains1 however1 other colloids or hydrogels whose absorptive powers are similar to those of clay4 ,it appears also to contain sometimes free aluminum hydroxid1 and colloidal ferric hydroxid1 and amorphous zeolitic compounds4 ,while the most careful mechanical separation can give at best only approximately the really plastic kaolinite substance1 yet it is far closer than that attained by determination of total alumina with boiling sulfuric acid4 ,by the latter treatment all the lime-kaolinite particles are decomposed and the method does not lead to even an approximate estimate of the soil's plasticity4 #bcj4 ,separation of the ,fine ,sediments4--,the sediments remaining after the separation of the clay and fine silt are ready for separation in the churn elutriator4 ,the apparatus mounted1 as already described1 is brought into use by beginning with a low velocity of the water in the upright tube4 ,the rate of flow should be set at from #j4be millimeter to #j4ej millimeter per second1 and the churn put in motion4 ,when the elutriating tube is partly full of water the sediments should be poured in from a small beaker which is perfectly cleaned by means of a washing flask4 ,the stopper and delivery tube of the elutriator are then put in place4 ,the rate of flow should be so regulated that the sediments shall have had a few seconds of subsidence before the water is within thirty millimeters of the top4 ,at this point the required velocity for the first sedimentation should be turned on2 viz41 #j4be millimeter per second4 ,at first the sediment passes off rapidly and the water in the elutriator is distinctly turbid4 ,this excess of turbidity ceases in a few hours and then some attention is necessary in order to determine when the process is complete4 ,in fact it never is completely finished1 but where no more than one milligram of silt comes off with one liter of water it may be said to be practically done4 ,the time required for the first operation varies from fifteen to ninety hours4 ,downward currents in the elutriator are likely to form in spite of all precautions1 and floccules of silt adhere to its walls4 ,these should be detached from time to time with a feather in order to bring them again in contact with the churn4 ,hilgard has found that1 practically1 #j4be millimeter per second is about the lowest velocity available within reasonable limits of time1 and that by successively doubling the velocities up to sixty-four millimeters a desirable ascending series of sediments is obtained2 provided always1 that a proper previous preparation has been given to the soil or clay4 ,it would seem that according to the prescription given above for the preliminary sedimentation1 no sediment corresponding to #j4be millimeter velocity should remain with the coarser portion4 ,that such is nevertheless always the case1 often to a large percentage1 emphasizes the difficulty1 or rather impossibility1 of entirely preventing or dissolving the coalescence of these fine grain sizes by hand stirring1 as in beaker elutriation4 ,it is only by such energetic motion as is above prescribed that this can be fully accomplished1 and the delivery of #j4be and #j4ej millimeter hydraulic value really exhausted4 ,it is desirable to run off the upper third of the column at intervals of fifteen to twenty minutes by temporarily increasing the velocity4 ,recent sediments1 river alluvium1 etc41 are more easily separated than soils of more ancient formation4 ,the second1 third1 etc41 separations are naturally accomplished in much less time than the first4 ,the respective velocities of the separations should be #j4be millimeter1 #j4ej millimeter1 one millimeter1 two millimeters1 four millimeters1 eight millimeters1 sixteen millimeters1 thirty-two millimeters1 and sixty-four millimeters a second4 ,below a velocity of four millimeters a second the mechanical stirrer is indispensable4 ,above this velocity the current of water in the conical base will be sufficient to bring the desired particles into the ascending column4 ,at this velocity also a smaller elutriating tube having one-half or one-quarter the cross-section of the first may be employed to hasten the operation and diminish the quantity of water required4 ,the quantity of water required for a complete separation is from #ajj to #abj liters4 ,any soft water free of organic matter may be used1 but distilled water is best4 ,hard water should be avoided4 ,the mean time required for the different separations is as follows3 #j4be millimeter hydraulic value1 thirty-five hours2 #j4ej millimeter hydraulic value1 twenty hours2 one millimeter hydraulic value1 seven and a half hours2 two to sixty-four millimeters hydraulic value1 eight hours4 ,with proper arrangements for night work1 an analysis may be finished in three or four days not counting the time required for the previous separation of the clay4 #bca4 ,weighing the ,sediments4--,the sediments should be dried at the same temperature used for drying the soils4 ,hilgard dries both at #ajj4 ,great care should be used in weighing the exceedingly hygroscopic clay sediments4 ,in the case of the sediment of #j4be millimeter hydraulic value it is allowed to subside as much as possible and after removing the supernatant water the residue1 twenty-five to fifty cubic centimeters1 is evaporated in a platinum dish and weighed therein4 ,the water can be completely decanted from the other sediments1 and they can be dried and weighed without any unusual precautions4 ,the loss in the separation of clays and subsoils containing but little organic matter is usually from #a4e to #b per cent4 ,this loss is partly due to the fine silt which comes off during the whole of the process and which is lost in the decanted waters of the sediments of #j4be millimeters hydraulic value and above4 ,the procedures indicated above are not strictly applicable to soils rich in humus and other organic matters1 but the destruction of these matters by ignition leaves the residual soil in a condition wholly unfit for sedimentary separation4 #bcb4 ,classification of ,results4--,a convenient method of stating the results of an analysis may be seen from the following classification4 ,the percentage obtained for each of the classes is to be entered in the column provided for that purpose4 ,no4 ,names of ,silt ,diameter of ,velocity of ,classes4 grains in current ,per millimeters4 millimeters cent4 hydraulic value4 ,sieves4 #a4 ,grits #a -#c #b4jg #b4 ,fine grits #j4e-a ,elutriator #c4 ,coarse sand #j4ej #fd #j4ee without churn4 #d4 ,medium sand #j4cj #cb #e4 ,fine sand #j4af #af ,elutriator #f4 ,finest sand #j4ab #h #j4ba with churn4 #g4 ,coarse silt #j4jgb #d #a4ba #h4 ,large silt #j4jdg #b #b4ib #i4 ,medium silt #j4jcf #a #g4cf #aj4 ,silt #j4jbe #j4e #h4hf #aa4 ,fine silt separated #j4jaf #j4be #g4he in elutriator ,beaker #ab4 ,fine silt separated #j4jaj #j4be #ce4bb sedimentation4 from clay water #ac4 ,clay #j4jjja #j4jjbc #cc4af ---------- ,total #ii4cf ,the measurements of diameters in the above table is of the best formed quartz grains in each class4 ,naturally the actual size of the particles may vary in each class within the extreme limits of the diameter next above and below4 ,it is not easy to indicate in popular language distinctions not popularly made but the grades of particles designated by the names grits1 sand and silt1 may serve1 at least1 to establish uniformity of expression4 ,the term grits is thus applied to all grains above one millimeter in diameter up to gravel4 ,below one millimeter down to #j4a millimeter may be called sand and below that silt may designate the particles down to an impalpable powder4 #bcc4 ,influence of ,size of ,tube4--,the diameter of the elutriating tube exerts a sensible influence on the character of the sediments4 ,the friction against the sides of a small tube is comparatively greater than in a large tube4 ,strictly speaking1 no class of sediments strictly corresponds to the hydraulic value calculated from the cross section of the tube and the quantity of water supplied thereto4 ,the sediments correspond actually to higher velocities1 due to the fact that the lateral friction causes a more rapid flow in the center of the water column4 ,this may be demonstrated by slightly diminishing the velocity while a sediment is copiously discharging4 ,the turbid column then remains stationary while clear water is running off4 #bcd4 ,statement of ,results4--,a complete silt analysis of a soil1 conducted by the method of ,hilgard1 depends largely for its practical value on an intelligible tabulation4 ,the method of collating results is illustrated in the table of analyses of ,mississippi soils shown on page #bcg4 ,the character of the soils entering into the given analyses is as follows3 ,nos4 #bdh1 #bjf1 #bji1 #cig1 #bai1 belong to the end of the drift period4 ,no4 #bcj is one of the two chief varieties of soils occurring in what is known as the flat-woods1 a level surface bordering on the cretaceous area1 having lower tertiary clays near the surface4 ,no4 #afe is a light soil which occurs in the former in irregular strips and patches1 is easily tilled1 absorbs rain water readily1 but is subject to drought and does not hold manure4 ,,silt ,,analyses ,,of ,,mississippi ,,soils ,,and ,,subsoils4 ,designation ,diameter4 ,velocity ,,drift of ,materials4,millimeters47,hydraulic value74 ,millimeters per second4 #bch ,white pipeclay4 ,tishomingo ,co4 #a;,coarse grits #a4j to #c4j #b;,fine #j4e to #a4j #c;,coarse sand #j4dj #f #j4jf #d,medium #j4cj #cb #e;,fine #j4af #af #f;,finest #j4ab #h #j4jh #g;,dust #j4jgb #d #j4jb #h;,coarsest silt #j4jdg #b #j4jd #i;,coarse #j4jcf #a #j4jh #aj,medium #j4jbe #j4e #j4jh #aa;,fine #j4jae #j4be #b4jj #ab;,finest #j4jjh #j4be #ba4ae #ac;,clay #j4jjja #j4jjbc #gd4fe #ih4af ,compactness 7resistance to tillage7 #ig4hj ,porosity #j4cf ,hygroscopic ,moisture 7#g to #ba7 #i4ji ,ferric ,oxide #j4ac ,designation ,,upland4 of ,materials4 ,,yellow ,,loam4 ,,sandy4 ,,loam4 #bdh #afe #bjf #bji #cig #bai ,tallahoma ,lt4 ,pine ,pine ,oxford ,table subsoil ,flatwoods,hill ,hill subsoil4 ,land ,jasper soil4 soil4subsoil4,lafayettesubsoil4 ,co4 ,chickasaw,smith ,smith ,co4 ,benton ,co4 ,co4 ,co4 ,co4 #a;,coarse grits #f4id #b4ij #j4cf #j4cf #j4bc #b;,fine #ag4fe #f4if #b4ih #j4hc #c;,coarse sand #ah4ha #b4ha #f4fb #f4ba #j4gi #a4dg #d,medium #aj4af #d4da #g4ge #c4ch #b4cc #e;,fine #b4ff #c4ac #c4ja #c4he #a4ag #f;,finest #a4ff #b4jb #a4ei #a4di #j4ah #j4gh #g;,dust #a4jb #b4bc #a4ai #j4fd #j4gh #j4gf #h;,coarsest silt #j4hh #e4jf #c4ef #b4fc #c4ef #i4gi #i;,coarse #a4if #i4fg #f4ej #e4dj #ac4ab #g4bf #aj,medium #g4hi #ad4ahac4ig #g4gg #af4fd #ac4ad #aa;,fine #h4dj #bb4jcad4bj #af4fe #bg4bh #ae4jg #ab;,finest #ae4ec #ae4fbbi4cf #cg4ge #ah4hg #bf4ej #ac;,clay #h4fc #g4hf #d4eh #aj4gj #ag4bc #ai4ai #ii4bh #ih4fhie4fg #ig4gg #ih4ce #ig4fe ,compactness 7res #cb4ef #de4ccdh4ad #de4aj #fc4ch #fj4hb ,porosity #ei4ee #dj4djcg4hi #dg4ac #bj4bc #bf4jd ,hygroscopic ,mois #a4hj #c4cf #b4dh #g4fi #h4gi #g4ba ,ferric ,oxide #a4aj #a4de;,g #a4be #d4ae #b4ec #e4aa ,designation ,,upland4 of ,materials4 ,,yellow ,,tertiary4 ,,loam4 ,,clay4 #agc #bcj #bdf #aif ,prairie ,high ,red ,hog subsoil4,flatwoods ,hills ,wallow ,monroe soil4 subsoil4subsoil4 ,co4 ,pontotoc ,attala ,jasper ,co4 ,co4 ,co4 #a;,coarse grits #b4aj #j4cc #a4ig #j4hc #b;,fine #j4ce #a4ai #c;,coarse sand #j4fb #j4gb #a4if #d,medium #b4cb #a4fd #e;,fine #b4ji #j4hh #f;,finest #j4bj #j4bc #j4gj #j4bf #g;,dust #a4bf #j4ah #a4bi #j4ai #h;,coarsest silt #b4ib #a4fa #a4ha #b4di #i;,coarse #g4cf #b4ff #c4fj #c4fg #aj,medium #h4ha #i4ac #b4gc #e4ci #aa;,fine #g4he #bf4fd #ac4cj #aj4ca #ab;,finest #ce4bb #cb4ce #be4cc #bd4ah #ac;,clay #cc4af #be4dh #dj4be #dg4jc #ii4ej #ig4hg #if4aa #ajj4jj ,compactness 7res #fi4gg #hd4dg #gh4hh #ha4eb ,porosity #ag4jd #f4dj #ci4ah #aj4ab ,hygroscopic ,mois #aa4ce #i4cc #ah4fj #ad4dh ,ferric ,oxide #e4db #e4ij;,g #aj4ej #d4jj ,designation ,,mississippi ,,bottom4 of ,materials4 ,champlain4 ,,modern4 ,swamp ,river4 ,,river ,,deposit4 ,,delta4 #cij #bcg #cfe #cgg #cie ,southwest ,southwest ,buckshot ,loess4 ,tallahatchie,frontland,dogwood ,pass4 mudlump4 soil4 ,claibornesoil4 ,panolasubsoil4 ridge ,plaquemine,plaquemine ,issaquena ,co4 ,co4 ,sunflower soil4 ,par4 ,par4 ,co4 ,co4 ,coahoma ,co4 #a;,coarse grits #j4ji #j4bd #j4ji #b;,fine #j4je #c;,coarse sand #j4cg #j4jd #j4cb #j4ae #j4ah #j4aj #d,medium #j4cf #j4fa #j4je #e;,fine #j4ic #j4ba #b4ig #j4dg #e4jb #f;,finest #j4ca #a4fe #a4cj #b4da #c4gd #g4jc #c4fh #g;,dust #j4bg #a4ie #b4fh #af4ij #ba4di #ab4ch #e4cd #h;,coarsest silt #a4ef #ad4be #i4ch #ai4gi #ba4hc #ac4bg #aj4ji #i;,coarse #b4bc #af4bj #i4hh #ac4ij #ad4ja #ae4hg #e4eh #aj,medium #c4fh #bj4jh #bj4cg #d4bg #i4ic #h4be #i4ed #aa;,fine #h4ig #e4ei #ai4gi #a4hi #i4eh #g4bf #h4ja #ab;,finest #ch4ai #cc4ch #be4cj #cj4jh #h4fe #ai4fg #cd4df #ac;,clay #dd4cj #b4ea #i4fd #e4ea #aj4ce #ab4bj #ah4ah #ajj4ja #ig4gd #ih4gc #ih4jd #ii4gb #if4eh #ajj4jj ,compactness 7res #hi4df #da4dh #ed4fc #cg4dh #bh4eg #ci4ac #fj4fe ,porosity #d4hg #ch4dd #bc4fc #eh4be #fa4ej #di4bj #bh4ha ,hygroscopic ,mois #ad4ca #d4ah #f4ab #e4fh #c4ie ,ferric ,oxide #e4hb;,g #c4bg #b4eh #b4ca #b4fi ,footnote ,g3 ,bog ore4 ,no4 #bdh is from a soil stratum three feet thick4 ,the soil is so light that the finer particles of it are carried away by high winds4 ,nos4 #bjf and #bji are typical of the soils producing the long-leaf pine4 ,this soil is much improved by an admixture of the subsoil ,no4 #bji1 which enables it to hold manure4 ,no4 #bai is a cotton upland soil of the best quality1 found in ,western ,mississippi and ,tennessee4 ,no4 #cig is the same soil of a second rate quality4 ,these lands are easily washed into gullies on account of their lack of perviousness to water4 ,they also easily swell up in contact with water1 and become thereby readily diffused4 ,the denudations produced by heavy rains are rapidly destroying the lands covered by these soils4 ,no4 #agc is a sedimentary or residual subsoil of the cretaceous prairies of ,northeastern ,mississippi1 forming a stratum from three to seven feet thick4 ,no4 #bcj is a residual soil which is formed by the disintegration of the old tertiary clays4 ,it yields good crops only in very favorable years1 and is easily injured both by wet and dry seasons4 ,no4 #bdf is a soil of the same origin1 but is more easily tilled than the foregoing1 does not crack1 but becomes very hard when dried slowly4 ,its superiority to the former soil as regards tillage consists in the presence of the large amount of iron and lime4 ,no4 #aif is a typical heavy clay soil2 is better suited for the potter than the farmer4 ,it cracks on drying1 whence its popular name4 ,on the accession of rain the edges of these cracks crumble and fall1 until finally the lumpy surface is produced which is locally known as hog wallows4 ,no4 #cij1 the richest soil of the ,yazoo ,bottom1 seems to have a physical composition like the preceding one4 ,its superiority is due not only to the increased quantity of plant food which it contains1 but to its property of crumbling on rapid drying4 ,even when plowed wet1 on drying each clod crumbles into a loose pile resembling buck-shot2 whence its name4 ,it is strongly calcareous4 ,as comparative data1 are added the soils #cfe1 #cgg1 and #cie1 representing alluvial deposits1 and two deposits from the ,delta of the ,mississippi4 #bce4 ,comparison of ,osborne's ,method with ,hilgard's ,method4#aed--,the comparative results obtained by ,osborne's method1 beaker elutriation1 and ,hilgard's method1 churn elutriation1 are given in the following tables3 ,,soil ,,from ,,experiment ,,station ,,garden1 ,,new ,,haven1 ,,conn4 ,,surface ,,soil1 ,,boiled ,,twenty-,,three ,,hours4 ,beaker elutriation4 ,average of four ,churn elutriation4 analyses4 ,diameter in millimeters4 per cent4 per cent4 per cent4 ,removed by sieves #dg4gg #dg4gg #dg4gg #j4be-j4je #bb4jf #ba4ie #bj4ge #j4je-j4ja #aa4bj #aa4fb #aa4ah #j4ja #i4hb #i4ad #aj4gb ,clay 7difference7 #b4cb #b4fi #b4ge ,loss on ignition #f4hc #f4hc #f4hc ------------ ------------ ------------ #ajj4jj #ajj4jj #ajj4jj ,,subsoil1 ,,boiled ,,twenty-,,three ,,hours4 ,churn elutriation4 ,beaker elutriation4 ,diameter in millimeters4 per cent4 per cent4 per cent4 per cent4 ,removed by sieve #ci4cc #ci4cc #ci4cc #ci4cc #j4be-j4je #cc4fa #cj4hc #cb4ce #cb4ie #j4je-j4ja #aj4ia #ab4be #aj4cb #aj4cg #j4ja #g4je #h4aa #h4bi #g4fd ,clay #e4jb #e4dj #e4fc #e4fc ,loss on ignition #d4jh #d4jh #d4jh #d4jh ------------ ------------ ------------ ------------ #ajj4jj #ajj4jj #ajj4jj #ajj4jj ,these analyses agree quite as well as could be expected from two such different methods4 ,elutriation of ,clayey ,soils4--,hilgard found that by churn elutriation no satisfactory results could be obtained on clay without long boiling and subsequent kneading of the finer sediments4 ,osborne examined a sample of clay by his method after previous boiling for twenty-three hours4 ,when the sediments were examined by the microscope they were found to contain many aggregations of particles which broke into dust under the pressure of the thin glass slide-cover4 ,these sediments were then gently crushed in the beaker with the help of a soft rubber stopper with a glass rod for a handle1 the grinding together of the particles being1 as much as possible1 avoided4 ,this pestling was continued with clear water as long as it occasioned turbidity4 ,comparison of the analyses shows that practically identical results were obtained on this soil whether it was boiled or not and indicates that the sediments are reduced to their elements by gentle pestling alone4 ,for such soils1 therefore1 it is demonstrated that pestling is a much safer treatment than boiling4 ,the same remark may be applied to the fertile prairie soil of ,mercer ,county1 ,illinois1 where boiling proved quite insufficient and in which the pestling process proved completely successful4 ,the general conclusions arrived at from the results obtained by ,osborne are as follows3 #a4 ,on sands and silts of pure quartz or similar resistant material ,hilgard's method and beaker elutriation give practically identical results4 #b4 ,with coarse sands and silts upon whose grains finer matter has been cemented by silicates1 etc41 and with soils containing soft slaty detritus1 the churn elutriator with preliminary boiling may give results too low for the coarse and too high for the finer grades4 ,in these cases beaker elutriation with pestling yields more correct figures4 #c4 ,some loamy soils containing no large amount of clay or of extremely fine silt1 as well as prairie soils rich in humus1 cannot be suitably disintegrated by twenty-four hours' boiling1 but are readily reduced by pestling4 #d4 ,beaker elutriation preceded by sifting1 gives results in five or six hours with use of two to three gallons of pure water1 which1 in churn elutriation1 require several days and consume eight to ten gallons of pure water4 #e4 ,hilgard found that practically #j4be millimeter is about the lowest velocity of water current per second available within reasonable limits of time in his elutriator4 ,such a current carries over particles up to #j4jae millimeter diameter and hence the silts of less dimensions cannot be conveniently separated by churn elutriation4 ,in beaker elutriation there is no difficulty in making good separations at #j4ja millimeter and at #j4jje millimeter4 #f4 ,beaker elutriation requires no tedious boiling or preliminary treatment and with careful pestling of the sediments gives1 we believe1 as nearly as possible1 a good separation of adhering particles and at every stage of the process carries with it1 in the constant use of the microscope1 the means of testing the accuracy of its work and of observing every visible peculiarity of the soil4 ,it is not claimed that pestling may not easily go too far1 but in any case a good judgment may be formed of its effects and of the extent to which it is desirable to carry it4 #g4 ,in beaker elutriation the flocculation of particles occasions little inconvenience and does not impair the accuracy of the results4 #bcf4 ,comparison of the ,osborne with the ,schloesing ,method4--,schloesing's method has been compared by ,osborne#aee with the beaker method of elutriation with the following results3 ,,schloesing',s ,,method4 ,per cent4 ,calcium carbonate #d4bj ,sand #fd4ia ,clay #bb4fe ,humus none ,loss on ignition #f4fj ,,by ,,the ,,direct ,,beaker ,,method4 ,per cent4 ,above #j4be millimeter diameter #a4jb #j4be-j4je millimeter diameter #j4gf #j4je-j4ja millimeter diameter #bj4ie ,below #j4ja millimeter diameter #ga4ja ,loss on ignition #f4fj ,it is seen by the above that there is little agreement between the results of the two methods4 ,with the prairie soil from ,mercer ,county1 ,ill41 the following results were obtained working on the original sample and the sand separated by the ,schloesing process3 ,,schloesing',s ,,method4 ,per cent4 ,calcium carbonate #j4hh ,humus #a4eg ,loss at #aej ,c4 #d4db ,sand #hb4hf ,clay #g4hf ---------- #ig4ei ,,beaker ,,method4 ,original ,schloesing's sand4 soil4 ,dried at #aej;,c41 ,ignited1 ,ignited1 per cent4 per cent4 per cent4 ,above #j4be millimeter diameter #j4ab #j4aj #j4ib #j4be-j4je millimeter diameter #c4eh #c4ee #b4hi #j4je-j4ja millimeter diameter #db4fi #da4hg #db4hf #j4ja-j millimeter diameter #bc4ff #bj4dg #ca4dd ,clay #ab4ha #aj4ad ,clay #g4dj ,loss on ignition #f4gc #ad4di ---------- ---------- ------------ #hb4hf #hb4hf #ajj4jj ,osborne says the above figures indicate that the treatment with acid has disintegrated the particles of less than #j4ja millimeter diameter so that one-third of this portion appears as clay1 according to the ,hilgard method of estimating clay1 which is the one employed4 ,as to the humus it may be noted that loss in the analysis by ,schloesing's method2 viz41 #b4da per cent1 plus loss at #aej #d4db per cent1 plus humus found #a4eg per cent1 plus carbon dioxid 7 of #j4hh 7 #j4fi per cent amounts to #i4ji per cent1 while the loss on ignition which represents humus1 carbon dioxid and water is #ad4di ,per cent4 ,the #e4dj per cent difference must evidently be1 for the most part1 humus which has escaped estimation by the ,schloesing method1 having been distributed among the sand and clay4 #bcg4 ,the ,mechanical ,determination of ,clay4--,schloesing's method for the separation of the clay as stated by ,osborne#aef is essentially one of subsidence for twenty hours from a volume of from #bjj to #bej cubic centimeters of water1 but of no specified height4 ,hilgard's conventional method requires the same time and a height of solution of #bjj millimeters4 ,such methods of separation assume1 first1 that most of the sand and1 second1 that little of the clay shall settle within the fixed time4 ,that both of these assumptions are fallacious1 the following experiments show4 ,the clay obtained by twenty hours subsidence from thirty grams of brick clay is suspended in four liters of distilled water and allowed to settle out completely1 which requires several days4 ,the water is then decanted so as to remove all soluble matters1 the jar again filled with distilled water1 and the clay and fine sand allowed to settle again for several days4 ,the upper three-quarters of the liquid are then decanted and made up to a volume of four liters1 and this is allowed to stand several days1 when a considerable sediment forms4 ,a decantation is again made as before4 ,the operations are repeated until the clay water has been so far freed from the clay as to become opalescent2 then it first ceases to deposit any appreciable sediment4 ,a microscopic examination of the several sediments thus collected shows them all to contain particles of sand4 ,it appears1 therefore1 that only after the liquid containing the clay has become opalescent does it cease to deposit fine particles of sand as well as of clay4 ,furthermore1 the character of the true clay itself is so changed under certain conditions that it loses the property of remaining in prolonged suspension in water4 ,a sample of clay which has been freed from particles of sand exceeding #j4jje millimeter diameter is suspended in water and precipitated from it by freezing4 ,it is then washed by decantation with alcohol and dried in the air4 ,a portion of this clay is shaken with water and allowed to stand a few hours1 during which time the greater part of it has settled4 ,after decanting the water and suspended clay and repeating this process a few times1 a very considerable part of the clay is left which will subside completely through #ajj millimeters in a few hours4 ,after standing under water for several months1 only a small part of the clay has regained the quality of prolonged suspension4 ,it has been found1 however1 that if this clay be pestled1 this quality of prolonged suspension is restored to it to a very considerable degree4 ,it is evident1 therefore1 that conventional methods depending on simple subsidence can give no accurate results because the ever varying amounts of finest sand and clay in different soils yield variable mixtures of the two when subjected to any simple course of treatment by elutriation and subsidence4 ,the method of persistent pestling and repeated subsidences and decantations continued until no further separation can be effected1 although extremely tedious1 is the only one which has so far yielded even approximately good separations on any of the clayey soils examined by ,osborne4 ,a single subsidence of the clay water for twenty-four hours will free it from all particles of sand having a diameter greater than #j4jje millimeter1 but in many cases a considerable amount of finer sand will remain in suspension for many hours or days4 ,on the other hand1 the sediment formed during the twenty-four hours subsidence will not be free from clay1 as may be easily seen by suspending it in water a second time and allowing it to stand again for twenty-four hours4 ,both ,hilgard and ,schloesing direct attention to these defects1 but assume that they do not usually influence the results to a sufficient extent to deprive them of value4 ,in many cases this is undoubtedly true1 as1 for example1 in such soils as that from the garden of the ,experiment ,station1 at ,new ,haven1 in which there is but little clay and fine sand2 but in soils of the opposite character1 as in the ,north ,haven brick clay where exact separations are most desirable1 a very considerable error is thus inevitably encountered4 #bch4 ,effect of ,boiling on the ,texture of ,clayey ,soils4--,most investigators who have worked upon mechanical soil analysis advise boiling with water in order to detach clay and sand from each other and make a good separation of the several mechanical elements practicable or possible4 ,in general1 however1 the instructions as to the time and manner of boiling are rather indefinite1 and no definite research as to the effects of this treatment has been undertaken4 ,the practice of ,hilgard1 to boil twenty-four hours or even longer in case of adhesive clays1 according to ,osborne#aeg appears to be objectionable in view of the dehydration and change of physical properties known to occur in case of many hydroxids1 especially those of iron and aluminum1 which may be present in the soil4 ,it is a familiar fact that the hydroxids above named and many other amorphous substances when precipitated from cold solutions are more bulky and less easily washed upon a filter than when thrown down hot4 ,it is also well known that their properties are considerably changed by warming or boiling with water4 ,heating with water to boiling for some hours or days gradually converts the bulky brown-red ferric hydroxid1 which when precipitated cold and air-dried for eighteen days1 contains thirty-eight per cent of water1 into a much denser1 bright red substance containing but two per cent of water4 ,st4 ,gilles has also observed the partial dehydration of aluminum hydroxid from ,al,o4#e;,h,o to ,al,o4#b;,h,o by prolonged boiling4 ,the hydrate of silica and the highly hydrated silicates are most probably affected in a similar manner1 and if such be the case1 boiling would evidently change the constitution of clay in a very essential degree4 ,the following experiments throw light on this subject3 ,ten grams of ,north ,haven brick clay were boiled continuously for nine days with about #gjj cubic centimeters of distilled water1 in a glass flask of one liter capacity and furnished with a reflux condenser4 ,fifteen grams were boiled in the same manner for eight and one-half days4 ,when the boiling was concluded1 the soil was found to have assumed a granular condition1 the clay and fine sand being collected into a mass of small grains resembling coarse sand and settling rapidly4 ,one portion thus boiled was elutriated by the beaker method1 the other by ,hilgard's4 ,the pestle was not used on either of those portions as it was desired to determine simply the effect of prolonged boiling4 ,the separations thus accomplished are here compared with the elutriations of the same soil boiled twenty-three hours and of the pestled but unboiled soil4 ,hilgard elutriation4 ,beaker elutriation4 ,not pestled4 ,not pestled4 ,not ,pestled4 ,pestled4 ,boiled ,boiled eight twenty-three ,boiled nine and a half hours1 days1 days4 ,not boiled4 ,diameter of particles4 per cent4 per cent4 per cent4 per cent4 ,by sieves #c4cf #c4bd #c4fc #c4di #j4be-j4je #a4ba #a4aa #a4ia #a4bi #j4je-j4ja #bh4bg #cc4jd #cc4fa #bg4jb #j4ja-j #ef4bi #dh4he #ed4gh #eb4ba ,clay #d4ib #c4je #a4ig #aj4ae ,loss on ignition #e4ie #e4ie #e4ie #e4ie ------------ ------------ ------------ ------------ #ajj4jj #ie4bd #aja4he #ajj4aa ,here it is observed that the eight to nine days boiling diminished the clay as determined by ,hilgard's conventional method by seven to eight per cent1 increasing the dust by two to three per cent1 and the silt by about six per cent4 ,under the microscope small1 rounded1 opaque1 brown granules were seen in large numbers1 which when pressed under the cover glass1 broke up into a multitude of very fine particles4 ,from these experiments it would appear to be conclusively proved that too long boiling precipitates clay and thereby defeats the very object of the operation4 ,in these experiments the time of boiling was prolonged in order to bring out unmistakably the effects of this operation4 ,if ebullition for eight or nine days reduces clay from ten to two per cent1 increasing the #j4je-j4ja millimeter diameter grades by six per cent1 it is evident that boiling for one day or a shorter time becomes a questionable treatment4 ,further experiments#aeh made by boiling clay in a platinum vessel with a platinum condenser showed that this precipitation of the clay was largely if not wholly due to the salts extracted from the soil4 ,when the clay has once been converted into the granular condition1 considerable difficulty is experienced in restoring it to the state in which it is capable of prolonged suspension in water4 ,the results of the studies herewith reported may be summed up as follows3 #a4 ,the ,berlin-,schne method of elutriation gives fairly correct separations with sandy soils containing little clay or matters finer than #j4ja millimeter diameter1 but on soils of fine texture1 as loams rich in humus and clays1 it gives results which are grossly inaccurate1 the error on single grades amounting to from eight to fourteen per cent4 #b4 ,in respect of rapidity1 economy of time1 and ease of operation1 the ,schne elutriation has no advantage over the beaker method4 #c4 ,schloesing's method on its mechanical side makes no satisfactory separations1 and the chemical treatment it employs is liable to alter seriously the texture of the soil4 #d4 ,the determination of clay from a single subsidence from any conventional depth or volume of water1 or for any conventional time1 is not a process certain to effect even a roughly approximate separation of the finest quartz grains from true clay4 #e4 ,boiling with water must be rejected as a treatment preliminary to mechanical analysis1 because it not only abrades and reduces the coarser sediments1 but may dehydrate and coagulate the true clay and thus alter essentially the texture and grain of the soil4 #bci4 ,general ,conclusions4--,the methods of ,hilgard and ,osborne have been given in detail and largely in the descriptive language used by the authors4 ,the other methods of elutriation in use in other countries have also been described4 ,for practical use the methods of ,hilgard and ,osborne are to be preferred to all others4 ,for simplicity and speed the ,osborne method has the preference over the ,hilgard4 ,for rigid control of the work the ,hilgard method is to be preferred4 ,the effect of long boiling on clay pointed out by ,osborne would suggest that the boiling process preliminary to the ,hilgard method be made as short as possible4 ,it would seem that the churn attrition in the ,hilgard method might well be regarded as a substitute for the soft pestling of the ,osborne process1 and any prolonged boiling in the former method might be safely omitted4 ,when carefully carried out1 the results of the ,hilgard and ,osborne method are fairly comparable4 #bdj4 ,distribution of ,soil ,ingredients4--,the determination of the distribution of the soil ingredients in the sediments obtained in silt analysis is illustrated by the following table3#aei ,hydraulic value ,clay #j4bemm #j4bemm4 #j4emm4 ,per cent in soil #ba4fd #bc4ef #ab4ed #ac4fg ,a ,b ,a ,b ,a ,b ,a ,b ,insoluble residue #ae4if #d4cegc4agag4bi #hg4ifaa4jc #id4acab4gb ,soluble silica #cc4aj #g4ag #i4ie #b4cd #d4bg #j4ec #b4ce #j4cb ,potash #a4dg #j4cb #j4ec #j4ab #j4bi #j4jd #j4ab #j4ja ,soda 7#a4gj7 #j4bd #j4jf #j4bh #j4jd #j4ba #j4jb ,lime #j4ji #j4jc #j4ac #j4jc #j4ah #j4jb #j4ji #j4ja ,magnesia #a4cc #j4bi #j4df #j4aa #j4bf #j4jc #j4aj #j4ja ,manganese #j4cj #j4jf #j4jj #j4jj #j4jj #j4jj #j4jj #j4jj ,ferric oxid #ah4gf #d4jf #d4gf #a4aa #b4cd #j4bi #a4jc #j4ad ,alumina #ah4ai #c4ig #d4cb #a4jd #b4fd #j4cc #a4ba #j4ag ,phosphoric acid #j4ah #j4jd #j4aa #j4jb #j4jc #j4jj #j4jb #j4jj ,sulfuric acid #j4jf #j4ja #j4jb #j4ja #j4jc #j4jj #j4jc #j4jj ,volatile matter #i4jj #a4cc #e4fa #a4dc #a4gb #j4bc #j4ib #j4bi ,total #ajj4adba4fdii4cjbc4efajj4jjab4edajj4baa c4fg ,total soluble matter4 #ge4ah #bj4eb #aj4cb #e4af bases #da4hd #aj4dd #e4ii #b4gf ,soluble silica in crude substance4 #j4ch #j4ja ,hydraulic value #a4jmm4 ,per cent in ,other ,total ,original soil #ac4aa sediments4sediments4 soil4 ,a ,b ,insoluble residue #if4ebab4gd #ac4gf #ga4hi #gj4ec ,soluble silica #j4cf #aj4cf #ab4cj ,potash #j4di #j4fc ,soda #j4ab #j4ji ,lime #j4ji #j4bg ,magnesia #j4dd #j4de ,manganese #j4jf #j4jf ,ferric oxid #e4fj #e4aa ,alumina #e4ea #h4ji ,phosphoric acid #j4jf #j4ba ,sulfuric acid #j4jb #j4jb ,volatile matter #c4fd #c4ad ,total #ac4aj #ih4bh #ajj4fc ,total soluble matter4 bases ,soluble silica in crude substance4 #j4ai ,a4 ,calculated on the amount of sediment4 ,b4 ,calculated on the amount of soil4 ,it is seen from the above analyses that the clay is by far the richest in mineral constituents1 of all the ingredients separated in silt analysis1 the amount in the clay being more than twice that of all the others combined4 ,its volatile matter is also the largest4 ,the large amount of soda1 however1 is probably in part due to the sodium chlorid used in the precipitation of the diffused clay4 ,the following points in regard to the distribution of the different ingredients are instructive3 #a4 ,the iron and alumina exist in almost identical relative proportions in each sediment1 making it probable that they are in some way definitely correlated4 #b4 ,potash and magnesia also exist in almost the same quantities1 and their ratio to each other in all the sediments being almost constant seems to indicate that they occur combined1 perhaps in some zeolitic silicate which may be a source of supply to plants4 #c4 ,manganese exists only in the clay1 a mere trace being found in the next sediment4 #d4 ,the lime appears to have disappeared in the clay1 having probably been largely dissolved in the form of carbonate by the large quantity of water used in elutriation4 ,its increase in the coarser portions may be owing to its existence in a crystallized form not so readily soluble4 #e4 ,in a summary of the ingredients1 it is seen that there is a loss in potash1 magnesia and lime in the sediments as compared with the original soil2 and this loss is doubtless due to the solution of these bodies in the water of elutriation4 ,a noteworthy fact shown in this table is the rapid decrease of acid-soluble matter in the coarser sediments2 even what is dissolved from so fine a sediment as #a4j millimeter hydraulic value1 equal to a diameter of #j4jd millimeter1 is in this case a negligible quantity4 ,this suggests forcibly the inutility of introducing into chemical soil analysis1 grains of as large a size as will pass a sieve of one millimeter aperture4 ,the hydraulic value of these grains would be somewhere between #aej and #bjj millimeters per second4 ,while the exact results of the above analysis may not be applicable to all soils1 yet the range is so wide that the systematic exclusion from chemical analysis of inert material1 by means of preliminary mechanical separation1 seems likely to lead to important improvements in the interpretation of the results4 #bda4 ,percentage of ,silt ,classes in ,different ,soils4--,the adaptation of a soil to different crops depends largely on the sizes of the particles composing it and consequently on the relative percentages of the silt classes4 ,the following table gives the mechanical analysis of some markedly different types of subsoils3#afj ,diameter1 ,conventional ,truck millimeters4 names4 and ,grass ,early small and truck4 fruit4 ,tobacco4 ,wheat4 wheat4 ,limestone4 #a #b #c #d #e #f #b-a ,fine gravel #j4di #j4jd #a4ec #j4jj #j4jj #a4cd #a-j4e ,coarse sand #d4if #a4ig #e4fg #j4dj #j4bc #j4cc #j4e-j4be ,medium sand #dj4ai #bh4fd #ac4be #j4eg #a4bi #a4jh #j4be-j4a ,fine sand #bg4ei #ci4fh #h4ci #bb4fd #d4jc #a4jb #j4a-j4je ,very fine sand #ab4aj #aa4dc #ad4ie #cj4ee #aa4eg #f4id #j4je-j4ja ,silt #g4gd #d4ie #bh4hf #ac4ih #ch4ig #bi4je #j4ja-j4jje ,fine silt #b4bc #b4jb #g4hd #d4jh #h4hd #aa4jc #j4jje-j4jjja ,clay #d4dj #h4gi #ad4ee #ba4ih #cb4gj #dc4dd ---------- ---------- ---------- ---------- ---------- ---------- #ii4gj #ig4eb #ie4jd #id4bj #ig4fc #id4bc ,org4 matter1 water and loss #j4cj #b4dh #d4if #e4hj #b4cg #e4gg #bdb4 ,description of the ,soils4--,number one represents the very early truck lands of southern ,maryland4 ,it is a light yellow sand1 belonging to the ,columbia terrace formation4 ,under an intense system of cultivation and heavy manuring with organic matter1 good crops of garden vegetables are produced which mature very early1 at least ten days or two weeks before the crops from any other part of the state4 ,under the prevailing meteorological and cultural conditions this soil maintains about five or six per cent of moisture1 while a heavier wheat and grass soil maintains from twelve to twenty per cent4 ,the truck soil is so loose and open in texture that the rain-fall passes through it very readily1 and it is undoubtedly owing to this drier soil that the plant is forced to the early maturity which secures it from competition from other parts of the ,state and insures a good market price4 ,number two represents the later truck and fruit lands of southern ,maryland4 ,these lands contain rather more clay than those just described2 they are somewhat heavier and closer in texture1 and are rather more retentive of moisture4 ,this land gives a larger yield per acre than the one just described1 and in every way crops make a more vigorous growth and development1 but the crop is about a week or ten days later in maturing1 and for this reason it brings a lower price in the market4 ,it is much better land than number one for small fruit and peaches4 ,these lands are altogether too light in texture for the profitable production of wheat1 and it would cost altogether too much to improve them so that even a moderate yield of wheat could be obtained4 ,number three is a tobacco land of southern ,maryland4 ,the finest tobacco lands of this locality come between the truck and wheat lands in texture1 and contain from ten to twenty per cent of clay4 ,the lighter the texture of the soil and the less clay it contains1 the less tobacco it will yield per acre1 but the finer the texture of the leaf4 ,the tobacco yields more per acre on the heavier wheat soils1 but the leaf is coarse and sappy and cures green and does not take on color4 ,it brings a very low price in the market and does not pay for cultivation4 ,the crop on the lighter lands is of much finer quality2 there is a smaller yield per acre but the leaf takes on a fine color in curing1 and brings a much better price per pound4 ,wheat is commonly raised on these tobacco lands to get advantage of the high manuring1 and because the rotation is better for the land than where tobacco is grown continuously on the same soil4 ,the finest tobacco lands are1 however1 too light in texture for the profitable production of wheat4 ,these lands belong to the neocene formation4 ,number four is a type of the wheat lands of southern ,maryland4 ,these lands represent soil of about the lightest texture upon which wheat can be economically produced under the climatic conditions which there prevail4 ,they contain from eighteen to twenty-five per cent of clay1 and are much more retentive of moisture than the best tobacco lands4 ,this type is about the limit of profitable wheat production4 ,these soils will maintain about twelve per cent of water during the dry season4 ,garden truck is so late in maturing on these lands that there is often a glut in the market when the crop matures1 and the crops often do not pay the cost of transportation4 ,the lands are too light in texture for a permanent grass sod4 ,they belong to the neocene formation4 ,number five represents the heavier wheat lands of southern ,maryland1 belonging probably to a different horizon of the neocene formation and containing about thirty per cent of clay4 ,this soil is much more retentive of moisture and produces very much larger crops of wheat than the last sample4 ,it is strong enough and sufficiently retentive of moisture to make good grass lands4 ,it is too close in texture and too retentive of moisture for the production of a high grade of tobacco1 or to be profitable for market truck4 ,number six is from a heavy limestone soil of lower ,helderberg formation4 ,it is a strong and fertile wheat and grass land4 #bdc4 ,interpretation of ,silt ,analysis4--,the primary conceptions upon which the interpretation of the mechanical analysis is based may be briefly stated as follows3#afa ,the circulation of water in the soil is due to gravity1 or the weight of water1 acting with a constant force to pull the water downward1 and also to surface tension1 or the contracting power of the free surface of water 7water-air surface71 which tends to move the water either up or down1 or in any direction1 according to circumstances4 ,there is a large amount of space between the grains in all soils in which water may be held1 ranging from about thirty per cent in light sandy lands to sixty-five or seventy per cent in stiff clay soils4 ,the relative rate of movement of water through a given depth of soil will depend upon how much space there is in the soil2 upon how much this space is divided up1 i4 e41 upon how many grains there are per unit volume of soil2 upon the arrangement of the grains of sand and clay2 and upon how this skeleton structure is filled in and modified with organic matter4 ,it also appears that the ordinary manures and fertilizers change this surface tension1 or pulling power of water2 that they also change the arrangement of the grains1 and consequently the texture or structure of the soil may be changed and the relation of the soil to water1 through the effect of the ordinary manures and fertilizers in causing flocculation or the reverse4 #bdd4 ,number of ,particles in a ,given ,weight of ,soil4--,the approximate number of particles in the soil can be calculated from the results of the mechanical analysis by the following formula3#afb 7a_/777d77_/#f77 ,a ,where a is the weight of each group of particles1 d the mean diameter of the particles in the several groups in centimeters1 is the specific gravity of the soil1 and ,a is the total weight of soil4 ,for the specific gravity of ordinary soils1 the constant #b4fe may be used4 ,in using the formula the per cents are expressed as grams4 ,thus1 if there were twenty per cent of silt1 this would be taken as twenty grams1 and if the results of the analysis added up ninety-seven per cent the whole weight of soil would be taken as ninety-seven grams4 ,the diameter d is taken as the mean for the extreme diameters taken for any group1 for instance1 for the silt this would be #j4jjc centimeter1 which is assumed to be the diameter of the particles in that group4 ,this formula can only give approximate values1 as the number of separations in a silt analysis must necessarily be small1 amounting usually to not more than eight or ten grades1 on account of the time and labor required for closer separations4 ,there is relatively rather a wide range in the diameters of grains within any one of these grades1 and absolute values could not be expected without a vast number of separations1 so that all the grains in each group would be almost exactly of the same size4 ,the clay group has relatively the widest limits1 which is unfortunate1 as this is the most important of all the groups on account of the exceedingly small size of the particles4 ,the figure #j4jjja millimeter is taken as the lowest limit of the diameter of the clay particles4 ,these particles have been heretofore assumed to be ultra-microscopic1 but by the use of a microscope of high power with oil-immersion objective and staining fluids1 it has been possible to define the clay particles in a turbid liquid which has stood so long as to be only faintly opalescent4 ,pending more exact measurements1 the figure #j4jjbee millimeter has been used as the diameter of the average sized particle in the clay group4 ,the following table gives the approximate number of grains per gram in the different types of subsoils calculated from the mechanical analysis of the typical soils already given3 ,,number ,,of ,,particles ,,of ,,each ,,class ,,in ,,one ,,gram ,,of ,,soil4 ,silt classes4 ,no4 #a ,no4 #b ,no4 #c ,diameter 7d7 in ,early truck4 ,truck and small ,tobacco4 centimeters4 fruit4 #j4ae #j #j #c #j4jge #he #cd #ajb #j4jcge #e1eaa #d1jaa #a1ijj #j4jage #cg1bcj #ed1faj #aa1hij #j4jjge #bjg1ejj #aii1gjj #bfg1ijj #j4jjc #b1jgc1jjj #a1cee1jjj #h1jib1jjj #j4jjjge #ch1baj1jjj #ce1cfj1jjj #adj1ijj1jjj #j4jjjbee #a1iae1jjj1jjj #c1iah1jjj1jjj #f1fcg1jjj1jjj -------------------------- -------------------------- -------------------------- #a1iee1jjj1jjj #c1ied1igc1cee #f1ghf1bgc1gie ,silt classes4 ,no4 #d ,no4 #e ,no4 #f ,diameter 7d7 in ,wheat4 ,grass and wheat4 ,limestone4 centimeters4 #j4ae #j #j #ab #j4jge #gbf #d #fj #j4jcge #h1bgc #aha #aeg #j4jage #cb1cdj #e1eef #a1def #j4jjge #eed1ajj #bjb1fjj #abe1ijj #j4jjc #c1ifb1jjj #aj1fgj1jjj #h1bca1jjj #j4jjjge #gc1iij1jjj #aed1ijj1jjj #aii1ijj1jjj #j4jjjbee #aj1aej1jjj1jjj #ad1egj1jjj1jjj #ai1dcj1jjj1jjj ---------------------------- ---------------------------- ---------------------------- #aj1bbh1edg1dci #ad1gce1ggh1cda #ai1fch1beh1ehe #bde4 ,estimation of the ,surface ,area of ,soil ,particles4--,the approximate extent of surface area of the soil grains in one gram of soil can be calculated from the foregoing by the following formula3#afc 7d7n in which d is the mean of the diameters of any group in centimeters1 and n is the number of particles in the group4 ,the following table gives the approximate extent of surface area of the particles in one gram of soil calculated from the preceding table3 ,,approximate ,,extent ,,in ,,square ,,centimeters1 ,,of ,,surface ,,area ,,in ,,one ,,gram ,,of ,,soil4 ,soil number4 ---------- ------------ ------------ ------------ ------------ ------------ ,diameter1 millimeters4 #a #b #c #d #e #f #a4e #j4j #j4j #j4d #j4j #j4j #j4a #j4ge #a4h #j4f #a4h #ab4h #j4a #j4a #j4cge #bd4c #ag4g #h4d #cf4e #ca4j #j4g #j4age #ce4h #eb4f #aa4d #ca4a #e4c #a4d #j4jge #ba4c #ce4c #dg4c #ig4i #ce4h #bb4b #j4jc #bah4h #ch4c #bbh4i #aab4j #cja4d #bcb4g #j4jjge #fg4d #fb4e #bdh4i #acj4h #bgc4e #cec4d #j4jjbee #cij4h #hjj4e #acee4j #bjgb4j #bigf4j #cife4j ---------- ------------ ------------ ------------ ------------ ------------ ,total #gfj4b #ajjg4e #aijb4a #bdic4a #ceic4a #dege4c #bdf4 ,logarithmic ,constants4--,the following logarithmic constants have been used in the calculation of the approximate number of grains per gram and of the surface area1 using #b4fe in all cases as the specific gravity of the soil4 ,diameter4 7d7 ,approximate number of grains4 ,surface area4 log477d7w7_/7#f7 log47d7 #j4ae centimeters #c4fgjc #b4hdic #j4jge #d4gfgd #b4bdgc #j4jcge #e4hfda #c4fdea #j4jage #f4hgaa #d4ihca #j4jjge #g4gfgd #d4bdgc #j4jjc #h4egcd #e4deac #j4jjjge #aj4gfgd #f4bdgc #j4jjjbee #aa4cfaf #g4caja #bdg4 ,mineralogical ,examination of the ,particles of ,soil ,obtained by ,mechanical ,analysis4--,the principal object of the mechanical analysis of soils as has already been set forth is the separation of the soil into portions1 the particles of which have the same hydraulic value4 ,it is evident without illustration that particles of the same hydraulic value do not necessarily have the same size4 ,the rate of flow of a liquid carrying certain definite particles does not imply that these particles are of the same dimensions4 ,of two particles of the same size and shape1 that one which has the lower specific gravity1 will be carried off at the lower rate of flow4 ,at the end of the operation1 therefore1 the several portions of the soil obtained will be found composed of particles of sizes varying within certain limits1 and of these particles the larger ones will tend to be composed of minerals of lower specific gravity1 and the smaller ones of minerals of higher specific gravity4 ,of the same mineral substance1 the particles which are most irregular1 exposing for a given weight the largest surface will be found to pass over at a lower velocity than those of a more nearly spherical shape4 ,the same law holds good for particles falling through a liquid at rest1 i4 e41 the heavier and more spherical particles1 weight for weight1 will sooner reach the bottom of the containing vessel4 ,to complete the value of a mechanical analysis1 it becomes necessary to submit the several portions of soil obtained not only to a chemical but also to a mineralogical examination4 ,only the outlines of the methods of examining silt separates for mineral constituents can be given here and special works in petrography must be consulted for greater details4#afd ,it is evident that the methods of separation and examination from a mineralogical point of view about to be described can only be applied to silts of the largest size4 ,the finer silts can not be separated into portions of different specific gravities by separating liquids of varying densities on account of the slowness with which they subside1 thus tending to adhere to the sides of the separating vessels and to form floccules which are not all composed of the same kind of mineral particles4 ,while1 therefore1 these processes are more appropriately described in connection with the silts obtained by hydraulic elutriation1 they can be applied with greater success to the fine particles passing the different sieves used in the preparation of the soil for analysis or to the finely pulverized soil as a whole4 ,the minerals which have contributed to soil formation1 moreover1 are better preserved in the larger silt particles and therefore more easily identified4 ,while the desirability of securing like determinations in the finer silts is not to be denied1 in the present state of the art the analyst must be content with the examination of the larger particles4 #bdh4 ,methods of ,investigation4--,the chief points to be observed in the examination of the fine particles of soil are the following3 7#a7 the size and shape of the particles2 7#b7 measurement of crystal angles2 7#c7 separation into classes of approximately the same specific gravity2 7#d7 separation by means of the magnet2 7#e7 determination of color and transparency2 7#f7 determination of refractive index2 7#g7 examination with polarized light2 7#h7 examination after coloring2 7#i7 chemical separation4 ,for many of the optical studies above noted1 it is first necessary to prepare thin laminae of the mineral particles and properly mount them for examination4 ,for the purposes of this manual only those processes will be described which are essentially connected with a proper understanding of the nature of the soil particles4 ,for the more elaborate methods of research the analyst will consult the standard works on mineralogy and petrography4 #bdi4 ,microscopical ,examination4--,the direct examination of the silt particles with the microscope should attend the progress of separation4 ,unless the particles obtained have the same general appearance1 the separation is not properly carried on4 ,especially is the microscope useful to determine that the value of the silt separation is not impaired by flocculation4 ,unless flocculation be practically prevented during the separation of the finest particles1 many of these will be left as aggregates to be brought over subsequently with particles of far different properties4 ,no special directions are necessary in the use of the microscope4 ,the silt particles are removed with a few drops of water by means of a pipette1 a drop of the liquid with the suspended particles is placed on the glass1 covered and examined with a convenient magnification4 ,a micrometer scale should be employed in order that the approximate sizes of the particles may be determined4 ,a camera lucida may also be conveniently used for the purpose of delineating the form of particles of peculiar interest4 #bej4 ,petrographic ,microscope4--,any good microscope furnished with polarizing apparatus may be used for the examination of the silt particles and sections4 ,for directions in manipulating microscopes the reader is referred to works on that subject4 ,a special form of microscope for petrographic work is made by ,bausch and ,lomb of ,rochester4 ,the stand of this instrument is shown in ,fig4 #cg4 ,the base1 upright pillars and arm are made of japanned iron4 ,the stage is made in two forms1 first1 plain revolving1 having silvered graduates at right angles and second1 a mechanical stage with silvered graduations on the edge with vernier and graduations for the rectangular movements4 ,the mirror bar is adjustable and graduated and the mirror is of large size1 plane and concave4 ,the double chambered box in the main tube carries the upper ,nicol prism 7analyzer74 ,the lower ,nicol prism 7polarizer7 is mounted in a cylindrical box beneath the stage to which it is held by a swinging arm4 ,it is adjustable also up or down and is provided with a compound lens for securing converged polarized light4 ,in revolving the prism a distinct click shows the position of the crossed ,nicols4 ,illustration3 ,,figure #cg4 #bea4 ,form and ,dimensions of the ,particles4--,in order to study the contour of the fine silt particles1 it is well to suspend them in a liquid whose refractive index is markedly lower than that of the particles themselves1 and for this purpose pure water is commonly used4 ,care must be taken that not too many particles are found in the drop of water which is to be placed on the object holder and protected with a thin1 even glass4 ,the tendency to flocculation in these fine particles will make the study of their form difficult if they are allowed to come too close together4 ,the size of the particles1 or linear diameter1 is to be determined by means of an eye-micrometer4 ,this consists of a glass plate on which a millimeter scale is engraved with a diamond1 or photographed4 ,the millimeter scale is the one usually employed1 each millimeter being divided into tenths4 ,on microscopes designed especially for photographic work the micrometer is fastened to the eyepiece1 and so adjusted as to read from left to right1 or at right angles thereto4 ,sometimes an eyepiece-micrometer has two scales at right angles so that dimensions may be read in two directions without change4 ,with an eyepiece-micrometer1 not the dimensions of the object1 but those of its magnified image are read1 and the degree of magnification being known1 the actual size of the object is easily calculated4 ,the actual measurements may also be obtained by placing in the field of vision1 a stage-micrometer and determining directly the relation between that and the eyepiece-scale4 ,if1 for example1 the stage-micrometer is ruled to #j4ja millimeter1 and the eye-micrometer to #j4a millimeter1 and one division of the stage-rule should cover three divisions of the eye-rule1 then the one division of the eye-micrometer would correspond to an actual linear distance of #j4jjcc millimeter in the object4 ,if the two lines of division in the two micrometers do not fall absolutely together1 the calculation may be made as follows3 suppose that six divisions1 #j4f millimeter1 in the eyepiece correspond to nearly five divisions1 #j4be millimeter1 in the stage piece4 ,to get at the exact comparison1 take ninety-six divisions of the eye-scale and they will be found to be somewhat longer than eighty-one and somewhat shorter than eighty-two divisions of the stage-scale4 ,it follows therefore that one division of the eye-scale #j4jjhdch millimeter1 and #j4jjheda 2 and1 hence1 one division of the eye-scale corresponds almost exactly to #j4jjhdhi linear measure4 #beb4 ,illustrations of ,silt ,classes4--,in figure #ch are shown the relative sizes and usual forms of a series of silt separates made by the ,osborne beaker method4 ,the photomicrographs were made by ,dr4 ,g4 ,l4 ,spencer from specimens furnished by ,prof4 ,m4 ,whitney4 ,the soil represented by the separates is from a truck farm near ,norfolk1 ,virginia4 ,the particles represented in each class are not all strictly within the limits of size described4 ,for instance1 in the largest size 7,no4 #a7 are two particles at least which show a diameter of more than one millimeter4 ,the particles in general1 however1 are within the limits of the class2 viz41 one-half to one millimeter1 and this general observation is true of all the classes4 ,in the case of the finer particles1 especially of clay1 the tendency to flocculation could not be overcome in the preparation of the slides for the photographic apparatus4 ,the clay particles are so fine as to present but little more than a haze at #aej diameters of magnification4 ,the particles seen are clearly1 in most cases1 aggregates of the finer clay particles4 ,the larger particles show the rounded appearance due to attrition and weathering4 ,it would have been more instructive to have had the particles of the different classes all photographed on the same scale1 but this is manifestly impossible4 ,the lowest power which shows any of the clay particles to advantage is at least #aej diameters1 and with the larger particles such a magnification would have been impracticable4 #bec4 ,measurement of ,crystal ,angles4--,the fine silt particles rarely retain sufficient crystalline shape to permit of the measurement of angles and the determination of crystalline form thereby4 ,the rolling and attrition to which the silt particles have been subjected have1 in most cases1 given to the fragments rounded or irregular forms which render1 even in the largest silts1 the measurement of angles impossible4 ,for the methods of mounting minute crystals and the measurement of microscopic angles1 the analyst is referred to standard works on mineralogy and petrography4 #bed4 ,determination of the ,refractive ,index4--,for a study of the theory of refraction1 works on optics should be consulted4 ,the general principles of this phenomenon which concern the determination of the refractive power of fine earth particles are as follows3 if a transparent solid particle is observed in the microscope imbedded in a medium of approximately the same refractive power and color1 its outlines will not be clearly defined1 but the imbedded particle will show in all of its extent the highest possible translucency4 ,if1 therefore1 the form or perimeter of the particle is to be studied with as much definiteness as possible1 it should be held in a medium differing as widely from it as possible in refractive power4 ,for minerals1 water is usually the best immersion material4 ,on the other hand1 when the internal structure of the particles is the object of the examination1 it should be imbedded in oil1 resin 7,canada balsam71 etc41 or in some of the liquids mentioned below4 ,if particles of different refractive powers and the same character of surface be studied in the same medium1 they will not all appear equally smooth on the field of the microscope4 ,some of the surfaces will seem smooth and even1 others will appear rough and wrinkled4 ,those particles whose refractive index is equal to or less than that of the liquid appear smooth1 because all the emergent light therefrom can pass at once into the environing medium4 ,on the other hand1 the surfaces of those particles which have a higher refractive power than the medium will appear roughened1 because1 on account of the unavoidable irregularities on the surface1 many of the emergent rays of light must strike at the critical angle and so suffer total reflection1 and consequently those portions of the surface will be less illuminated1 producing the phenomenon of apparent roughness above noted4 ,in the case of any given particle1 liquids of increasing refractive power can be successively applied until the change in the appearance of the surface of the particle is noticed4 ,the refractive index of the liquid being known1 that of the particle is in this way approximately to be determined4 ,the following liquids1 having the indexes mentioned1 are commonly employed3 ,substance4 ,refractive index4 ,water #a4ccc ,alcohol #a4cfe ,glycerol #a4dfj ,olive oil #a4dgj ,canada balsam #a4edj ,oil of cinnamon #a4ehj ,oil of bitter almonds #a4fjj ,oil of ,cassia #a4fjf ,concentrated solution of potassium and mercuric iodid #a4gcc ,concentrated solution of barium and mercuric iodid #a4gge ,the solution of potassium and mercuric iodid may also be used for all refractive indexes from #a4gcc to #a4ccd by proper dilution with water4 ,the mineral particle may also be imbedded in ,canada balsam and over it a drop of a liquid of known refractive power placed4 ,by a few trials one of the liquids will be found having practically the refractive index of the particle under examination4 #bee4 ,examination with ,polarized ,light4--,the internal structure of a mineral particle can often be determined by its deportment with polarized light4 ,the theory of polarization is fully set forth in works on optics and will not be discussed here4 ,the principle on which the utility of polarized light in the examination of soil particles rests is found in the information it may give in respect of crystalline structure4 ,the structure of mineral particles which make up the bulk of an ordinary soil is1 as a rule1 so thoroughly disintegrated that all trace of its original form is lost4 ,some particles may exist1 however1 in which there is no determinable element of shape and which yet possess an internal crystalline structure which the microscope with polarized light may be able to reveal4 #bef4 ,staining ,silt ,particles4--,the finer silts and clays before microscopic examination should be colored or stained4 ,the methods used in staining bacteria may be employed for the clay particles4 ,evaporation to dryness with a solution of magenta will often impart a color to the clay particles which is not removed by subsequent suspension in water4 ,the harder and larger silt particles are not easily stained1 especially if they be firm and undecomposed4 ,on the other hand1 if the particles be broken and seamed1 and well decomposed1 the stain will be taken up and held firmly in the capillary fissures4 ,valuable indications are thus obtained respecting the nature of the silt particles4 ,particles of mica1 chlorite and talc are easily distinguished in this way from the firmer and less decomposed quartz grains4 ,the staining of the particles after ignition and treatment with acids gives better results than the direct treatment4 ,particles of carbonate which are stained with difficulty before ignition take the stain easily afterwards on account of the decomposition produced by the loss of carbon dioxid4 ,this is the case also with particles containing water of composition or crystallization4 #beg4 ,cleavage of ,soil ,particles4--,a microscopic examination of the cleavage of soil particles may be useful in determining their mineral origin4 ,the course followed by cleavage lines and their mutual position is dependent on the direction in which the separation of the mineral fragment takes place4 ,the character of the microscopic fragments produced by crushing a soil particle is determined primarily by the system of crystallization to which it belongs4 ,perhaps the most distinguishing cleavage marks in soil particles will be found in fragments of mica and orthoclase4 ,these characteristic forms are shown in ,figs4 #ci and #dj4 ,the first 7,fig4 #ci7 shows the pinacoidal cleavage in a fragment of mica4 ,fig4 #dj illustrates the appearance of the cleavage lines in a fragment of orthoclase4 ,figs4 #da and #db show the characteristic cleavage lines in fragments of epidote and titanite4 #beh4 ,microchemical ,examination of ,silt4--,the methods of quantitative chemical examination of silts will be given in another part of this manual4 ,certain qualitative and microchemical tests1 however1 are useful in identifying silt particles4 ,for instance1 any soluble iron mineral will be detected1 even in minute quantity1 by the blue coloration of the solution produced by the addition of potassium ferrocyanid4 ,manganese will be revealed by fusion with soda and saltpeter on platinum foil1 in the oxidizing flame1 producing the well-known green coloration due to the sodium manganate formed4 ,more valuable indications of the character of the fragments examined are obtained by microchemical processes4 ,the best method of decomposing the silt particles for this purpose is by treatment with hydrofluosilicic acid4 ,when the particles are composed of silicates1 pure hydrofluoric acid is to be preferred4 ,the method of treatment is essentially that of ,boricky4#afe ,the slide used is protected by a film of ,canada balsam1 and a few of the silt particles are placed thereon1 and fixed in place by slightly warming the balsam4 ,each particle is then treated with a drop of hydrofluosilicic acid1 care being taken not to let the drops flow together4 ,the acid must be pure1 leaving no residue on evaporation4 ,the acid should be prepared by the analyst from a mixture of barium fluorid1 sulfuric acid and quartz powder1 or the commercial article should be purified by distillation before using4 ,the acid should be kept in ceresin or gutta-percha bottles and must be applied with a ceresin or gutta-percha rod4 ,each particle should be as completely dissolved as possible by the acid1 and the rate of solution may be hastened by gentle warming1 provided the heat is not great enough to remove the balsam and allow the acid to attack the glass4 ,the bases present in the silt particles crystallize on drying as fluosilicates4 ,in case of a too rapid crystallization1 the mass may be dissolved in a drop of water or of very dilute hydrofluosilicic acid1 and allowed to evaporate more slowly4 ,some fragments need more than one treatment with acid to secure complete solution1 and particles of mica may even resist repeated applications4 ,in such a case the decomposition may be made in a platinum crucible with hydrofluoric acid1 adding afterwards an excess of hydrofluosilicic acid and evaporating to dryness4 ,the crystals may then be dissolved in a little water and a drop of the solution allowed to crystallize on the slide4 #bei4 ,special ,reactions4--,the number of microchemical reactions is very great1 but there will be given here only some of the more important for silt identification4 ,sodium4--,sodium mineral fragments dissolved in hydrofluosilicic acid and dried give the combinations shown in ,fig4 #dc4 ,with sodium and aluminum the forms shown in ,figs4 #dd and #de are obtained4 ,with an increasing amount of lime in the mineral1 the crystals tend to become longer4 ,for microscopic work it is not advisable to try to produce the tetrahedral crystals of the double uranium sodium acetate because the commercial uranium acetate often contains sodium and even the pure article will often take up sodium from the bottles4 ,potassium4--,fragments containing potash give isotropic clear cubes1 or octahedra of low refracting power1 or combinations of these forms with each other and with rhombic dodecahedra4 ,these crystals have the composition ,k,si,f4 ,their forms are shown#aff in ,figs4 #df and #dg4 ,in case much sodium be present1 the first crystals obtained may be strongly double refractive rhombohedra1 but on dissolving in water and allowing to recrystallize1 the normal forms will be obtained4 ,if the crystals be dissolved in hydrochloric or sulfuric acids1 and treated with platinum chlorid1 the characteristic yellow octahedral crystals of ,k,pt,cl will be obtained4 ,ammonium and cesium compounds also give this reaction4 ,lithium4--,when fragments containing lithium are treated with the solvent mentioned1 monoclinic crystals are produced on drying4 ,these crystals dissolved in sulfuric acid and freed from calcium sulfate by treatment with potassium carbonate give aggregates of lithium carbonate resembling a snowflake4 ,at a high temperature lithium solutions treated with sodium phosphate give spindle-shaped crystals of lithium phosphate4 ,the double lithium aluminum silicofluorid is shown in ,fig4 #dh4 ,the ease with which traces of lithium may be detected by the spectroscope renders unnecessary any further description of its microchemical reactions4 ,calcium4--,nearly all mineral particles1 save quartz grains1 contain calcium4 ,when these particles are dissolved by treatment with hydrofluosilicic acid1 they form on drying hydrated monoclinic crystals of calcium silicofluorid 7,ca,si,f #b;,h,o74 ,these crystals assume many forms1 some of which are shown in ,figs4 #di and #ej4 ,these crystals are easily decomposed by sulfuric acid1 the well-known long prismatic crystals of gypsum taking their place4 ,on treatment of silt particles containing lime with hydrofluoric and sulfuric acids1 only a part of the lime passes into solution if the content thereof be large4 ,where but little lime is present and the sulfuric acid is in large excess1 all the lime passes into solution and the characteristic gypsum crystals appear as in ,fig4 #ea4 ,magnesium4--,rhombohedral crystals of magnesium silicofluorid separate from the solution of particles containing magnesium in hydrofluosilicic acid4 ,they have the composition ,mg,si,f#f;,h,o and their common forms are shown in ,fig4 #eb4 ,quite characteristic also are the crystals of struvite 7,,nh,mg,p,o #f;,h,o71 which are produced in a very dilute solution of the magnesium compound first obtained by carefully adding ammonium hydroxid and chlorid until a faint alkaline reaction is produced1 and then placing a drop of dilute sodium phosphate at the edge of the solution4 ,the crystals should be allowed to form slowly in the cold4 ,their form is shown in ,fig4 #ed4 ,illustration3 ,,figure #ch4 ,,photomicrographs ,,of ,,silt ,,particles4 ,no4 ,diameter in mm4 ,name4 ,magnification4 ,diameters4 #a #a4j-j4e coarse sand #aj #b #j4e-j4be medium sand #aj #c #j4be-j4a fine sand #aj #d #j4a-j4je very fine sand #cj #e #j4je-j4ja silt #cj #f #j4ja-j4jje fine silt #aej #g #j4jje-j4jjja clay #aej ,illustration3 ,figures #ci-db1 show examples of the various degrees of perfection and relative positions of cleavage lines4 ,figure #ci1 illustrates pinacoidal cleavage in mica from granite4 ,magnified thirty diameters4 ,figure #dj4 ,a cleavage of orthoclase from augite syenite magnified twenty-seven diameters4 ,figure #da4 ,cleavage of epidote magnified sixty diameters4 ,figure #db4 ,cleavage of titanite magnified seventy-five diameters4 ,figure #dc4 ,sodium fluosilicate crystals magnified seventy-two diameters4 ,figure #dd4 ,the same with aluminum fluosilicate magnified twenty-seven diameters4 ,taken from ,rosenbusch1 ,mikroskopische ,physiographie4 ,illustration3 ,figure #de4 ,sodium and aluminum silicofluorid crystals magnified #ajj1 #adj and #afj diameters4 ,figure #df4 ,potassium silicofluorid crystals magnified #acj diameters4 ,figure #dg4 ,another preparation of the same magnified #adj diameters4 ,figure #dh4 ,lithium and aluminum silicofluorid crystals magnified #ajj diameters4 ,figure #di4 ,calcium silicofluorid crystals magnified #de diameters4 ,figure #ej4 ,another preparation of the same magnified #db diameters4 ,illustration3 ,figure #ea4 ,calcium sulfate crystals magnified twenty diameters4 ,figure #eb4 ,magnesium silicofluorid crystals magnified thirty diameters4 ,figure #ec4 ,cesium aluminum sulfate crystals magnified twenty diameters4 ,figure #ed4 ,ammonium magnesium phosphate crystals magnified ten diameters4 ,figure #ee4 ,the same crystallized from dilute solution magnified thirty diameters4 ,figure #ef4 ,ammonium phosphomolybdate crystals magnified #adj diameters4 ,barium4--,from solution of barium bearing minerals in hydrofluosilicic acid fragments1 no characteristic crystals1 are obtained4 ,treated with hydrofluoric and sulfuric acids the barium is left as sulfate4 ,if this salt be dissolved in boiling oil of vitriol and a drop of the solution placed on the slide1 a mixture of rectangular tablets and ,st4 ,andrew's cross-shaped growths will be separated before any crystals of gypsum which may be present appear4 ,when strontium is present1 the barium sulfate residue obtained by treatment with hydrofluoric and sulfuric acids should be fused with sodium and potassium carbonate1 washed with water until the sulfuric acid is removed1 the residue dissolved in hydrochloric or nitric acids1 and the solution treated with potassium chromate4 ,pale yellow crystals of barium chromate are thus obtained1 which resemble in form those secured by dissolving the barium sulfate in oil of vitriol4 ,strontium is not precipitated by this treatment4 ,if potassium ferrocyanid be used instead of barium chromate with the hydrochloric acid solution1 crystals of barium potassium ferrocyanid are formed of a bright yellow color and rhombohedric shape4 ,strontium4--,from a hydrofluosilicic acid solution1 strontium crystallizes in columns or tablets of the monoclinic system as strontium silicofluorid1 ,sr,si,f4 ,on treating these with sulfuric acid1 rhombic plates of strontium sulfate are formed1 which serve to distinguish this element from calcium4 ,on treatment of the particles of the original mineral with hydrofluoric and sulfuric acids1 the strontium remains in the insoluble residue4 ,when this residue is treated with boiling oil of vitriol1 rhombic plates of celestine are separated4 ,if the residues above mentioned be dissolved by fusion with the alkaline carbonates1 washed with water1 dissolved in hydrochloric acid and treated with oxalic acid1 octahedral crystals of strontium oxalate are formed4 ,iron4--,mineral particles containing iron give crystals1 when treated as is first described above1 which are fully isomorphous with those obtained from magnesium4 ,by moistening the crystalline mass with potassium ferrocyanid1 the presence of iron is at once revealed by the blue coloration produced4 ,aluminum4--,no crystals containing aluminum are formed from the mineral particles containing this substance when dissolved in the solvent already mentioned4 ,if1 however1 the gelatinous mass be dissolved in a little sulfuric acid and a fragment of a cesium salt added1 beautiful crystals of cesium alum are obtained1 illustrated in ,fig4 #ec4 ,phosphorus4--,when a mineral fragment containing phosphorus is treated according to the usual analytical methods for securing the ammonium magnesium phosphate1 crystals are obtained of the form shown in ,figs4 #ed and #ee4 ,a phosphatic fragment of silt may be identified when soluble by treatment with nitric acid and ammonium molybdate4 ,on slowly drying1 rhombohedral crystals are produced1 yellow by reflected1 and green by transmitted light4 ,their form is shown in ,fig4 #ef4 #bfj4 ,petrographic ,examination of ,silt ,particles4--,the larger silt particles and the minute fragments of minerals in the soil can best be studied in thin sections4 ,for this purpose the following plan1 proposed by ,thoulet1 may be used4 ,mix the soil minerals in considerable proportion--,thoulet recommends ten per cent1 but a greater percentage is often better--with zinc oxid and make into a paste with sodium silicate4 ,the paste should be worked to the consistence of putty and then rolled into little tablets about one-eighth of an inch thick and an inch in diameter4 ,after drying a day or two without heating1 the tablets become hard enough to mount and grind like rock sections4 ,these tablets are mounted in ,canada balsam on glass slides and ground as thin as possible with fine emery on the turn-table or glass plate1 as rock sections are treated4 ,as these tablets are not as strong as rock sections usually are1 they require care in this treatment4 ,some of the grains also are apt to be torn out in the process of grinding and to compensate for this loss a number of slides should be prepared with each lot of soil minerals4 ,when this operation has been successful1 the optical properties of the various minerals can be studied as in rock sections4 ,as the iron oxid contained in the soils obscures the transparency of the minerals1 it is well to treat a portion of the material under examination with hot hydrochloric acid for a short time to remove this oxid and then prepare slides with the cleansed material and compare results with the untreated4 ,as the acid will dissolve phosphates and carbonates1 and will partly or wholly decompose some other minerals1 the operator must be guided by his judgment in its use4 #bfa4 ,machine for ,making ,mineral ,sections4--,a convenient apparatus for this purpose has been described by ,williams#afg and is represented in ,fig4 #eg4 ,it is supported on a substantial table provided underneath with electric batteries and a motor for driving the cutting disks seen on the top4 ,the table is three feet six inches square and two feet nine inches high4 ,illustration3 ,,figure #eg4 ,,machine ,,for ,,making ,,mineral ,,sections4 ,the grinding apparatus consists of two circular disks of solid copper1 nine inches in diameter1 and three-eighths inch thick1 which may be used alternately as different grades of emery are required4 ,they are attached either by a screw or square socket to a vertical iron spindle which revolves smoothly in a conical bearing4 ,the grinding disk is surrounded when in use by a large cylindrical pan of tin1 which is not shown in the cut1 which has an opening in its center to allow of the passage of the spindle4 ,the sawing apparatus consists of a horizontal countershaft placed on a different part of the table and connected with the motor by a separate belt4 ,it carries at one end a vertical wheel of solid emery1 and at the other an attachment1 level-table and guide for the diamond-saw4 ,a small water-can with spout1 not shown in the cut1 is suspended over the edge of the table to keep the saw wet when it is in use4 ,the machine is very conveniently driven by a storage battery when street circuits cannot be drawn on4 ,for the details of making mineral sections1 the works on petrography may be consulted4 #bfb4 ,separation of ,silt ,particles by ,specific ,gravity ,solutions4--,in silt separates the specific gravity of the different mineral particles present may vary from graphite 7#a4i-b4c7 to hematite 7#e4b-e-c74 ,the following list gives the specific gravities of some of the more common minerals which may be met with in soils3 ,gypsum #b4ca ,albite #b4ef-b4fc ,quartz #b4fe ,talc #b4gd ,chlorite #b4gh ,muscovite #b4he ,calcite #b4e-b4gh ,dolomite #b4ij ,tourmaline #b4id-c4c ,biotite #c4ja ,apatite #c4af ,pyroxenes #c4bb-c4e ,epidote #c4ci ,titanium ,minerals #c4dh-d4ge ,iron oxids #e4b-e4c ,the finest particles of silt are separated by gravity with great difficulty1 inasmuch as they tend to remain suspended in the solutions for an indefinite period4 ,with the coarser silts1 however1 useful data are often obtained by this method4 ,the separation is preceded by extraction of the particles with hydrochloric acid to remove encrusted soluble matter1 and by ignition to destroy any traces of organic matter4 ,those mineral matters which are soluble in acid or are changed by ignition must1 of course1 be sought for in separate portions of the silt1 #bfc4 ,thoulet's ,solution4#afh--,the standard solution is of such a density that particles of #b4fe specific gravity-will just float thereon1 using for this purpose a solution of about #b4g specific gravity4 ,the solution from which the above standard is prepared is made as follows3 ,one part of potassium iodid is weighed and placed in a beaker and one and one-quarter part of mercuric iodid is placed on top of it4 ,then water is added in the proportion of ten cubic centimeters to #ajj grams of the mixture1 and after some time 7twelve to twenty-four hours71 with occasional stirring1 the salts will nearly completely dissolve4 ,filter from the undissolved residue and evaporate in a porcelain dish until crystals form on the surface of the liquid4 ,allow to cool1 pour off the liquid from the crystals and evaporate the liquid for another crop4 ,the first solution1 after cooling1 has a specific gravity between #c4aj and #c4bj1 the second a specific gravity of #c4bh1 practically the limit of density of the solution4 ,the solution of #b4g specific gravity and other densities are made by cautiously adding a few drops of water at a time and ascertaining the specific gravity by the ,westphal balance or other convenient method4 ,the strong solution1 according to ,goldschmidt1#afi may be prepared directly by using potassium iodid and mercuric iodid in the ratio of #a 3 #a4bd4 ,twenty-five cubic centimeters of water1 #baj grams of potassium iodid1 and #bhj grams of mercuric iodid afford a solution of #c4aif specific gravity at #ae1 on which fluorspar fragments will float4 #bfd4 ,klein's ,separating ,liquid4--,a solution of cadmium borotungstate1 of the composition #b;,h,o1#b;,cd,o1,b,o1#i,,wo #af;,h,o1 has been proposed by ,klein#agj for separating silt particles4 ,this salt is obtained by dissolving pure sodium tungstate in five times its weight of water1 adding one and a half parts of boric acid and boiling until1 complete solution takes place4 ,on cooling2 the borax is separated in crystalline form4 ,the mother-liquor after the removal of the crystals is carefully concentrated by boiling4 ,by stirring the cold solution1 there is a further separation of sodium borate and polyborate4 ,this operation is continued until glass will float on the mother-liquor4 ,the salt in solution then has the following composition3 #d,na,o1#ab,,wo1,b,o4 ,to this boiling concentrated solution1 is added a boiling saturated solution of barium chlorid1 in the proportion of one part of the chlorid to three parts of the original double tungstate4 ,an abundant pulverulent precipitate is formed1 making the whole mass mushy4 ,the mass is filtered under pressure and well-washed with hot water4 ,the residue is then suspended in hot water containing one part in ten of hydrochloric acid of #a4ah specific gravity4 ,it is then evaporated to dryness in the presence of an excess of hydrochloric acid and decomposed1 by which process hydrated tungstic acid is separated4 ,the boiling mass is taken up with water and the boiling continued for two hours with occasional addition of water to take the place of that evaporated1 and the tungstic acid separated by filtration4 ,from the solution1 beautiful quadratic crystals separate having the composition #i,,wo1,b,o1#b;,ba,o,h #ah;,h,o4 ,these are purified by several recrystallizations and freed from any scales of boric acid by washing with alcohol4 ,any reducing action1 revealed by a violet coloration of the crystals1 can be avoided by adding a few drops of nitric acid4 ,from a boiling solution of these crystals1 the cadmium salt desired is obtained by treatment with the proper amount of cadmium sulfate solution to precipitate the barium4 ,the barium sulfate is separated by filtration4 ,the cadmium borotungstate is soluble in less than ten parts by weight of water4 ,from this solution it is obtained in pure form by evaporation under a vacuum1 or by carefully concentrating on a water-bath and cooling4 ,a saturated solution of these crystals at #ae has a bright yellow color and a specific gravity of #c4bh4 ,if a dilute solution of the above salt be carefully evaporated on a water-bath1 any violet color which may be present disappears when the specific gravity reaches #b4g4 ,if the evaporation be continued until a crystal of augite will float on the hot liquid1 crystals may be obtained on cooling which1 dissolved in as little water as possible1 make a solution which will almost support olivine4 ,if the two solutions be united1 the specific gravity of the mixture is #c4cj-c4cf4 ,the highest attainable specific gravity2 viz41 #c4f1 is produced by continuing the evaporation on a water-bath until the liquid will support olivine1 and then allowing to stand in a closed place for twenty-four hours4 ,the crystals of cadmium borotungstate thus obtained are freed as much as possible from the mother-liquor by drainage and then melted at about #ge in their own water of crystallization4 ,a liquid is thus obtained on which spinel will float4 ,the same concentration may also be obtained by careful heating on a water-bath4 ,at its highest specific gravity this solution has an oily consistence and this renders its practical use in the separation of fine particles somewhat restricted4 ,by filtering the liquor when a crystalline crust begins to form during evaporation1 a cold solution of #c4cfj-c4cfe specific gravity is obtained which is found practically useful4 ,it has a higher specific gravity than ,thoulet's mixture1 is not injurious to any of the mineral particles1 not even of iron with which it is brought into contact1 but the trouble of preparing it is far greater than that of the mixture of mercuric and potassium iodids4 #bfe4 ,rohrbach's ,solution4--,the solution of barium mercuric iodid recommended by ,rohrbach#aga for this purpose was originally prepared by ,suchsin4 ,the solution must be rapidly prepared on account of the tendency of the barium salt to decomposition4 ,the solution is prepared by weighing rapidly #ajj grams of barium and #acj grams of mercuric iodid1 mixing the two salts well in a dry flask and adding twenty cubic centimeters of water4 ,the mixture is raised to a temperature of #aej-bjj on an oil-bath4 ,the formation and solution of the double salt are promoted by constant stirring4 ,after solution1 the liquor is boiled for a few minutes and then evaporated on a water-bath until it will bear a crystal of epidote4 ,on cooling1 a small quantity of a yellow double salt is separated by crystallization and the resulting mother-liquor is dense enough to carry a fragment of topaz4 ,inasmuch as the liquor is filtered with difficulty1 the clear mother-liquor should be separated by decantation after standing for several days4 ,this solution has the disadvantage of not being dilutable with water1 the addition of which causes a separation of red mercuric iodid4 ,were this solution not so easily decomposed1 it would prove of high value in silt separation4 #bff4 ,braun's ,separating ,liquid4--,in many respects the separatory solution proposed by ,braun#agb is superior to those already mentioned4 ,it is the commercial methylene iodid1 ,,ch,i1 which has at #af a specific gravity of #c4cb1 at #e of #c4ce1 and at #be of #c4ca4 ,it is a strongly refractive liquid having a refractive index of #a4gdff for the yellow ray4 ,as a separating medium the liquid is open to two objections2 viz41 first1 it cannot be diluted with water and1 second1 it turns brown on heating or on long exposure to the sunlight4 ,when dilution is necessary1 it should be accomplished with benzene or xylene4 ,to bring the diluted liquor again to its maximum density1 the benzene must be removed by evaporation1 which causes a considerable loss in the liquid4 ,when this substance becomes opaque1 the transparency may be restored by removing the separated iodin by shaking with potash lye1 washing with pure water1 drying by the addition of pieces of calcium chlorid and filtering4 ,the same result may also be reached by freezing and separating the liquid portion4 ,the frozen portion on melting will have the density of the original liquid4 #bfg4 ,method of ,bron4--,instead of a solution of a salt1 ,bron#agc has proposed to use salts in a fused state for separating mineral particles4 ,lead and zinc chlorids may be used for this purpose in a melted state1 having the specific gravities of #e4j and #b4d1 respectively4 ,by mixing the molten salts in different proportions1 any desired specific gravity between the extremes mentioned may be secured4 ,the fusion is accomplished at #djj in a test-tube4 ,the silt is added gradually with constant stirring until a sharp separation is secured between the sinking and floating particles4 ,after cooling1 the tube is broken1 the two parts separated1 and the silt recovered by dissolving the mixed salts in hot water containing a little nitric acid4 ,only the coarser silts can be separated by this method4 ,fused silver nitrate1 melting point #aih1 specific gravity #d4a1 has also been used for separation4 #bfh4 ,the ,separation4--,forty cubic centimeters of the solution in the ,thoulet process are placed in the separatory tube ,a1 ,fig4 #eh1 together with from one to two grams of the silt and the stopper ,f inserted4 ,the tube ,g is connected with a vacuum apparatus by means of which any air particles adhering to the mineral fragments are removed4 ,the silt which sinks in the solution is removed after ,g has been disconnected by opening the cock ,c and sucking through ,b at ,i4 ,the cock ,c is closed and the separated particles washed into a beaker at ,h after opening ,d4 ,water is next added to the materials left in ,a in quantities previously determined to secure a given specific gravity and thus a second1 a third1 etc41 separation secured4 ,an intimate mixture of the solutions in ,a can be effected by closing ,d1 opening ,c1 and blowing through ,b in such a way that no liquid is allowed to pass through ,c4 ,illustration3 ,,fig4 #eh4 ,,thoulet',s ,,separating ,,apparatus4 ,the quantity of water to be added in each case to secure a given specific gravity is determined by the formula v 7v7,d d77_/7d #a71 in which v is the volume of the solution1 ,d its specific gravity1 and d and v the specific gravity desired and volume of the water to be added4 ,example4--,let the specific gravity of the original solution be #c4b1 its volume thirty cubic centimeters1 and the desired specific gravity of the new solution #b4he4 ,then v 7#cj7c4b #b4he77_/7b4he #a7 #e4fh4 ,the desired specific gravity is therefore secured by adding #e4fh cubic centimeters of water1 which is easily accomplished by means of the graduations on the tube4 ,according to ,rosenbusch1#agd the calculated specific gravity as made above is not wholly reliable on account of the contraction which takes place4 ,an empirical process is rather to be commended which consists in introducing a fragment of mineral of known or desired specific gravity and then adding water drop by drop until the fragment remains suspended in the mixture4 ,should too much water be added1 the necessary increase in density can be secured by adding a little of the strong solution4 #bfi4 ,method of ,packard4--,a separatory funnel1 according to ,packard1#age may be safely used to hold the solution while separation is going on4 ,as the lighter minerals form the bulk of soils1 the heavier constituting only a small percentage1 it is well to use a wide funnel holding as much as one-half liter for quantitative separations1 because a large quantity of soil1 say #ajj grams1 is necessary from which to recover the small quantity of heavy particles satisfactorily4 ,the soil is introduced into the solution contained in the funnel1 agitated1 stirred with a glass rod1 and allowed to stand some time4 ,this operation may be repeated as often as desired4 ,separation is not absolute by this operation1 the heavy and light particles being sometimes so united that they sink or float together according as one or the other preponderates4 ,there are also particles having so nearly the same specific gravity as the solution that they remain indifferent to its action in any position4 ,after separation has been effected1 the heavy portion is drawn off through the stop-cock of the funnel and the lighter is skimmed off the top4 ,both must be thoroughly washed from the adhering heavy solution for further examination with the microscope1 and by chemical1 microchemical1 and blow-pipe tests4 ,one who has familiarized himself with the appearance of minerals in minute fragments under the microscope1 in ordinary and polarized light1 will be able to determine some minerals in that way4 ,but for certain identification it is necessary to ascertain their optical properties as is done in the case of the minerals in thin sections of rocks4 ,illustration4--,the following example from the work of ,packard will serve to illustrate the results of separating a soil by the specific gravity method3 ,one hundred grams of soil1 residual clay from the ,trenton limestone1 were placed in the ,thoulet's solution contained in the large separatory funnel4 ,the heavy portion1 after washing and drying1 weighed #j4fhhf gram1 or #j4fi per cent4 ,of this1 the magnet removed #j4afce gram1 or #j4af per cent4 ,this heavy material consisted of rounded yellowish and brown grains up to twenty-five millimeters in diameter1 mingled with lustrous angular black grains which were seen under the microscope to be cubes with striated faces1 cubes penetrating each other and aggregations of cubes4 ,combinations of cubes with octahedra and instances of the pentagonal dodecahedron were also observed4 ,these forms1 characteristic of pyrites1 were also seen in the fine sand obtained as a residue on elutriating the same soil4 ,as these crystals dissolved in hydrochloric acid1 giving a strong iron solution1 they were regarded as pseudomorphs of iron oxid after pyrites4 ,the yellowish grains on treatment with acid left a grayish residue which contained some grains of quartz but was not wholly quartz4 ,the lighter portion of the soil1 over ninety-nine per cent1 which floated in the ,thoulet's solution of #b4h was next examined4 ,it was colored red by the iron oxid which coated and adhered to the other minerals4 ,it contained all the quartz1 the feldspars if present1 and the other minerals whose specific gravity is less than #b4h4 ,it was examined by the microscope and found to consist largely of irregular grains of a mineral which acted on polarized light1 obscured somewhat by the iron oxid1 and was apparently quartz2 and another mineral which was yellowish-brown in color and seemed to be dull and not transparent4 ,besides there was a large quantity of indistinguishable amorphous material4 ,to clean these minerals the material was treated with hydrochloric acid to remove the iron oxid and other matter soluble in acid1 when the quartz grains appeared transparent and gave interference colors in polarized light4 ,but mingled with these were grains of the other mineral which now appeared grayish1 dull1 and without action on polarized light4 ,the character of this mineral substance could only be determined by chemical analysis4 #bgj4 ,harada's ,apparatus4--,although it has been affirmed by some analysts that in the subsidence of small particles it is advisable that the containing vessels have parallel sides1 yet in the method just given1 and in those about to be described1 good results are obtained in a funnel or pear-shaped holder4 ,illustration3 ,,figure #ei4 ,,harada',s ,,apparatus4 ,in the apparatus of ,harada1#agf ,fig4 #ei1 the separating vessel a is made of thick glass furnished with a glass stopper above and a glass stop-cock h below4 ,the separating liquid and silt are placed in the pear-shaped vessel a1 the stopper inserted1 and the whole well-shaken4 ,as soon as a ring of clear liquid is seen between the sinking and floating silt1 the lower end of the apparatus is brought near the bottom of a conical glass b1 the cock h opened and the heavy silt allowed to fall out4 ,very little of the liquor will flow out because of the air pressure4 ,should an air bubble enter the apparatus and be held at the stop-cock1 it should be made to ascend by gently tapping4 ,when all the heavy silt has passed into the conical glass1 the cock h is closed and some water poured over the solution and silt in b4 ,the separatory apparatus is now raised until the beveled end of it is in the water layer1 when the water at once rises to h and thus washes all the silt particles adhering to the glass into b4 ,the liquid in a may then be diluted by inverting the apparatus1 adding the required amount of water through h1 again shaken after closing h1 and another separation secured as before4 ,this apparatus is somewhat easier to manipulate than ,thoulet's but does not admit of the same quantitative dilution of the separating liquid4 ,illustration3 ,,fig4 #fj a4 ,,fig4 #fj b4 ,,fig4 #fj c4 ,,br,,gger',s ,,apparatus4 #bga4 ,apparatus of ,brgger4--,all silt separations in narrow tubes are open to the objection of permitting more or less flocculation4 ,some of the lighter particles are thus carried down by the heavier1 and1 on the other hand1 some of the heavier float with the lighter4 ,this disturbing action ,brgger#agg seeks to avoid by the following device1 ,fig4 #fj1 a1 b1 c4 ,the length of the apparatus is forty-six centimeters1 and its greatest diameter #c4e centimeters4 ,the opening in the large stop-cock ,a is the same diameter as that of the apparatus at that point4 ,the cubical content of the apparatus with ,a open and ,b closed is about seventy-five cubic centimeters4 ,in conducting the separation the cock ,b is closed1 the separating liquid and silt introduced1 ,a being open1 the stopper ,k inserted and the whole well-shaken4 ,in the first separation1 the silt ,s1 lying over ,b is contaminated with some of the lighter particles ,s1 while the lighter particles above ,a1 ,s1 are mixed with some of the heavier particles1 ,s4 ,after closing ,a the apparatus is again well-shaken and inverted as in ,fig4 #fj b4 ,the two parts of the silt will now undergo another separation as indicated4 ,the apparatus is now carefully inclined as in c1 when the various grades of silt will flow in the directions indicated by the arrows1 but without mixing1 passing each other on opposite sides of the apparatus4 ,when the movement is complete1 ,a is carefully opened1 the apparatus still being held as in c1 and the light silt formerly between ,a and ,b will flow above ,a1 while the heavy silt above ,a will flow down and join the silt collected over ,b4 ,this operation may be repeated until a perfect separation is effected4 ,finally ,b is opened and the heavy silt collected in a beaker1 and the lighter silt then removed from the upper part of the apparatus4 ,illustration3 ,,figure #fa4 ,,apparatus ,,of ,w,,lfing4 #bgb4 ,method of ,wlfing4--,a somewhat more convenient method of purifying the silt segregates and freeing them of mechanically occluded particles of differing specific gravities has been proposed by ,wlfing4#agh ,an elliptical ring of heavy glass tubing carries glass stop-cocks ,a and ,b1 ,fig4 #fa1 at the two extremities of the ellipse1 each arm of which is provided with a lateral glass-stoppered neck4 ,the perforation in the stop-cocks has the same diameter as the sides of the ellipse4 ,the apparatus has an interior cubical content of about forty cubic centimeters4 ,thirty cubic centimeters of the separating fluid are introduced through one of the lateral apertures and brought to the same height in the two arms by opening the cock ,b4 ,the silt is then introduced in equal quantities into each of the arms4 ,the stoppers having been inserted1 the whole is well-shaken4 ,at the beginning of the separation1 the apparatus being held in position #a1 the lighter soil above and the heavier soil below are somewhat mixed by reason of flocculation and mechanical entanglement4 ,at this point ,b is opened and the apparatus placed in the inclined position #b4 ,the heavier particles ,s l1 on the right arm1 are thus united with the same class of particles in the left arm making #b,s #bl4 ,this operation is hastened by opening ,a and allowing the higher column of liquid in the right arm to pass into the left4 ,the liquid in the left arm is allowed to rise to ,a4 ,after all of ,s l in the right arm has passed into the left ,b is closed1 the apparatus then placed back in position #a and inclined in the opposite direction until ,l s in the top of the left arm has been transferred to the ,l s in the top of the right1 and the same quantity of liquid is found in each arm4 ,the operation is then repeated and this continued until all ,s s is found in the bottom of the left arm and all ,l l in the top of the right arm4 #bgc4 ,separation with a ,magnet4--,particles of magnetic iron oxid are easily separated from the fine soil particles by means of a magnet4 ,a strong bar or horseshoe magnet may be used4 ,electro-magnets are rarely necessary except for the separation of particles of feeble magnetic power4 ,particles of iron which may be found would owe their origin to the mortars in which the soil had been pulverized1 or they might come from a recently crushed meteorite4 ,some minerals1 as limonite1 after ignition are attracted by the magnet and it is advisable to subject a part of the sample to this treatment4 ,the best method of separation consists in spreading the particles evenly on paper and gradually bringing the magnetic particles to one side by moving the magnet underneath4 #bgd4 ,color and ,transparency4--,but little can be learned from the color and transparency of the smallest silt particles1 but these properties in the larger grains have considerable diagnostic value4 ,many minerals of distinct color appear wholly colorless in petrographic sections or in silt particles1 as for instance1 highly-colored quartz4 ,on the other hand1 even the smallest particle of chlorite will show its distinctive tint4 ,the colors in some minerals are due to occluded matter not essential to their structure1 and these foreign bodies would naturally escape when the crystal mass is reduced to an almost impalpable powder4 #bge4 ,value of ,silt ,analyses4--,as in the case of chemical analyses a silt analysis of a soil which is not typical or representative has little value4 ,on the other hand1 a systematic separation of soils into classes of particles can not fail to reveal a definite correspondence of mechanical composition to soil properties4 ,the production of a crop is the result of certain functions1 chief among which are temperature1 moisture1 and plant food4 ,in a given soil the temperature is markedly affected by its physical state4 ,it has been demonstrated in previous paragraphs that the circulation of moisture in the soil and its capacity to be held therein are chiefly functions of the state of aggregation of the soil itself4 ,the availability of plant food in a soil is not measured by its quantity alone1 but rather by its state of subdivision4 ,it is not therefore a matter of surprise that the fertility of a soil is found1 caetris paribus1 to be commensurate to a certain limit with the percentage of fine silt and clay which it contains4 ,it is true that two soils quite different in fertility1 may have approximately the same silt percentages1 but in such a case it is demonstrable that even in the poorer soil the measure of fertility is largely the percentage of fine particles and not its actual content of plant food4 ,in other words1 almost all soils1 even the poorest1 have still large quantities of plant food1 but these stores1 owing to certain physical conditions1 are not accessible to the rootlets of plants4 ,an illustration of this is seen in the use of concentrated fertilizers4 ,it might seem absurd to suppose that the addition of #ajj pounds of sodium nitrate would prove useful to a plat containing already many tons of nitrogen2 but the nitrate is at once available and its beneficial influences are easily seen4 ,the full value of silt analysis will only be appreciated when many typical soils from widely separated areas are carefully studied in respect of their chemical and physical constitution and the character of the crops which they produce4 ,,authorities ,,cited ,,in ,,part ,,fourth4 ,footnote #aba3 ,annual ,report1 ,connecticut ,agricultural ,experiment ,station1 #ahhg4 ,footnote #abb3 ,american ,journal of ,science1 ,march #ahgi1 p4 #bje4 ,footnote #abc3 ,bulletin1 ,no4 #d1 ,united ,states ,weather ,bureau1 p4 #ai4 ,footnote #abd3 ,chemical ,news1 ,vol4 #cj1 ,august #g1 #ahgd1 p4 #eg4 ,footnote #abe3 ,american ,journal of ,science1 ,vol4 #bi1 #ahhe1 p4 #a4 ,footnote #abf3 ,american ,journal of ,science1 ,vol4 #cg1 7#ahhi71 p4 #abb4 ,footnote #abg3 ,proceedings ,national ,academy of ,science1 ,baltimore ,meeting1 #ahib4 ,footnote #abh3 ,manuscript communication to author4 ,footnote #abi3 ,division of ,chemistry1 ,bulletin #ch1 p4 #bjj4 ,footnote #acj3 ,anleitung zur ,wissenschaftlichen ,bodenuntersuchung1 ,s4 #bc4 ,footnote #aca3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #ch1 ,ss4 #cji1 et seq4 ,footnote #acb3 ,berichte der deutschen chemischen ,gesellschaft1 ,band #ae1 ,s4 #cjbe4 ,footnote #acc3 ,connecticut ,agricultural ,experiment ,station1 ,annual ,report1 #ahhf1 pp4 #ada1 et seq4 ,footnote #acd3 ,knig1 ,untersuchung ,landwirtschaftlich und ,gewerblich ,wichtiger ,stoffe1 ,s4 #g4 ,footnote #ace3 ,wahnschaffe1 ,anleitung zur ,wissenschaftlichen ,bodenuntersuchung1 ,s4 #be4 ,footnote #acf3 ,vid4 #ae1 ,s4 #bd4 ,footnote #acg3 ,knig1 op4 cit4 #ad1 ,s4 #ac4 ,footnote #ach3 ,tenth ,census of the ,united ,states1 ,vol4 #c1 pp4 #hgb-c4 ,footnote #aci3 ,wahnschaffe1 op4 cit4 #ae1 ,s4 #bf4 ,footnote #adj3 ,le ,stazioni ,sperimentali ,agrarie ,italiane1 ,vol4 #ag1 pp4 #fgb1 et seq4 ,footnote #ada3 ,vid4 #ac4 ,footnote #adb3 ,encyclopedie ,chimique1 ,tome #d1 pp4 #aee1 et seq4 ,footnote #adc3 ,annales de la ,science ,agronomique1 #ahia1 ,tome #a1 ,seconde ,fasicule1 pp4 #bej1 et seq4 ,footnote #add3 ,vid4 #bb4 ,footnote #ade3 ,petermann1 ,l',analyse du ,sol41 p4 #ae4 ,footnote #adf3 ,vid4 #bj4 ,footnote #adg3 ,zeitschrift fr analytische ,chemie1 ,band #c1 ,ss4 #hi1 et seq4 ,footnote #adh3 ,zeitschrift fr analytische ,chemie1 ,band #e1 ,ss4 #bie1 et seq4 ,footnote #adi3 ,bulletin de la ,socit des ,naturalistes de ,moscou1 ,tome #dj1 pp4 #cbd1 et seq4 ,footnote #aej3 ,journal fr ,landwirtschaft1 ,band #ch1 ,theil #b1 ,s4 #afb4 ,footnote #aea3 ,connecticut ,agricultural ,experiment ,station1 ,annual ,report1 #ahhg1 pp4 #ade1 et seq4 ,footnote #aeb3 ,division of ,chemistry1 ,bulletin ,no4 #ch1 pp4 #fj1 et seq4 ,the figures are from original drawings under the direction of ,prof4 ,hilgard4 ,footnote #aec3 ,op4 cit4 supra1 pp4 #fe-fi4 ,footnote #aed3 ,op4 cit4 #ac1 p4 #aej4 ,footnote #aee3 ,op4 cit4 #ca1 p4 #aeb4 ,footnote #aef3 ,op4 cit4 #ca1 p4 #aeg4 ,footnote #aeg3 ,op4 cit4 #ca1 p4 #aei4 ,footnote #aeh3 ,connecticut ,agricultural ,experiment ,station1 ,annual ,report1 #ahhh1 p4 #aed4 ,footnote #aei3 ,loughridge1 ,proceedings ,american ,association for the ,advancement of ,science1 ,vol4 #bb1 p4 #ha4 ,footnote #afj3 ,whitney1 ,united ,states ,weather ,bureau1 ,bulletin ,no4 #d4 ,footnote #afa3 ,whitney1 op4 cit4 #dj4 ,footnote #afb3 ,vid4 #dj4 ,footnote #afc3 ,vid4 #dj4 ,footnote #afd3 ,vid4 ,anleitung zur ,mineralogischen ,bodenanalyse von ,franz ,steinreide2 and ,mikroskopische ,physiographie von ,h4 ,rosenbusch4 ,footnote #afe3 ,elemente einer neuen ,chemisch-,mikroskopischen ,mineral und ,gesteinsanalyse1 #ahgg4 ,footnote #aff3 ,rosenbusch1 ,mikroskopische ,physiographie1 ,plate #aa1 ,fig4 #c4 ,the figures of crystals of potassium1 sodium1 calcium1 magnesium1 etc41 are taken from the same work1 ,plates #aj1 #aa1 and #ab4 ,footnote #afg3 ,williams1 ,american ,journal of ,science1 ,february #ahic1 p4 #bjc4 ,footnote #afh3 ,op4 cit4 #df1 ,s4 #bca4 ,footnote #afi3 ,op4 et41 loc4 cit4 #dh4 ,footnote #agj3 ,op4 cit4 #df1 ,s4 #bcc4 ,footnote #aga3 ,op4 cit4 #df1 ,s4 #bce4 ,footnote #agb3 ,op4 cit4 #df1 ,s4 #bcf4 ,footnote #agc3 ,op4 cit4 #df1 ,s4 #bcg4 ,footnote #agd3 ,op4 cit4 #df1 ,s4 #bcb4 ,footnote #age3 ,manuscript ,communication from ,r4 ,l4 ,packard4 ,footnote #agf3 ,op4 cit4 #df1 ,s4 #bda4 ,footnote #agg3 ,op4 cit4 #df1 ,s4 #bdb4 ,footnote #agh3 ,op4 cit4 #df1 ,s4 #bdc4 ,,note4--,the analyses on page #bcg are by ,hilgard and ,loughridge from ,proceedings ,american ,association for the ,advancement of ,science1 ,portland ,meeting1 #ahgc4 ,,part ,,fifth4 ,,estimation ,,of ,,gases ,,held ,,in ,,soils4 #bgf4 ,relation of ,soil ,composition to ,gases4--,the power of a soil for occluding gases rests primarily on its composition as determined by silt analysis4 ,the discussion of this part of the subject is so nearly related to that of the physical properties of the soil that it might properly have been included in that part of the work4 ,since1 however1 we deal in this part more with the determination of the gas constituents of the soil1 it was deemed preferable to place it after the silt analysis and as introductory to the general estimation by more strictly analytical processes of the chemical constituents of the soil4 #bgg4 ,occurrence of ,carbon ,dioxid4--,the amount of organic matter in the soil1 according to ,wollny1#agi is no indication of the quantity of carbon dioxid when the organic matter is in excess4 ,the percentage of carbon dioxid is only proportional to the amount of organic matter when this is in small quantities4 ,large quantities of organic matter do increase the amount of carbon dioxid1 but the increase is not a proportional one1 since a larger quantity of this gas in the air of a soil reduces the activity of the organisms which produce oxidation4 ,water and temperature have a greater influence on the oxidation1 and act in an opposite direction to that of the organic matter4 ,the amount of free gas in the soil affords no indication either of the intensity of the action of oxidation or of the amount of organic matter4 ,the addition of liquid manure to the soil results in a reduction of the decomposition of the organic matter when the quantity of the salts therein contained is greater than that already present in the soil4 ,but if the liquid manure is dilute1 and the absorptive power of the soil for salts is great1 then the decomposition is promoted4 #bgh4 ,absorption of ,aqueous ,vapor4--,the power of a soil to resist drought depends largely upon its coefficient of absorption for aqueous vapor4 ,hilgard has shown#ahj that at temperatures between #g and #ba1 the amount of aqueous vapor absorbed by a thin layer of a clay or soil not unusually rich in humus1 in a saturated atmosphere1 is sensibly constant4 ,in general1 clay soils are more absorbent than sandy ones1 yet there is no direct connection between the amount of clay present and the absorbent power of the soil4 ,evidently the hygroscopic coefficient is largely controlled by the presence with the clay of the powdery ingredients which determine its looseness of texture1 and it is found that the finer silts themselves possess a considerable absorbing power4 ,according to ,whitney this is largely dependent upon the extent of the surface area of the soil grains and upon the size and arrangement of these grains4 ,again1 the presence of hydrated ferric oxid materially influences this power1 so that the amount of iron present must always be taken into consideration4 #bgi4 ,methods of ,study4--,the study of the deportment of a soil with vapors or gases may be divided into two general classes4 ,the first depends on the subjection of a sample of soil to the saturating influence of a given vapor or gas and measuring the amount thereof absorbed1 either directly by increase of weight1 or by the diminution in the amount of gas originally supplied4 ,the maximum absorbent capacity of a soil under given conditions for a gas or vapor is in this way determined4 ,in the second class the determination consists in accurately estimating the amount of gas which is absorbed by a soil in natural conditions or in situ1 thus giving the natural percentages of the gaseous constituents of the soil4 ,in the first case in general1 the principle of the method depends upon the exposure of the soil for a given time under given conditions1 to an atmosphere of the gas to be absorbed4 ,the principle of the second class of determinations depends upon the extraction1 usually by means of suction1 from a given mass of soil of the gaseous matters therein contained4 ,the general details of the methods of procedure for the first class are found in the following directions for manipulation3 #bhj4 ,determination of the ,maximum ,hygroscopic ,coefficient4--,the fine earth1 in ,hilgard's method1 is exposed to an atmosphere saturated with moisture for about twelve hours at the ordinary temperature 7#fj ,f47 of the cellar in which the box should be kept4 ,the soil is sifted in a layer of about one millimeter thickness upon glazed paper1 on a wooden table1 and placed in a small water-tight covered box1 twelve by nine by eight inches1 in which there is about an inch of water2 the interior sides and cover of the box should be lined with blotting paper1 kept saturated with water1 to insure the saturation of the air4 ,air-dried soil yields results varying from day to day to the extent of as much as thirty to fifty per cent1 nor have we any corrective formula that would reduce such observations to absolute measure4 ,knop's law1 that the absorption varies directly as the temperature1 while applicable to low percentages of saturation1 is wide of the truth when saturation is approached4 ,the ordinary temperature of cellars will serve well in these determinations without material correction4 ,after eight to twelve hours the earth is transferred as quickly as possible1 in the cellar1 to a weighed drying tube and weighed4 ,the tube is then placed in a paraffin bath2 the temperature gradually raised to #bjj ,c4 and kept there twenty to thirty minutes1 a current of dry air passing continually through the tube4 ,it is then weighed again and the loss in weight gives the hygroscopic moisture in saturated air4 ,the reason for adopting #bjj ,c4 as the temperature for drying instead of #ajj is that water will continue to come off from most soils at the latter temperature for an indefinite time1 a week or more1 before an approach to constancy of weight is attained2 and that up to #bjj only an arbitrary limit can be assigned for the expulsion of hygroscopic moisture4 ,moreover1 the great majority of soils1 especially those poor in humus1 will reabsorb moisture from a saturated atmosphere to the full extent of that driven off at #bjj ,c4 #bha4 ,estimation of the ,absorption ,power of ,soils for ,aqueous ,vapors4#aha--,method ,a4--,the fine earth1 ten to twenty grams1 is spread out on a surface of about twenty-five square centimeters1 and left for several days with the observation of the temperature of the air and the loss of weight determined from time to time4 ,this evaporation is continued until the weight remains practically constant4 ,afterwards by drying the sample at #ajj the amount of hygroscopic moisture is determined4 ,a similar result can be reached if the sample is first dried at #ajj1 or over sulfuric acid at ordinary temperatures1 and then the increase in weight observed which the sample acquires on being exposed for several days to the atmosphere under ordinary conditions4 ,soils with about the same content of humus show variations in the power to absorb aqueous vapors which are almost proportional to the amount of clay which they contain4 ,with the increase of humus substance1 the power of the soil for absorbing moisture is increased1 so that a sandy soil which is rich in humus often will retain as much moisture in an air-dried state as a clay soil which is poor in humus4 ,if the experiment is carried on by drying over sulfuric acid instead of at #ajj1 the sample should be left from four to seven days in order that a constant weight may be reached4 ,even after this time the loss in weight is #j4b to #a4e per cent less than when the sample is dried at #ajj4 ,method ,b4--,in order to determine the amount of aqueous vapor which a soil will absorb in an atmosphere saturated with the vapor the following method is used3 ,the sample of air-dried soil in a flat dish of given surface2 viz41 about twenty grams of soil to twenty-five square centimeters surface is placed in a vessel over water without contact with the water1 and the whole of the apparatus is covered with a glass bell-jar4 ,the sample is weighed at intervals of six or eight hours until no appreciable increase of weight is observed4 ,an empty vessel of the same size and character as that containing the soil is kept under the bell-jar1 also in the same conditions1 so that any increase in weight by the deposition of moisture on this vessel may be determined4 ,this increase in weight is to be deducted from the total increase in weight of the vessel and the soil4 ,sandy and loamy soils become saturated in this manner in the course of the first twenty-four hours and remain after that unchanged in weight4 ,very clayey soils1 and also those which are very rich in humus1 require a much longer time1 three or four days even4 ,in this case it is better to take a smaller sample of the soil2 viz41 ten grams4 ,the temperature of the air within the glass vessel1 of course1 must be taken into consideration4 ,method ,c4--,the same flat dish and the same quantity of soil as in the other methods are taken in this one4 ,the sample is left out over night where it can be fully saturated with dew4 ,the amount of dew which appears on the bushes should be noted and also the temperature of the air and the percentage of clouds in the sky4 ,an experiment should also be made on spots of earth which are entirely free from vegetation in order that the difference in the amount of water absorbed in places practically devoid of dew and in places where the dew is abundant may be observed4 ,method ,d4--,deeper flat dishes should be used for this determination so that the depth of soil contained in them shall be from one to three1 or even six centimeters4 ,the sample of soil should be completely air-dried and in a state of fine subdivision4 ,the vessels containing the soil should be placed in a locality saturated with aqueous vapor or in the open air during the night where they are subjected to the influence of the cooling of the atmosphere and the deposition of dew4 ,note should be made of the different amounts of moisture absorbed by the layers of earth of different thicknesses in a given time4 ,observation should also be made of the depth to which the moisture sinks in the sample of soil under consideration4 #bhb4 ,estimation of the ,absorption ,power of the ,soil for ,oxygen and ,atmospheric ,air4#ahb--;,from fifty to one hundred grams of air-dried soil are placed in a glass vessel of about #ejj cubic centimeters capacity1 and the flask closed with a stopper after the addition of enough water to make the percentage of moisture in the soil about twenty4 ,after from eight to fourteen days the air contained in the vessel is analyzed for oxygen1 nitrogen1 and carbon dioxid1 with special reference to the determination of how much oxygen has disappeared and how much the carbon dioxid has been increased4 ,as an alternative method1 twenty-five grams of the soil may be moistened with tolerably concentrated potash lye in a small glass vessel1 which is itself joined with air-tight connections to an azotometer in which a known volume of air is confined by quicksilver4 ,the glass vessel is frequently shaken during the progress of the experiment4 ,the diminution of the volume of air in the apparatus after from one to four days gives approximately the quantity of oxygen absorbed4 #bhc4 ,general ,method of ,determining ,absorption4--,this method1 due to ,freiherrn von ,dobeneck1#ahc is as follows3 ,the soil1 in a state of fine powder1 is dried at #ajj to #aje to a constant weight4 ,it is then placed in an absorption tube of the following construction3 ,the absorption tube consists of a shaped wide glass tube1 both ends of which are supplied with small glass tubes sealed upon the end of the tube1 and those are furnished with tightly-ground glass stop-cocks4 ,above these stop-cocks these small tubes are bent in opposite directions at right angles4 ,on the bend of the is sealed another tube which is furnished with a ground glass stopper4 ,through this opening the tube can be filled with the sample of soil4 ,when the tube is filled1 the glass stopper inserted1 and the two stop-cocks on the small tubes closed1 the contents of the tube are completely excluded from the external atmosphere4 ,many of these tubes can be used at once so as to hasten the progress of the work4 ,the tubes after being filled are placed in a drying oven with the stop-cocks open4 ,the stop-cocks are then closed before the tubes are removed1 when they are placed in a desiccator for cooling preparatory to weighing4 ,the weighed tubes are held in a tin box which can be placed in a water-bath which is kept at a given temperature by means of a thermostat4 ,the top of the tin box should be hinged and made of a thick non-conducting material so as to prevent any rapid change of temperature within4 ,on the inner side of the box a small thin-walled glass tube is carried around four times4 ,one end of this tube passes through an opening in the side of the box by means of which it can be connected with the gas apparatus outside4 ,the other end of it is connected directly with the absorption tubes4 ,the absorption tubes are so connected among themselves that when ammonia or carbon dioxid is employed the gas passes through one of the tubes before it can reach the next1 and so on4 ,for experiments with water-gas1 however1 that is1 air charged with aqueous vapor1 the arrangement must be different4 ,while in the case of ammonia and carbon dioxid the composition of the gas is not changed by passing through the samples of soil1 the case is quite different when air charged with aqueous vapor passes through4 ,in the latter case the amount of aqueous vapor in the air would be notably lessened in passing from sample to sample on account of the retention of a part of the aqueous vapor by the soil4 ,in this case1 therefore1 the saturated air1 after it has passed through the glass tube around the inside of the box in order to reach the proper temperature1 is conducted into a receptacle of glass which has a number of connections equal to the number of absorption tubes so that the saturated air can pass directly into each one of them4 ,the gases which are to be used for the experiments are prepared in proper apparatus and are forced through the samples of soil1 either by pressure as in the case of ammonia or carbon dioxid1 or by means of aspirators as in the case of air saturated with aqueous vapor4 ,the carbon dioxid employed is purified by passing over sodium carbonate and calcium chlorid4 ,the ammonia is prepared by the action of finely powdered lime on ammonium chlorid1 and is dried by passing over lime and sticks of potassium hydroxid4 ,the air which is to be saturated with aqueous vapor1 in order to purify it from dust1 carbon dioxid1 and ammonia1 is passed through two flasks in which are contained respectively1 diluted sulfuric acid and potash lye4 ,it is afterwards thoroughly saturated with aqueous vapor at the temperature desired4 ,various kinds of soil material may be employed as follows3 7#a7 ,pure quartz sand4--,freed from all fine particles by subjection to silt analysis1 afterwards boiled with hydrochloric acid and washed with water to free it from all clayey materials4 ,the sand prepared in this way should be passed through different sieves in order to prepare it in different states of fineness4 7#b7 ,quartz powder4--,prepared from pure quartz crystals by grinding in an iron mortar4 7#c7 ,kaolin4--,material such as is used in the manufacture of the finest porcelain which1 after being freed of all foreign matter1 is rubbed to a fine powder in a porcelain mortar4 7#d7 ,humus4--,washed with ether and alcohol1 boiled with hydrochloric acid1 washed1 dried and reduced to a state of fine powder4 7#e7 ,iron oxid4 7#f7 ,calcium carbonate4--,precipitated1 washed1 and dried4 7#g7 ,soil mixtures4--,prepared artificially by mixing the kaolin1 quartz1 and humus1 above mentioned4 ,the quantity of gas absorbed by each of these materials is determined by filling the tubes1 as above mentioned1 with the dried material4 ,the content of each tube is previously determined by filling with mercury and weighing4 ,having determined the weight of the substance to the exclusion of the air contained within its pores1 it is treated with the gas in the apparatus described above and weighed from time to time until no further increase of weight takes place4 ,the method of calculating the results is shown in the following scheme3 ,v content of the absorption tube obtained by filling with mercury and weighing4 ,p weight of the empty tube filled with air at #ajj4 pl weight of the air in the tube 7pl ,v specific gravity of the air at #ajj74 pt weight of the tube 7pt ,p pl74 ,p 7second weighing7 weight of the tube filled with the substance with the included air at #ajj4 vs volume of the substance calculated according to the formula vs 7,p ,p7_/7ss specific gravity of air74 ss specific gravity of the substance4 vl volume of the air in the flask filled with the substance 7vl ,v vs74 pl 7weight of this included air7 vl specific gravity4 ps weight of the substance 7pl p pt pl7 ,p weight of the apparatus at the end of the experiment4 sg specific gravity of the gas employed for saturation4 pg 7weight of the gas remaining over the substance7 vl sg4 pa 7weight of the absorbed gas7 ,p pt ps pg4 ps gram of substance absorbs pa gram of the gas and #ajj grams of substance would absorb 7#ajj pa7_/7ps7 grams4 ,the specific gravities of the gases employed are calculated from the tables given by ,landolt and ,brnstein in 8,physical and ,chemical ,tables10 page #e4 ,the specific gravity of the quartz sand employed was #b4fci2 of the quartz powder1 #b4fbb2 of the kaolin1 #b4ejc2 of the humus1 #a4dfb2 of the iron hydroxid1 #c4gbh2 and of the calcium carbonate1 #b4fgh4 ,one liter of ammonia1 at a pressure of #gfj millimeters of mercury and a temperature of #j1 weighs #j4gfaf gram2 one liter of carbon dioxid1 #a4igha grams2 one liter of aqueous vapor1 #j4hjfd gram2 and one liter of dried air1 #a4bica grams4 ,at a pressure of #gbj millimeters1 and at #bj temperature1 a liter of air saturated with aqueous vapor at #j weighs #a4achc grams2 saturated at #h4f1 #a4acfb grams2 saturated at #aj1 #a4aceh grams2 saturated at #ad1 #a4acdj grams2 saturated at #ah4b1 #a4accj grams2 saturated at #bj1 #a4acba grams2 saturated at #cj1 #a4acac grams4 ,the general results of the experiments are as follows3 ,,absorption ,,at #j4 ,aqueous vapor ,ammonia4 ,carbon dioxid4 from saturated air4 ,grams4 ,cubic ,grams4 ,cubic ,grams4 ,cubic cm4,h cm4,h cm4,h #ajj grams quartz #j4aei #aig #j4ajg #ade #j4jbc #ab kaolin #b4eeh #c1agb #j4gba #idg #j4cbi #aff humus #ae4ijd #ai1gbb #ah4deb #bd1bbh #b4eja #a1bfc ,fe7,,oh7 #ae4eab #ai1bcf #d4jjd #e1bge #f4ige #c1ebf ,ca,c,o #j4bbd #bgh #j4bef #cbj #j4jbh #ad ,footnote ,h3 ,reduced to #j and #gfj millimeters pressure mercury4 ,the foregoing methods will suffice to show the procedures to be followed in estimating the maximum amount of any common gas or vapor a given quantity of soil may be made to absorb4 ,we pass next to consider the quantities of gases or vapor soils in situ may hold4 #bhd4 ,method of ,boussingault and ,lewey4#ahd--,this method is the oldest and most simple procedure for estimating the nature of the gases held in a soil in situ4 ,for the purpose of collecting the sample of gas from the soil a hole1 thirty to forty centimeters in depth1 is dug1 and a tube placed in it in a vertical position1 having on its lower extremity a bulb perforated with fine holes4 ,the hole is filled and the earth closely packed around the tube which is left for twenty-four hours4 ,at the end of that time the tube is slowly aspirated until a volume of gas approaching from five to ten liters is obtained4 ,estimation of ,carbon ,dioxid4--,the carbon dioxid in the sample of gas is estimated by allowing it to bubble through a solution of barium hydroxid4 ,estimation of the ,oxygen4--,the oxygen is estimated in a separate sample of the gas by means of potassium pyrogallate4 ,the chief objection to this simple process is the uncertainty of being able to obtain an average sample of the occluded gas4 ,in digging the hole and refilling1 there must evidently be a considerable disturbance of the original distribution of the gas or vapor4 ,the methods of ,pettenkofer#ahe and ,aubry#ahf are essentially like that just described4 ,pettenkofer found the largest quantities of carbon dioxid in the earth gases in ,july1 ,august1 and ,september1 and the smallest quantities in the winter months4 ,no greater detail concerning these methods of the direct aspiration of the air is considered necessary inasmuch as the methods about to be described1 while more elaborate1 are superior in accuracy to the older methods mentioned4 ,in general1 in these experiments1 it is deemed sufficient to determine the carbon dioxid only4 ,illustration3 ,,figure #fb4 ,,schloesing',s ,,soil-,,tube ,,for ,,collecting ,,gases4 #bhe4 ,method of ,schloesing4--,the apparatus used by ,schloesing#ahg in the collection of the soil gases consists of a steel tube 7,fig4 #fb7 a little over one meter in length1 ten millimeters in external diameter1 and one and one-half to two millimeters in internal diameter4 ,the end which penetrates the soil is made slightly conical for a distance of twenty-five to thirty centimeters4 ,by reason of the shape of the tube1 when it is driven into the soil all connection between the orifice in the point of the tube and the external air is prevented4 ,the obstruction of the internal canal of the tube is prevented by introducing a thread of steel which penetrates the whole length of the tube4 ,this thread1 represented by ,a1 ,b1 ,c1 ,d1 is flush with the interior extremity of the tube at ,d4 ,it extends for about three centimeters above the upper end of the tube in order to be easily handled when it is to be removed4 ,for the purpose of driving the tube into the soil its upper part is covered with a cylindrical piece of steel1 ,,ef1 in the interior of which are freely engaged ,h and ,a4 ,this head piece rests upon a ring of steel1 ,k4 ,this ring is fastened solidly into the tube4 ,on striking the piece ,,ef the tube and the steel wire in the center are driven together into the soil4 ,the tube is flattened at ,l and ,l in order to be embraced by the key ,,mm1 the employment of which is necessary in order to revolve the tube around its axis when it is being driven into the soil4 ,when the tube has been driven to the depth desired1 the steel wire is withdrawn and it is immediately connected at ,h with the rubber tube ,n 7,fig4 #fc7 belonging to the system ,,pqt1 and furnished with a pinch-cock ,x4 ,the system ,,pqt comprises the following elements3 ,,pqt made of a capillary glass tube in the form of a ,t4 ,the lower end of the tube ,p is closed by the larger glass tube ,o1 sealing the end of ,p with a little mercury4 ,o is held to ,p by the cork ,s1 which is attached firmly enough to prevent ,o from dropping off1 but is furnished with a canal in order to allow the air to flow in or out freely4 ,this system is connected with the system ,,uv by the rubber connection ,t4 ,u is a glass vessel having the constrictions as indicated in its stem above and below the bulb4 ,v is a glass vessel of convenient size connected with ,u by the rubber tubing as indicated4 ,the capacity of the cylindrical portion of ,u should be from fifteen to eighteen cubic centimeters4 ,illustration3 ,,figure #fc4 ,,schloesing',s ,,apparatus ,,for ,,collecting ,,gases ,,from ,,soil4 ,to take a sample of soil gas1 ,v is lifted above ,u4 ,the air is driven from ,u and escapes through ,o1 which acts as a true valve4 ,when the mercury has completely filled ,u the pinch-cock ,x is opened and ,v depressed gradually4 ,the gas coming from the soil is thus collected in ,u4 ,a few cubic centimeters of the soil gas are collected in this way1 the pinch-cock ,x is again closed and ,v is raised in order to drive the whole of the contents of ,u again through ,o4 ,in this way the whole of the air which the capillary vessel originally contained is removed and all parts of it remain filled with soil gas4 ,two or three operations1 using from five to ten centimeters of soil gas in all1 will be sufficient to completely free the apparatus from its original content of air4 ,u is then entirely filled by depressing ,v1 and it is then hermetically sealed at the two constricted points by means of an alcohol lamp4 ,the sealed tube can then be transported to the laboratory and its contents subjected to eudiometric analysis4 ,without displacing the tube from the soil1 several samples of gas can be taken from the same spot4 ,a sufficient number of the bulbs ,v should be at hand to hold the required number of samples4 ,instead of submitting the sample to eudiometric analysis it is usually sufficient to determine the quantity of carbon dioxid which it contains1 inasmuch as numerous experiments have shown that in #ajj parts of soil gas the oxygen and carbon dioxid together constitute twenty-one parts4 ,no appreciable trace of marsh gas1 or other combustible gas1 has yet been detected in ordinary arable soils4 ,these gases have only been found in special soils from marshes1 in the neighborhood of gas wells1 etc41 and not in arable soils4 ,illustration3 ,,figure #fd4 ,,schloesing',s ,,apparatus ,,for ,,determination ,,of ,,carbon ,,dioxid4 #bhf4 ,apparatus for ,estimating the ,carbon ,dioxid4--,the apparatus used for determining the carbon dioxid in ,schloesing's work consists of the apparatus shown in ,fig4 #fd4 ,a represents a glass vessel surrounded by a jacket of glass1 full of water1 and sealed on its lower part to the tube ,,bc of about six millimeters internal diameter4 ,on its upper part it is sealed to the capillary tube ,d4 ,the tube ,,bc is graduated from ,c in hundredths of the volume of ,,dac1 which volume is about twelve cubic centimeters4 ,on its lower part it is connected by a rubber tube with a reservoir ,f which is capable of being raised or lowered4 ,,ghk are capillary tubes connected together by the rubber tubes ,l and ,m1 which are furnished with pinch-cocks4 ,the tube ,g is connected to a vacuum by the rubber tube ,n4 ,the rubber tube should be of very small internal diameter and from forty to fifty centimeters in length4 ,to the tube ,h are sealed1 at right angles1 the branch ,d and another branch ,o4 ,this last dips into a little mercury which the tube ,p contains4 ,it serves as a valve1 permitting the exit of the gases but not their entrance4 ,the tube ,k carries some lines engraved on its inferior part and is sealed to the system of the two bulbs ,q and ,r4 ,the bulb ,q contains a concentrated solution of potash4 ,it carries a number of pieces of glass tubing for the purpose of increasing the surface of the potash solution4 ,all the parts of the apparatus are fixed upon a rectangular board1 nineteen centimeters broad by twenty centimeters long4 ,this forms one of the faces of a wooden box to which it is hinged and which serves for the transportation of the apparatus in a vertical position4 ,the graduation of the tube ,,bc is recorded behind this tube upon a card fixed upon the board4 ,by means of these two graduations1 the height of the mercury in the tube ,,bc is most easily read1 even when the tube is not perfectly vertical4 ,each one of the pinch-cocks ,l and ,m1 on its upper part is fixed in a sort of guard which prevents it from being displaced laterally during the processes of the manipulation1 thus avoiding all danger of breakage4 ,after the operation is finished a little air is sent into ,q in such a manner as to sensibly lower the level of the solution of potash1 and the upper extremity of ,r is closed with a rubber stopper4 ,afterward1 the apparatus can be transported without any danger of the potash becoming engaged in the tube ,k and reaching the measuring tank ,a4 ,to proceed to the analysis1 a stake is driven into the soil to which all of the apparatus can be fixed4 ,at the side of the stake the apparatus for taking the sample1 already described1 is driven into the soil and this apparatus is connected by the tube ,n with the apparatus for determining the carbon dioxid4 ,the pinch-cocks ,l and ,m being closed1 ,f is lifted until the mercury which runs from it fills ,a and approaches ,d4 ,during this time the air which the apparatus contains has been driven out through ,o4 ,the tube ,,ngd is freed from air by opening the pinch-cock ,l1 lowering ,f and drawing into ,a the gas coming from the soil2 afterward closing ,l and driving out the gas through ,o4 ,after two or three rinsings of this kind1 which employ altogether only ten to twelve cubic centimeters1 the gas which is to be analyzed is sucked into ,a4 ,for this purpose ,f is lowered until the mercury in the tube ,,bc is very near ,c4 ,the pinch-cock ,l is closed and ,m opened4 ,the reservoir ,f is displaced little by little by pressing lightly against the rectangular board in order to give it greater firmness in such a way as to fix the level of the mercury exactly at ,c1 and the line is noticed where the solution of potash in ,k stands4 ,the gas contained in the apparatus is under a pressure1 the difference of which from the external pressure is represented by the column of the potash solution between the mark just noticed and the level of the same solution in the bulb ,r4 ,in order to absorb the carbon dioxid1 ,f is lifted until the mercury stands between ,d and ,e4 ,the gas thus passes from ,a into ,q4 ,it gives up immediately its carbon dioxid to the potash solution4 ,it is then made to come again into ,a1 and afterward a second time into ,q in order to free it from the last trace of dioxid4 ,finally it is made to return to ,a and ,f is kept at such a height that the potash solution maintains in the tube ,k the same level as at the commencement of the operation4 ,the gas is then at the same pressure to which it was subjected before absorption4 ,the level of the mercury is then read on ,,bc4 ,at the time the apparatus is used1 the measuring tube ,a should be slightly moist4 ,if it is not so1 a small quantity of water should be introduced which is afterward rejected1 but which leaves a sufficient quantity of moisture upon the internal walls of ,a4 ,in this way the gas will always1 before or after absorption of carbon dioxid1 be saturated with vapor of water1 and the figure read in the last place upon the tube ,,bc represents the percentage of carbon dioxid in #ajj parts of the gas extracted from the soil supposed to be saturated with vapor at the temperature of the experiment4 ,during the course of the analysis1 the temperature of the measuring flask1 which is almost entirely surrounded with water1 does not vary sensibly1 but in a series of experiments which are executed at different times1 the temperature of the measuring apparatus1 which is that of the ambient air1 may change much4 ,it may oscillate between #aj to #be1 and exceptionally between #j and #cj1 whence there are notable variations in the tension of the vapor of the gas measured4 ,if it should be desired to calculate to #ajj parts of dry gas the observations made at #cj upon #ajj parts of saturated gas1 it would be necessary to increase the percentage of carbon dioxid by about of its value4 ,it is noticed that with the apparatus described above1 the gas upon which the estimation is really conducted comprises not only that which the measuring apparatus contains from ,e to ,c before the absorption of the carbon dioxid1 but also the small quantity which remains in the capillary tube ,,kme at the moment when closing the pinch-cock ,m1 after the second rinsing1 the gas from the soil is aspired into ,,eac4 ,on the other hand1 there is left in the same tube ,,kme1 when the final reading is made1 some gas which belongs to that which has been measured at the end4 ,these two small gaseous portions which we consider in the tube ,,kme to be sensibly equal1 do not contain any carbon dioxid and may be left out of consideration4 ,that is why the volume of the measuring apparatus is limited to ,e and the graduation of the tube ,,bc is in hundredths of the volume comprised from ,e to ,c4 ,in reality the two portions are not absolutely equal because the two successive levels of the potash solution1 which limit them in the tube ,k1 are not absolutely identical4 ,these two levels can differ in such a manner as to correspond to a volume of about of the measuring apparatus4 ,thus the estimation is really made upon a volume of gas which may be greater or less by than the volume of ,,eac2 whence there might result an error of in the estimation of the carbon dioxid1 an error which is wholly negligible4 ,as a result of numerous analyses it is concluded1 first1 that the oxygen exists normally in the atmosphere of soils in large proportion2 second1 very probably the gaseous atmosphere of arable soils1 to a depth of sixty centimeters1 contains scarcely one per cent of carbon dioxid and about twenty per cent of oxygen2 third1 the highest percentages of carbon dioxid correspond to epochs of highest temperature and periods of greatest calm2 fourth1 the proportion of carbon dioxid increases ordinarily with the depth at which the samples are taken4 ,this disposition of the carbon dioxid would appear almost necessary1 since near the surface the internal atmosphere is almost constantly diluted by external air by virtue of diffusion4 ,fifth1 from one epoch to another the composition of the atmosphere of the soil can undergo considerable variation4 #bhg4 ,determination of ,diffusion of ,carbon ,dioxid in ,soil4--,the method proposed by ,hannn#ahh is a convenient one to use in studying the rate of diffusion of carbon dioxid in soils4 ,a large ,woulff's bottle with three necks serves for the reception of the gas4 ,the two smaller outer necks of the bottle carry two glass tubes bent outwards and provided with stop-cocks4 ,one of these passes to near the bottom of the bottle and the other just through the stopper4 ,the middle tubule of the bottle is of a size to give in section an area of about twenty-two square centimeters4 ,it is made with a heavy rim two centimeters wide and plane ground4 ,this rim carries a plane-ground glass plate with a circular perforation in one-half of it1 of the size of the opening in the central tubule of the bottle4 ,a glass cylinder1 carrying a fine wire-gauze diaphragm near the lower end1 fits with a ground-glass edge air-tight1 over this aperture1 being held in position by a brass clamp4 ,the ground-glass plate moves air-tight between the cylinder and the bottle1 so that the cylinder can be brought into connection with the bottle or cut off therefrom without in any way opening the bottle to the air4 ,the plate and all ground movable surfaces should be well lubricated with vaseline4 ,the experiment is carried on as follows3 ,the glass cylinder is filled with the soil to be tested1 closed above with a rubber stopper carrying a gas tube1 and then by moving the perforated-glass plate brought into connection with the bottle4 ,the side tube1 with short arm inside the bottle1 is then closed1 and carbon dioxid introduced through the other lateral tube until the gas passing from the tube at the top of the cylinder is pure carbon dioxid4 ,the lateral tube is then closed and the bottle is placed in a water-bath and kept at a constant temperature of #bj4 ,when the temperature within and without the apparatus is the same the reading of the barometer is made1 the stopper removed from the top of the cylinder1 and the process of diffusion allowed to begin4 ,after from six to ten hours the glass plate is moved so as to break the connection between the cylinder and bottle4 ,the carbon dioxid remaining in the bottle is driven out by a stream of dry1 pure air4 ,the air is allowed to pass through the apparatus for about ten hours4 ,the carbon dioxid driven out is collected in an absorption apparatus and weighed4 ,the absorption apparatus should consist of a series of ,geissler potash absorption bulbs and finally a form soda-lime tube4 ,in front of the absorption apparatus is placed a drying bulb containing sulfuric acid4 ,inasmuch as the temperature and pressure can be readily determined1 the weight of carbon dioxid obtained is easily calculated to volume4 ,the weight of #a1jjj cubic centimeters of carbon dioxid at #j and #gfj millimeters pressure is #a4ifejc grams4 ,therefore one milligram is equivalent to #j4ejhi cubic centimeter of the gas4 ,the volume of the bottle should be carefully determined by calibration with water4 ,the results should be calculated to cubic centimeters per square centimeter of exposed surface in ten hours4 ,the depth of the soil layer is conveniently taken at twenty centimeters4 #bhh4 ,statement of ,results4-- ,,the ,,soil ,,packed ,,loosely ,,in ,,the ,,diffusion ,,tube4 ,,diffusion ,,time1 ,,ten ,,hours4 ,diameter of ,weight of ,pure carbon ,carbon dioxid ,cubic soil soil taken1 dioxid at at end of centimeters particles1 grams4 beginning of experiment1 of carbon millimeters4 experiment1 cubic cm4 dioxid cubic cm4 diffused for each square cm4 #j4ja-j4jga #ebj #bedi4d #abcj4c #ei4i #j4jga-j4aad #eej #bede4i #abfi4b #eh4j #j4aad-j4aga #eij #beef4d #aced4b #ed4f #j4aga-j4bej #fbj #bech4i #accf4a #ed4f #j4bej-j4ejj #ffj #becb4j #acgd4e #eb4f #j4ejj-a4jjj #fhj #bebh4b #addj4b #di4e #a4jjj-b4jjj #fij #bdif4f #acif4i #ej4j ,mixture of #gbj #bead4c #aegb4e #db4h the above ,in greater detail the calculation and statement of the results may be illustrated by the following data3 ,in the first experiment given in the above table the diameter of the soil particles varied from #j4jaj to #j4jga millimeter4 ,the weight of soil in the diffusion tube was #ebj grams4 ,the volume of gas1 at #j and #gfj millimeters1 before the diffusion began was #bedi4d cubic centimeters4 ,the volume of carbon dioxid under standard conditions remaining after ten hours of diffusion was #abcj4c cubic centimeters4 ,this volume is calculated from the weight of carbon dioxid obtained in the potash bulbs1 each milligram being equal to #j4ejhi cubic centimeter of carbon dioxid4 ,the volume of carbon dioxid diffused is therefore #bedi4d #abcj4c #acai4a cubic centimeters4 ,the per cent of carbon dioxid diffused is #acai4a #bedi4d #ea4gd4 ,the volume of carbon dioxid diffused for each square centimeter of cross section of the diffusion tube is #acai4a #bb #ei4i cubic centimeters4 ,the carbon dioxid should be passed long enough to secure complete expulsion of the air before the determination is commenced4 #bhi4 ,general ,conclusions4--,the general results of the experiments with the diffusion apparatus to determine the effect of the physical condition of the soil upon the rate of diffusion are as follows3 #a4 ,the diffusion of carbon dioxid through the soil is1 at a constant temperature1 chiefly dependent upon the pores in the cross section of the column of soil4 ,therefore1 the absolute quantity of the diffused gas is greater the larger the total volume of the pores and vice versa4 #b4 ,every diminution of the volume of the pores1 whether secured by pressure of the soil or by an increase in the moisture thereof1 is followed by a decrease in the volume of diffused gas4 ,the giving up of the carbon dioxid present in the soil atmosphere to the upper atmosphere by the method of diffusion is therefore the less the finer the soil is1 the more compressed the soil particles are1 and the larger the water capacity of the sample and vice versa4 #c4 ,the quantity of diffused carbon dioxid is diminished according to the measure of compression to which the soil is subjected but is not strictly proportional to the height of the soil layer4 #d4 ,in soils in which rain water percolates slowly the diffusion of the carbon dioxid on account of this property is depressed to a greater or less extent4 ,,authorities ,,cited ,,in ,,part ,,fifth4 ,footnote #agi3 ,proceedings of the ,american ,association for the ,advancement of ,science1 #ahgb1 p4 #cbh4 ,footnote #ahj3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 #ahhi1 ,s4 #aig4 ,footnote #aha3 ,knig1 ,untersuchung ,landwirtschaftlich und ,gewerblich ,wichtiger ,stoffe1 ,ss4 #fd-ff4 ,footnote #ahb3 ,knig1 op cit4 supra4 ,footnote #ahc3 ,forschungen auf dem ,gebiete der ,agricultur-,physik1 ,band #ae1 ,s4 #aij4 ,footnote #ahd3 ,annales de ,chimie et de ,physique1 ,tome #cg1 #ahec2 ,encyclopedie ,chimique1 ,tome #d1 p4 #aed4 ,footnote #ahe3 ,zeitschrift fr ,biologie1 ,band #g1 ,s4 #cie and ,band #i1 ,s4 #bej4 ,footnote #ahf3 ,jahresbericht fr ,agriculturchemie1 ,band #a1 ,s4 #afj4 ,footnote #ahg3 ,annales de ,chimie et de ,physique1 #ahia1 ,sixime ,srie1 ,tome #bc1 pp4 #cfb1 et seq4 ,footnote #ahh3 ,op4 cit4 #e1 #ahib1 ,ss4 #h1 et seq4 ,,part ,,sixth4 #bij4 ,preliminary ,considerations4--,the sample of soil intended for chemical analysis should consist of the fine earth which has passed at least a one-millimeter mesh sieve and subsequently been completely air-dried4 ,according to ,petermann the air-drying of a soil should continue for about four days for an ordinary arable soil1 and about six days for one very rich in organic matter4 ,with peat and muck soils ,i have found that ten or twelve days with frequent stirring1 even when in thin layers1 are necessary to attain approximately a constant weight4 ,the soil is conveniently spread on a zinc or other metal sheet of sufficient area so that the layer will be only one or two centimeters in thickness4 ,the weight before and after desiccation will give the percentage of moisture lost on air-drying1 which1 of course1 will depend chiefly on the degree of saturation of the sample when taken and the atmospheric conditions prevailing during drying4 ,if samples of soil are taken in very dry times it is often necessary to moisten them with distilled water in order to prepare them properly for air-drying4 ,the quantity of hygroscopic water which the sample loses at #ajj-aje should be determined1 and all subsequent calculations of the percentages of the various constituents be based on the water-free material4 ,when a soil which has been dried at #ajj-aje to a constant weight is heated to #adj-aej it loses additional weight not due to loss of water of constitution4 ,a part of this loss may be due to hygroscopic moisture which is not given off at #ajj-aje1 and a part may be hydrocarbons1 or other easily volatile organic or inorganic bodies4 ,before estimating the total loss on ignition it is recommended by most chemists to dry at #adj-aej4 ,the samples of soil1 however1 intended for chemical examination should never be dried beyond the point which is reached by exposure in thin layers at ordinary room temperatures4 ,the state of aggregation1 degree of solubility1 and general properties of a soil1 may be so changed by absolute desiccation as to render the subsequent results of chemical investigation misleading4 ,in the methods which follow the actual processes employed have been given1 which in some instances transgress the general principle stated above1 but in all cases standard and approved methods are given in detail1 even if some of their provisions seem unnecessary or imperfect4 #bia4 ,order of ,examination4--,first of all in a chemical study of the soil should be determined1 its reaction 7with litmus71 its water-holding power in the air-dried state 7hygroscopicity71 its content of combined water 7giving hydrous silicates of alumina71 its organic matter 7humus and organic nitrogen71 its content of carbon dioxid 7carbonates of the alkaline earths71 and the part of it soluble in acids4 ,a determination of these values gives the analyst a general view of the type of soil with which he is engaged1 and leads him to adopt such a method of more extended analysis as the circumstances of the case may demand4 ,for this reason those operations which relate to the above determinations are placed first in the processes to be performed1 while the estimation of the more particular ingredients of the soil is left for subsequent elaboration4 ,next follows a description of the standard methods of estimating the more important elements passing into solution on treatment of a soil sample with an acid4 ,the method of treating the insoluble residue1 and the detection and estimation of rare or unimportant soil constituents1 closes the analytical study of the soils4 ,with respect to the determination of nitrogen as nitric or nitrous acid in the soil and drainage waters1 it has been thought proper to collect all standard methods relating particularly thereto into one group1 and they will appear separate from the methods under nitrogen analysis in fertilizers4 ,the question of the utility of chemical soil analyses is one which has been the subject of vigorous discussion1 a discussion which finds no proper place in a work of this character4 ,unless1 however1 intelligent soil analysis be productive of some good it would be a thankless task to collect and arrange the details of the processes employed4 ,an accurate determination of the constituents of a soil may not enable the chemist to recommend a proper course of treatment1 but it will help in many ways to develop a rational soil diagnosis which will permit the physician in charge of the case1 who last of all is the farmer1 to follow a rational treatment which in the end will be productive of good4 ,the analyst will find in the methods given all that are approved by bodies of official or affiliated chemists1 or by individual experience1 and among them some method may be found which1 it is hoped1 will be suited1 in the light of our present knowledge1 to each case which may arise4 #bib4 ,reaction of the ,soil4--,in soils rich in decaying vegetable matter the excess of acid is often great enough to produce a distinct acid reaction4 ,on the contrary1 in arid regions the accumulation of salts near the surface may produce the opposite effect4 ,the reaction of the soil may be determined with a large number of indicators among which1 for convenience1 sensitive litmus paper1 both red and blue1 stand in the front rank4 ,a sample of the soil1 from fifteen to thirty grams1 is mixed with water to a paste and allowed to settle4 ,the litmus paper is then dipped into the supernatant liquid4 #bic4 ,determination of ,water in ,soil4--,the following problems are presented3 7a7 ,the ,determination of ,water in ,fresh ,samples taken in situ4--,the content of water in this case varies with the date and amount of rain-fall1 the capacity of the soil for holding water1 the temperature and degree of saturation of the atmosphere1 and many other conditions1 all of which should be noted at the time the samples are taken4 7b7 ,the ,determination of ,water in ,air-,dried ,samples4--,in this case the soil is allowed to remain in thin layers1 and exposed to the air until it ceases to lose weight4 ,the quantity of water left is dependent on the capacity of the soil to hold hygroscopic water and to the temperature and degree of saturation of the air4 7c7 ,the ,determination of the ,total ,water by ,ignition4--,this process not only gives the free and hygroscopic moisture1 but also combined water present in the hydrous silicates and otherwise4 ,the estimation is complicated by the presence of carbonates and organic matter4 #bid4 ,determination of ,water in ,fresh ,samples4--,this determination requires that the sample1 when taken in the field1 should be so secured as to be weighed before any loss of moisture can take place4 ,for this purpose it can be sealed up in tubes or bottles and preserved for examination in the laboratory4 ,according to ,whitney1 the relations of soils to moisture and heat are such prominent factors in the distribution and development of agricultural crops1 that the determination of the actual moisture content of soils in the fields should be considered a necessary part of the meteorological observations1 and of far more importance1 indeed1 or having far more meaning to the agriculturist than the simple record of the rain-fall4 ,in order to determine the relation of the soil to moisture1 uninfluenced by the varying conditions of cultivation and of the different size of crop1 he recommends that a small plot of ground be reserved at each station1 adjacent to the soil thermometers1 where the samples may be taken for the moisture determinations4 ,no crops should be allowed to grow on this area and the soil is not to be disturbed1 except that weeds and grass are carefully removed by hand when necessary4 ,samples of the soil should be taken every morning at #h o'clock1 by correspondents in the principal soil formations from the different parts of the area under observation1 and sent by mail to the laboratory4 ,the samples should be taken as described in paragraph #fe4 ,the locality and date are written on a label attached to the tube4 ,the tube contains about sixty or seventy grams of soil1 and the moisture determination is made on this in the laboratory in the usual way4 ,it would be desirable to have this sample represent a depth of from six to nine inches1 thus rejecting the surface three inches which are more liable to sudden and accidental changes4 ,these tubes are very inexpensive1 and a sufficient number should be purchased to keep each station supplied4 ,the sample represents a definite depth1 and it does not have to be subsampled or even transferred in the field4 ,this record of the moisture of the soil will show the amount of moisture which the different soils can maintain at the disposal of the plants1 which1 together with the temperature of the soil1 is believed to be a most important factor in crop distribution and development4 #bie4 ,method of ,berthelot and ,andr4--,the estimation of the water according to ,berthelot and ,andr#ahi should be made under three forms2 viz41 #a4 ,water eliminated spontaneously at ordinary temperatures4 #b4 ,water eliminated by drying to constant weight at #aaj4 #c4 ,water eliminated at a red heat4 ,the water may be determined directly on a sample weighed at the time of taking and afterwards dried in the open air1 and finally1 if necessary1 in a desiccator4 ,for a general idea the desiccation should be made on a sample of #ajj grams1 for exact work on ten grams4 ,the dish in which the drying takes place should be shallow1 and during the time the sample should be frequently stirred and thoroughly pulverized with a spatula which is weighed with the dish4 ,the drying in the air should continue several days4 ,the data obtained are not fixed since they depend on the temperature and the degree of saturation of the air with aqueous vapor4 ,the variations due to these causes1 however1 are not very wide4 ,the process may be regarded as practically finished when successive weights sensibly constant are obtained4 ,in this state the soils contain very little water eliminable at #aaj4 #bif4 ,estimation of ,water ,remaining after ,air-,drying4--,the sifted sample is placed in quantities of five or ten grams in a flat-bottomed dish and dried at #aaj to constant weight4 ,this treatment not only removes the moisture1 but all matters volatile at that temperature4 ,petermann1#aij in the ,agricultural ,station1 at ,gembloux1 practices drying the sample to constant weight at #aej4 ,it is further recommended by ,petermann to determine total volatile and combustible matters by igniting to incipient redness1 allowing to cool1 moistening with distilled water1 and drying at #aej4 ,the ,german experiment stations#c estimate hygroscopic moisture for analytical calculations by drying to constant weight at #ajj4 ,in determining loss on ignition1 however1 the preliminary drying is made at #adj1 with the exception of peaty samples where so high a temperature is not admissible4 ,the ,official ,agricultural ,chemists#aia place five grams of air-dried soil in a flat-bottomed and tared platinum dish2 heat in an air-bath to #aaj for eight hours2 cool in a desiccator1 and weigh2 repeat the heating1 cooling1 and weighing1 at intervals of an hour till constant weight is found1 and estimate the hygroscopic moisture by the loss of weight4 ,weigh rapidly to avoid absorption of moisture from the air4 ,in the ,german laboratories1 according to ,knig1#aib from ten to twenty grams of the fine earth1 properly prepared by air-drying and sifting1 for analysis1 are heated at #ajj to constant weight4 ,for control1 five grams are placed in a desiccator over sulfuric acid for two or three days4 ,wolff directs that a small portion of the well-mixed earth1 for example1 twenty grams1 be spread out on a flat zinc plate1 and its changes in weight observed through several days4 ,these observations are continued until the variations are so slight that the means can be determined with sufficient exactness from the last weighings4 ,the soil is then dried at #abe in a hot air-chamber4 ,the loss in weight will give the mean hygroscopic moisture in the soil under the conditions in which the experiment is made4 #big4 ,drying in a ,desiccator4--,the sample dried as indicated previously by the method of ,berthelot and ,andr is placed in a desiccator over sulfuric acid4 ,it is better to have the sample traversed by a current of perfectly dry air1 and in this case it should be placed in a tube1 which is closed while weighing1 to prevent absorption of moisture4 ,much time is also required for this operation1 and it does not possess the practical value of the method of drying in the free air4 #bih4 ,water ,set ,free at #aaj4--,this is determined by ,berthelot and ,andr on a weight of five to ten grams of soil4 ,the sample which has been employed for the preceding determination may be used4 ,while this is going on in an air-bath heated to #aaj1 about ten times as much soil should be dried for the same time at the same temperature1 and this should be preserved in a well-stoppered flask4 ,all subsequent determinations are to be made with the soil dried at #aaj4 ,the loss of weight in a soil increases with the temperature to which it is exposed4 ,the apparent quantity of water1 therefore1 determined at #adj or #ahj is always greater than that obtained at #aaj4 ,but when the temperature exceeds #aaj there is danger of decomposing organic bodies with the loss of a part of their constituent elements4 ,carbon dioxid and ammonia may also be lost1 as well as acetic acid and other volatile bodies4 #bii4 ,loss on ,ignition4--,the loss on ignition represents any hygroscopic moisture not removed by previous drying1 all water in combination with mineral matters as water of constitution1 all organic acids and ammoniacal compounds1 all organic matter when the ignition is continued until the carbon is burned away1 all or nearly all of the carbon dioxid present in carbonates1 and1 finally1 some of the chlorids of the alkalies1 if the temperature have been carried too high or been continued too long4 ,the loss of carbon dioxid in carbonates may be mostly restored by moistening the ignited mass two or three times with ammonium carbonate1 followed by gentle ignition for a few minutes to incipient redness1 to remove excess of the reagent4 ,the apportionment of the rest of the loss justly among the remaining volatile constituents of the original sample is a matter of some difficulty but may be approximately effected by the methods to be submitted4 #cjj4 ,determination of ,loss on ,ignition4--,method of the ,official ,agricultural ,chemists4 ,the platinum crucible and five grams of soil used to determine the hygroscopic moisture may be employed to determine the volatile matter4 ,heat the crucible and dry soil to low redness4 ,the heating should be prolonged till all organic material is burned away1 but below the temperature at which alkaline chlorids volatilize4 ,moisten the cold mass with a few drops of a saturated solution of ammonium carbonate1 dry1 and heat to #aej to expel excess of ammonia4 ,the loss in weight of the sample represents organic matter1 water of combination1 salts of ammonia1 etc4 ,according to ,knop#aic the total loss on ignition is determined as follows3 ,about two grams of the fine earth are carefully ignited until all organic matter is consumed4 ,the sample is then mixed with an equal volume of finely powdered1 pure oxalic acid1 and again heated until all the oxalic acid is decomposed4 ,after cooling1 the sample is weighed1 again mixed with oxalic acid1 ignited1 cooled1 weighed1 and the process continued until the weight is constant4 ,the method recommended by ,knig consists in igniting about ten grams of the fine earth at the lowest possible temperature until all the humus is destroyed4 ,thereafter the sample is repeatedly moistened with a solution of ammonium carbonate and ignited after drying at #ajj1 until constant weight is obtained4 ,in soils rich in carbonates some carbon dioxid may be lost by the above process4 ,for this a proper correction can be made by estimating the carbon dioxid in the sample1 both before and after the execution of the above described process4 ,the method described by ,frhling as much used in the ,german laboratories1 consists in igniting ten grams of the fine earth1 previously dried at #adj in a crucible placed obliquely on its support and with the cover so adjusted over its mouth as to give a draft within the body of the crucible4 ,the ignition1 at a gentle heat is continued until on stirring with a platinum wire no evidence of unconsumed carbon is found4 ,the moistening with solution of ammonium carbonate1 should not take place until the contents of the crucible are cool4 ,subsequent ignition1 at a low heat for a short time1 will remove the excess of ammonium salt4 #cja4 ,method of ,berthelot and ,andr4#aid--,the earth dried at #aaj contains still a greater or less quantity of combined water4 ,this is the water united with alumina1 silica and certain salts1 but not the water of constitution belonging to organic bodies4 ,the exact estimation of this water offers many difficulties4 ,the determination of loss obtained at a red heat embraces3 7#a7 ,the water combined with zeolitic silicates1 with alumina and with organic compounds4 7#b7 ,the water produced by the combustion of the organic compounds4 7#c7 ,the carbon dioxid resulting from the partial decomposition of the calcium and magnesium carbonates4 7#d7 ,the carbon burned and the nitrogen lost during ignition4 ,the measure of the loss of weight in an earth heated to redness in contact with the air is not therefore1 an exact process of estimating water or even volatile matters4 ,a better defined result is obtained in carefully burning a known weight of earth either in a current of free oxygen1 or with lead chromate4 ,the water produced in such a combustion is secured in a tube filled with pumice stone saturated with sulfuric acid1 the carbon dioxid being absorbed afterwards in potash bulbs and by solid potash4 ,the weight of earth burned is chosen so as to furnish a convenient weight of both water and carbon dioxid4 ,in general about five grams are sufficient4 ,when the combustion is made with oxygen1 the soil is contained in a boat and the products of the combustion are carried over a long column of copper oxid heated to redness4 ,the residue left in the boat is weighed at the end of the operation1 and in this residue it is advisable to determine any undecomposed carbonate4 ,should the sample burn badly and be mixed with carbonaceous matter at the end of the operation1 it will be necessary to substitute the lead chromate method4 ,in this case1 of course1 the residue left after combustion is not weighed4 ,whichever method is employed gives a quantity of water originally combined with the soil1 plus the quantity arising from the combustion of the hydrogen of the organic matter4 ,the details of the processes for organic combustion1 will be given in a subsequent part of this manual4 ,it is not possible to divide the water between these two sources directly1 but this can be done by calculation1 which gives results lying within the limits of probability4 ,the method follows3 ,the organic nitrogen1 determined separately1 by soda-lime1 the method of ,kjeldahl1 or volumetrically1 is derived from proteid principles resembling albuminoids containing about one-sixteenth of their weight of nitrogen4 ,the nitrates contained in the earth are in such feeble proportion1 as to be negligible in this calculation4 ,the total weight of these nitrogenous principles in the soil is therefore easily calculated4 ,the carbon contained in the proteids is then calculated on a basis of #ec per cent of their total weight1 and the hydrogen on a basis of #g4b per cent4 ,from the weight of the total organic carbon 7determined as described further on7 is subtracted the carbon present in the proteids4 ,the remainder corresponds to the organic carbon present as carbohydrates1 7ligneous principles7 containing #dd4d per cent carbon and #f4b per cent hydrogen4 ,by adding together the weight of the hydrogen contained in the ligneous principles1 and the hydrogen contained in the proteids1 and multiplying the sum by #i1 the weight of water formed by the combustion of all the organic matter in the sample is obtained4 ,this is subtracted from the weight of the total water obtained by direct determination as described above4 ,the difference represents the weight of water combined with the silicates1 etc41 as well as with organic matters4 #cjb4 ,method of ,von ,bemmeln4#aie--;,according to the view of ,von ,bemmeln1 the soil contains colloidal humus and colloidal silicate1 which complicate the determination of water4 ,the colloids retain water in varying quantities1 depending upon the following conditions3 7#a7 ,upon their composition and state of molecular equilibrium4 7#b7 ,upon the pressure of the aqueous vapor of the room4 7#c7 ,upon the temperature4 ,at each degree of temperature1 the quantity of absorbed water which a colloid can retain in a room saturated with aqueous vapor1 is different4 ,the quantity of water which air-dried earth gives off at #ajj1 has therefore1 no special significance unless all conditions are known4 ,in addition to the estimation of the quantity of water which soils1 in their natural condition1 are capable of taking up and holding1 at ordinary temperatures1 the estimation of the quantity of water which they can take up in different temperatures in rooms saturated with aqueous vapor should be of interest4 ,it follows1 therefore1 that there is no special value in data obtained by drying earth at #ajj or #aaj4 ,for the purpose of comparison1 he prefers to select that point at which the soil is dried over sulfuric acid1 the point at which the tension of the water vapor in the earth1 at a temperature of plus or minus #ae1 approaches zero4 ,the water which still remains in the earth under these conditions is characterized as firmly combined water4 ,von ,bemmeln truly observes that only in soils which contain no carbonates and no chlorids and sulfids1 can the loss on ignition be regarded as the sum of the humus and water content4 ,by moistening with ammonium carbonate1 the correction for lime or carbon dioxid cannot be correctly made as has been the custom up to the present time4 ,in the first place1 ignited magnesia1 when it has lost its carbon dioxid1 does not take this up completely on moistening with ammonium carbonate2 in the second place1 reactions with the chlorids may take place2 and in the third place1 the lime which is in the humus will be converted into calcium carbonate4 ,chlorids on ignition may be volatilized or oxidized4 ,the sulfuric acid formed from the sulfids1 on ignition1 can expel carbon dioxid2 further than this the iron of pyrites takes up oxygen on ignition4 ,all these influences make the numbers obtained from loss on ignition extremely variable4 ,with sea soils1 ,von ,bemmeln has weighed the soil after the elementary analysis and estimated1 in addition to the carbon dioxid1 both chlorin and sulfuric acid therein4 ,the comparison of these estimations with those of ,,co1 ,cl1 ,,so and ,s1 made in the original soil1 gave the necessary corrections2 viz41 for the increase in the weight through oxidation of sulfur and iron1 and for the decrease in weight through the volatilization of sodium chlorid1 sulfur1 and carbon dioxid4 ,a trace of chlorin was evolved as ferric chlorid1 nevertheless1 the molecular weight of sodium chlorid1 #eh4e1 is scarcely different from the equivalent quantity of ferric chlorid #ed4a4 ,for this reason the estimation of loss of water1 on ignition1 of sea soils is less exact than that of soils which are free from carbonates and sulfids and which1 as is usually the case with tillable soils1 contain only small quantities of chlorids and sulfates4 ,the ,strongly ,combined ,water4--,water which1 at a temperature of plus or minus #ae1 in a dry room1 still remains in the soil1 is chiefly combined according to ,von ,bemmeln with the colloidal bodies therein4 ,its estimation1 presents1 naturally1 difficulties and is not capable of any great exactness4 ,the quantity of strongly combined water1 on the one hand is determined from the difference between the loss on ignition and the quantity of humus present1 calculated from the content of carbon2 on the other hand1 from the difference between the water obtained by elementary analysis and the water which corresponds to the calculated quantity of humus4 ,if the hydrogen content of humus is correctly taken and no appreciable error is introduced through the factor #a4gbd1 both of these differences must agree4 ,on the other hand the hydrogen content of the humus can be computed from the difference between the water found and the calculated content of the firmly combined water4 ,the hydrogen content of humus bodies1 dried at #ajj1 varies between four and five per cent4 ,eggertz has found the content from #d4c to #f4f per cent of hydrogen in thirteen soils which he first treated with dilute hydrochloric acid then extracted with ammonia or potash lye and precipitated this alkaline extract with acid4 ,the method of applying these principles to soil analysis is indicated in the following scheme3 ,a volcanic earth from ,deli gave1 on elementary analysis3 ,per cent4 ,carbon #b4id ,water #ad4gh ,nitrogen #j4bh ,loss on ignition #ag4ed ,,first ,,calculation4 ,per cent4 ,loss on ignition #ag4ed ,humus carbon1 #b4id #a4gbd #e4jg ,difference firmly combined water #ab4dg ,assuming that a humus dried over sulfuric acid contains five per cent of hydrogen1 the second calculation is made as follows4 ,,second ,,calculation4 #e4jj humus #e per cent #j4be per cent of hydrogen in humus corresponding to #b4bh per cent of water4 ,per cent4 ,water found #ad4gi ,difference firmly combined water #ab4ea ,,third ,,calculation4 ,per cent4 ,firmly combined water #ab4dg ,water from the hydrogen in humus #b4bh ,total water #ad4ge ,found #ad4gi ,in this way1 in three other volcanic earths and in an ordinary alluvial clay from ,rembang1 there were found by analysis and by calculation the following percentages of water3 #a4 #b4 #c4 #d4 #e4 ,percentage of water calculated #ad4ge #g4gd #h4jf #d4ij #f4ja found #ad4ig #g4fc #h4je #d4gj #f4jj ,on the contrary1 when the calculation is made from sea-slime taken from under the water a higher content of hydrogen must be assumed2 viz41 about six per cent4 ,in two samples of sea-slime calculated in this way the following numbers were obtained3 ,percentage of water calculated #h4fa #c4ga found #h4ec #c4eg ,it is1 therefore1 quite evident that the organic compounds of soil taken from under the sea-water are richer in hydrogen than those exposed to the air or in cultivation4 #cjc4 ,general ,conclusions4--,in the foregoing paragraphs have been collected the most widely practiced methods of determining moisture in soil in both a free and combined state4 ,the following conclusions may serve to guide the analyst who endeavors to determine the water in any or all of its conditions3 7#a7 ,in determining water in fresh samples the method of ,whitney is satisfactory4 ,although the samples taken by this method are small they may be easily secured in great numbers over widely scattered areas1 and can be easily transported without change4 ,these samples should be dried at #ajj to #aaj for rapid work1 or where time can be spared may be air-dried4 7#b7 ,for a simple determination of the water left in the soil after air-drying 7hygroscopic water7 the method of the ,association of ,official ,agricultural ,chemists may be followed4 ,there is much difference of opinion in respect of the proper temperature at which this moisture is to be determined4 ,much here depends on the nature of the soil4 ,an almost purely mineral soil may safely be dried at #adj or #aej4 ,a peaty soil1 on the contrary1 should not be exposed to a temperature above #ajj4 ,for general purposes the temperature chosen by the official chemists is to be recommended4 7#c7 ,water of composition can only be determined by ignition4 ,as has been fully shown1 this process not only eliminates the water1 but also destroys organic matter1 decomposes carbonates and sulfids1 and1 to some extent1 chlorids4 ,subsequent repeated treatment with ammonium carbonate may restore the loss due to carbon dioxid1 but in many cases not entirely4 ,the water which comes from organic matter may be approximately calculated from the humus content of the sample1 but as will be seen further on the methods of estimating humus itself are only approximate4 ,nevertheless1 in distributing the losses on ignition properly to the several compounds of the soil there is no better method now known than that of taking into consideration the humus content and carbonates present4 ,the principles of procedure established by ,berthelot and ,andr1 and ,von ,bemmeln1 are to be applied in all such cases1 modified as circumstances may arise according to the judgment of the analyst4 #cjd4 ,estimation of the ,organic ,matter of the ,soil4--,the organic matter in the soil may be divided into two classes4 ,first1 the undecayed roots and other remains of plant and animal life1 and the living organisms existing in the soil4 ,the study of the organisms which are active in the condition of plant growth will be the subject of a special chapter4 ,second1 the decayed or partially decayed remnants of organic matter in the soil known as humus4 ,such matter may be present in only minute traces1 as in barren sand soils1 or it may form the great mass of the soil under examination1 as in the case of peat1 muck1 and vegetable mold4 ,it is with the investigation of the second class of matter that the analyst has chiefly to do at present4 ,the problems which are to be elucidated by the analytical study of such bodies are the following3 7#a7 ,the total quantity of such matter in the soil4 7#b7 ,the determination of the organic carbon and hydrogen therein4 7#c7 ,the determination of total nitrogen4 7#d7 ,the determination of the availability of the nitrogen for plant growth4 7#e7 ,the estimation of the humic bodies 7humus1 humic acid1 ulmic acid1 etc474 ,the importance of humus in the promotion of plant growth is sufficient excuse for the somewhat extended study of the principles which underlie the analytical methods1 and the methods themselves1 which follow4 #cje4 ,total ,quantity of ,organic ,matter4--,the total approximate quantity of organic matter in the soil can be determined by simple ignition1 in the manner noted in paragraphs #bid and #bie4 ,the proper correction for free and combined water being applied by the further copper oxid or lead chromate combustion of the sample1 and for carbonates and volatile chlorids1 the approximate total of the organic matter of all kinds is obtained4 #cjf4 ,estimation of the ,organic ,carbon4--,to estimate the organic carbon in an earth the sample may be burned in a current of oxygen1 or after mixing with lead chromate4 ,in a ,current of ,oxygen4--,when burned in a current of oxygen the sample is held in a boat and the gases arising from the combustion directed over copper oxid at a red heat4 ,the carbon thus disappears as carbon dioxid and is absorbed and weighed in the usual way4 ,with ,lead ,chromate4--,the lead chromate employed should be previously tested since it often contains other compounds1 especially lead acetate and nitrate1 furnishing in the one case both carbon dioxid and water1 and in the other hyponitric acid4 ,from two to ten grams of earth are employed1 according to its richness in organic matter4 ,the total carbon dioxid is obtained in this process both from carbonates and organic bodies4 ,the water and carbon dioxid are secured and weighed in the usual manner4 ,the oxygen method should be used in all cases possible4 ,although it does not always give the whole of the carbon dioxid present as carbonates1 the rest can be easily estimated by treating the residue in the boat with hydrochloric acid1 in an apparatus for estimating that gas4 ,calculation of ,results4--,the whole of the carbon dioxid is determined either by direct combustion with lead chromate1 or by taking the sum of the amounts by burning in a stream of oxygen and treating the residue in a carbon dioxid apparatus4 ,the carbon dioxid contained in the original carbonates should be determined by direct treatment of the sample in the usual way4 ,the carbon in organic compounds is determined by subtracting the carbon present as carbonates from the total4 ,from the organic carbon contained in the soil the humus is calculated by ,wolff on the supposition that it contains fifty-eight per cent of carbon4 ,it is1 therefore1 only necessary to multiply the percentage of carbon found by #a4gbd1 or the carbon dioxid found by #j4dga1 to determine the quantity of humus in the dried soil4 #cjg4 ,details of the ,direct ,estimation of ,carbon in ,soils by ,various ,methods4--7#a7 ,oxidation by ,chromic ,acid4--,the method of ,wolff by oxidation with chromic acid has been worked out in detail by ,warington and ,peake4#aif ,it consists in treating the soil with sulfuric acid and potassium bichromate1 or by preference with a mixture of sulfuric and chromic acids1 the carbon dioxid evolved being estimated in the usual way4 ,this method is recommended by ,fresenius as an alternative to a combustion of the soil with copper oxid or lead chromate4 ,it is apparently the method which has been most generally employed in agricultural investigations4 ,ten grams of the finely powdered soil are placed in a flask of about #bej cubic centimeters capacity1 provided with a caoutchouc stopper1 through which pass two tubes1 one for the supply of liquids1 the other for the delivery of gas4 ,the soil is treated with twenty cubic centimeters of water and thirty cubic centimeters of oil of vitriol2 and the whole1 after being thoroughly mixed1 is heated for a short time in a water-bath1 the object in view being the decomposition of any carbonates existing in the soil4 ,air is next drawn through the flask to remove any carbon dioxid which has been evolved4 ,the stopper is next removed1 and coarsely powdered potassium bichromate introduced4 ,in the case of a soil containing three per cent of carbon1 six grams of bichromate will be found sufficient1 a portion remaining undissolved at the end of the experiment4 ,the stopper is then replaced1 its supply-tube closed by a clamp1 and the delivery-tube connected with a series of absorbents contained in tubes4 ,the first of these tubes contains solid calcium chlorid2 the second1 fragments of glass moistened with oil of vitriol2 the third and fourth are nearly filled with soda-lime1 a little calcium chlorid being placed on the top of the soda-lime at each extremity4 ,the last named tubes are for the absorption of carbon dioxid1 and have been previously weighed4 ,the series is closed by a guard-tube containing soda-lime1 with calcium chlorid at the two ends4 ,the flask containing the soil and bichromate is now gradually heated in a water-bath1 the contents of the flask being from time to time mixed by agitation4 ,a brisk reaction occurs1 carbon dioxid being evolved in proportion as the soil is rich in organic matter4 ,the temperature of the water-bath is slowly raised to boiling as the action becomes weaker1 and is maintained at that point till all action ceases4 ,as bubbles of gas are slowly evolved for some time1 it has been usual in these experiments to prolong the digestion for four or five hours4 ,when the operation is concluded the source of heat is removed1 an aspirator is attached to the guard-tube at the end of the absorbent vessels1 and air freed from carbon dioxid is drawn through the flask and through the whole series of tubes4 ,the tubes filled with soda-lime are finally weighed1 the increase in weight showing the amount of carbon dioxid produced4 ,the object of the calcium chlorid placed on the surface of the soda-lime is to retain the water which is freely given up when the soda-lime absorbs carbon dioxid4 ,the second tube filled with soda-lime does not gain in weight till the first is nearly saturated2 it thus serves to indicate when the first tube requires refilling4 ,the same tubes may be used several times in succession4 ,no increase in the carbon dioxid evolved is obtained by substituting chromic acid for potassium bichromate4 ,the organic matter of the soil appears to the eye to be completely destroyed by the digestion with sulfuric acid and potassium bichromate2 the residue of soil remaining in the flask when washed with water is perfectly white1 or the dark particles1 if any1 are found to be unaltered by ignition1 and therefore to be inorganic in their nature4 ,under these circumstances considerable confidence has naturally been felt in this method4 ,the complete destruction of the humic matter of the soil does not1 however1 necessarily imply that the carbon has been entirely converted into carbon dioxid as has been pointed out by ,wanklyn4 ,according to his demonstration of the action of chromic acid on organic matter the oxidation frequently stops short of the production of carbon dioxid4 ,while oxidation with chromic acid apparently leads to a complete reaction when the carbon is in the form of graphite1 it would probably yield other products than carbon dioxid when the carbon exists as a carbohydrate4 ,the doubt thus raised as to the correctness of the results yielded by the chromate method makes it desirable to check the work by the use of other methods for the determination of carbon4 ,for this purpose ,warington and ,peake recommend3 7#b7 ,oxidation with ,potassium ,permanganate4--,in the trials with this method ten grams of soil are digested in a closed flask with a measured quantity of solution of caustic potash containing five grams of potash for each twenty cubic centimeters1 and crystals of potassium permanganate4 ,seven grams of the permanganate are found to be sufficient for a soil containing #c4c per cent of carbon4 ,the flask is heated for half an hour in boiling water1 and then for one hour in a salt-bath4 ,the flask during this digestion is connected with a small receiver containing a little potash solution1 to preserve an atmosphere free from carbon dioxid2 distillation to a limited extent is allowed during the digestion in the salt-bath4 ,the first part of the operation being completed a rubber stopper1 carrying a delivery and supply-tube1 is fitted to the flask1 which is then connected with the system of tubes already described4 ,dilute sulfuric acid is then poured down the supply-tube1 a water-bath surrounding the flask is brought to boiling1 and maintained thus for one hour1 after which air1 free from carbon dioxid1 is drawn through the apparatus1 the tubes containing soda-lime being finally disconnected and weighed4 ,in the first stage of this method the carbon of the organic matter is converted into carbonate1 and probably also into potassium oxalate4#aig ,in the second stage the oxalate is decomposed by the sulfuric acid and permanganate1 and the carbon existing1 both as oxalate and carbonate1 is evolved as carbon dioxid1 and absorbed by the weighed soda-lime tubes4 ,both ,f4 ,schulze and ,wanklyn have employed potassium permanganate for the determination of organic carbon1 but they have preferred to calculate the amount of carbon from the quantity of permanganate consumed1 as1 however1 by so doing everything oxidizable by permanganate is reckoned as carbon1 it seems better to make a direct determination of the carbon dioxid formed4 ,from the amount of carbon dioxid found1 is to be subtracted that existing as carbonates in the soil1 and in the solution of potash used4 ,for this purpose an experiment is made with the same quantities of soil and potash previously employed1 but without permanganate1 and the carbon dioxid obtained is deducted from that yielded in the experiment with permanganate4 ,if the potash used contains organic matter two blank experiments will be necessary1 one with potash and permanganate1 and one with soil alone4 ,a further difficulty arises from the presence of chlorids in the materials1 which occasions an evolution of free chlorin when the permanganate solution is heated with sulfuric acid4 ,this error occurs also with the chromic acid method1 but in that case the quantity of chlorid is merely that contained in the soil1 which is usually very small2 in the permanganate method we have also the chlorid present in the caustic potash1 and this is often considerable4 ,corrections for chlorin by blank experiments are unsatisfactory1 the amount of chlorin which reaches the soda-lime tubes depending in part on the degree to which the calcium chlorid tube has become saturated with chlorin4 ,it is better therefore to remove the chlorin in every experiment by the plan which ,perkin has suggested1 by inserting a tube containing silver foil1 maintained at a low red heat1 between the flask and the absorbent tubes4 ,the amount of carbon dioxid yielded by oxidation with potassium permanganate is found to be considerably in excess of that obtained by oxidation with chromic acid2 to ascertain whether these higher results really represented the whole of the carbon present in the soil1 trials were next made by actual combustion of the soil in oxygen4 7#c7 ,combustion in ,oxygen4--,the most convenient mode of carrying out the combustion of soil is to place the soil in a platinum boat1 and ignite it in a current of oxygen in a combustion tube partly filled with cupric oxid4 ,a wide combustion tube is employed1 about twenty inches long1 and drawn out at one end2 the front of the tube is filled for eight inches with coarse cupric oxid1 the hind part is left empty to receive the platinum boat4 ,the drawn out end of the combustion tube is connected with a series of absorbent tubes1 quite similar to those employed for the estimation of carbon dioxid in the chromic acid method4 ,between these absorbent vessels and the combustion tube is placed a three-bulbed ,geissler tube filled with oil of vitriol4 ,the oil of vitriol is quite effective in retaining nitrous fumes4 ,the wide end of the combustion tube is connected with a gas-holder of oxygen2 the oxygen gas is made to pass through a tube of soda-lime before entering the combustion tube1 to remove any possible contamination of carbon dioxid4 ,in starting a combustion the part of the combustion tube containing the cupric oxid is brought to a red heat1 and oxygen is passed for some time through the apparatus4 ,ten grams of soil1 previously dried1 are placed in a large platinum boat1 which is next introduced at the wide end of the combustion tube4 ,the combustion is conducted in the usual manner1 a current of oxygen being maintained throughout the whole operation4 ,it is very useful to terminate the whole series of absorbent vessels with a glass tube dipping into water2 the rate at which the gas is seen to bubble1 serves as a guide to the supply of oxygen from the gas-holder1 the consumption of oxygen varying1 of course1 with different soils1 and at different stages of the combustion4 ,at the close of the combustion1 oxygen1 or air freed from carbon dioxid1 is passed for some time through the apparatus to drive all carbon dioxid into the absorbent vessels4 ,one experiment can be followed by another as soon as the hind part of the combustion tube has cooled sufficiently to admit a second platinum boat4 ,the same combustion tube can be employed for several days1 if packed in the usual manner in asbestos4 ,the presence of carbonates in the soil occasions some difficulty in working the combustion method1 as a part of this carbon dioxid will1 of course1 be given up on ignition1 and be reckoned as carbon4 ,the simplest mode of meeting this difficulty is to expel the carbon dioxid belonging to the carbonates before the combustion commences4 ,the method of ,manning2 namely1 treatment with a strong solution of sulfurous acid1 may be employed for this purpose4 ,the ten grams of soil taken for combustion are placed in a flat-bottomed basin1 covered with a thin layer of sulfurous acid1 and frequently stirred4 ,after a time the action is assisted by a gentle heat4 ,when the carbonates have been completely decomposed the contents of the basin are evaporated to dryness on a water-bath2 the dry mass is then pulverized1 and removed to the platinum boat for combustion in oxygen4 ,for the action of the sulfurous acid to be complete it is essential that the carbonates should be in very fine powder1 since even chalk is but imperfectly attacked when present in coarse particles4 #cjh4 ,comparison of ,methods4--,a considerable number of soils analyzed by the chromic acid method and by the combustion1 method1 by ,warington and ,peake1 with the assistance of ,cathcart1 shows the following comparisons3 ,,percentage ,,of ,,carbon ,,found ,,by ,,two ,,methods ,,in ,,soils ,,dried ,,at #ajj4 ,chromic acid method4 ,combustion method4 ,no4 ,kind of ,exp4 #a4 ,exp4 #b4 ,mean4 ,exp4 #a4 ,exp4 #b4 ,mean4 ,per soil4 cent4 yielded by chromic acid4 #a4 ,old pasture #b4he #b4gi #b4hb #c4eh #c4ee #c4eg #gi4j #b4 #b4hc #b4gi #b4ha #c4eg #c4ec #c4ee #gi4a #c4 #b4gf #b4gf #b4gf #c4df #c4df #c4df #gi4g #d4 #b4gd #b4gf #b4ge #c4cg #c4ch #c4ch #ha4d #e4 #b4fd #b4ed #b4ei #c4ca #c4cf #c4cd #gg4e #f4 #b4ea #b4dc #b4dg #c4ae #c4ae #c4ae #gh4d #g4 #b4dj #b4dd #b4db #c4ji #c4ac #c4aa #gg4h #h4 ,new pasture #a4ib #a4ic #a4ic #b4da #b4dj #b4da #hj4a #i4 #a4ff #a4ha #a4gd #b4ci #b4dc #b4da #gb4b #aj4 ,arable soil #a4gh #a4gh #a4gh #b4ad #b4ac #b4ad #hc4b #aa4 #a4ba #a4ad #a4ah #a4dj #a4dc #a4db #hc4a #ab4 ,subsoil #j4bh #j4bg #j4bh #j4cg #j4ch #j4ch #gc4g ,of the above soils the arable soils1 ,nos4 #aj and #aa1 were the only ones containing carbonates in any quantity exceeding a minute trace4 ,the two soils in question were treated with sulfurous acid before combustion1 the others not4 ,all the determinations by the chromic acid method were made by ,mr4 ,p4 ,h4 ,cathcart1 with the exception of ,nos4 #i and #ab1 which were executed by another experimenter1 and are seen to give distinctly lower results4 ,excluding these two analyses the relation of the carbon found by the two methods is tolerably constant1 the average being #gi4i of carbon found by oxidation with chromic acid for #ajj yielded by combustion in oxygen4 ,the results obtained by the chromic acid method thus appear to be very considerably below the truth4 ,four typical soils were analyzed by the permanganate1 as well as by the chromic acid and combustion methods4 ,the results obtained were as follows3 ,,percentage ,,of ,,carbon ,,found ,,by ,,three ,,methods ,,in ,,soils ,,dried ,,at #ajj4 ,permanganate method4 ,kind of ,chromic ,yielded by soil4 acid permanganate ,combustion method4 if carbon by method4 ,mean4 ,exp4 #a4 ,exp4 #b4 ,mean4 combustion ,mean4 ,per ,per ,per ,per ,per #ajj4 ,per cent4 cent4 cent4 cent4 cent4 cent4 ,old pasture #c4ee #b4ha #c4bf #c4cj #c4bh #ib4d ,new pasture #b4da #a4ic #b4bi #b4cj #b4cj #ie4d ,arable soil #a4db #a4ah #a4bh #a4cc #a4ca #ib4c ,subsoil #j4ch #j4bh #j4cd #j4cd #j4cd #hi4e ,oxidation by permanganate thus gives a much higher result than oxidation with chromic acid2 but even the permanganate fails to convert the whole of the carbon into carbon dioxid1 the product with permanganate being on an average of the four soils #ib4d per cent of that yielded by combustion in oxygen4 ,wanklyn states that a temperature of #afj-ahj is necessary in some cases to effect complete oxidation with permanganate and caustic potash4 ,such a temperature is found impracticable when dealing with soil1 from the action of the potash on the silicates present2 hence possibly the low results obtained4 ,combustion in oxygen appears from these experiments to be the most satisfactory method for determining carbon in soil1 nor is this method1 on the whole1 longer or more troublesome than the other methods investigated4 ,warington and ,peake have further determined the loss on ignition of the four soils mentioned above1 with the view of comparing this loss with the amount of organic matter calculated from the carbon actually present4 ,in making this calculation they have taken as the amount of carbon in the soil1 that found by combustion in oxygen1 and have assumed with ,schulze1 ,wolff1 and ,fresenius1 that fifty-eight per cent of carbon will be present in the organic matter of soils4 ,the four soils were heated successively at #ajj1 #abj1 and #aej1 till they ceased to lose weight2 the loss on ignition in each of these stages of dryness is shown in the following table3 ,,percentage ,,loss ,,on ,,ignition ,,compared ,,with ,,organic ,,matter ,,calculated ,,from ,,carbon4 ,organic matter at fifty-eight ,between #ajj ,between #abj ,between #aej per cent and ignition4 and ignition4 and ignition4 carbon4 ,kind of soil4 ,per cent4 ,per cent4 ,per cent4 ,per cent4 ,old pasture #i4bg #i4jf #h4ej #f4ab ,new pasture #g4jg #f4hh #f4ee #d4af ,arable soil #e4ie #e4gj #e4fa #b4dd ,clay subsoil #e4hb #e4ci #d4gf #j4fe ,the loss on ignition is seen to be in all cases very considerably in excess of the organic matter calculated from the carbon1 even when the soil has been dried at as high a temperature as #aej4 ,the error of the ignition method is least in soils rich in organic matter1 as1 for instance1 the old pasture soil in the above table4 ,the error reaches its maximum in the case of the clay subsoil1 which contains very little carbonaceous matter1 but is naturally rich in hydrated silicates1 which part with their water only at a very high temperature4 ,the above methods of ,warington and ,peake have been given in detail1 and in almost the verbiage of the authors for the reason that the working directions are clearly set forth1 and may serve1 therefore1 as guides to the previous methods where only general indications of manipulation have been given4 #cji4 ,estimation of ,organic ,hydrogen4--,the estimation of the total hydrogen is made without difficulty either by burning the sample in a current of oxygen or with lead chromate1 and weighing the water produced4 ,this water comes from two sources1 the pre-existing water and organic hydrogen4 ,there is no direct method of distinguishing one from the other4 ,they may1 however1 be estimated indirectly4 ,the method of calculating the organic hydrogen has already been given 7paragraph #bii74 ,experience shows that the hydrogen thus calculated is a little greater than is necessary to form water with the whole of the oxygen found in the organic matters4 #caj4 ,estimation of ,organic ,oxygen4--,the determination of this oxygen cannot be made directly4 ,it is obtained by calculation1 according to ,berthelot and ,andr1#aih from the oxygen in the proteid and ligneous matters4 ,let p represent the weight of the proteid bodies in a sample of soil4 ,then ,o 7p #cc4e7_/7ajj7 ,let p weight of ligneous bodies4 ,then ,o 7p #di4d7_/7ajj7 ,the total oxygen ,o ,o4 ,an approximate result is thus obtained1 very useful to have when account is taken of the oxidizing processes which go on in the soil during agricultural operations4 #caa4 ,estimation of ,humus 7,matire ,noire74--,the original method of determining this substance is due to ,grandeau4#aii ,it is carried on as follows3 ,ten grams of the fine earth are mixed with coarse sand previously washed with acids and ignited4 ,the mixture is placed in a small funnel1 the bottom of which is filled with fragments of glass or porcelain4 ,the mass is moistened with ammonia diluted with an equal volume of distilled water1 and allowed to digest for three or four hours4 ,the ammonia dissolves the dark matter without attacking the silica4 ,the ammoniacal solution is displaced by treating the mass with pure water1 or water to which some ammonia has been added1 and the whole of the dark matter is thus obtained in a volume of twenty to fifty cubic centimeters of filtrate4 ,the filtrate is evaporated to dryness in a weighed platinum dish1 and the weight of residue is determined and the percentage of matire noire calculated therefrom4 ,the residue is incinerated1 and when in sufficient quantity the phosphoric acid is determined in the ash4 ,in soils poor in humus a larger quantity than ten grams may be taken4 ,if the soil be previously treated with hydrochloric acid1 ,grandeau recommends that the phosphoric acid be determined always in the ash of the dark matter4 ,the method has undergone various modifications and1 as given by ,hilgard1 is now practiced as follows3 ,about ten grams of soil are weighed into a prepared filter4 ,the soil should be covered with a piece of paper 7a filter7 so as to prevent it from packing when solvents are poured on it4 ,it is now treated with hydrochloric acid from five-tenths per cent to one per cent strong 7twenty-five and one-third cubic centimeters of strong acid and #hjh cubic centimeters of water7 to dissolve the lime and magnesia which prevent the humus from dissolving in the ammonia4 ,treat with the acid until there is no reaction for lime2 then wash out the acid with water to neutral reaction4 ,dissolve the humus with weak ammonia water1 prepared by diluting common saturated ammonia water 7#agh cubic centimeters of ammonia to #dbb cubic centimeters of water74 ,evaporate the humus solution to dryness in a weighed platinum dish at #ajj2 weigh1 then ignite2 the loss of weight gives the weight of humus4 ,the residue from ignition is carbonated with carbon dioxid1 heated and weighed1 thus giving the ash4 ,it is then moistened with nitric acid and evaporated to dryness4 ,the residue is treated with nitric acid and water1 allowed to stand a few hours1 and the solution filtered from the insoluble residue1 which is ignited and weighed1 giving the silica4 ,the soluble phosphoric acid is determined in the solution by the usual method1 as magnesium pyrophosphate4 ,it usually amounts to a fraction1 varying from one-half to as little as one-tenth of the total in the soil4 ,while the phosphoric acid so determined is manifestly more soluble and more available to vegetation than the rest of that found by extraction with stronger acid1 it is clearly not as available as that which1 when introduced in the form of superphosphates1 exerts such striking effects even though forming a much smaller percentage of the whole soil4 ,nevertheless1 very striking agreement with actual practice is often found in making this determination4 ,the estimation of humus by combustion1 in any form1 of the total organic matter in the soil1 gives results varying according to the season1 and having no direct relation to the active humus of the soil4 ,the same objection lies against extraction with strong caustic lye4 #cab4 ,modification of ,grandeau's ,method for ,determining ,humus in ,soils4--,according to ,huston and ,mc,bride#bjj the function of the vegetable matter in the soil has long been a matter of contention among those interested in the science of agriculture4 ,two factors have contributed to the uncertainty existing in this matter3 ,first1 the very complex and varying nature of the compounds resulting from the decomposition of vegetable matter in the soils2 and second1 the lack of uniformity in the methods of determining either the total amount of organic matter present in a soil1 or the amount that has been so far decomposed as to be of any immediate agricultural value4 ,prominent among these methods are the methods in which a combustion is resorted to1 the substance being either burned in air or in a combustion tube with some agent supplying oxygen4 ,the loss on ignition is no measure of the amount of organic matter present since it is practically impossible to remove all the water from the soil previous to ignition1 and neither of the methods gives information regarding the extent of the decomposition of the organic matter4 ,pure cellulose and the black matter of a fertile soil are of very different agricultural value4 ,determinations of carbon in soils by oxidation with chromic and sulfuric acid1 and with alkaline permanganate have been used4 ,the method with alkaline permanganate agrees fairly well with combustion with copper oxid or lead chromate1 but the chromic sulfuric acid method gives only about eighty per cent of the carbon found by combustion processes4 ,however valuable these processes may be for determining the total carbon in the soil1 they furnish no information regarding the condition of the carbonaceous soil constituents1 and as the determination is really one of carbon1 the organic matter must be calculated by using an arbitrary factor4 ,generally the organic matter of the soil is considered to have fifty-eight per cent carbon2 yet different values are given from forty to seventy-two per cent4 ,there is a general opinion that the black or dark brown material of the soil1 resulting from the decay of vegetable matter1 has a much higher agricultural value than the undecomposed vegetable matter4 ,no very sharp dividing line can be drawn1 for changes in the soil are continually going on1 and material may be found in almost every stage between pure cellulose and carbon dioxid4 ,the character of the intermediate products will vary according to the conditions of tillage and the supply of air and water4 ,for agricultural purposes some means of determining the amount of decomposed matter is very desirable4 ,several solvents have been tried for this purpose4 ,the earlier attempts were made by treating the soil with successive quantities of boiling half-saturated solution of sodium carbonate until the soil appeared to yield no more coloring matter to the solvent4 ,the solutions were then united1 rendered acid with ,h,cl1 which precipitated the humic acid1 which was then washed1 dried1 and weighed4 ,this was considered the more soluble portion of the humic acid4 ,the soil was afterward treated with caustic potash solution in the same manner1 and the humus thus extracted was called insoluble humus4 ,this last process was really more in the nature of manufacturing humus1 for sawdust treated with caustic potash yields humic acid1 and the inert organic matter in the soil was decomposed to some extent by the caustic alkali4 ,neither of the processes provided for the separation of the humic acid from the lime1 magnesia1 alumina1 and iron with which it is usually combined in the soil4 ,in case results of different workers are to be compared1 it is of the greatest importance that methods should be used that are of such a nature that errors resulting from difference of manipulation1 and from difficulty of reproducing duplicate work can be reduced to a minimum4 ,hence1 a simple modification of the ,grandeau method has been tried which has the advantage of keeping a definite amount of the soil in contact with a definite volume of ammonia for a fixed time1 the strength of the ammonia remaining constant4 ,the process is as follows3 ,the soil is washed with acid and water as usual4 ,it is then washed into a #ejj cubic centimeter cylinder with ammonia1 the cylinder closed and well shaken and allowed to remain for a definite time1 usually thirty-six hours4 ,the material is shaken at regular intervals4 ,the cylinder is left inclined as much as possible without having the fluid touch the glass stopper1 thus allowing the soil to settle on the side of the cylinder and exposing a very large surface to the action of the ammonia4 ,during the last twelve hours the cylinder is placed in a vertical position to allow the soil to settle well before taking out the aliquot part of the solution4 ,the process of washing the soil with hydrochloric acid1 water and ammonia1 is very tedious when performed in the usual way with the wash-bottle4 ,a simple automatic washing apparatus was devised by which a fixed volume of the washing fluid can be delivered at regular intervals1 giving ample time for the thorough draining between each addition of the fluid1 and requiring no attention4 ,by this apparatus work can be continued day and night4 ,instead of washing on the usual form of filter paper in funnels1 it is preferable with this apparatus to hold the soils on a disk of filter paper resting on a perforated porcelain disk in the bottom of the funnel4 ,this removes the necessity of washing out the filter papers1 does not permit of the accumulation of humus on the edge of the filter paper when the ,grandeau process is used1 and insures that all the washing fluids pass through the soil and not around it4 ,this form of apparatus reduces the labor to a minimum and permits many determinations to be carried on at once4 ,this form of apparatus was only lately devised and has only been used long enough to test it and to show its advantages4 ,the reported results were obtained by the ordinary methods of washing4 ,in all the work reported1 five grams were used1 as the soils contained so much humus that this amount gave enough humus for good work in the final weighings4 ,the results obtained so far appear in the following tables3 ,,table ,i4 ,,comparison ,,of ,,method ,,of ,,grandeau ,,with ,,huston',s ,,modification ,,and ,,of ,,influence ,,of ,,strength ,,of ,,ammonia ,,solution4 ,,time ,,of ,,digestion ,,in ,,modified ,,method ,,thirty-,,six ,,hours4 ,two per cent ,four per cent ,,nh4 ,,nh4 ,grandeau4 ,huston4 ,grandeau4 ,huston4 #a4 ,peat soil1 #af4dj #bj4jf ,bogus #ac4ih #bj4hj #ag4dc ---------- ---------- ,mean #ae4id #bj4dc #b4 ,peat subsoil1 #ac4ih #ai4ch ,bogus #ac4he #bj4cj ---------- ---------- ,mean #ac4ib #ai4hd #c4 ,peat soil1 #i4je #ae4fj #ad4ga #ba4bd ,good #aj4bg #ae4hh #ae4cd #bj4bj ---------- ---------- ---------- ---------- ,mean #i4fa #ae4gd #ae4jc #bj4gb #d4 ,peat subsoil1 #af4ge #bd4cd ,good #ah4fj #bc4eb ---------- ---------- ,mean #ag4fh #bc4ic #e4 ,black soil1 ,a #c4ij #f4ij 7#a4hf7 #g4db 7#a4fg7 #f4ih ,b #c4hh #g4jj #d4db #d4bj ---------- ---------- ---------- ---------- ,mean #c4ii #f4ie 7#c4je7 #g4bj #d4ca #f4 ,clay loam1 #a4hf #d4bj #b4dj #d4bf ,west side1 ,a #d4bh ,b #a4gf #d4cf #b4dh 7#c4dj7 7#c4aj7 ---------- ---------- ---------- ---------- ,mean #a4ha #d4bh #b4dd 7#c4gf7 #d4bg #g4 ,clay loam1 ,a #a4ij #d4ab 7#a4fj7 7#d4ei7 ,lysimeter soil1 ,b #a4fa #d4bb 7#a4da7 7#d4eh7 ,c #a4hj #d4ab ,d #a4ie #d4jd ,e #a4ib #c4he ,f #a4ie #d4jh ,g #a4ij #c4ic ,h #a4ij #c4hj ---------- ---------- ---------- ---------- ,mean #a4gf #d4ag 7#a4hj7 7#d4ab7 #a4ij #c4ig ,seven per cent ,eight per cent ,,nh4 ,,nh4 ,grandeau4 ,huston4 ,grandeau4 ,huston4 #a4 ,peat soil1 ,bogus ,mean #b4 ,peat subsoil1 ,bogus ,mean #c4 ,peat soil1 #ai4gg #ba4gj #af4je #ba4db ,good #ai4he #ba4ij #ae4dj #ba4hj ---------- ---------- ---------- ---------- ,mean #ai4ha #ba4hj #ae4gc #ba4fa #d4 ,peat subsoil1 ,good ,mean #e4 ,black soil1 ,a ,b ,mean #f4 ,clay loam1 #b4ad #d4jb #a4he #d4ab ,west side1 ,a ,b #b4ac #d4dh #a4ij #d4dj ---------- ---------- ---------- ---------- ,mean #b4ad #d4be #a4hh #d4bf #g4 ,clay loam1 ,a ,lysimeter soil1 ,b ,c ,d ,e ,f ,g ,h ,mean ,,note4--,numbers in parentheses indicate results1 generally the earliest ones1 which the authors do not consider strictly comparable with the rest of the work4 ,they are given solely for the purpose of exhibiting all the work that has been done to date4 ,when a mean is included in parentheses it indicates that it is calculated from all the results obtained1 including those not considered strictly comparable4 ,bogus is a name given to a peaty soil which is very sterile4 ,,table ,,ii4 ,,influence ,,of ,,time ,,of ,,digestion4 ,,four ,,per ,,cent ,,of ,,ammonia ,,used ,,throughout4 ,,huston',s ,,method4 ,thirty-six ,forty-eight ,sixty-eight ,ninety-eight hours4 hours4 hours4 hours4 ,peat ,soil1 #ba4bd #bb4bh #bd4jd ,good #bj4bj #ba4gj #bc4id ---------- ---------- ---------- ,mean #bj4gb #ba4ii #bc4ii ,clay loam1 #d4bh #d4jj #d4dj #d4bf #d4ja #d4he ,west side 7#c4dj7 7#c4je7 ------------ ---------- -------- ,mean #d4bg #d4ja #d4fc ,,table ,,iii4 ,,influence ,,of ,,time ,,of ,,extraction4 ,,time1 ,,ten ,,days4 ,,grandeau',s ,,method1 ,,four ,,per ,,cent ,,ammonia4 ,,peat ,,soil4 ,a4 ,b4 ,mean4 ,remarks4 ,per ,per ,per cent4 cent4 cent4 #ast extraction1 #gej cc #af4ij #ah4if #ag4ic #bnd #bej #b4hj #b4ch #b4ei #crd #bej #a4gg #a4aj #a4dd #dth #bej #a4cd #a4cj #a4cb ,stood over night4 #eth #bej #j4hi #j4he #j4hg #fth #bej #a4da #a4fe #a4ec ,stood overnight4 #gth #bej #b4aj #a4hj #a4ie ,washed again with ,h,cl for ,ca4 ,trace found4 ,h,cl washed out1 but trace of chlorids found in ash4 ,probably ,h,cl absorbed from air as humus showed small quantity of a white volatile solid on evaporation4 #hth #bej #j4fg #j4fe #j4ff #ith #bej #j4eg #j4ej #j4ec -------- ---------- ---------- ---------- ,total #bgej #bh4de #bi4ai #bh4hb #cac4 ,summary of ,results4--#a4 ,the modified method gives much higher results than the original method of ,grandeau4 #b4 ,in the ,grandeau method marked irregularities follow a change in the strength of the ammonia solution4 ,these differences in results bear no relation to the strength of the solution used4 ,they seem to be errors due to the difficulty of securing uniform and complete washing of the soil by the ammonia solution4 ,in the modified method the change in the strength of the ammonia solution makes practically no difference in the amount of humus extracted1 except in the case of the peat soil where two per cent ammonia failed to extract all the humus4 ,but the results show no considerable increase when the strength is increased to over four per cent4 #c4 ,the factor of time has not been fully investigated1 but the results so far obtained indicate that the time exerts less influence in the modified than in the ,grandeau method4 #d4 ,table ,,iii shows that considerable quantities of the peat soil are still passing into solution in the ,grandeau method at the end of ten days4 ,with ordinary soils this is not true2 but in the case of soil ,no4 #e1 a black soil1 the solutions were colored at the end of a week4 ,on the peat soil the modified method extracted from ten to fifty per cent more than the ,grandeau1 and on the ordinary soil from two to three times as much humus4 #e4 ,in comparing duplicate results by both methods it is found that with soil ,no4 #c1 peat soil1 the following differences appear calculated to percentage of the total amount involved in the determination3 ,per cent4 ,per cent4 ,per cent4 ,per cent4 ,strength of ammonia #b4 #d4 #g4 #h4 ,modified #a4g #e4 #a4j #a4h ,grandeau #ac4j #d4c #j4e #c4d ,special attention was paid to this point in case of soil ,no4 #g1 an ordinary soil2 taking all results into consideration the greatest difference in percentage of total amount involved was1 by the modified method1 nineteen per cent1 and by the ,grandeau1 thirty per cent4 ,in the set of six special determinations made by both methods to test this point and which are strictly comparable with each other1 the maximum range was by the modified method #g4h per cent and by the ,grandeau #h4c per cent of the total amount involved in the determination4 ,from which it appears that the modified method is on the whole capable of yielding rather more concordant results than the ,grandeau4 #cad4 ,estimation of ,free ,humic ,acids4--,this process1 due to ,mntz#bja is essentially that of ,huston and ,mc,bride4 ,twenty grams of the soil are reduced to a fine powder and saturated with fifty cubic centimeters of concentrated ammonia and allowed to digest two or three days in a warm place4 ,the volume is then made up to one liter with water1 well shaken1 and set aside for one day in order to permit the subsidence of the solid matter4 ,at the end of this time #ejj cubic centimeters of the supernatant liquor are taken and acidified with hydrochloric acid in order to precipitate the humic bodies4 ,the humus is collected on a filter1 dried and weighed4 ,it is then ignited and the weight of ash deducted from the first weight thus giving the actual weight of the humus obtained1 free from mineral matter4 ,this process gives the free humic acids4 ,by previous treatment of the sample with hydrochloric acid as in the process of ,huston and ,mc,bride1 the total humus is obtained4 ,the estimation of the free humic acids is of importance in determining the quantity of lime or marl which should be added to acid lands4 #cae4 ,humus ,method of ,von ,bemmeln4#bjb--,von ,bemmeln obtains the content of humus by the multiplication of the content of carbon in the soil by the factor of ,wolff2 viz41 #a4gbd4 ,the estimation of carbon1 water1 and of the loss on ignition is conducted in combustion tubes in a current of oxygen4 ,the nitrogen estimation is carried on according to the method of ,dumas4 ,in soils containing calcium carbonate the carbon content is derived from the carbon dioxid taken up by the potash bulbs during combustion 7a72 from other carbonates not decomposed on ignition and which are subsequently determined in the residue by treatment with hydrochloric acid in a carbon dioxid apparatus1 7b7 and the total carbon dioxid derived from the carbonates in the soil 7c74 ,for each estimation from three to five grams of the soil are taken1 because with smaller quantities the errors of analysis too strongly influence the results4 ,the carbon is then calculated according to the formula3 ,carbon 7a b c74 ,the ,carbon ,dioxid of ,carbonates4--,it is necessary to expel the carbon dioxid at ordinary temperatures1 because on heating to boiling1 carbon dioxid would be formed from the humus4 ,in a flask1 as small as possible1 the soil is treated at ordinary temperature1 with dilute sulfuric or citric acid1 the escaping gas dried over sulfuric acid and taken up with soda-lime4 ,behind the soda-lime is a small tube filled with pieces of glass and moistened with sulfuric acid1 which retains any moisture taken out of the soda-lime4 ,a stream of about one liter of air1 free from carbon dioxid1 is sufficient to drive out all of the carbon dioxid when the estimation is made at ordinary temperatures4 ,a volcanic earth from ,deli1 which contained five per cent of humus1 gave1 at a temperature plus or minus #ae1 #j4ja per cent ,,co4 ,at boiling temperature two analyses gave #j4ed and #j4ef ,,co4 ,this soil contained no carbonate1 and the carbon dioxid found at the boiling temperature1 must have come from the humus substances under the influence of the dilute acids4 ,a heavy clay containing #f4i per cent of humus gave1 at plus or minus #ae1 #c4fj per cent ,,co2 at #ajj without boiling1 it gave an additional #j4ec per cent1 and with boiling an additional #j4aa per cent1 or a total of #d4bd per cent ,,co4 ,a light clay containing #c4b per cent of humus1 gave1 at #ae1 #e4ji per cent ,,co2 at a boiling temperature an additional #j4dc per cent1 and by continued boiling an additional #j4bg per cent4 #caf4 ,estimation of ,humus by the ,german ,method4--,the ,german experiment stations follow the method of ,loges1#bjc depending on the oxidation of the humic bodies with copper oxid after evaporation of the sample with phosphoric acid4 ,the object of the preliminary evaporation is to set the humic acids free in order that they may be better and more easily oxidized than when burned in the combined state4 ,the sample of soil is placed in a ,hoffmeister dish 7,schlchen71 moistened with dilute phosphoric acid and evaporated to complete dryness4 ,the dish and its contents are rubbed up with pulverized copper oxid and placed in a combustion tube of sixty centimeters in length1 open at both ends4 ,there is then placed in the tube1 and held in place by asbestos plugs1 granular copper oxid to a length of twenty centimeters4 ,the combustion tube is placed in a proper furnace and one end connected with two washing-flasks1 the first containing potash lye1 and the other a solution of barium hydroxid4 ,these flasks are to free the aspirated air from carbon dioxid4 ,the other end of the combustion tube is connected with an appropriate apparatus for absorbing the carbon dioxid4 ,loges recommends the ,pettenkofer absorption tube and a ,fresenius drying cylinder4 ,between the absorption apparatus and the aspirator1 is also placed a washing-flask containing barium hydroxid solution1 serving to detect any unabsorbed carbon dioxid4 ,the layer of granular copper oxid is first heated1 the air being slowly aspirated through the apparatus meanwhile1 but not through the absorption bulbs4 ,all the carbon dioxid is thus removed from the apparatus4 ,the absorption system being connected1 the tube is heated slowly from the front1 backwards1 and after the tube is well heated a slow current of air is drawn through and continued until the combustion is complete1 which is usually in about three-quarters of an hour4 ,after the tube is cool the powdered copper oxid and residue of combustion are removed1 and for this reason the tube is stopped with a cork at both ends instead of being drawn out and sealed at one end4 ,the tube can thus be refilled without disturbing the granular layer of copper oxid4 ,the drying cylinder used between the combustion tube and the absorption system has its upper part filled with cotton to avoid the deleterious effects of the nitric oxid produced in the combustion4 ,with this arrangement the use of metallic copper in the combustion tube to reduce the nitric oxid can be dispensed with1 the moist cotton holding back the acid fumes4 ,the per cent of humus is obtained by multiplying the per cent of carbon found by #a4gbd4 #cag4 ,method of ,raulin for the ,estimation of ,humus4#bjd--,the volumetric estimation of humus in soil by a solution of potassium permanganate would be convenient and practical if the combustion of the organic matter were complete1 and if the browning of the liquor did not render the end of the reaction uncertain4 ,the process of ,schmidt1 modified as below1 has given satisfactory results4 ,in a small flask1 with flat bottom1 containing about #bej cubic centimeters1 are introduced ten cubic centimeters of a solution of manganese sulfate containing sixteen grams of the anhydrous salt per liter1 and ten cubic centimeters of a ten per cent solution of potassium permanganate4 ,the solution is heated for a few minutes1 the liquor is decolorized and manganese bronze is precipitated4 ,one hundred cubic centimeters of water are added1 and four cubic centimeters of sulfuric acid containing #aej cubic centimeters of monohydrated acid per liter4 ,there is now added an exactly measured volume of the humic liquid properly prepared1 so that in oxidizing completely it destroys at most only half of the manganese dioxid4 ,the mixture is submitted to gentle ebullition for eight hours1 the water being kept at a constant volume4 ,the excess of manganese dioxid remaining is dissolved hot by a measured portion of decinormal oxalic acid in slight excess1 and the excess of oxalic acid is removed by a solution of potassium permanganate containing one gram per liter4 ,the volume of oxalic acid not destroyed by manganese dioxid is calculated from the amount of permanganate consumed4 ,the volume of oxalic acid1 which corresponds to the same quantity of dioxid as the introduced humus1 is also calculated by taking the difference between the volume of oxalic acid necessary to destroy all the dioxid formed by ten cubic centimeters of the ten per cent permanganate solution1 and the volume of the oxalic acid which has destroyed the dioxid remaining after the action of the humus4 ,the first volume of oxalic acid1 that is to say1 that which destroys the dioxid formed by ten cubic centimeters of ten per cent permanganate is determined in a preliminary titration4 ,in regard to the humic liquor1 it is prepared by treating ten grams of earth with soda solution in the usual manner4 ,it will be easy to calculate the volume of the oxalic solution equivalent to the total volume of the humic solution1 of which a determined fraction has been assayed1 and consequently the volume of oxalic solution equivalent to the humus in ten grams of the dry earth4 ,this number of cubic centimeters of the decinormal oxalic solution multiplied by #j4h will express in milligrams the weight of oxygen necessary to burn the humus from ten grams of dry earth4 ,humus not being a definite compound1 but a residue of complex organic matters partially oxidized1 it will require as much more oxygen to complete the combustion as the previous oxidation has been less pronounced4 ,this weight of oxygen necessary to burn the humus from ten grams of dry earth may serve to detect the total value as well as the weight of the humus itself4 ,however1 if we wish to have directly the weight of the humus1 resource can be had to a table which1 without being rigorous1 can be regarded as sufficiently exact when the variability of the constitution of humus is taken into account4 ,volume of decinormal oxalic acid ,corresponding humus1 directly for ten grams of earth4 determined4 ,cubic centimeters4 ,milligrams4 #ej #hj #ajj #aej #bjj #bhj #cjj #djj #djj #eaj #ejj #faj #fjj #gje #gjj #gij #hjj #hhe #ijj #ige #a1jjj #a1jfj #a1bjj #a1bbe #a1djj #a1cij #a1fjj #a1efj #a1hjj #a1gbj #b1jjj #a1hij #b1ejj #b1cae #c1jjj #b1gce #c1ejj #c1agj #d1jjj #c1fje #d1ejj #d1jce #e1jjj #d1dfj #e1ejj #d1hij #f1jjj #e1caj #f1ejj #e1gde #cah4 ,pasturel's ,method4--,according to ,pasturel#bje the process of ,raulin does not furnish figures that are rigorously exact only with soil of which the humus contains forty-five per cent of carbon4 ,when the richness in organic carbon is less1 the results of the estimation are too high4 ,pasturel modifies the process as follows3 ,manganese ,sulfate4--,dissolve sixteen grams of the pure anhydrous manganese sulfate in distilled water and make the solution up to one liter4 ,potassium ,permanganate4--,make a solution of ten grams of potassium permanganate in one liter of water2 #ajj cubic centimeters of the liquor just mentioned are diluted to one liter and constitute the potassium permanganate solution one to ten4 ,oxalic and ,sulfuric ,acids4--,a solution of oxalic acid is prepared containing #f4c grams of the acid in one liter of water1 and a dilute solution of sulfuric acid1 by dissolving #aej grams of the monohydrated acid in one liter of water4 ,humus ,solution4--,the solution of humus is prepared by the following process3 ,ten grams of fine earth are freed from all their carbonates by dilute hydrochloric acid4 ,after washing1 the filter is broken and the dirt is washed into a small flask4 ,not more than twenty or thirty cubic centimeters of water should be employed for this purpose4 ,twenty cubic centimeters of a liquor containing two grams of caustic soda are added1 and the flask is placed upon a sand-bath and maintained at a boiling temperature for six hours4 ,it is then diluted with water1 filtered and washed as long as the waters are colored4 ,the liquor is treated with dilute sulfuric acid until almost the whole of the soda is saturated4 ,it is indispensable1 however1 to maintain a slight alkalinity in order that the organic matter may rest totally dissolved4 ,the precipitation of silica which is almost always produced is without inconvenience4 ,afterward the volume is completed to #ejj cubic centimeters and the humus solution is then ready for use4 ,estimation of the ,humus4--,ten cubic centimeters of the manganese sulfate are placed in a flask and ten cubic centimeters of the permanganate added1 and the whole is then slightly heated1 and afterward #ajj cubic centimeters of water and four cubic centimeters of sulfuric acid are added4 ,the humic liquor is now introduced in such proportion that the humus which it contains dissolves at the greatest1 a half of the precipitated manganese and the rest of the process is continued as described by ,raulin4 #cai4 ,estimation of ,carbonates in ,arable ,soil4--,the principle of the determination depends on the liberation of the carbon dioxid from its compounds in the soil by acting on them with strong acid1 and the desiccation1 absorption1 and weighing of the evolved gas4 ,any of the ordinary forms of apparatus for estimating carbon dioxid may be used in this determination4 ,the apparatus of ,knorr#bjf has been used with satisfaction for many years in the laboratory of the ,department of ,agriculture4 ,illustration3 ,,figure #fe4 ,,knorr',s ,,apparatus ,,for ,,the ,,determination ,,of ,,carbon ,,dioxid4 ,the apparatus consists of a flask ,a1 ,fig4 #fe1 in which the carbon dioxid in the soil is liberated4 ,a condenser1 ,d1 fits by means of a ground-glass joint into the neck of the flask in which the liberated gas1 together with any air or aqueous vapor which may be carried forward1 is cooled4 ,this prevents any excess of vapor of water from entering the absorbing bulbs1 which could easily happen at the end of the experiments when the contents of ,a are raised to the boiling point4 ,the bulb ,b contains the acid1 usually hydrochloric1 which is employed for decomposing the carbonates4 ,it is provided with a guard bulb-tube1 ,c1 which serves to absorb any carbon dioxid which might enter the apparatus with the air during aspiration at the close of the determination4 ,the carbon dioxid is dried in the bulb-tube1 ,e1 in oil of vitriol1 and absorbed in the potash solution in ,f4 ,it is advisable to aspirate a slow current of air through the apparatus by means of the tube ,g during the whole of the operation4 ,the quantity of the sample to be taken depends on its richness in carbonates4 ,many soils are so poor in carbonates as to render any attempt at exact determination nugatory4 ,on the other hand1 a comparatively small sample of marls will be sufficient4 ,a preliminary qualitative test will indicate1 in a general way1 the quantity of the sample to be taken4 ,the sample of soil1 five to fifty grams1 having been transferred to ,a1 which should be perfectly dry1 is made into a batter with freshly boiled distilled water4 ,when all the parts of the apparatus are properly connected gas-tight1 the cock between ,b and ,a is slowly opened and the hydrochloric 7nitric7 acid in ,b allowed to flow into ,a at such a rate as will secure a moderate evolution of gas4 ,when the carbonate is entirely decomposed1 a lamp is brought under ,a and its contents gradually raised to the boiling point4 ,the aspiration of air1 free from carbon dioxid1 is meanwhile continued until all the liberated gas has been absorbed in ,f4 ,usually about fifteen minutes will be sufficient to accomplish this purpose4 #cbj4 ,bernard's ,calcimeter4--,for a rapid and approximately accurate method of determining the amount of carbonate in the soil1 estimated as calcium carbonate1 ,bernard makes use of the well-known method of the volumetric estimation of carbon dioxid4 ,the sample to be examined should not be powdered in any way4 ,the sample in a natural state1 but well air-dried1 is gently broken up by the fingers and passed through a sieve having ten meshes to the centimeter4 ,of the fine earth thus obtained1 one gram is taken1 for the determination4 ,if the percentage of carbonate in the soil exceeds fifty then only half a gram is taken4 ,illustration3 ,,figure #ff4 ,,bernard',s ,,calcimeter4 ,the apparatus employed is one well known4 ,the small erlenmeyer ,c is fitted with a rubber stopper carrying an exit tube for the gas and a small thermometer4 ,this flask is connected by means of a rubber tube and small glass tube to the measuring burette ,b4 ,this burette is graduated from #j to #ajj cubic centimeters4 ,below1 by means of a rubber tube1 it is connected with the open bulb ,a1 which1 by means of a cord about its neck1 can be suspended by the hook as shown in the figure4 ,the measuring tube is filled with water through ,a until the level of the liquid in ,b is slightly above the zero mark4 ,meanwhile the one gram of earth has been placed in ,c1 together with the tube ,d three-fourths filled with an equal mixture of water and strong hydrochloric acid4 ,the greatest care must be taken that no part of the acid be spilled4 ,the rubber stopper is now forced into ,c until the level of the water in ,b is just at the zero mark4 ,grasping ,c in the right hand and ,a in the left1 the operator inclines ,c until the contents of ,d are emptied4 ,meanwhile as the gas is evolved1 ,a is lowered at such a rate as to always keep the level of the water in ,b and ,a on the same plane4 ,in a few moments the evolution of gas is complete1 and the volume given off is read at once without correction4 ,this volume multiplied by #j4d gives the percentage of carbonate in the sample examined4 ,it is understood that the determination is made at ordinary temperatures2 viz41 #ag to #bb4 ,example3 ,one gram of a soil treated as above1 gave of carbon dioxid 7uncorrected7 #fe cubic centimeters4 #fe #j4d #bf4jj per cent calcium carbonate in sample4 ,the above method is useful in the classification of soils and in determining approximately the quantity of calcium carbonate which they contain4 ,the practical use of this method is of great value in determining the character of fertilizer to be applied4 ,it is well to know the percentage of carbonate in selecting mineral fertilizers4 #cba4 ,soils ,deficient in ,carbonates4--,when a soil contains but a small quantity of carbonates1 ,mller#bjg has called attention to the fact that the carbon dioxid absorbed by the water in which the soil is rubbed up may vitiate the result4 ,instead of water a titrated solution of sodium carbonate is employed4 ,the apparatus is composed of a flask containing the mixture of the sodium carbonate and the soil on which the hydrochloric acid is to act4 ,the hydrochloric acid is contained in a small tube1 as in ,scheibler's apparatus4 ,the gas is received in a rubber tube #a4e meters long and three to four millimeters interior diameter1 and connected with a burette1 the open mouth of which dips into the water of a cylinder of proper length4 ,the volume of gas is read when the burette is raised or lowered in the cylinder until the liquid within and without stands at the same level4 ,during the action of the acid on the carbonates the flask is constantly shaken4 ,several readings of the volume of gas are made1 the evolution flask being vigorously shaken before each one4 ,finally1 in order to allow for the variations in temperature and pressure of the exterior air which may take place between the beginning and the end of the reaction1 a second flask containing air is placed by the side of the evolution flask and communicating with a narrow tube half filled with water4 ,any variations in the volume of the air in the flask will be shown by variations in the height of the liquid in the two arms of the tube1 and the volume of the variation can be easily determined by having the tube calibrated4 ,if now a equals the volume per cent of carbon dioxid in the atmosphere of the evolution flask at the end of the reaction1 v the volume of gas disengaged1 and ,v the volume of the atmosphere in the evolution flask1 the per cent of carbon dioxid contained in a given length of the rubber tube will be equal to a_/#b4 ,this arises from the fact that the first gas which passes into the rubber tube is composed solely of air1 while the last contains a per cent of carbon dioxid4 ,by reason of the shaking of the flask the mean richness of the contents of the tube in carbon dioxid1 will be sensibly a_/#b4 ,from the above data the following equations are derived3 #a4 va_/#b ,va v4 #b4 a v_/7v_/#b ,v7 ,if the weight of the carbon dioxid dissolved in ,v cubic centimeters of the liquid in the evolution flask be represented by q1 the coefficient of the solubility of pure carbon dioxid in this liquid will be1 according to the law of the solubility of a gas1 equal to k 7q7_/7,va7 ,the volume of k has been determined for various strengths of the sodium carbonate solution1 using five cubic centimeters of hydrochloric acid containing #a4f grams pure hydrochloric acid4 ,for solutions disengaging from five to fifty milligrams of carbon dioxid1 the mean value of k was found to be #a4h milligrams in the absence of calcium chlorid4 ,when calcium chlorid was present in quantities varying from #j4jc to #j4jg gram per cubic centimeter of liquid in the evolution flask1 the value of k was #a4d milligrams4 ,by adopting1 according to circumstances1 the one or the other of the above numbers and multiplying it by ,va1 as determined by experiment1 results are obtained differing only #j4b to #j4c milligram from those secured by direct weighing of the evolved gas4 ,dietrich#bjh has called attention to the necessity of adding the volume of the dissolved gas to the measured volume in such determinations1 and this volume or weight is easily determined by the above formulas4 #cbb4 ,belgian ,method4--,the method pursued at the ,gembloux ,station#bji consists in taking from five to fifty grams of the sample of soil1 according to its content in carbonate1 rubbing it up in a porcelain dish with distilled water in order to make a thin paste4 ,the mass is worked to drive out all the air1 the whole washed into a flask of #cjj cubic centimeters capacity1 and the amount of carbon dioxid estimated by setting free with an acid1 and collecting the carbon dioxid evolved in potash bulbs4 ,,digestion ,,of ,,soils ,,with ,,solvents4 #cbc4 ,general ,considerations4--,there are two points in connection with the determination of mineral matters in the soil which must always be kept in view2 viz41 first1 the estimation of the total quantities of material in the soil1 and second1 the study of those materials which are more easily brought into solution and thus made available for the food of plants4 ,it is well understood that the soil particles do not give up entirely to the plant the food materials which they contain4 ,the practical value therefore of an analysis of a soil depends more upon the exact determination of the plant food available than upon its total quantity4 ,from a mineral and geological point of view1 on the other hand1 an idea of the total composition of the soil is the object to be attained4 ,for the determination of the available plant food1 various solvents have been proposed1 none of which1 perhaps1 imitates very accurately the natural solvent action of organic life and moisture on the soil materials4 ,a description of the standard methods of preparing soil extracts will be the subject of a few succeeding paragraphs4 #cbd4 ,estimation of the ,quantity of ,materials ,soluble in ,water4#baj--;,five hundred grams of the air-dried soil are treated in a flask with #a1ejj cubic centimeters of water1 less the quantity of water already contained in the air-dried soil1 which is volatile at #abe4 ,the mass is frequently shaken and1 after seventy-two hours1 #gej cubic centimeters of the liquid filtered4 ,the filtrate is evaporated to dryness in a platinum dish1 dried at #abj and weighed4 ,this is then incinerated and1 after treatment with ammonium carbonate and gentle ignition1 is again weighed4 ,the further examination of the residue for acids and bases is made by some of the methods hereafter described4 #cbe4 ,treatment with ,water ,saturated with ,carbon ,dioxid4--,two thousand five hundred grams of the air-dried soil are treated with #hjjj cubic centimeters of distilled1 and afterwards with #bjjj cubic centimeters of water1 which have previously1 at room temperature1 been saturated with carbon dioxid4 ,the mixture is left in a closed flask for seven days1 frequently shaken1 after which #g1ejj cubic centimeters of the liquid are filtered4 ,the clear filtrate1 after treatment with a little hydrochloric acid and a few drops of nitric acid1 is evaporated to dryness4 ,after the separation of the silica the traces of iron1 alumina1 lime1 sulfuric acid1 magnesia1 potash1 and soda1 are estimated in the liquid in the manner hereinafter to be described4 ,phosphoric acid is always present in such a case1 in such small quantities as to make its estimation unnecessary4 #cbf4 ,treatment with ,water ,containing ,ammonium ,chlorid4--,in the flask containing the residue from the last experiment2 viz41 the soil with #b1ejj cubic centimeters of liquid1 are added #a1ejj cubic centimeters of water saturated with carbon dioxid1 and #h1jjj cubic centimeters of pure water in which five grams of ammonium chlorid are dissolved4 ,the mixture is then left for seven days1 with frequent shaking1 and #g1ejj cubic centimeters of the liquid are then filtered1 and the substances dissolved1 determined in the filtrate4 ,in addition to the usual quantities of lime and magnesia1 from two to four times as much alkali is dissolved by this treatment as is found in the solution from the water containing carbon dioxid alone4 #cbg4 ,treatment with ,water ,containing ,acetic ,acid4--,the acetic acid should be of such a strength that after it has fully acted on the soil it should still contain twenty per cent of free acid4 #ajjj grams of the soil dried at #ajj are taken and the acid added in proper proportions and treated in the manner to be described for determining the solvent action of hydrochloric acid4 #cbh4 ,treatment with ,citric ,acid ,solution4--,in ascertaining the quantities of soil materials soluble in a solution of citric acid1 ,dyer#baa recommends the use of a carefully prepared citric acid solution4 ,the digestion is carried on as follows3 ,place in a flask or bottle1 holding about three liters1 #bjj grams of air-dried soil and two liters of distilled water1 in which are dissolved twenty grams of pure citric acid4 ,the soil is left1 at room temperature1 in contact with the one per cent acid for seven days1 with thorough shaking several times a day4 ,at the end of the digestion the solution is filtered and #ejj cubic centimeters of the filtrate1 corresponding to fifty grams of the soil1 are taken for analysis for each ingredient to be determined4 ,the digestion in citric acid is especially recommended by ,dyer because of its supposed near resemblance to the methods of solution of plant food practiced by the rootlets of plants4 ,it is evident1 however1 that this process is in no sense an imitation of natural methods4 ,the solution is to be used exclusively for the estimation of potash and phosphoric acid4 ,dyer concludes1 from a comparison of the action of a solution of citric acid on soils of known fertility1 that when as little as #j4ja per cent of phosphoric acid is dissolved from a soil by this treatment it is justifiable to assume that it stands in immediate need of phosphatic manure4 ,the methods used by ,dyer to determine the phosphoric acid and potash in the citric acid solution will be given in their appropriate place4 #cbi4 ,treatment with ,hydrochloric ,acid4--,the solutions of soils usually subjected to chemical analysis are those obtained by long treatment with hot mineral acids1 among which the most common is hydrochloric4 ,it has long been assumed by soil analysts1 perhaps not with justness1 that such treatment removed from the soil1 all those elements of plant food which could possibly be available for the needs of the growing crop4 ,in this connection1 however1 the analyst must not forget that nature1 in a series of years1 with her own methods may easily accomplish what he in five days1 even with the help of a hot mineral acid1 may not be able to secure4 ,since1 however1 this method of solution has been so long practiced it is not the place here to throw doubt on its effectiveness without being able to suggest a better way4 ,of the mineral acids available no one possesses solvent powers for soils in a higher degree than hydrochloric4 ,a somewhat detailed description will therefore be given of the methods of its use4 #ccj4 ,strength of ,acid to be ,employed4--,the fact that hydrochloric acid of nearly constant strength2 viz41 specific gravity #a4aae1 equivalent to #bb4i per cent hydrochloric acid1 may be obtained by distillation1 led ,owen to use acid of this density in his classic work on soil analysis4 ,hilgard has lately reviewed the conditions of constant strength in the solvent with results confirming the statements of ,owen4#bab ,he evaporated on a steam-bath1 to one-half its bulk1 fifty cubic centimeters of hydrochloric acid1 specific gravity #a4aaf1 obtained by using the distillate from a stronger acid after rejecting the first third4 ,the same operation was conducted with similar acid diluted with ten per cent of water4 ,the acid used contained #bb4if per cent hydrochloric acid4 ,the residual acid contained #ba4di per cent hydrochloric acid4 ,these results lead ,hilgard to believe that the changes arising from evaporation in hydrochloric acid during soil digestion are insignificant1 compared with those due to its action on the soluble matters1 and that evaporation during digestion is effective in maintaining a definite strength in the solvent4 ,for this reason it is contended that evaporation in a porcelain beaker covered by a watch-glass is more effective in constancy of conditions than digestion in a closed flask under pressure4 #cca4 ,influence of ,time of ,digestion and ,strength of ,acid4--,loughridge has made an interesting study of the influence of the strength of acid and time of digestion on the extraction of soils4#bac ,the method of preparing the soil for the determination of the above points is as follows3 ,the soil1 having been passed through the appropriate number of sieves to obtain the fine earth is pulverized with a wooden pestle and thoroughly mixed4 ,the hygroscopic moisture is determined1 after exposing it in a place saturated with vapor1 in a layer not exceeding one millimeter in thickness for twelve hours1 and subsequently drying at #bjj in a paraffin-bath4 ,of this dried substance1 from two to three grams are used in the general analysis1 the methods employed being in general those adopted by ,peter4#bad ,the quantities of materials dissolved by acids of different densities are shown below4 ,the determinations were made by methods hereafter to be described4 ,specific gravity of acid4 ,ingredients4 #a4jj #a4aae #a4afj ,insoluble residue #ga4hh #gj4ec #gd4ae ,soluble silica #aa4ch #ab4cj #i4db ,potash #j4fj #j4fc #j4dh ,soda #j4ac #j4ji #j4ce ,lime #j4bg #j4bg #j4bc ,magnesia #j4de #j4de #j4de ,manganese oxid #j4jf #j4jf #j4jf ,ferric oxid #e4ae #e4aa #e4jd ,alumina #f4hd #h4ji #f4bb ,sulfuric acid #j4jb #j4jb #j4jb ,volatile matter #c4ad #c4ad #c4ad ------------ ------------ ---------- ,total #ajj4jb #ajj4fi #ii4bi ,amount of soluble matter #bd4jj #bg4jb #bb4bg bases #ac4ej #ad4gj #ab4hc ,from the above table it is seen that the strongest acid exerts the least soluble effect upon the substances present in the soil1 while the greatest degree of solution was obtained by the acid of #a4aae specific gravity4 ,this result indicates that while lime and magnesia are probably present chiefly as carbonates1 potash as well as alumina1 and to some extent lime1 are present as silicates1 and for that reason are not as fully extracted by acid of low strength as by that of medium concentration4 ,in regard to the influence of the time of digestion1 the acid of specific gravity #a4aae being used1 the data obtained are given in the following table3 ,number of days digested4 ,ingredients4 #a4 #c4 #d4 #e4 #aj4 ,insoluble residue #gf4ig #gb4ff #ga4hf #gj4ec #ga4gi ,soluble silica #h4fj #aa4ah #aa4fd #ab4cj #aj4if ,potash #j4ce #j4dd #j4eg #j4fc #j4fb ,soda #j4jf #j4jf #j4jc #j4ji #j4bh ,lime #j4bf #j4bi #j4bh #j4bg #j4bg ,magnesia #j4db #j4dd #j4dg #j4de #j4dd ,manganese oxid #j4jd 4#jf #j4jf #j4jf #j4jf ,ferric oxid #d4gg #e4ja #e4dc #e4aa #d4he ,alumina #e4ae #g4ch #g4jg #g4hh #g4af ,phosphoric acid #j4ba #j4ba ,sulfuric acid #j4jb #j4jb #j4jb #j4jb #j4jb ,volatile matter #c4ad #c4ad #c4ad #c4ad #c4ad ---------- ------------ ------------ ------------ ---------- ,total #ii4fc #ajj4fh #ajj4ee #ajj4fi #ii4hj ,amount of soluble matter #ai4fg #bd4hh #be4eg #bg4jb #bd4hg bases #aa4je #ac4fh #ac4ia #ad4di #ac4fh ,from this table it appears that the amount of dissolved ingredients increases up to the fifth day1 the increase becoming1 however1 very slow as that limit is approached4 ,it is also found that the ingredients offering the greatest resistance to this action are the same as those whose amounts were sensibly affected by the strength of the acid2 namely1 silica1 potash1 and alumina4 ,in regard to lime and magnesia1 one day's digestion not being sufficient for full extraction1 it is evident that they do not exist in the soil as carbonates or hydric oxids only1 as has been supposed1 but also as silicates4 ,a comparison of the results of the five and ten days' digestion shows that the solvent action of the acid has substantially ceased at the end of five days1 there being no further increase of the amount of dissolved matter4 #ccb4 ,digestion ,vessels4--,hilgard prescribes that the digestion of the sample of soil with acid be conducted in a small porcelain beaker covered with a watch-glass4#bae ,kedzie1 however1 prefers beakers of bohemian glass1 and shows that hydrochloric acid attacks the porcelain with greater energy than the glass4#baf ,platinum would be the ideal material for the digestive vessels1 but its great cost would exclude its general use4 ,in most cases it will be found that the error introduced into the analysis by the use of porcelain or bohemian glass beakers is quite small and not likely to affect the quantitative estimation of soluble soil ingredients to any extent4 ,in this laboratory some comparative tests made by ,mr4 ,w4 ,d4 ,bigelow have shown that vessels of hard glass of special manufacture are less soluble in hot hydrochloric acid of #a4aae specific gravity than porcelain1 thus confirming the observation of ,kedzie4 ,following are the data showing the weights of material dissolved in fifty hours3 ,berlin porcelain #b4h milligrams ,bohemian glass #a4g ,kaehler and ,martini glass #a4b ,in each case twenty-five cubic centimeters of the acid were used4 ,the vessels all had approximately a capacity of #bjj cubic centimeters4 #ccc4 ,processes ,employed--,hilgard's ,method4--,the sample of soil sifted through a #j4e millimeter mesh sieve and thoroughly air-dried1 is conveniently preserved in weighing tubes4 ,the actual content of hygroscopic and combined moisture may be previously made on a separate sample of soil4 ,in determining the amount of material to be employed for the general analysis regard must be had to the nature of the soil4 ,this is necessary because of the impracticability of handling successfully such large precipitates of alumina as would result from the employment of as much as five grams in the case of calcareous clay soils2 while in the case of very sandy soils even that quantity might require to be doubled in order to obtain weighable amounts of certain ingredients4 ,for soils in which the insoluble portion ranges from sixty to eighty per cent1 two and a half to three grams are about the right measure for general analysis1 while for the phosphoric acid determination not less than three grams should be employed in any case4 ,it has been alleged that larger quantities must be taken for analysis in order to secure average results4 ,it is difficult to see why this should be true for soils and not for ores1 in which the results affect directly the money value1 while in the case of soils the interpretation of results allows much wider limits in the percentages4 ,correct sampling must be presupposed to make any analysis useful2 but with modern balances and methods it is difficult to see why five grams should be employed instead of half that amount1 which in some cases is still too much for convenient manipulation of certain precipitates4 ,the weighed quantity1 usually of two to two and a half grams1 is brought into a small porcelain beaker1 covered with a watch-glass1 treated with eight to ten times its bulk of hydrochloric acid of #a4aae specific gravity1 and two or three drops of nitric acid1 and digested for five days over the laboratory steam-bath4 ,at the end of this time it is evaporated to dryness1 first on the water-bath and then on the sand-bath4 ,by this treatment all the silica set free is rendered insoluble4 #ccd4 ,provisional ,method of the ,official ,agricultural ,chemists4--,place ten grams of the air-dried soil in a round bottom #aej to #bjj cubic centimeter bohemian flask1 add #ajj cubic centimeters of pure hydrochloric acid of specific gravity #a4aae1 insert the stopper1 wire it securely1 place in a steam-bath1 and digest for thirty-six hours at the temperature of boiling water4 ,pour the contents of the flask into a small beaker1 wash with distilled water1 add the washings to the contents of the beaker and filter through a washed filter4 ,the residue is the amount insoluble in hydrochloric acid4 ,add a few drops of nitric acid to the filtrate1 and evaporate to dryness on the water-bath2 take up with hot water and a few drops of hydrochloric acid1 and again evaporate to complete dryness4 ,take up as before1 and filter into a liter-flask1 washing with hot water4 ,cool and make up to the mark4 ,this is solution ,a4 ,the residue represents the silica originally dissolved4 ,in comparing the two preceding methods it is found that the former2 viz41 digestion in flasks covered only with a watch-glass gives a larger quantity of dissolved matter in five days than the digestion under pressure does in thirty-six hours4 ,in comparative tests in this laboratory made by ,mr4 ,w4 ,d4 ,bigelow the respective quantities of soluble and insoluble matter obtained by the two methods in two soils are as follows3 ,soil ,no4 #a4 ,soil ,no4 #b4 ,per cent4 ,per cent4 ,method of ,digestion4 ,insoluble4 ,soluble4 ,insoluble4 ,soluble4 ,open flask #ge4fb #bd4ch #gi4fb #bj4ch ,closed flask #gf4ha #bc4ai #hj4dh #ai4eb #cce4 ,the ,german ,station ,method4--,the method recommended by the ,german ,stations#bag is greatly different from that described above1 both in temperature and time of digestion4 ,to one part of the soil are added two parts by volume of a twenty-five per cent hydrochloric acid solution1 the quantity being increased to correspond to any excess of carbonates4 ,the mixture is left for forty-eight hours with frequent shaking4 ,as an alternate method1 one part of soil is treated with two parts by volume of ten per cent hydrochloric acid1 and heated on the water-bath1 with frequent shaking1 for three hours4 ,the soluble materials are determined in the filtrate by some of the methods usually employed4 #ccf4 ,the ,gembloux ,method4--,the method of making the acid extract of the soil at the ,gembloux ,station does not differ greatly from some of those already described4 ,the quantity of air-dried material taken is such that it may weigh exactly #cjj grams exclusive of the moisture which it contains4 ,it is dried at #aej for at least six hours4 ,the drying is necessary in order to obtain an extract in hydrochloric acid of exactly #a4ah specific gravity4 ,the dry earth is placed in a flask of two or three liters capacity to which one liter of hydrochloric acid of #a4ah specific gravity is added1 being careful to take precautions to prevent frothing if much carbonate be present4 ,the acid is allowed to act for twenty-four hours1 it being frequently shaken meanwhile4 ,after settling it is decanted and filtered upon a double folded filter1 the apex of which rests upon a small funnel covered with a plain filter of strong paper4 ,five hundred cubic centimeters of the filtrate are taken for the estimation1 and in this filtrate are estimated the silica1 phosphoric and sulfuric acids1 potash1 soda1 iron1 alumina1 lime1 and magnesia4 ,the filtrate is evaporated to dryness in a porcelain capsule1 a few drops of nitric acid added and the liquid kept well stirred4 ,the residue should be taken up with water1 and if not perfectly bright a second and even a third evaporation with nitric acid should take place1 until all the organic matter is destroyed1 which will be indicated by the clear yellow or reddish-yellow color of the liquid1 caused by the iron oxid4 ,after the last evaporation the material is dried in a drying oven one hour at #aaj4 #ccg4 ,treatment with ,cold ,hydrochloric ,acid4--,according to the digestion method of ,wolff#bah the soil sample is treated with cold concentrated hydrochloric acid4 ,the process is as follows3 ,four hundred and fifty grams of the soil dried at #ajj are placed in a glass flask and treated with #a1ejj cubic centimeters of hydrochloric acid of #a4ae specific gravity1 corresponding to thirty per cent of gaseous hydrochloric acid4 ,for every five per cent of calcium carbonate which the soil may contain1 an additional fifty cubic centimeters of hydrochloric acid are added4 ,with frequent stirring1 the soil is left in contact with the acid for forty-eight hours and then #a1jjj cubic centimeters of liquid1 as clear as possible1 are poured off1 which corresponds to #cjj grams of the soil4 ,after dilution with water it is filtered and the filtrate treated with a few drops of nitric acid and evaporated to dryness4 ,after the separation of the silica the solution is again made up with water to #a1jjj cubic centimeters4 ,two hundred cubic centimeters of this solution1 corresponding to sixty grams of the soil1 are taken for the estimation of iron1 alumina1 lime1 manganese1 and magnesia4 ,four hundred cubic centimeters of the solution1 corresponding to #abj grams of the soil1 are left for the estimation of sulfuric acid and alkalies4 ,this method gives from five to six times less alkalies and a much smaller quantity of iron than the treatment with hot acid4 ,in the use of hot acid1 therefore1 ,wolff reduces the quantity of soil acted on to #aej grams4 #cch4 ,treatment with ,nitric ,acid4--,for the purpose of estimating phosphoric acid ,grandeau#bai directs that the soil be extracted with nitric acid4 ,for this purpose #ajj grams of the air-dried fine earth are placed in a bohemian flask and treated cautiously with nitric acid in small quantities at a time4 ,if the soil be calcareous in its nature it should be previously moistened with water1 and the acid so added as to avoid undue effervescence1 the flask being inclined during the operation4 ,sufficient acid is added to strongly saturate the sample and it is then digested on the sand-bath for two hours2 or at least until the organic matters are destroyed1 which will be indicated by the cessation of evolution of nitrous vapors4 ,when the supernatant liquid has become clear it is decanted4 ,the residue is washed with distilled water and separated on a filter1 and washed until the wash-water is colorless4 ,the decanted portion is united with the filtrate and the whole made up to a volume of one liter4 ,the determinations are made in portions of #bjj cubic centimeters each4 #cci4 ,digestion with ,hydrofluoric and ,sulfuric ,acids4--,when a complete disintegration of the siliceous substances in soils is desired as in analysis in bulk1 the decomposition is easily accomplished by digestion with the above named acids in a platinum dish4 ,the fine earth is saturated with a concentrated aqueous solution of hydrofluoric acid to which a few drops of sulfuric acid are added4 ,it is then digested until nearly dry4 ,if any undecomposed particles remain1 the treatment is continued until complete decomposition is secured4 ,the silica is thus all volatilized as hydrofluosilicic acid and the bases pre-existing in the soil are left as sulfates4 ,this method of treatment is especially recommended when it is desired to estimate the whole quantity of any of the soil constituents with the exception of silica4 ,the silica may1 however1 be determined in the distillate4 ,instead of using the solution of hydrofluoric acid1 ammonium fluorid may be employed4 ,in this process the sample of earth reduced to an impalpable powder by grinding in an agate mortar is mixed with four or five times its weight of the ammonium fluorid in a platinum dish and thoroughly moistened with sulfuric acid and allowed to stand at room temperature for several hours4 ,it is then gently heated until all fumes of hydrofluosilicic acid have been driven off1 but is not raised to a red heat4 ,if any undecomposed particles remain1 the above treatment is repeated4 ,,determination ,,of ,,the ,,quantity ,,of ,,dissolved ,,matter4 #cdj4 ,substances in ,solution4--,by treatment with solvents as indicated in the preceding paragraphs1 greater or less quantities of the original constituents of soil are brought into solution4 ,the total quantity of dissolved matters is determined by drying and weighing the insoluble residue and the percentages of soluble and insoluble matters should be noted2 and each portion saved for further examination4 ,in this country the common practice of soil analysis is to digest the sample with hydrochloric acid4 ,the following paragraphs1 therefore1 will be devoted to the general methods of determining the matters dissolved by that treatment1 leaving for later consideration the special methods of analysis4 ,the fundamental principle on which the treatment with hydrochloric acid rests is based on the belief that such treatment practically extracts from the soil all those elements which are likely to become1 immediately or in the near future1 available for plant food4 #cda4 ,provisional ,methods of the ,official ,agricultural ,chemists4#bbj--7a7 ,the ,analytical ,operations are conducted with solution ,a1 paragraph #ccd4 7#b7 ,ferric ,oxid1 ,alumina1 and ,phosphoric ,acid4--,to #ajj or #bjj cubic centimeters1 according to the probable amount of iron present1 of the solution ,a1 add ammonium hydroxid to alkaline reaction to precipitate ferric and aluminum oxids and phosphates4 ,expel the excess of ammonia by boiling1 allow to settle1 decant the clear solution through a filter2 add to the flask fifty cubic centimeters of hot distilled water1 boil1 settle1 and decant as before4 ,after pouring off all the clear solution possible1 dissolve the residue with a few drops of warm hydrochloric acid and add just enough ammonium hydroxid to precipitate the oxids4 ,wash by decantation with fifty cubic centimeters of distilled water1 and then transfer all the precipitate to the filter and wash with hot distilled water till the filtrate becomes free from chlorids4 ,save the filtrate and washings which form solution ,b4 ,dry the filter and precipitate at #aaj1 transfer the precipitate to a tared platinum crucible1 burn the filter and add the ash to the precipitate1 heat the whole red hot1 cool in a desiccator1 and weigh4 ,the increase of weight1 minus the ash of filter and the phosphoric acid 7found in a separate process71 represents the weight of the ferric and aluminum oxids4 7#c7 ,ferric ,oxid4--,precipitate #ajj cubic centimeters of solution ,a1 as under 7#b71 except that only one precipitation is made2 wash with hot water2 dissolve in dilute sulfuric acid2 reduce with zinc and estimate as ferrous oxid by a standard solution of potassium permanganate4 ,to prepare the potassium permanganate solution1 dissolve #c4aef grams of pure crystallized potassium permanganate in #a1jjj cubic centimeters of distilled water1 and preserve in a glass-stoppered bottle1 shielded from the light4 ,standardize this solution with pure ferrous sulfate1 ammonium ferrous sulfate or oxalic acid4 7#d7 ,alumina4--,the calculated weight of ferric oxid deducted from that of ferric oxid and alumina with corrections for filter ash and phosphoric acid1 will give the weight of alumina in two grams of air-dried soil4 7#e7 ,phosphoric ,acid4--,this may be estimated in the above iron solution1 if the soil is sufficiently rich1 by the molybdate method1 given under fertilizers2 or if the quantity of soil represented in the iron solution is not sufficient1 a fresh portion of solution ,a may be taken1 and the phosphoric acid determined directly by the molybdate method4 7#f7 ,manganese4--,concentrate the filtrate and washings 7solution ,b7 to #bjj cubic centimeters or less2 add ammonium hydroxid to alkalinity2 add bromin water and heat to boiling1 keeping the beaker covered with a watch-glass2 as the bromin escapes1 the beaker is allowed to cool somewhat1 ammonia and bromin water again added1 and heated as before4 ,this process is continued until the manganese is completely precipitated1 which requires from thirty to sixty minutes1 and the solution filtered while still warm2 the precipitate is washed1 dried1 ignited and weighed2 estimate as manganese protosesquioxid4 7#g7 ,lime4--,if no manganese is precipitated1 add to solution ,b1 or the filtrate and washings from 7#f7 twenty cubic centimeters of a strong solution of ammonium chlorid and forty cubic centimeters of saturated solution of ammonium oxalate to completely precipitate all the lime as oxalate and convert the magnesia into soluble magnesium oxalate4 ,heat to boiling and let stand for six hours till the calcium oxalate settles clear1 decant the clear solution on a filter1 pour fifty cubic centimeters of hot distilled water on the precipitate and again decant the clear solution on the filter1 transfer the precipitate to the filter1 and wash it free from all traces of oxalates and chlorids4 ,dry and ignite the precipitate over the blast-lamp until it ceases to lose weight1 weigh and estimate as calcium oxid2 carefully moisten with sulfuric acid1 heat the inclined covered crucible gently to avoid loss1 then intensely1 and weigh as calcium sulfate4 7#h7 ,magnesia4--,concentrate the filtrate and washings 7from #g7 to #bjj cubic centimeters1 place in a half-liter erlenmeyer1 add thirty cubic centimeters of a saturated solution of sodium phosphate and twenty cubic centimeters of concentrated ammonium hydroxid1 cork the flask1 and shake violently at intervals of a few minutes till crystals form1 then set the flask in a cool place for twelve hours4 ,filter the clear liquid through a tared gooch1 transfer the precipitate to the filter1 and wash with dilute ammonium hydroxid 7#a 3 #c7 till the filtrate is free from phosphates2 dry and ignite the crucible1 at first gently and then intensely1 to form magnesium pyrophosphate4 ,the increase of weight #j4cfjbd ,mg,o4 ,by using an erlenmeyer free from scratches and marks1 and shaking violently instead of stirring with a glass rod1 the danger is almost entirely avoided of crystals adhering to the sides of the vessel2 but if crystals do adhere they are readily removed by a rubber-tipped glass rod4 7#i7 ,sulfuric ,acid4--,evaporate #bjj cubic centimeters of solution ,a 7#a7 nearly to dryness on a water-bath to expel the excess of acid2 then add #ajj cubic centimeters of distilled water1 heat to boiling and add ten cubic centimeters of a solution of barium chlorid1 and continue the boiling for five minutes4 ,when the precipitate has settled1 pour the clear liquid on a tared gooch1 treat the precipitate with fifty cubic centimeters of boiling water1 and transfer the precipitate to the filter and wash with boiling water till the filtrate is free from chlorids4 ,dry the filter and ignite strongly4 ,the increase in weight is barium sulfate1 which multiplied by #j4cdcca ,,so in two grams of air-dried soil4 7#aj7 ,potash and ,soda4--,to another portion of #bjj cubic centimeters of solution ,a1 add barium chlorid in slight excess1 and make alkaline with ammonia to precipitate sulfuric and phosphoric acids1 ferric oxid1 etc4 ,then precipitate the calcium and barium by ammonium oxalate4 ,evaporate the filtrate and washings to dryness1 heat to a low red heat to decompose oxalates and expel ammonia salts1 dissolve in twenty-five cubic centimeters of distilled water1 filter and wash the precipitate2 add to the filtrate and washings ten cubic centimeters of baryta water1 and digest for an hour4 ,filter and wash the precipitate1 add ammonium carbonate to the filtrate to complete precipitation of baryta1 filter and wash this precipitate4 ,evaporate the filtrate and washings in a tared platinum dish1 gently ignite the residue to expel ammonia salts1 cool and weigh4 ,the increase of weight represents the potassium and sodium chlorids in two grams of air-dried soil4 #cdb4 ,hilgard's ,methods4#bba--7a7 ,soluble ,silica4-- ,the acid filtrate obtained by the process given in paragraph #ccc is employed for the following determinations4 ,after the solution obtained has been evaporated to dryness to render silica insoluble1 it is moistened with strong hydrochloric acid and two or three drops of nitric acid4 ,the mass is warmed1 and after allowing to stand for a few hours on a steam-bath is taken up with distilled water4 ,after clearing1 it is filtered from the insoluble residue1 which is strongly ignited and weighed4 ,if the filtrate should be turbid the insoluble residue which has gone through the filter can be recovered in the iron and alumina determination4 ,the insoluble residue is next boiled for fifteen or twenty minutes in a concentrated solution of sodium carbonate1 to which a few drops of caustic lye should then be added to prevent reprecipitation of the dissolved silica4 ,the solution must be filtered hot4 ,the difference between the weight of the total residue and that of undissolved sand and mineral powder is recorded as soluble silica1 being the aggregate of that set free by the acid treatment and that previously existing in the soil4 ,the latter1 however1 rarely reaches five per cent4 7#b7 ,destruction of ,organic ,matter4--,the acid filtrate from the total insoluble residue is evaporated to a convenient bulk4 ,in case the filtrate should indicate by its color1 the presence of any organic matter1 it should be oxidized by aqua regia1 otherwise there will be difficulty in separating alumina4 7#c7 ,precipitation of ,iron and ,alumina4--,the filtrate thus prepared is now brought to boiling and treated sparingly with ammonia1 whereby iron and alumina are precipitated4 ,it is kept boiling until the excess of ammonia is driven off1 and then filtered hot4 7,filtrate ,a47 ,the previous addition of ammonium chlorid is usually unnecessary4 ,if the boiling is continued too long1 filtration becomes very difficult and a part of the precipitate may redissolve in washing4 ,filtration may be begun as soon as the nose fails to note the presence of free ammonia2 test paper is too delicate4 ,failure to boil long enough involves the contamination of the iron-alumina precipitate with lime and manganese4 7#d7 ,estimation of ,iron and ,alumina4--,the iron and alumina precipitate with filter of 7#c7 is dissolved in a mixture of about five cubic centimeters of hydrochloric acid and twenty cubic centimeters of water4 ,then filter and make up to #aej cubic centimeters4 ,take fifty cubic centimeters for the determination of iron and alumina together by precipitation with ammonia1 after oxidizing the organic matter 7filter7 with aqua regia2 also fifty cubic centimeters for iron alone2 keep fifty cubic centimeters in reserve4 ,determine the iron by means of a standard solution of potassium permanganate after reduction2 this latter is done by evaporating the fifty cubic centimeters almost to dryness with strong sulfuric acid1 adding water and transferring the solution to a flask1 and then reducing by means of pure metallic zinc in the usual way4 ,the alumina is then determined by difference4 ,this method of determining the two oxids in their intermixture is in several respects more satisfactory than the separation with alkaline lye1 which1 however1 has served for most determinations made1 until within the last ten years4 ,it is1 however1 much more liable to miscarry in unpracticed hands than the other4 7#e7 ,estimation of ,lime4--,the filtrate ,a from iron and alumina is acidified slightly with hydrochloric acid1 and if too bulky is evaporated to about twenty-five cubic centimeters1 unless the soil is a very calcareous one1 and the lime is precipitated from it by neutralizing with ammonia and adding ammonium oxalate4 ,the precipitation of the lime should be done in the hot solution1 as the precipitate settles much more easily4 ,it is allowed to stand for twelve hours1 then filtered 7filtrate ,b71 washed with cold water1 and dried4 ,by ignition the lime precipitate is partially converted into the oxid4 ,it is then heated with excess of powdered ammonium carbonate1 moistened with water1 and exposed to a gentle heat 7#ej-hj7 until all the ammonia is expelled4 ,it is then dried below red heat and weighed as calcium carbonate4 ,when the amount of lime is at all considerable1 the treatment with ammonium carbonate must be repeated till a constant weight is obtained4 7#f7 ,estimation of ,sulfuric ,arid4--,the filtrate ,b from the calcium oxalate is put into a bohemian flask1 boiled down over the sand-bath1 and the ammoniacal salts destroyed with aqua regia4 ,from the flask it is removed to a small beaker and evaporated to dryness with excess of nitric acid4 ,this process usually occupies four to five hours4 ,the residue should be crystalline-granular2 if white-opaque1 ammonium nitrate remains and must be destroyed by hydrochloric acid4 ,the dry residue is now moistened with nitric acid1 and the floccules of silica usually present separated by filtration from the filtrate1 which should not amount to more than ten or fifteen cubic centimeters2 sulfur trioxid is then precipitated by treatment with a few drops of barium nitrate1 both the solution and the reagent being heated to boiling4 ,if the quantity of sulfuric acid is large it may be filtered after the lapse of four or five hours 7filtrate ,c74 ,if very small let it stand twelve hours4 ,the precipitate is washed with boiling water1 dried1 ignited1 and weighed4 ,care should be taken in adding the barium nitrate to use only the least possible excess1 because in such a small concentrated acid solution the excess of barium nitrate may crystallize and will not readily dissolve in hot water4 ,care must also be taken not to leave in the beaker the large heavy crystals of barium sulfate1 of which a few sometimes constitute the entire precipitate1 rarely exceeding a few milligrams4 ,should the ignited precipitate show an alkaline reaction on moistening with water1 it must be treated with a drop of hydrochloric acid1 refiltered and weighed4 ,the use of barium acetate involves unnecessary trouble in this determination4 7#g7 ,estimation of ,sodium and ,potassium4--,filtrate ,c is now evaporated to dryness in a platinum dish2 the residue is treated with an excess of crystallized oxalic acid1 moistened with water1 and exposed to gentle heat4 ,it is then strongly ignited to change the oxalates to carbonates4 ,this treatment with oxalic acid must be made in a vessel which can be kept well covered1 otherwise there is danger of loss through spattering4 ,as little water as possible should be used1 as otherwise loss from evolution of carbon dioxid is difficult to avoid4 ,spatters on the cover should not be washed back into the basin until after the excess of oxalic acid has been volatilized4 ,the ignited mass should have a slightly blackish tinge to prove the conversion of the nitrates into carbonates4 ,white portions may be locally retreated with oxalic acid4 ,the ignited mass is treated with a small amount of water1 which dissolves the alkaline carbonates and leaves the magnesium carbonate1 manganese protosesquioxid1 and the excess of barium carbonate behind4 ,the alkalies are separated by filtration into a small platinum dish 7filtrate ,d71 and the residue is well but sparingly washed with water on a small filter4 ,when the filtrate exceeds ten cubic centimeters it may1 on evaporation1 show so much turbidity from dissolved earthy carbonates as to render refiltration on a small filter necessary1 since otherwise the soda percentage will be found too large and magnesia too small4 ,if1 on dissolving the ignited mass1 the solution should appear greenish from the formation of alkaline manganates1 add a few drops of alcohol to reduce the manganese to insoluble dioxid4 ,the residue of barium1 magnesium1 and manganese compounds is treated on the filter with hydrochloric acid1 and the platinum dish is washed with warm nitric acid 7not hydrochloric1 for the platinum dish may be attacked by chlorin from the manganese oxid7 dissolving any small traces of precipitate that may have been left behind4 ,the filtrate ,d1 which should not be more than ten or fifteen cubic centimeters1 containing the carbonates of the alkalies1 is evaporated to dryness and gently fused1 so as to render insoluble any magnesium carbonate that may have gone through2 then redissolved and filtered into a small weighed platinum dish containing a few drops of dilute hydrochloric acid1 to change the carbonates into chlorids2 evaporated to dryness1 exposed to a gradually rising temperature 7below red heat71 by which the chlorids are thoroughly dried and freed from moisture1 so as to prevent the decrepitation that would otherwise occur on ignition4 ,then1 holding the platinum basin firmly by forceps grasping the clean edge1 pass it carefully over a very low bunsen flame1 so as to cause1 successively1 every portion of the scaly or powdery residue to collapse1 without fully fusing4 ,there is thus no loss from volatilization1 and no difficulty in obtaining an accurate1 constant weight4 ,the weighed chlorids are washed by means of a little water into a small beaker or porcelain dish1 treated with a sufficient quantity of platinum chlorid1 and evaporated to dryness over the water-bath4 ,the dried residue is treated with a mixture of three parts absolute alcohol and one part ether1 leaving the potassium platinochlorid undissolved4 ,this is put on a filter1 and washed with ether-alcohol4 ,when dried1 the precipitate and filter are put into a small platinum crucible and exposed to a heat sufficiently intense to reduce the platinum chlorid to metallic platinum and to volatilize the greater part of the potassium chlorid4 ,this is easily accomplished in a small crucible1 which is roughened by being constantly used for the same purpose 7and no other71 the spongy metal causing a ready evolution of the gases4 ,the reduced platinum is now first washed in the crucible with hot acidulated water1 then with pure water2 then all moisture is driven off and it is weighed4 ,from the weight of the platinum1 is calculated the potassium chlorid and the oxid corresponding2 the difference between the weights of the total alkaline chlorids and potassium chlorid gives the sodium chlorid1 from which may be calculated the sodium oxid4 ,when the heating of the platinum precipitate has not been sufficient in time or intensity1 instead of being in a solid spongy mass of the color of the crucible itself1 small black particles of metallic platinum will obstinately float on the surface of the water in the crucible1 and it becomes difficult to wash without loss4 7#h7 ,estimation of ,manganese4--,the solution containing the magnesium and manganese chlorids is freed from barium salts by hot precipitation with sulfuric acid1 and the barium sulfate1 after settling a few hours1 is separated by filtration4 ,the filtrate is neutralized with ammonia1 any resulting small precipitate 7of iron7 is filtered1 and the manganese precipitated with ammonium sulfid1 let stand twelve hours and filtered 7filtrate ,e72 wash with cold water1 dry1 ignite1 and weigh as manganese protosesquioxid1 ,mn,o4 ,if preferred the manganese may be precipitated with chlorin or bromin water as dioxid2 but the process requires a rather longer time and may fail in inexpert hands more readily than the other4 7#i7 ,estimation of ,magnesium4--,the filtrate ,e from the manganese is now freed from sulfur by acidulating with hydrochloric acid1 evaporating1 if necessary1 and filtering4 ,from the filtrate the magnesia is precipitated by adding an equal bulk of ammonia water and then sodium phosphate4 ,after standing at least twenty-four hours1 the magnesium salt may be filtered1 washed with ammoniacal water1 dried1 ignited1 and weighed as magnesium pyrophosphate4 #cdc4 ,examination of ,acid ,extract by the ,methods of ,petermann4--,estimation of the ,silica4--,the ,gembloux method of estimating silica consists in taking up the dry extract obtained from the treatment of the earth1 in the manner described in paragraph #ccf1 with water and a few drops of hydrochloric acid1 heating for a short time on a sand-bath to facilitate the solution1 and filtering1 washing1 drying1 igniting1 and weighing the residue obtained as silica4 ,estimation of the ,sulfuric ,acid4--,the method employed consists in heating the filtrate obtained in the estimation of silica for half an hour with a few drops of nitric acid and making the volume up to #ejj cubic centimeters4 ,one hundred cubic centimeters of this are precipitated with barium chlorid1 diluted to double its volume1 heated for some time1 the precipitate of barium sulfate collected and weighed1 and the quantity of sulfuric acid calculated therefrom4 ,potash and ,soda4--,potash and soda are estimated at the ,gembloux ,station by heating the filtrate obtained in the estimation of the sulfuric acid and precipitating the excess of barium in the hot solution after the addition of ammonia by ammonium oxalate and carbonate4 ,the whole is allowed to digest for six hours at a gentle heat and then allowed to remain at rest for twenty-four hours1 filtered1 washed1 and the filtrate evaporated to dryness in a large platinum dish and the ammoniacal salts driven off at a low temperature4 ,at the end1 the temperature is carried a little higher until it reaches low redness4 ,the residue is taken up by distilled water1 filtered into a weighed platinum dish1 a few drops of hydrochloric acid added1 evaporated1 dried1 heated with great care and the sodium and potassium chlorids obtained weighed together4 ,the respective quantities of potash and soda in the earth are estimated in the usual way by precipitating the potash with platinum chlorid4 ,estimation of the ,iron and ,aluminum ,oxids4--,the iron and aluminum oxids are estimated by taking twenty-five cubic centimeters of the primitive solution obtained with hydrochloric acid and adding ammonium carbonate almost to complete neutralization1 that is to say until the precipitate formed is just redissolved in the feeble excess of hydrochloric acid which remains4 ,dilute with distilled water and precipitate with a little excess of ammonium acetate1 and boil for a moment2 after boiling1 the basic iron and aluminum acetate and the small quantity of iron and aluminum phosphate present are easily deposited1 and the supernatant liquid should be completely limpid and colorless4 ,wash the precipitate by decantation1 boiling each time1 filter1 wash the filter with boiling water to which a little ammonium acetate has been added1 dry1 ignite1 and weigh4 ,the material obtained consists of ferric oxid1 aluminum oxid1 and iron and aluminum phosphates4 ,deduct from the whole1 the phosphoric acid determined in another portion4 ,the residue will be the sum of the iron and aluminum oxids4 ,estimation of the ,lime4--,the filtrate from the portion used for the estimation of the iron and alumina is treated with ammonium oxalate4 ,the mixture is kept at a low temperature for at least twelve hours1 after which it is filtered1 washed with hot water1 dried1 and ignited over a blast-lamp to constant weight and weighed as calcium oxid4 ,estimation of the ,magnesia4--,for the estimation of the magnesia the filtrate obtained in the estimation of lime is evaporated to dryness in a platinum dish1 the ammoniacal salts driven off1 the residue taken up with water slightly acidified with hydrochloric acid1 filtered1 the filtrate saturated with ammonia and heated some time to the boiling point to precipitate any traces of iron and alumina which may have remained in solution4 ,filter1 wash1 allow to cool and precipitate the magnesia by the addition of sodium phosphate4 ,it is then allowed to stand for twelve hours1 collected on a filter1 ignited1 and weighed as pyrophosphate1 and the quantity of magnesia calculated from the weight of salt obtained4 ,estimation of the ,phosphoric ,acid4--,the phosphoric acid is estimated by taking #ajj cubic centimeters of the original solution obtained by the treatment of the soil with hydrochloric acid and evaporating it to dryness on the water-bath4 ,the residue is taken up with water to which a few drops of nitric acid have been added and filtered4 ,the total phosphoric acid is then obtained by precipitation with ammonium molybdate in the usual way4 #cdd4 ,analysis of the ,insoluble ,residue4--,the insoluble residue left after digestion with hydrochloric acid is not without interest from an agricultural and analytical point of view4 ,while it is true that the plant food1 therein contained1 is not immediately available1 yet it must not be forgotten that the method of the chemist may not fix a limit to nature's method of collecting nutriment for plants4 ,in however refractory a state they may exist1 it is possible that all nutritive elements may eventually become available for assimilation4 ,for the completion of an estimate of the total nutritive power of a soil1 therefore a further examination of the insoluble residue should be made4 ,the methods of securing this are essentially those of making a bulk analysis of the soil4 ,the principle of the method depends on the reduction of the sample to an impalpable powder and the subsequent decomposition of the insoluble portions by treatment with hydrofluoric and sulfuric acids or by fusion with the alkalies4 #cde4 ,method of ,wolff for ,treating ,residue ,insoluble in ,hot ,acid4--,the well-washed residue is dried with the filter1 then separated therefrom1 the filter burned and the ash weighed with the whole of the residue4 ,about eight grams of the residue are ignited and serve for the estimation of the insoluble mineral matter4 ,another portion of ten grams of the dried1 but not ignited1 residue is boiled with a concentrated solution of sodium carbonate with the addition of caustic soda1 and the quantity of dissolved silicic acid estimated4 ,a third portion of about fifteen grams is treated with about five times its weight of pure concentrated sulfuric acid1 and is evaporated until the mass has taken the form of a dry powder4 ,after moistening with concentrated hydrochloric acid the mass is boiled with water1 filtered1 and the filtrate examined according to the ordinary methods for silicic acid1 alumina1 iron1 lime1 magnesia1 and alkalies4 ,the residue after treatment with concentrated sulfuric acid is dried1 but not ignited1 and boiled with a concentrated solution of sodium carbonate with the addition of a little caustic soda1 filtered1 heated1 and the silicic acid separated from the solution4 ,after thorough washing1 the residue1 after ignition1 is weighed and represents the material insoluble in concentrated hydrochloric and sulfuric acids4 ,the silicic acid found as before1 together with the small quantity dissolved in the hydrochloric acid extract1 gives1 in connection with the alumina contained in the sulfuric acid extract1 approximately the quantity of pure water-free clay contained in the soil4 ,in six samples of soils of very different compositions which were examined by the above process1 it was found that the clay had the following mean composition3 ,silicic acid1 #ee4a to #fa4e per cent1 alumina1 #ch4f to #dd4i per cent2 as a mean #eh4je per cent silicic acid and #da4ie per cent alumina4 ,finally1 four or five grams of the residue1 after treatment with sulfuric acid and sodium carbonate1 are rubbed up in an agate mortar and completely separated into silt by water4 ,the silt mass is dried1 lightly ignited1 and three grams of it spread in a flat platinum dish moistened with sulfuric acid1 and subjected to the action of hydrofluoric acid in a lead oven at #fj1 until a complete decomposition of the material is accomplished4 ,in the solution all the different bases can be determined4 #cdf4 ,method of the ,belgian ,chemists4--,the method employed by ,petermann#bbb at the ,gembloux ,station in the examination of the part of the soil insoluble in hydrochloric acid consists in washing the insoluble portion by decantation with distilled water until all acid reaction is removed4 ,place the contents of the flask and of the filter in a porcelain dish and dry4 ,after a careful mixing of the mass take out about fifty grams and wash upon the filter until all reaction for chlorin has disappeared1 dry1 detach the mass from the filter1 and incinerate4 ,place in a platinum crucible two grams of the ground and ignited residue and mix it1 using a platinum stirring rod1 with twelve grams of ammonium fluorid2 heat slightly over a bunsen burner in a muffle with a good draught and regulate the flame in such a way that the operation shall continue for about one hour4 ,after complete decomposition add about two cubic centimeters of sulfuric acid in such a way as to moisten completely the residue1 drive off the sulfuric acid carefully at a low red heat and take up the residue with water slightly acidulated with hydrochloric acid and wash the whole into a flask of #ejj cubic centimeters capacity4 ,oxidize by heating for an hour with nitric acid1 make up to the mark and filter4 ,the percentages of potash1 soda1 lime1 magnesia1 and the silicates are determined exactly as in the hydrochloric acid extract4 #cdg4 ,bulk ,analysis4--,it is frequently desirable to determine the total composition of a soil sample as well as the nature of that part of it soluble in any of the solvents usually employed4 ,the latest methods for this purpose have been well studied by ,packard#bbc who finds that the variations which occur between duplicates are probably due to the small quantities of material taken for analysis1 it being difficult to obtain average samples of a material which is not very finely powdered when small quantities are taken4 ,moreover1 as it is likely to become of importance to know whether the proportions of lime and magnesia vary by as much as one-tenth per cent1 and such small variations are within the limits of error of an analysis1 and as the total proportion of lime and magnesia in highly siliceous soils1 probably does not exceed one-tenth per cent1 it is deemed best to take a large quantity of soil for the bulk analysis in each case4 ,the amount adopted for the highly siliceous soils containing much quartz is ten grams4 ,this quantity1 taken after quartering down the entire sample1 is ground to an impalpable powder and used for the determination of the lime1 magnesia1 and alkalies1 the silica1 iron oxid1 alumina1 and loss on ignition1 being determined in one gram samples4 ,the ten grams are decomposed by hydrofluoric and sulfuric acids in a large platinum dish1 the solution evaporated1 at first on the water-bath until all water is removed and then at a higher temperature until all the free sulfuric acid is driven off1 when the residue is heated in a muffle at a low red heat for several hours4 ,at this temperature the sulfuric acid combined with the iron oxid and alumina is driven off1 leaving the remaining sulfates unchanged and the iron oxid and alumina are in the form of a powder of no great volume which is easily and quickly washed4 ,this operation is usually successful at first but in some cases the decomposition is not complete as is shown by the appearance of a precipitate on adding ammonia to the filtrate from the aluminum and iron oxids4 ,in such cases the precipitate is dissolved in hydrochloric acid1 reprecipitated by ammonia and removed by filtration4 ,in the filtrate from the thoroughly washed aluminum and iron oxids1 lime is precipitated as oxalate and separated by filtration2 the filtrate is evaporated to dryness and the ammonia salts driven off by heat2 the magnesia in the unfiltered watery extract of this residue is precipitated by baryta water1 which also removes the sulfuric acid with which the bases had been combined4 ,in the filtrate from this precipitate baryta is precipitated by ammonium carbonate and removed by filtration1 leaving the alkalies to be determined in the usual way after conversion into chlorids4 ,the mixed precipitate of magnesia and barium sulfate is treated with hydrochloric acid1 filtered1 the baryta present removed as sulfate1 and the magnesia precipitated in the filtrate from the latter as phosphate4 ,the advantages of this method are that the large quantity of material employed gives some assurance that an average sample has been operated on1 and all the bases present in small proportions are estimated in the same sample4 ,the objection to it is the time consumed both in grinding the samples and in determining all the bases in one solution4 ,as a small quantity of material is generally used for determining the silica1 iron oxid1 alumina1 and loss by ignition1 and a larger quantity for the remaining bases1 slight differences in the unground samples are unavoidable1 especially when the quartz grains are somewhat large1 it being practically impossible to take two small samples of such a soil which would have the same number of quartz grains4 ,consequently tedious grinding of large quantities of the soils for the bulk analysis is necessary4 ,this objection does not apply to the official analysis or assay of soils in which considerable quantities are extracted by acid and the solution analyzed1 and silica is not determined4 ,in any case1 it may be said1 when it becomes an object to know whether a soil contains a total of #j4a or #j4b per cent of lime or magnesia1 of #j4g or #j4e per cent of potash1 one analysis even of the large quantity of ten grams would be insufficient to decide the point1 and at least the mean of two determinations should be taken4 ,,special ,,methods ,,of ,,determination ,,of ,,soil ,,constituents4 #cdh4 ,preliminary ,considerations4--,in the foregoing paragraphs the general outline of the chemical methods of soil examination have been given4 ,there are often occasions1 however1 which demand a special study of some particular soil constituent4 ,it has been thought proper1 therefore1 to add here some of the best approved methods of special determinations which have been approved in this and other countries4 ,in the main1 the final determination of any particular element of the soil1 and its previous separation from accompanying elements1 are based on the general processes already given4 ,the variations in many instances1 however1 seem to require special mention4 #cdi4 ,condition of ,potash in ,soils4--,potash exists in the soil in very different states4 ,that part of it which is combined with the humus material1 or with the hydrated silicates1 is easily set free from its combinations and is to be regarded as the more assimilable portion4 ,the potash in the soil is found chiefly in combination with silicates1 and particularly with the hydrated aluminum silicates1 forming clay4 ,as the particles with which it is combined are found in a state of greater or less fineness1 the potash itself is set free under the influences of the agents which are active in the soil1 with greater or less rapidity1 passing into a form in which it can be utilized by plants4 ,in silicates which are very finely divided1 such as clay1 the potash becomes active in a relatively short time1 while in the dbris of rocks in a less advanced state of decomposition it may rest for an indefinite period in an inert state4 ,the estimation of the potash which is assimilable in the clay is quite as important for agricultural purposes as to determine that which may be present in the soil in firmer combination4 ,treating the sample of soil with water does not furnish any useful information in regard to the potash which it contains4 ,indeed1 the absorbing properties of the soil tend to prevent the elimination of the potash in this way1 even when it is found in the soluble state4 ,it is therefore1 necessary to employ an acid to set the potash free1 but variable results are obtained1 according to the employment of acids of greater or less concentration and for longer or shorter periods of contact4 #cej4 ,estimation of the ,potash ,soluble in ,concentrated ,acids4--,in the method of the ,french agricultural chemists#bbd twenty grams of the earth are placed in a dish with a flat bottom1 eleven centimeters in diameter1 and rubbed up with twenty to thirty cubic centimeters of water4 ,there is added carefully1 and in small quantities1 some nitric acid of #cf ,baum until all effervescence has ceased1 the mass meanwhile being thoroughly stirred4 ,when the carbonates have been decomposed1 which can be told by the cessation of the effervescence1 twenty cubic centimeters more of the same acid are added4 ,the dish is heated on the sand-bath for five hours1 regulating the heating in such a way that there still remains some acid at the end of the operation and the mass is not thoroughly dry4 ,the acid mass is then taken up with hot water1 filtered1 and washed with hot water until the amount of filtrate is about #cjj cubic centimeters4 ,the filtrate should be received in a flask of about one liter capacity4 ,the filtrate will contain the dissolved potash1 soda1 magnesia1 lime1 iron and aluminum oxids1 and traces of sulfuric and phosphoric acids4 ,for the elimination of the other substances1 with the exception of potash1 soda and magnesia1 a few drops of barium nitrate are added1 afterwards sufficient ammonia to render the solution alkaline1 and finally an excess of ammonium carbonate in powder added in small portions4 ,these materials are added successively and the whole is left to stand for twenty-four hours4 ,by this operation the sulfuric acid is separated in the form of barium sulfate2 the iron and aluminum oxids are precipitated1 carrying down with them the phosphoric acid1 and the lime is thrown down in the form of carbonate4 ,the mass is now filtered and washed several times with hot water4 ,the filtrate contains in addition to potash1 soda1 magnesia1 and the ammoniacal salts which have been introduced4 ,the ammonium salts are destroyed by adding aqua regia and evaporating the liquid to a very small volume1 as described in the method for the estimation of magnesia4 ,the mass is now evaporated in a porcelain dish with a flat bottom1 of about seven centimeters diameter1 and an excess of perchloric acid added4 ,the evaporation is carried to dryness on a sand-bath1 and the heating prolonged until the last white fumes of perchloric acid are disengaged4 ,the mass is now left to cool4 ,there are then added five cubic centimeters of alcohol1 of #ij strength4 ,the mass is triturated by a stirring rod1 the extremity of which is flattened1 in such a manner as to reduce it all to an impalpable powder4 ,it is then left to settle and the supernatant liquid is decanted upon a small filter4 ,the treatment with alcohol of the kind1 quantity1 and strength described1 is continued four or five times4 ,afterwards1 as there may still remain a trace of the sodium and magnesium perchlorates in the interior of the crystals of potassium perchlorate1 there are added to the capsule in which all of the alkaline residue has been collected1 two or three cubic centimeters of water1 and it is evaporated again to dryness and taken up twice with small quantities of alcohol4 ,there are thus removed the traces of sodium and magnesium perchlorates4 ,by means of a jet of boiling water the stirring rod and the filter1 which contains the small quantities of potassium perchlorate1 are washed1 and the liquid passing through is received in the capsule which contains the larger part of the salt4 ,it is then evaporated to dryness and weighed4 ,when there is very little magnesia present1 as is generally the case1 the estimation of the potash is made without any difficulty by the process just mentioned1 but when the proportion of magnesia is high it is found useful to separate it before the transformation into perchlorates4 ,the magnesia is separated by carbonating the residue as indicated in the method for the estimation of magnesia1 by treatment with oxalic acid and ignition4 ,by extracting the carbonates formed with very small quantities of water1 and filtering1 the alkalies are obtained free from magnesia4 ,it is advisable to test the purity of the potassium perchlorate formed which sometimes contains a little silica4 ,for this purpose it is dissolved in boiling water1 and any residue which remains is weighed1 and that weight deducted from the total weight of perchlorate4 ,by multiplying the weight of potassium perchlorate found by the coefficient #j4cci1 the quantity of potash contained in the twenty grams of earth submitted to analysis is obtained4 ,estimation of the ,potash ,soluble in ,cold1 ,dilute ,acids4--7,method of ,schloesing47 ,introduce #ajj grams of the soil into a one or one and a half liter flask with #fjj to #hjj cubic centimeters of water4 ,a little nitric acid1 of #cj ,baum1 is added until the carbonate is decomposed and a slight acid reaction is obtained4 ,afterwards five cubic centimeters of the same acid are added and it is left to digest for six hours1 shaking every fifteen minutes4 ,instead of taking the whole of the wash-water for the examination1 it is better to extract only a portion of it and so dispense with washing4 ,this process is conducted in the following manner3 ,the weight ,p of the full flask having been determined1 as much as possible of the solution1 is decanted by means of a very small siphon1 of which the flow is moderated by fixing a rubber tube with a pinch-cock to its lower extremity4 ,after the decantation is complete1 the flask is again weighed1 giving the weight of ,p2 the weight of liquid taken1 therefore1 is equal to ,p ,p4 ,to determine the total weight of the liquid1 throw upon a filter the earthy residue insoluble in the acid1 and after washing and drying it determine its weight r4 ,the weight of the empty dry flask p is also determined4 ,the total weight of the soil will be1 therefore1 ,p r p4 ,the part of the liquid which was extracted from the flask1 and upon which the analytical operation is to be conducted is represented by the fraction 7,p ,p7_/7,p r p74 ,this method avoids washing and evaporation which would be of very long duration4 ,it rests upon the supposition that the solid matter from which the liquor is separated has no affinity for the dissolved substances1 and that the total of these substances has passed into the liquor1 and that the solution is homogeneous4 ,in the liquor first decanted as described before1 the potash is estimated4 ,this liquor contains in addition to potash1 soda1 lime1 magnesia1 iron and aluminum oxids1 as well as phosphoric1 sulfuric1 and hydrochloric acids4 ,there is first added to it a little barium chlorid to precipitate the sulfuric acid4 ,it is then heated to about #dj in a glass flask and some ammonium carbonate added in a solution containing an excess of ammonium hydroxid4 ,by this process the lime and baryta are precipitated in the form of carbonates2 the alumina and iron as oxids1 and the phosphoric acid in combination with the last two bases4 ,the magnesium carbonate is not precipitated because it is soluble in the ammonium carbonate with which it forms a double salt4 ,the employment of a gentle heat favors the formation of the precipitate of calcium carbonate in a granular form which lends itself easily to filtration4 ,the contents of the flask are now thrown upon a filter and the insoluble residue washed4 ,the filtrate contains the potash1 soda1 magnesia1 ammonia1 and nitric and hydrochloric acids4 ,it is concentrated as rapidly as possible by heating in a flask1 and afterwards the ammoniacal salts are destroyed by weak aqua regia and the whole is then transferred to a porcelain dish and evaporated to dryness4 ,there is thus obtained a mixture of potassium1 sodium1 and magnesium nitrates1 from which the potash is separated by means of perchloric acid in the manner already described4 ,estimation of the ,total ,potash4--,beside the potash which can be dissolved by the boiling concentrated acids the soil contains potash combined with silicates1 which becomes useful for plant life with extreme slowness4 ,it is often of great interest to estimate the total potash contained in a soil1 that is to say1 the reserve for the future4 ,in this case it is necessary to free entirely this base from its combinations by means of hydrofluoric acid4 ,the operation is conducted upon two grams of earth previously ignited and reduced to an impalpable powder4 ,the decomposition is conducted in a platinum capsule by sprinkling the sample with a few cubic centimeters of hydrofluoric acid1 or solution of ammonium fluorid1 and adding a few drops of sulfuric acid4 ,it is then evaporated to dryness and dissolved in boiling hydrochloric acid4 ,the part which remains insoluble is treated a second time by hydrofluoric and sulfuric and afterwards by hydrochloric acid4 ,all of the potash is thus brought into solution4 ,the estimation of the potash1 after having obtained it in a soluble state1 is conducted in the manner previously described4 ,estimation of the ,potash as ,platinochlorid4--,instead of estimating the potash as perchlorate it can also be transformed into platinochlorid4 ,this process gives as good results as the preceding one but it is necessary in all cases1 to separate the magnesia4 ,after having treated the soil as indicated in the case of the estimation of the potash as perchlorate1 the separation of the sulfuric and phosphoric acids1 of alumina and iron1 of magnesia1 and the destruction of the ammoniacal salts in the manner already described1 there are finally left the alkalies potash and soda in the form of carbonates4 ,these are transformed into chlorids by adding hydrochloric acid2 afterwards they are evaporated to dryness and the mixture of the two chlorids weighed in order to determine what quantity of platinum chlorid it is necessary to add1 in order that it be in excess4 ,the quantity of chlorid to be added is calculated so as to be in sufficient quantity to saturate the whole of the chlorids weighed1 whether they may be composed wholly of sodium or potassium4 ,in this way there is a certainty of having an excess of platinum4 ,the solution of platinum chlorid used should contain in #ajj cubic centimeters seventeen grams of platinum4 ,each cubic centimeter of this solution will be sufficient for a decigram of the sodium and potassium double chlorids4 ,after the addition of the platinum chlorid the mixture is evaporated in a capsule with a flat bottom1 on a water-bath4 ,it is important that the temperature should not exceed #ajj4 ,if the temperature should go above this there would be a tendency to form some platinum subchlorids insoluble in alcohol4 ,the evaporation is continued until the contents of the dish are in a pasty condition and form a rather solid mass on cooling4 ,it is necessary to avoid a complete desiccation4 ,after cooling1 the residue is taken up by alcohol of #ie strength4 ,it is allowed to digest with alcohol of this strength for some time1 after having been thoroughly mixed and shaken therewith in order to obtain a complete precipitation of the platinochlorid4 ,this digestion should take place under a small bell-jar resting upon a piece of ground glass4 ,the evaporation of the alcohol is thus prevented4 ,the mass is then washed by means of alcohol of the same strength and the liquors decanted upon a small filter placed within another filter of identical weight1 which serves as a tare for it on the balance4 ,the washing is prolonged until the filtrate becomes colorless4 ,all of the particles in the dish should be brought upon the filter by means of a hair-brush4 ,the filters are now dried at a temperature not exceeding #ie and the platinochlorid received upon the interior filter is weighed4 ,the precipitate may also be washed from the small filter into the capsule in which it was formed by means of a jet of alcohol4 ,the alcohol is evaporated and the precipitate weighed in the capsule4 ,the weighing should be made rapidly on account of the hygroscopicity of the material4 ,the weight obtained multiplied by #j4aic gives the corresponding quantity of potash in the soil4 ,purification of the ,oxalic ,acid4--,the commercial oxalic acid used in separating the magnesia1 often contains lime1 magnesia1 and potash4 ,when this reagent is used in a sufficiently large quantity in the estimation of the above substances1 it is indispensable to free it entirely from them4 ,this is secured by submitting the oxalic acid to successive recrystallizations which are obtained by dissolving it in warm water1 filtering and leaving to cool4 ,the mother waters are thrown away4 ,after two or three successive crystallizations the traces of potash and magnesia have disappeared and the oxalic acid obtained after ignition leaves no trace of residue4 ,the purification may also be secured in the following manner3 ,at a temperature of #fj a saturated solution of oxalic acid is made2 the liquid is decanted1 carried to the boiling point and filtered4 ,five per cent of nitric acid are added and it is allowed to cool4 ,the crystals which are deposited are collected upon a funnel in which a plug of cotton has been placed1 and are washed with a little cold water4 ,purity of the ,ammonium ,carbonate4--,the ammonium carbonate employed should not leave any residue whatever after volatilization4 ,in general1 it may be said of all the reagents employed in analyses and especially of those employed in large quantities1 that it is indispensable to be sure that they contain no traces of the substances which are to be estimated4 ,the acids1 ammonia1 etc41 should always be examined with this point in view4 ,estimation of the ,soda4--,it is often of interest to estimate the soda in the soil1 not that it is an element of any great fertility but rather because it is hurtful when in excess4 ,it is determined in the residue obtained in the estimation of potash and is estimated by difference4 ,the weight of the mixture of sodium and potassium chlorids being known when the potash is determined1 the weight of its chlorid is to be deducted from the weight of the two chlorids and thus the direct weight of the sodium chlorid is obtained4 ,a better way is to make a direct estimation4 ,the soda is found entirely dissolved in the alcoholic solution obtained by washing the potash salt as before described1 for the separation of the potassium platinochlorid4 ,this alcoholic liquor is evaporated to dryness on a water-bath1 in a bohemian flask of about #ajj cubic centimeters capacity4 ,the residue obtained consists of sodium platinochlorid and a little platinum chlorid4 ,there is now fitted to the bohemian flask a cork stopper carrying two tubes4 ,the apparatus is placed upon a water-bath and kept at about #ajj4 ,through the tube which reaches to the bottom of the bohemian flask1 a current of pure hydrogen is passed4 ,the hydrogen passes off through the second tube4 ,the hydrogen completely reduces the salts of platinum4 ,in order that the decomposition may go on more rapidly a few drops of water are added4 ,when the whole mass in the flask has become black owing to the separation of the platinum1 it is shaken1 evaporated to dryness and hydrogen passed through a second time4 ,this operation is repeated three or four times1 being stopped when the water no longer shows a yellow color4 ,there is then in the flask only a mixture of reduced platinum and sodium chlorid4 ,no trace of sodium chlorid has been lost because the temperature has never exceeded #ajj4 ,the sodium chlorid is dissolved by washing with water and filtered4 ,the liquor1 which must be absolutely colorless1 is evaporated to dryness in a platinum capsule and weighed4 ,there is thus obtained the weight of the sodium chlorid4 ,for verification1 the sum of the weight of potassium chlorid calculated from the platinochlorid and the weight of the sodium chlorid should be equal to the initial weight of the mixture of the two chlorids4 #cea4 ,potash ,methods of the ,german ,experiment ,stations4#bbe--;a4 ,to one volume of air-dried fine earth which is obtained by sifting through a three millimeter sieve1 two volumes of twenty-five per cent hydrochloric acid are added1 or more if the soil contains much carbonate4 ,the acid is allowed to act with frequent stirring for forty-eight hours at room temperature4 b4 ,to one volume of the soil1 as above prepared1 are added two volumes of hydrochloric acid and allowed to stand for three hours with frequent shaking1 at the temperature of boiling water4 c4 7,halle method47 ,one hundred grams of the fine earth are treated with #ejj cubic centimeters of forty per cent hydrochloric acid1 made up to one liter with water and allowed to stand for forty-eight hours with frequent shaking4 ,after filtering1 a large aliquot part of the filtrate is evaporated for the estimation of the potash4 ,the evaporated residue is washed into a half-liter flask in which the sulfuric acid is precipitated with barium hydroxid the flask filled to the mark and an aliquot part of the filtrate in a half-liter flask1 treated with ammonium carbonate1 filtered and the potash estimated as platinochlorid by the usual method4 #ceb4 ,method of ,raulin for the ,estimation of ,potash in ,soils4#bbf--,the process rests upon the very feeble solubility in aqueous solution of potassium phosphomolybdate1 while sodium1 magnesium1 calcium1 iron1 and aluminum phosphomolybdates are more or less soluble4 ,the process does not require complicated separation and permits of the treatment of a small quantity of soil1 since the weight of the phosphomolybdate obtained is equivalent to nineteen times that of the potash4 ,the reagent is prepared by dissolving #ajj grams of crystallized ammonium molybdate in as little water as possible and adding six and a half grams of neutral crystallized ammonium phosphate dissolved in a little water4 ,aqua regia is now added cold and some ammonium phosphomolybdate is precipitated4 ,the mixture is heated1 adding a little aqua regia from time to time1 until the solution of the precipitate is accomplished4 ,the whole is then evaporated to dryness1 the final temperature of evaporation not being carried above #gj4 ,four hundred cubic centimeters of water are now added and five cubic centimeters of nitric acid1 and the contents of the dish heated and filtered4 ,the reagent is then ready for use4 ,the liquid to be used for washing the potassium phosphomolybdate is prepared by dissolving twenty grams of sodium nitrate in one liter of water1 two cubic centimeters of pure nitric acid1 and a mixture of about twenty cubic centimeters of the phosphomolybdic reagent and one and a half cubic centimeters of a solution of potassium nitrate containing eighty grams per liter1 slightly heated in order to saturate the liquid with potassium phosphomolybdate4 ,the solution is shaken1 allowed to rest1 and the liquid decanted4 ,for the preparation of the solution in which the potash is to be estimated1 a sample of soil is carefully weighed of such magnitude as to contain about fifteen milligrams of anhydrous potash4 ,the potash salts are dissolved by the usual processes and are separated from the largest part of the calcium1 iron1 and aluminum salts1 and converted into nitrates4 ,the solution is reduced to a volume of a few cubic centimeters and slightly acidulated with nitric acid4 ,four cubic centimeters of the phosphomolybdic reagent are added for every ten milligrams of anhydrous potash supposed to be present4 ,the solution is evaporated to dryness at #ej and immediately brought upon very small weighed filters1 of which each one is double1 by using sixty cubic centimeters of the washing liquor mentioned above4 ,the tared filter is likewise washed with the same liquid at #ej and weighed4 ,the weight multiplied by #j4jeb gives the anhydrous potash4 ,this method for a direct precipitation of the potash salts does not have the merits of the perchlorate process and both are inferior in accuracy to the usual platinochlorid procedure4 #cec4 ,russian ,method for ,estimating ,potash in ,soils4#bbg--,ten grams of the soil are digested with #ajj cubic centimeters of ten per cent hydrochloric acid on a steam-bath for twenty-four hours4 ,after adding five cubic centimeters of nitric acid to the filtrate it is evaporated to dryness1 taken up with dilute hydrochloric acid1 filtered1 the filtrate saturated with ammonia1 the excess of ammonia driven off1 again filtered1 and the lime separated by ammonium oxalate4 ,the filtrate is treated with a little barium chlorid for the removal of sulfuric acid and afterwards with ammonium carbonate in excess1 and digested for twenty-four hours4 ,after filtering1 the solution is evaporated in a platinum dish1 the excess of ammonia driven off1 the residue taken up with water1 filtered1 treated with hydrochloric acid1 evaporated to dryness1 and ignited at low heat4 ,the residue is again dissolved in water1 filtered1 and the potash precipitated with platinum chlorid and estimated in the usual way4 #ced4 ,potash ,method of the ,italian ,stations4#bbh--,the potash in the soil should be determined in three forms2 viz41 #a4 ,assimilable potash4 #b4 ,potash soluble in concentrated acid4 #c4 ,total potash4 ,for determination of the first1 #ajj grams of earth are put into a retort holding a liter and digested with dilute nitric acid4 ,for the analysis1 an aliquot portion of the clear liquid is taken or weighed1 and the determination of the potash is made by the common methods4 ,for an alternate method1 from twenty to fifty grams of earth are put into a retort of #ejj cubic centimeters1 moistened with water1 and nitric acid is gradually added4 ,after one or two hours there are added from #bjj to #cjj cubic centimeters of water2 the liquid is poured without filtering into a retort and the residue washed by decantation4 ,in the liquid1 after the elimination of the other substances with barium chlorid1 ammonium carbonate1 etc41 the potash is determined by the ordinary methods4 ,in the second case1 by using warm concentrated acids1 a portion of the insoluble silica is decomposed1 but this decomposition is always partial and the quantity of the potash extracted depends upon the temperature1 upon the concentration1 upon the duration of the action1 and upon the nature of the acid4 ,the method of moistening twenty to fifty grams of earth with water and adding1 thereto1 concentrated nitric acid of #a4bj density1 in such a manner that the earth shall be completely saturated1 may also be employed4 ,then the temperature is kept at #ajj during two hours4 ,in the solution1 the potash is determined as usual4 ,in the third case the soil is to be decomposed by hydrofluoric and sulfuric acids1 or by fusion with alkaline carbonates1 and the total potash determined by one of the standard methods4 ,if it is desired to adopt a general method for the determination of the potash the following points must be carefully considered3 #a4 ,the quantity of the earth to be examined4 #b4 ,the state of humidity or dryness of the same4 #c4 ,the quantity1 nature1 and concentration of the acid4 #d4 ,the quantity of the water4 #e4 ,the duration of the treatment4 #cee4 ,method of ,j4 ,lawrence ,smith for ,potash4--,this method1 designed especially for mineral analysis1 has been fully approved by the general experience of analysts4 ,the principle of the method#bbi depends upon the decomposition of silicates on ignition with calcium carbonate and ammonium chlorid4 ,the object of this mixture is to bring into contact with the mineral1 caustic lime in a nascent state at a red heat1 the caustic lime being soluble to some extent in calcium chlorid at a high temperature4 ,pure calcium carbonate1 made by precipitation of marble1 should be used4 ,the ammonium chlorid should be prepared by taking crystals of pure1 sublimed sal ammoniac1 dissolving in water1 and filtering1 and evaporating the solution until small crystals are deposited1 the solution being well-stirred until one-half or two-thirds of the whole has crystallized4 ,the mother-liquor is poured off while still hot1 and the crystals dried on an asbestos filter at ordinary room temperature4 ,a special platinum crucible should be used in the ,smith method1 but the common crucible1 especially if very deep1 can be employed4 ,the special crucible is of about double the usual length4 ,smith recommends a crucible ninety-five millimeters in length1 diameter at top twenty-two millimeters1 at bottom sixteen millimeters1 and weighing thirty-five to forty grams4 ,the object of the long crucible is to have the part of the bottom containing the silicate subjected to a high heat1 while the top of the crucible is at a much lower temperature1 thus preventing the loss of alkalies by volatilization4 ,method of ,analysis4--,the samples of soil or silicate containing the alkalies are well pulverized in an agate mortar1 and from one-half to one gram of the finely pulverized material taken for analysis4 ,this is carefully mixed with the same weight of finely powdered sal ammoniac and the mineral and sal ammoniac rubbed well together in a mortar4 ,eight parts by weight of calcium carbonate are next added in three or four portions1 and the whole intimately mixed after each addition4 ,the contents of the mortar are emptied on a piece of glazed paper and then introduced into the crucible1 which is tapped gently upon the table until the contents are well settled4 ,it is then fixed in the furnace which is used for heating1 and a small bunsen burner is placed beneath the crucible1 and the heat applied just about at the top of the mixture and gradually carried toward the lower part until the sal ammoniac is completely decomposed1 which requires from four to five minutes4 ,the heat is then applied by means of a blast-lamp and the crucible kept at a bright red heat for from forty to sixty minutes4 ,the crucible is allowed to cool1 the contents detached and placed in a platinum or porcelain dish of about #aej cubic centimeters capacity1 and sixty to eighty cubic centimeters of distilled water added4 ,the solution of the flux may be hastened by heating the water to the boiling point4 ,the crucible and its cover are also well washed with hot water until all matter adhering to them is dissolved4 ,after the slaking of the mass it is best to continue the digestion with hot water for six or eight hours1 although this is not absolutely necessary4 ,the contents of the crucible are filtered and washed well with about #bjj cubic centimeters of water4 ,the filtrate contains in solution all the alkalies of the mineral1 or soil1 together with calcium chlorid and caustic lime4 ,a solution of pure ammonium carbonate containing about one and one-half grams of the pure salt is added to the filtrate4 ,this precipitates the lime as carbonate4 ,the dish containing the material is placed on a water-bath and its contents evaporated to about forty cubic centimeters4 ,two additional drops of ammonium carbonate are added1 and a few drops of caustic ammonia1 to precipitate any lime which may be redissolved by the action of the ammonium chlorid solution on the calcium carbonate4 ,filter on a small filter and wash with as little water as possible and collect the filtrate in a small beaker4 ,the filtrate contains all the alkalies as chlorids1 together with a little ammonium chlorid4 ,add a drop of ammonium carbonate solution to be sure all the lime is precipitated1 evaporate on a water-bath in a deep platinum dish1 in which the alkalies are to be weighed4 ,the dish should have from thirty to sixty cubic centimeters capacity1 and during the evaporation should never be more than two-thirds filled4 ,after the evaporation has been completed the dish is slowly heated and then gently ignited over a gas-flame to drive off any ammonium chlorid which may be present4 ,during this process the platinum dish may be covered with a thin piece of platinum to prevent any possible loss by the spitting of the salt after the ammonium chlorid has been driven off4 ,the heat should be gradually increased until it is brought to a point a little below redness1 leaving the cover off4 ,the platinum dish is again covered1 and when sufficiently cooled placed on a balance and weighed4 ,if lithium chlorid be present it is necessary to weigh it quickly as the salt being very deliquescent takes up moisture rapidly4 ,the alkalies may now be separated in the usual way4 ,if the sample under examination contains magnesia the residue in the capsule should be dissolved in a little water and sufficient pure lime-water added to render the solution alkaline4 ,it should then be boiled and filtered4 ,the magnesia will1 in this way1 be completely separated from the alkalies4 ,the solution which has passed through the filter is treated with ammonium carbonate in the manner first described1 and the process continued and completed as above mentioned4 ,if it be suspected that the whole of the alkalies have not been obtained by the first fusion1 the residue upon the filter can be rubbed up in a mortar with an amount of ammonium chlorid equal to one-half the weight of the mineral1 mixed with fresh portions of calcium carbonate and treated exactly as in the first instance4 ,any trace of alkali remaining from the first fusion is thus recovered in the second one4 ,method of ,heating the ,crucible4--,the apparatus used by ,smith for igniting the crucible is shown in ,fig4 #fg4 ,it consists of an iron filter-stand ,,hg1 a clamp1 ,,ed1 carrying the muffle ,,nc1 attached by the supports ,,ab1 and heated by the lamp ,f4 ,the muffle ,,nc is a chimney of sheet iron1 eight to nine centimeters long1 ten centimeters high1 the width at the bottom being about four centimeters on one side and three centimeters on the other4 ,it is made with the sides straight for about four centimeters and then inclining toward the top so as to leave the opening at the top about one centimeter in width4 ,a piece is cut out of the front of the chimney of the width of the diameter of the hole in the iron support and about four centimeters in length1 being semi-circular at the top1 fitting over the platinum crucible4 ,just above this part of the chimney1 is riveted a piece of sheet iron in the form of a flattened hook1 ,n1 which holds the chimney in place by being slipped over the top of the crucible support2 it serves as a protection to the crucible against the cooling effects of the currents of air4 ,illustration3 ,,figure #fg4 ,,smith',s ,,muffle ,,for ,,decomposition ,,of ,,silicates4 #cef4 ,international ,method for ,assimilable and ,total ,potash4--,in the ,international ,congress of ,chemists held in ,paris in #ahhi1bcj the discrimination between the assimilable and total potash was declared to be of prime importance4 ,unfortunately no method is known by which the potash which is present in the soil in a state suited to the wants of plants can be determined with approximate accuracy4 ,in general1 that portion which is given up to weak acids may be assumed to be available4 ,in the treatment of soils with weak acid1 as pointed out in the ,congress1 it is demonstrable that with a #j4je to #j4a per cent nitric acid solution1 the quantity of potash which goes into solution increases by continued stirring of the mixture with the time of action of the acid up to a certain maximum which is reached in from three to four hours1 and after that1 it is not changed even when the strength of the acid mixture is increased to two per cent4 ,from this time on1 concentrated acids withdraw from the soil which has already been exhausted by the weak acid1 a new quantity of potash4 ,the soils which have been exhausted by concentrated acids yield also an additional quantity of potash when they are treated with hydrofluoric acid1 or melted with barium or sodium carbonate4 ,potash1 therefore1 appears to exist in the soil in various forms4 ,first4 ,in the form of indecomposable silicates which have1 agriculturally perhaps1 very little interest4 ,second4 ,in the form of silicates which are more basic than those just mentioned4 ,these silicates are attacked by strong acids and give up probably every year a portion of their potash to vegetation4 ,third4 ,in a form which is easily soluble in weak acids and consequently directly assimilable by plants4 ,in view of the fact that it would be of interest to chemists and agronomists to establish certain methods of investigation so as to be able to obtain comparative results1 it was decided to adopt the original method recommended by ,gasparin for the estimation of the potash decomposable by concentrated acids4 ,this method consists in the treatment of the soil with boiling aqua regia until the sand which is not decomposed1 is white4 ,determination of the ,fineness of the ,earth which is ,used for ,analysis4--,for the estimation of potash1 the soil should be divided as finely as possible1 and passed through a sieve of thirty meshes to the centimeter4 ,the decomposition is then completed in two hours1 while if a sieve of only ten perforations per centimeter is used1 the acid must be allowed to work for twelve hours4 ,the determination of the potash after solution1 is accomplished by any of the standard methods4 #ceg4 ,method of ,tatlock as ,used by ,dyer4--,attention was called in paragraph #cbh to the estimation of the total plant food in the soil by extraction of the sample with citric acid4 ,dyer first determines the total potash by ,tatlock's method which is as follows3 ,to determine potash ten grams of fine dry soil are treated with ten cubic centimeters of hydrochloric acid and evaporated to dryness on the water-bath1 the residue taken up with another ten cubic centimeters of acid1 warmed1 diluted with water1 boiled1 filtered1 and washed4 ,the filtrate and washings are concentrated and gently incinerated to get rid of organic matter1 and the residue redissolved in hydrochloric acid1 and evaporated slowly with a considerable quantity of platinum chlorid4 ,if the evaporation be conducted slowly1 the potassium platinochlorid settles out well1 despite the iron1 aluminum1 and calcium salts1 and is easily washed with some more platinum chlorid solution1 followed by alcohol4 ,the application of this modification of the platinum chlorid process to solutions containing comparatively minute quantities of potash amid an overwhelming excess of iron1 aluminum1 and calcium salts is probably new to many chemists4 ,it works admirably1 and obviates the necessity for removing iron1 aluminum1 calcium1 magnesium1 etc41 with the necessary use of ammonia1 and the tedious processes of concentration and final volatilization of the ammonium salts2 but1 of course1 the process cannot be employed if soda also is to be determined4 ,the potash1 soluble in hydrochloric acid1 having been thus determined1 the undissolved siliceous matter is incinerated1 weighed1 and finely ground in an agate mortar4 ,a weighed portion of it is then1 as in the ,smith method1 mixed with a large bulk of pure calcium carbonate and a little ammonium chlorid and heated1 beginning with a low temperature1 rising slowly to bright redness4 ,the mass is then boiled with water1 washed1 incinerated1 reground1 mixed with some more ammonium chlorid1 and again heated1 boiled1 and washed4 ,the process is repeated and the filtrates from all the treatments concentrated1 the calcium being removed as carbonate1 and the potash determined in the filtrate1 after evaporation and incineration at a low temperature1 by means of platinum chlorid4 ,five hundred cubic centimeters of the citric acid solution of the soil1 made as described in paragraph #cbh1 corresponding to fifty grams of soil1 are evaporated to dryness in a platinum dish and ignited at a low temperature4 ,the residue is dissolved in hydrochloric acid filtered and washed1 and the filtrate again evaporated to dryness and treated again as just described4 ,the potash is then determined as above4 #ceh4 ,estimation of ,total ,alkalies and ,alkaline ,earths4--,to properly determine the exact amount of these substances in a sample of soil it is necessary first to remove the silica4 ,this is accomplished in the process of ,berthelot and ,andr#bca by intimately incorporating with the sample1 in a state of very fine powder1 four or five times its weight of ammonium fluorid4 ,the mixture1 in a platinum dish1 is moistened with strong sulfuric acid and allowed to stand for a few hours4 ,it is then gently heated until all fumes of hydrofluosilicic acid have disappeared1 but the mass is not raised to a red heat4 ,if there is any doubt about the complete decomposition of the silica the treatment is repeated4 ,at the end of the operation there remain only sulfates without excess of sulfuric acid4 ,the sulfates likely to be present are of potash1 soda1 lime1 magnesia1 alumina1 and iron4 ,the separation of these bodies is conducted in the ordinary manner4 ,fusing the soil with potash does not give reliable results but it can be used in certain cases for the rapid estimation of alumina and iron4 ,in this case after the separation of the silica in the ordinary way the iron can be determined as ferric oxid4 ,the iron can also be directly determined by reducing to the ferrous state and titrating with potassium permanganate4 ,comparison of ,fluorin ,method with ,common ,methods4--,to establish the difference in the data obtained by the old and new processes samples of the same earth were treated by ,berthelot and ,andr by different methods with the following results3 ,by the ,by the cold ,by the ,by fluorin dilute concentrated incineration method4 hydrochloric hydrochloric and acid method4 acid method4 subsequent treatment with boiling hydrochloric acid method4 ,per cent4 ,per cent4 ,per cent4 ,per cent4 ,potash #j4hhf #j4jba #j4adi #j4agf ,soda #j4baa #j4jbd #j4jcc #j4jdb ,magnesia #j4jhg #j4jcc #j4jcc #j4jfg ,lime #a4afj #j4hgi #a4abj #a4jfj ,alumina #c4iej #j4ajb #a4jji #b4fca ,ferric oxid #b4aej #j4bif #a4dja #a4fgh ,the impossibility of getting all the alkalies and oxids into solution by even the prolonged action of a boiling acid is clearly set forth in the above table4 ,boiling sulfuric acid might do a little better but would not give correct results4 ,lime alone of the elements in the soil can be correctly determined by solution in boiling hydrochloric acid1 a circumstance due to the fact that lime is found chiefly as carbonate1 sulfate1 and phosphate in the soil1 and these compounds are easily soluble in hot hydrochloric acid with the exception of the sulfate4 ,even lime could not be thus determined in soils containing silicates rich in lime4 ,the other mineral elements cannot be determined by the wet method4 ,this is due to the forms in which they occur1 being mostly silicates of different composition1 with excess of silica4 ,as to the silicates they may be divided into two groups4 ,the first of these are the hydrated silicates1 resembling the zeolites1 capable of being completely decomposed by boiling acids4 ,the first group of silicates is doubtless of greater importance to vegetable life than the second since it would1 doubtless1 give up its alkalies with greater ease4 ,this distinction is1 however1 arbitrary4 ,it is1 in fact1 impossible to place on one side the soluble and on the other the insoluble silicates4 ,this distinction represents only the unequal degrees in the speed of decomposition of the different silicates contained in the primitive rocks under the influence of atmospheric agents1 the soil being nothing more than the products of the decomposition of these rocks with vegetable mold4 ,the second group is insoluble in acids4 ,that part of the silicates least decomposed at any given moment will be attacked more easily by acids1 while that portion whose decomposition has been pushed furthest will be more slowly attacked4 ,the action of the acid will grow more feeble as the time of contact is prolonged1 and after a time a point is apparently reached where the results are nearly constant4 ,but it is evident that this distinction is purely conventional and bears no necessary or even probable connection with the quantity of alkali really assimilable by plants4 ,vegetables1 moreover1 exert on a soil1 for the extraction of its alkalies and other matters1 chemical reactions peculiar to themselves1 altogether distinct from the tardy action of atmospheric agents and still more distinct from the rapid action of mineral acids4 ,it is well known with what energy1 it ought to be said with what admirable instinct1 plants take from the soil the least traces of phosphorus1 of sulfur1 of potash1 of iron1 and other substances necessary to their sustenance4 ,these specific actions of vegetables on the soil merit1 in the highest degree1 the attention of analysts and agronomists4 ,their intervention plays a most important part in the restitution to the soil1 by means of complementary fertilizers1 the mineral elements removed by vegetable growth4 #cei4 ,estimation of ,lime by the ,french ,method4--,the quantity of lime contained in the soil varies within wide limits4 ,sometimes this base is entirely absent to such a degree that it is even impossible to discover feeble traces of it4 ,sometimes it composes almost the whole of the earthy mass4 ,lime is found in the soil principally in the state of carbonate4 ,it is also found combined with organic matter under the form of humates1 with sulfuric acid1 etc4 ,it is customary to estimate the lime as a whole1 without distinguishing between the different states in which it exists4 ,the quantity of material which is used in the ,french method#bcb varies in proportion to the amount of calcareous matter contained in it4 ,for a soil which contains a large amount of lime1 one or two grams would be sufficient for the analysis4 ,for a soil which is poor in calcareous matter ten or even twenty grams must be taken4 ,the quantity of lime dissolved differs according to the strength of the acids employed and length of contact of the acid with the soil4 ,the calcium carbonate1 the sulfate1 the nitrate1 and the humate rapidly pass into solution when treated with acid as above1 but this is not the case with calcium silicates which are attacked much more slowly4 ,sometimes the silicates give only an insignificant increase in the amount of lime1 and in this case it is immaterial what process of solution is employed4 ,for simplicity it is best to adopt the method of solution in boiling concentrated nitric acid1 prolonging the boiling for a period of five hours4 ,this method of operation is sufficient to bring into solution at one treatment1 not only the lime1 but also the potash and magnesia4 ,after having heated with acid for the necessary time there are added in the capsule in which the solution took place ten cubic centimeters of nitric acid and fifty cubic centimeters of water4 ,the mixture is heated1 collected upon a filter and the residue washed4 ,to the filtrate1 the volume of which should be from #djj to #ejj cubic centimeters1 a sufficient quantity of ammonia is added to render it slightly alkaline4 ,there is formed a precipitate of alumina and of iron oxid containing phosphoric acid and also sometimes a trace of the lime combined with the same acid4 ,in order to keep the whole of the lime in solution it is necessary to add a little acetic acid1 about ten cubic centimeters more than is necessary to neutralize the ammonia which has been added in excess4 ,if the liquid is turbid on account of the presence of the iron and aluminum phosphates it is necessary to filter it4 ,there is afterwards added a slight excess of ammonium oxalate in solution1 and the whole is left for twenty-four hours in order that the calcium oxalate may deposit4 ,indeed1 the complete precipitation is not always immediate1 and especially in the presence of magnesia it takes place with slowness4 ,the calcium oxalate is collected upon a filter and washed with hot water4 ,to determine the quantity of the lime the best procedure consists in transforming the oxalate into carbonate by a careful ignition1 and afterwards heating in a ,schloesing or ,leclerc furnace for four or five minutes4 ,the oxalate for this purpose should be contained in a covered platinum crucible4 ,by this method the calcium carbonate is transformed into calcium oxid1 in which form it is weighed rapidly to avoid absorption of moisture4 ,in laboratories which have no means of securing so high a temperature as is mentioned before1 the lime may be weighed as sulfate4 ,for this purpose the calcium oxalate is transformed into carbonate by ignition in a platinum crucible4 ,afterwards it is treated with nitric acid until the carbon dioxid is completely driven off4 ,the platinum crucible is now covered with a funnel which is afterwards washed in order to bring back into the dish the small drops which have been projected in the process of boiling4 ,an excess of sulfuric acid is added and evaporated to dryness on a sand-bath4 ,afterwards1 in a muffle1 the temperature is carried to a feeble redness until the vapors of sulfuric acid are all driven off4 ,the lime is weighed in the form of sulfate1 and the weight multiplied by #j4dab gives the lime contained in the quantity of earth analyzed4 ,in special researches in which it is desired to avoid attacking the siliceous pebbles of the soil1 the concentrated nitric acid is replaced by dilute nitric acid in slight excess1 and heated for a few moments only4 ,the calcium carbonate is then dissolved with the other calcareous salts not combined with silica in the rock products4 ,the analysis is continued in other respects as just described4 #cfj4 ,estimation of the ,actual ,calcium ,carbonate4--,the lime which is found in the state of carbonate plays one of the most important rles in the chemical phenomena which take place in the soil4 ,it is often of great importance to determine it4 ,the most certain process is to estimate the carbon dioxid which is disengaged from the carbonate under the influence of an acid and to receive this gas in a jar graduated to measure it by volume4 ,the flask recommended by the ,french ,commission for this purpose contains about #cjj cubic centimeters4 ,the neck of the flask is connected with a condensing tube of about one centimeter interior diameter1 which is cooled by a current of water4 ,according to the presumed richness in calcium carbonate varying quantities of earth are taken for analysis1 from as little as half a gram for soils which are rich in carbonate1 up to five or even ten grams for soils which are poor in carbonate4 ,the apparatus is connected with a mercury pump for the purpose of exhausting the air as completely as possible therefrom4 ,for this purpose the flask in which the carbonate is disengaged is made in the shape of a tubulated retort4 ,through the opening into the retort1 a narrow tube is introduced and connected with a small funnel by means of a rubber tube supplied with a pinch-cock4 ,when the retort has been connected with the mercury pump a slight vacuum is produced and the pinch-cock is opened and forty cubic centimeters of distilled water allowed to enter4 ,the pinch-cock is closed soon enough to retain a portion of the water in the funnel4 ,the retort is then heated and a vacuum partially produced by means of the pump4 ,when the flask is boiling1 the steam drives out the air4 ,a refrigerating jacket is connected with the tube leading from the retort to the pump by means of which the steam is condensed and falls back into the flask4 ,after some minutes of boiling1 a vacuum is produced2 the lamp is then taken away and a cylinder1 graduated at #ajj cubic centimeters and filled with mercury1 is placed over the lower orifice of the pump1 and there is introduced into the apparatus1 by the funnel above described1 some hydrochloric acid in small quantities1 but sufficient only to saturate the whole of the carbonate in the sample of soil taken4 ,usually three or four cubic centimeters will be sufficient4 ,the acid should be added in such quantities as to prevent the production of any large amount of foam4 ,if frothing should be excessive a little oil can be added to the flask4 ,the whole of the carbon dioxid produced in the reaction is withdrawn by means of the mercury pump and collected in the graduated jar4 ,towards the end of the operation the flask is heated anew in order to produce an ebullition which is continued for some time4 ,the volume of gas collected is measured after making the proper corrections for pressure and temperature4 ,afterwards the carbon dioxid which has been produced is absorbed by two or three cubic centimeters of a solution of potash of #db baum4 ,this potash is introduced into the graduated jar by means of a pipette bent into the form of a in the lower portion4 ,if the whole of the gas is not absorbed the volume which remains is read1 and this is subtracted from the original volume after having made the proper corrections for pressure and temperature4 ,the difference gives the quantity of carbon dioxid contained in the amount of earth employed4 ,from this the actual weight of the calcium carbonate is computed4 ,this official ,french method does not appear to possess any advantage in accuracy to the usual absorption method and is far more complicated4 #cfa4 ,estimation of the ,active ,calcareous ,matter in ,soils4--,like other soil elements1 the calcium carbonate exists in different degrees of fineness and availability in the soil4 ,it must be admitted that the fine particles play the most important rle4 ,the calcium carbonate1 which exists in large fragments1 presents only a circumscribed surface and remains almost inactive1 although it is easily corroded by the rootlets of plants4 ,it is possible to estimate in a rapid way1 the quantity of fine carbonate in the soil1 considering that in a time relatively short1 feeble acids act upon calcareous matter proportionally to the surface which it presents1 and that it attacks1 therefore1 especially the finest particles4 ,by measuring the amount of carbon dioxid set free under the action of dilute acids it is possible to estimate the content of available calcareous matter in the soil4 ,the apparatus of ,mondesir is used for this purpose by the ,french chemists4 ,it is composed of a tubulated flask of about #fjj cubic centimeters capacity4 ,the interior tubulature carries a manometer fixed by means of a stopper4 ,this is formed of a rubber tube1 terminated by a glass tube1 whose extremity is united to a little rubber bag1 very flexible1 placed in the interior of the flask4 ,graduation of the ,apparatus4--,if the apparatus is new it is necessary to begin by graduating it4 ,the rubber bag is filled with water1 the air being carefully excluded1 in such a way that the level of the water comes just a little above the bend in the tube4 ,there are placed in the flask #abe cubic centimeters of water and it is shaken for a few seconds4 ,the flask and the manometer are then unstoppered and the level of the water in the manometer is made to equal the level of the water in the flask4 ,with a rubber ring the level of the water in the manometer tube is marked4 ,the manometer is then stoppered4 ,there are then added to the flask two-tenths gram of pure calcium carbonate4 ,the flask is closed and shaken for a minute4 ,there are then added1 enclosed in a little piece of filter paper1 six-tenths of a gram of pulverized tartaric acid and the flask immediately closed and shaken several times4 ,the manometer tube is then uncorked and moved until the level of the water reaches the point marked before4 ,the difference in level after the height of the water remains constant is then read4 ,the depression in the level observed1 corresponds to two-tenths gram of pure calcium carbonate4 #cfb4 ,estimation of the ,available ,calcareous ,matter in the ,soil4--,there is introduced into the flask of the apparatus a quantity of soil varying in amount in accordance with the content of carbonate which it is supposed to contain4 ,there are added #abe cubic centimeters of water and the flask is shaken for a minute4 ,as in the test given before1 the level of the water in the manometer is then made to correspond to that of the water in the flask4 ,the level in the manometer is marked as before with a rubber band1 and the manometer is then closed4 ,there are then added1 contained in a piece of filter paper1 two grams of pulverized tartaric acid and the operation is finished as described before4 ,the amount of tartaric acid added1 in general1 should be three times as much as the amount of calcium carbonate supposed to be contained in the earth4 ,the pressure in the manometer being proportional to the quantity of carbon dioxid disengaged1 it is easy to calculate the quantity of calcium carbonate in a state of fine division contained in the soil taken for the test4 ,in order to fill the rubber bag it is necessary to put it in its proper place in the apparatus4 ,the flask is filled with water in order to flatten the rubber bag and expel the air from it4 ,it is then closed with a cork4 ,afterwards1 with the aid of a small funnel and with a copper wire placed in the tube1 the lower extremity of which descends just to the elbow1 the air in the tube is replaced by water4 ,the operation is finished by uncorking the flask and inclining it or shaking it after a partial vacuum has been established4 ,it is useless to attempt to drive off the last particles of the air4 ,the rubber bag should have a content of about double the volume of the whole of the interior of the manometric tube4 ,in the washing which is necessary between two successive operations1 it is well to fill the flask entirely with water in order to expel all the carbon dioxid which it may contain4 ,the same remark may be made of this method of determination as was made of the last one4 ,in the present case1 however1 the operation is not quite so complicated4 ,when the apparatus is once arranged1 it will admit of rapid determinations4 #cfc4 ,lime ,method at the ,riga ,station4--,ten grams of the non-ignited sample of the fine earth are digested with #ajj cubic centimeters of ten per cent hydrochloric acid1 in a #bej cubic centimeter erlenmeyer for twenty-four hours on the steam-bath1 with frequent shaking4 ,the filtrate1 with washings after the addition of five cubic centimeters strong hydrochloric acid1 is evaporated to dryness in a porcelain dish and the residue taken up with dilute hydrochloric acid4 ,after filtering1 ammonia is added in excess1 the excess removed by evaporation1 and the mass is again filtered4 ,in the filtrate1 the lime is thrown down with ammonium oxalate1 filtered1 ignited1 and weighed as calcium oxid4 ,the above method cannot give exact results chiefly because more or less lime may be carried down with the phosphoric acid4 ,also if manganese be present it will be thrown down with the lime4 ,these errors are compensatory1 but only by chance could the compensation lead to exactness4 ,it would be better in all cases to remove the iron and alumina in such a way as would avoid loss of time4 #cfd4 ,estimation of ,assimilable ,lime4--,in the determination of the total lime in soils or even of that part present as carbonate1 it is not to be assumed that the quantity assimilable by plants is known2 particles of lime minerals in soils are corroded only superficially by the rootlets of plants and any process which would attack only the superficies of the lime particles would thus more nearly resemble the activity of the solvent forces of plant growth4 ,oxalic acid is a reagent of this kind1 attacking only the surfaces of lime particles4 ,reverdin and de la ,harpe guided by this fact have based a method for determining the amount of lime present in the soil in an available state on the solvent action of oxalic acid4#bcc ,after the total lime content has been determined1 twenty grams of the soil sample are covered with #bjj cubic centimeters of a solution containing in molecular proportion a known quantity of sodium oxalate and carbonate4 ,the mixture is digested on the water-bath for one hour4 ,by this treatment all lime minerals are converted superficially into oxalate while particles containing magnesia are not affected4 ,after filtering and washing well1 the filtrate and wash-waters are acidulated with hydrochloric acid4 ,if any precipitate of organic matter be produced separate it by filtration4 ,treat the filtrate with a slight excess of sodium acetate by which process the excess of hydrochloric acid is replaced with acetic after which the oxalic acid may be separated by treatment with calcium chlorid and subsequently titrated with potassium permanganate in presence of excess of sulfuric acid4 ,the oxalic acid obtained1 deducted from the quantity originally present will give the amount consumed on the surfaces of the lime particles and consequently the amount of lime corresponding thereto which may be considered as available for plant growth4 #cfe4 ,method of the ,halle ,station for ,lime4#bcd--;a4 ,in ,phosphates1 ,limestones1 etc4--,four grams of the prepared substance are heated with fifty cubic centimeters of hydrochloric acid and five cubic centimeters of nitric acid1 in a porcelain dish on the water-bath to dryness1 and left for a few hours at #aje for the purpose of separating the silicic acid4 ,the dry residue is moistened with hot water and a few drops of hydrochloric acid1 and allowed to stand for some time with frequent stirring4 ,the contents of the dish are then washed into a half-liter flask1 filled up to the mark and the separated silicic acid removed by filtration4 ,if the silicic acid is not taken into account1 the solution can be made directly in a half-liter flask4 ,after filtration1 an aliquot part of the filtrate is neutralized in a #ejj or #bej cubic centimeter flask with ammonia1 again acidified with a few drops of hydrochloric acid and allowed to stand six hours at least1 in the cold1 with ammonium acetate4 ,for each four grams of the substance fifty cubic centimeters of an ammonium acetate solution are used1 made by dissolving in one liter of water #ajj grams of ammonium acetate4 ,if phosphoric acid is present in excess1 iron and aluminum oxids are precipitated completely as phosphates4 ,if iron and aluminum oxids are in excess1 the excess must be precipitated by ammonia4 ,if it is feared that in the subsequent precipitation of the lime by ammonium oxalate there may be still some phosphoric acid in solution1 before precipitation with ammonium acetate the proper amount of ferric chlorid is added and the iron is afterwards precipitated with ammonia4 ,it is certain that in the presence of oxalic acid and phosphoric acid the lime is precipitated as oxalate1 but should it be feared that traces of calcium phosphate are precipitated with the iron and aluminum phosphates the precipitate of iron and aluminum phosphates may be dissolved in hydrochloric acid1 neutralized with ammonia1 again acidified and a second time precipitated with ammonium acetate and the filtrate added to that first obtained4 ,for the further estimation the filtrates are united and a quantity corresponding to a given part of the original sample1 and being in volume from fifty to one hundred cubic centimeters is made slightly acid with acetic acid and while hot precipitated with dilute ammonium oxalate4 ,the filtrate must contain acetic acid since calcium oxalate is best precipitated from a slightly acetic acid solution4 ,the filtering of the calcium oxalate should not take place until from six to twelve hours after precipitation1 and during this time it should stand in a warm place4 ,filter paper of the best quality should be used for the purpose4 ,the dried precipitate is brought into a platinum crucible together with the filter2 the filter is first incinerated over an ordinary bunsen and the calcium oxalate converted into calcium oxid by ignition for fifteen minutes over the blast4 ,it is then cooled in a well-closed desiccator and weighed as oxid4 ,if in the precipitation of the iron and aluminum phosphates sodium acetate be employed instead of ammonium acetate1 the precipitation must take place hot and filtration also be accomplished on a hot filter4 b4 ,estimation of ,lime in ,soils4--,for the estimation of lime in soils there may be used either the acid soil-extract1 prepared as under the direction for the estimation of potash1 or twenty grams of the soil may be treated with hydrochloric acid and a few drops of nitric acid1 and evaporated to dryness in a porcelain dish and the silicic acid separated as described for the estimation of lime in phosphates and limestones4 ,in the case of soils1 iron and aluminum oxids can be precipitated directly with ammonia since the small quantity of phosphoric acid usually contained in soils is not sufficient to influence in any way the estimation of the lime4 ,for example suppose there is #j4aj per cent of phosphoric acid contained in a soil4 ,in case the whole of this phosphoric acid is taken down with the lime it would only amount to about #j4aj per cent of calcium oxid precipitated as phosphate4 ,this case1 however1 is very improbable since it is much more likely that the iron and aluminum phosphates will be precipitated and the whole of the phosphoric acid be carried down with them instead of being precipitated with the lime4 ,the precipitation of the lime and its subsequent treatment are to be conducted as just described4 #cff4 ,estimation of the ,magnesia4--,magnesia is a much more rare element in the soil than lime4 ,it is usually necessary to operate upon considerable quantities of earth in order to determine the magnesia with any degree of precision4 ,from ten to twenty grams of the soil are taken4 ,the decomposition is accomplished as in the case of lime4 ,a few drops of barium nitrate are added for the purpose of precipitating any sulfuric acid present4 ,some ammonia and ammonium carbonate are added to precipitate the iron and aluminum oxids1 the lime and the excess of barium introduced1 as well as the phosphoric acid4 ,the operation is best conducted on a dilute solution having a volume of from #djj to #ejj cubic centimeters4 ,the solution from which the lime has been precipitated1 contains with the magnesia1 large quantities of ammoniacal salts which it is necessary to destroy4 ,for this purpose the solution is concentrated in a flask until its volume is about ten cubic centimeters4 ,about ten cubic centimeters of nitric acid are added and the whole brought to the boiling point4 ,afterwards a few drops of hydrochloric acid are added4 ,continuing the heating1 hydrochloric acid is added in small portions and1 from time to time1 some nitric acid until the bubbles indicating the setting free of gaseous nitrogen1 resulting from the action of the nascent chlorin upon the ammonia1 have completely ceased to appear4 ,the whole is then evaporated on a sand-bath in a porcelain dish in order to separate the silica4 ,the residue is taken up by water containing a few drops of nitric acid4 ,it is filtered and evaporated to dryness in a covered porcelain dish4 ,upon the residue four or five grams of oxalic acid1 in a state of powder1 are placed4 ,a little water is added in such a way that the moist mass covers entirely the matter in the dish4 ,in order to avoid all losses there is placed upon the dish a funnel which serves as a cover4 ,the dish is heated on a sand-bath1 but when the film which is formed begins to break there are added from time to time1 a little more oxalic acid and water until there is no longer any disengagement of the vapor of nitric acid4 ,afterwards it is evaporated to dryness and the heat raised to a low redness4 ,the magnesia is found in a free state or mixed with alkalies4 ,it is washed with a small quantity of water and collected upon a very small filter paper4 ,the filter paper is dried1 burned1 the ignition carried to redness and afterwards cooled and weighed4 ,in order to test the purity of the magnesia it is transformed into sulfate by the addition of a few drops of sulfuric acid4 ,the excess of sulfuric acid is driven off by heating moderately by means of a gas-burner moving it in a circular manner round the bottom of the capsule and lifting the cover from time to time in order to allow the vapors of sulfuric acid to escape4 ,the weight of the magnesium sulfate should correspond to that of the magnesia from which it was formed4 ,magnesia exists most often in the soil in the state of carbonate or silicate4 ,in this last state it is especially abundant in some soils1 such as those which are derived from mica schists1 serpentines1 etc4 ,in treating earth of this last quality with concentrated1 nitric acid there is dissolved also a notable part of the magnesia of the silicates4 ,if1 however1 it is treated for some minutes only with dilute hydrochloric acid the amount of magnesia present as carbonate alone can be estimated separately4 #cfg4 ,estimation of ,magnesia in ,soils4--,method of the ,halle ,station4--,for the estimation of magnesia the sample of soil or fertilizer is brought into solution in the same way as is given for the estimation of lime4 ,after the separation of the silicic acid1 the iron and alumina are precipitated with sodium acetate4 ,in the case of phosphoric fertilizers1 ferric chlorid should first be added in order that the excess of phosphoric acid shall be in all cases certainly combined with the iron4 ,after this the lime is separated as usual with ammonium oxalate4 ,after the precipitation of the lime1 the magnesia is precipitated in an ammoniacal solution with sodium phosphate and the ammonium magnesium phosphate estimated exactly as in the case with the estimation of phosphoric acid1 as magnesium pyrophosphate4 ,a simpler method for the estimation of magnesia consists in precipitating it as ammonium magnesium phosphate in the presence of a solution of ammonium citrate1 the other bases remaining in solution4 ,in this case the operation is carried on in an inverse way as described under the estimation of phosphoric acid1 the proper quantity of the acid solution being neutralized with ammonia and after the addition of sodium phosphate1 the required quantity of citrate solution added and a further excess of ammonia supplied4 #cfh4 ,estimation of ,manganese4--,the estimation of manganese in the presence of ,fe,o1 ,al,o1 ,ca,o1 etc41 presents peculiar difficulties4 ,in ordinary alluvial clays the quantity of manganese is proportionately small and its estimation may be neglected4 ,in volcanic clays the quantity of manganese1 in proportion to the lime and magnesia1 is much larger4 ,the method used for estimating manganese is that of ,carnot4#bce ,the hydrochloric acid extract of the soil is evaporated to dryness and heated with potassium bisulfate in order to destroy the organic substance1 the neutralized solution of the residue precipitated with twenty cubic centimeters of hydrogen peroxid solution and thirty cubic centimeters of ammonia4 ,the colorless filtrate gives1 with nitric acid and bismuth peroxid1 no trace of reaction for manganese4 ,the precipitate1 washed by decantation1 is carried into a carbon dioxid apparatus and treated with oxalic acid and dilute sulfuric acid4 ,from the amount of carbon dioxid obtained1 the quantity of manganese is calculated on the supposition that the precipitate corresponds to the formula ,mn,o4 #cfi4 ,estimation of the ,manganese by the ,french ,method4--,manganese exists in all plants and its presence in small quantities seems necessary to vegetation4 ,the method of estimation adopted by the ,french ,commission is the one proposed by ,leclerc and is applicable even when the base exists in small quantities4 ,twenty grams of the soil are taken and the organic matter destroyed by incineration4 ,in a flask of #bjj cubic centimeters capacity1 are placed thirty cubic centimeters of water and1 little by little1 some hydrochloric acid for the purpose of decomposing the calcium carbonate4 ,when effervescence has ceased ten cubic centimeters of the same acid are added and boiled for half an hour1 filtered1 washed1 and the wash-water and filtrate evaporated to dryness in a porcelain dish4 ,afterwards there are added twenty cubic centimeters of nitric acid of one and two-tenths density1 and ten cubic centimeters of water4 ,the liquor is boiled with constant shaking4 ,afterwards there are thrown in1 in two or three portions1 ten grams of lead dioxid4 ,the boiling is stopped just at the moment when all the lead oxid is introduced into the liquor and the mixture is then shaken vigorously4 ,the manganese is transformed by this treatment into a highly oxygenized compound having a deep rose coloration4 ,it is transferred immediately afterwards to a graduated cylinder of #ajj cubic centimeters capacity1 with the wash-waters the volume is completed to #ajj cubic centimeters and it is vigorously stirred with a rod1 flattened at its extremity1 in order to obtain a complete homogeneity of the liquid4 ,the stirring rod is withdrawn and the liquid left to settle4 ,at the end of some minutes the principal part of the liquid is clear1 and it is decanted by means of a pipette graduated at fifty cubic centimeters1 and this quantity of the clear liquid is poured into a small glass precipitating jar to which is added immediately1 with constant stirring1 a solution of mercurous nitrate from a graduated burette4 ,the addition of the nitrate is arrested at the moment when the rose color of the liquor disappears1 and the volume of the mercurous nitrate employed is read from the burette4 ,it is now necessary to determine the strength of the mercurous nitrate1 that is the quantity necessary to decolorize one milligram of manganese4 ,for this purpose dissolve by means of five cubic centimeters of hydrochloric acid #aej milligrams of manganese dioxid1 which is prepared perfectly pure by means of precipitation4 ,when the solution is complete evaporate to dryness1 add one cubic centimeter of sulfuric acid and heat on a sand-bath until white fumes of sulfuric acid appear4 ,redissolve in water and make the volume up to #ajj cubic centimeters4 ,each cubic centimeter of this solution should contain one milligram of manganese4 ,take five cubic centimeters of this solution1 equivalent to five milligrams of manganese1 treat in a capsule with twenty cubic centimeters of nitric acid and ten cubic centimeters of water1 afterwards add ten grams of lead dioxid1 carrying on the operation exactly as described above4 ,fifty cubic centimeters1 taken as before described1 are then decolorized by the solution of mercurous nitrate1 and thus it is easy to calculate the quantity of manganese which corresponds to one cubic centimeter of the mercurous nitrate employed4 ,by a simple proportion the quantity of manganese contained in the twenty grams of earth to be analyzed is calculated4 ,the mercurous nitrate is prepared by dissolving five grams of crystallized mercurous nitrate in one liter of water2 it is allowed to repose for some time and is preserved in a well-stoppered flask4 #cgj4 ,estimation of ,iron4--,iron1 in general1 is quite abundant in the soil where it is met with1 principally in the state of anhydrous sesquioxid or the hydrated sesquioxid of silicates4 ,some soils1 however1 only contain iron in small proportions and it can happen that the introduction of iron as a fertilizing element may be useful4 ,plants assimilate iron only in small quantities1 but it appears to be indispensable to their development and to the proper functional activity of their assimilating faculties4 ,the method of estimation which is recommended is based upon the decoloration of potassium permanganate by iron in the ferrous state4 ,the following description1 based on the method proposed by the ,french ,commission1 will illustrate the process to be followed4 ,ten grams of the soil are ignited in a porcelain capsule until all organic matter is destroyed4 ,the ignited mass is then introduced into a flask of #ajj cubic centimeters capacity with thirty cubic centimeters of hydrochloric acid and fifteen cubic centimeters of water4 ,it is boiled for about half an hour4 ,the iron oxid is dissolved and is found in solution in the form of ferric chlorid4 ,after filtering and washing1 the volume of the filtrate is reduced by evaporation to about twenty-five cubic centimeters4 ,the liquor is afterwards placed in a flask of from #ajj to #aej cubic centimeters capacity1 which is closed by a stopper carrying a tube furnished with a valve destined to prevent the re-entrance of the air4 ,ten cubic centimeters of dilute sulfuric acid are added from a mixture containing twenty cubic centimeters of strong acid and eighty cubic centimeters of water4 ,afterwards the iron is reduced to the ferrous state by introducing into the flask1 in quantities of about five decigrams1 metallic zinc and waiting after each addition until the portion last added is dissolved before adding another4 ,this addition of zinc is continued until the iron is all reduced4 ,when this point is reached and the last portion of zinc added is dissolved1 the contents of the flask are transferred rapidly to a precipitating glass of about one liter capacity1 in which there has been placed a little lately boiled but cold water4 ,the flask is washed several times with cold water1 previously boiled1 to remove from it all traces of oxygen4 ,the volume is made up to #ejj cubic centimeters1 and afterwards1 without any loss of time1 by means of a graduated burette and with constant stirring1 a solution of potassium permanganate is added which is stopped exactly at the moment when the liquor begins taking on a light rose tint4 ,the quantity of permanganate employed is read from the burette and is proportional to the amount of iron contained in the soil4 ,a blank operation is made for the purpose of detecting traces of iron which the zinc may contain4 ,if1 as often happens1 the soil contains a large amount of iron it is advisable to use only one gram of it for this operation4 ,the aspect of the earth will indicate in general if it be very ferruginous4 ,preparation and ,standardization of the ,permanganate ,liquor4--,in one liter of water are dissolved ten grams of crystallized potassium permanganate and the quantity of iron which corresponds to one cubic centimeter of this liquor is determined4 ,it may be well enough to remark that this liquor does not remain constant and it is necessary to titrate it from time to time4 ,for this purpose pure iron is taken4 ,piano wire may be used1 being almost pure iron4 ,one-tenth of a gram of this wire is dissolved in a flask in the manner recommended for treating the soil and with the same quantities of acid and water4 ,when the solution is complete it is transferred to the flask to be estimated4 ,it is made up to one liter and permanganate added1 just as in the case before mentioned1 until the rose color persists4 ,there is thus determined the quantity of iron which corresponds to each cubic centimeter of the permanganate1 and by a simple proportion1 the quantity of iron contained in the soil analyzed is determined4 ,the ,italian agricultural chemists proceed essentially in the same manner in determining the iron in soils1 first igniting the sample and afterwards extracting the iron in the ferric state with boiling hydrochloric acid1 reducing with hydrogen1 and titrating with potassium permanganate4 ,the following are the reactions which take place3 ,fe,o #f;,h,cl ,fe,cl #c;,h,o4 ,fe,cl #b;,h #b;,fe,cl #b;,h,cl4 #aj;,fe,cl ,k,mn,o #af;,h,cl #e;,fe,cl #b,k,cl #b,mn,cl #h;,h,o4 ,sulfuric may take the place of hydrochloric acid in the above reactions4 ,illustration3 ,,figure #fh4 ,,apparatus ,,by ,,sachsse ,,and ,,becker4 #cga4 ,method of ,sachsse and ,becker4#bcf--;,ferric oxid 7not as silicate7 in soils can be estimated by reducing with hydrogen1 and measuring the hydrogen which is evolved by the action of the reduced iron on an acid4 ,the sample of soil is weighed in a platinum boat1 the boat put into a wide glass tube and heated in a stream of dry hydrogen4 ,while this is going on1 water is boiled in the flask ,a 7see ,fig4 #fh7 from which the stopper has been removed1 to drive out the air4 ,when the reduction of the ferric oxid is complete1 the boat is slipped out of the tube into the flask without interrupting the hydrogen evolution4 ,in order to accomplish this without allowing the reduced iron to come in contact with the air the flask is inclined1 the end of the glass tube inserted until it is covered with water and the boat is then dropped beneath the water4 ,the flask is closed with a cork provided with a funnel tube1 ,b1 and a delivery tube ,c2 the tap a is opened1 and tube b connected with a carbon dioxid apparatus from which the gas is passed into ,a until all the air is displaced4 ,this point is determined by filling the burette ,d with potash-lye by aspiration at ,c and allowing the escaping gas from ,c to enter the burette as indicated in the figure4 ,any residual gas in ,d is removed by aspiration at ,c and allowing the potash-lye in e to enter in its place4 ,the end of the tube ,c is now placed under the measuring tube ,d1 and the clamp f opened and the tap a closed4 ,the funnel is filled with dilute1 boiled sulfuric acid1 the cork of b replaced and connected with the carbon dioxid apparatus4 ,the burner under ,a is lighted and acid let in4 ,by continued boiling1 all the hydrogen is driven into ,d1 the carbon dioxid being absorbed4 ,the measuring tube is then placed in a tall cylinder of water1 the volume of gas read and reduced to #j and #gfj millimeters barometric pressure4 ,to be certain that all carbon dioxid is absorbed1 some fresh potash-lye may be introduced into ,d by carefully opening d4 ,the iron is then computed from the volume and weight of the hydrogen by the formula 7#a7 ,fe ,h,,so #b;,h ,fe,s,o4 ,if the substance analyzed contains iron silicates1 these may be partly decomposed with formation of ferrous sulfate1 according to the reaction 7#b7 #b;,fe ,fe7,,so7 #c;,fe,s,o4 ,this will redissolve a part of the metallic iron and yield ferrous oxid4 ,in this case the contents of the flask are cooled in an atmosphere of carbon dioxid1 made up to #ejj cubic centimeters1 of which #bej cubic centimeters are quickly filtered and titrated with permanganate4 ,in order to properly distribute the iron in harmony with its previously existing states the following computations may be made3 ,represent the ferrous oxid corresponding to formula 7#a7 by x and that 7#b7 by z and that found by titration with permanganate by a4 ,we have then the equation x z a4 ,since seventy-two parts by weight of ferrous oxid formed by formula 7#a7 are equivalent to two parts by weight of hydrogen1 x parts of ferrous oxid would set free x_/#cb parts of hydrogen2 and this corresponds to the hydrogen found in ,d2 viz41 b4 ,if a then by solving the equations3 ,z a #cf;b and ,x #cf;b4 ,the ferrous oxid arising according to formula 7#b71 however1 is derived in such a way that only one-third of it corresponds to metallic iron4 ,then3 ,x 77z 77a #bd;b4 ,for computing the total ferric oxid reduced by hydrogen there must1 therefore1 be added twenty-four parts by weight of hydrogen for one-third of the ferrous oxid found by titration with permanganate1 and this quantity of ferrous calculated to ferric oxid4 ,some silicates1 such as the micas1 give ferrous oxid with hot dilute sulfuric acid4 ,a correction for this is made by making one or more determinations without previously reducing with hydrogen4 ,the method of procedure above described appears to be capable of giving in an easily attainable manner some valuable indications of the state in which iron exists in a soil4 ,while plants do not use any notable quantity of iron during their growth nevertheless its physiological importance is unquestioned4 ,the chief points of difficulty to be considered are found in the changes which the iron may undergo even while heating in a stream of hydrogen1 and the practical difficulties of obtaining carbon dioxid entirely free of air4 ,the latter difficulty may be overcome by making blank experiments with carbon dioxid alone and estimating the volume of residual gas4 ,the total volume of hydrogen obtained is then to be diminished by the ascertained amount4 ,in regard to the second point it is known that both ferrous and ferric oxids when ignited with hydrated silicates partly decompose and form new silicates4 ,care should therefore be taken not to carry the temperature too high during the process of ignition4 #cgb4 ,carnot's ,method for ,estimating ,phosphoric ,acid in ,soils4--,carnot#bcg proposes the following procedure for the estimation of phosphoric acid in soils4 ,the principle of this method depends upon the isolation of silica by the double precipitation of phosphomolybdate4 ,ten grams of the sifted soil1 dried at #ajj1 are charred if organic matter be present4 ,the charred mass is next moistened with water and afterwards with nitric acid1 until the carbonates are decomposed4 ,afterwards the mass is digested with ten cubic centimeters of nitric acid for two hours at about #ajj1 with frequent stirring and the addition of fresh acid1 from time to time1 to replace that which has been evaporated4 ,after filtering and washing with hot water the filtrate is evaporated to a volume of fifty cubic centimeters and treated with five cubic centimeters of concentrated nitric acid and half a gram of crystals of chromic acid4 ,after covering the dish with a funnel to return condensed vapors its contents are heated to the boiling point for half an hour4 ,at the end of this time five grams of ammonium nitrate are added and afterwards fifty cubic centimeters of molybdate solution and the mixture kept at a temperature of about #ajj for an hour4 ,the precipitate obtained is washed twice by decantation with water containing one-fifth of its volume of ammonium molybdate solution4 ,it is then dissolved in thirty cubic centimeters of ammonia diluted with an equal bulk of warm water4 ,the solution and the washings should measure eighty cubic centimeters and the ammonia therein is neutralized with nitric acid1 keeping the temperature below #dj4 ,when the yellow precipitate formed ceases to redissolve on stirring1 a mixture of three cubic centimeters of pure nitric acid and five cubic centimeters of water is added1 together with the same quantity of molybdate solution4 ,the precipitate is brought upon a filter1 washed first with water containing one per cent of nitric acid and finally with a little pure water1 and dried at #ajj and weighed4 ,the weight of the precipitate multiplied by the factor #j4jcgc gives the quantity of phosphoric acid4 ,the object of the second precipitation is to relieve the process of the necessity of rendering the silica insoluble1 as the presence of silica in the solution as above treated does not interfere with the complete precipitation of the phosphate4 ,this was proved by the author1 by the introduction of considerable quantities of sodium silicate and these were found not to interfere with the accuracy of the operation4 ,the results are as accurate as those obtained by the methods of the consulting committee of the agricultural stations4 ,the coefficient employed2 viz41 #j4jcgc1 is not the same as that recommended by the committee2 viz41 #j4jdc4 ,the committee1 however1 itself has recognized the inaccuracy of the latter number4 ,the composition of the compound obtained by double precipitation according to ,carnot is ,p,o#bd,mo,o#c7,,nh7,o #c;,h,o4 #cgc4 ,method of the ,halle ,experiment ,station4--,the available or easily soluble phosphoric acid in soils is estimated by ,maercker and ,gerlach1 as follows3#bch ,sixty grams of the air-dried soil as prepared for analysis1 are placed in an erlenmeyer with #cjj cubic centimeters of two per cent citric acid solution and digested for twenty-four hours in the cold4 ,it is necessary in this time to shake the flask four or five times and to put the stoppers in loosely in order to allow the escape of any evolved carbon dioxid4 ,of this mixture #bjj cubic centimeters are filtered and evaporated in a #cjj cubic centimeter dish to dryness4 ,there remains1 in most cases1 a sirupy-like mass from which even by strong heating the silica is not completely separated4 ,in order to reach this result the residue is treated with twenty cubic centimeters of concentrated sulfuric and five cubic centimeters of fuming nitric acid and heated over a bunsen4 ,as soon as the appearance of foam denotes the beginning of the reaction the lamp must be removed4 ,with strong foaming and the evolution of red-brown vapors the citric acid is completely oxidized4 ,after the reaction is ended the contents of the dish are heated for about fifteen minutes over a small flame so that a continuous1 yet not too violent evolution of sulfuric acid fumes takes place4 ,after the silicic acid and the greater part of the lime have been separated in this way the contents of the dish are diluted with water1 stirred with a glass rod1 washed into a #bjj cubic centimeter flask1 cooled1 filled up to the mark1 and filtered4 ,from the filtrate #ajj cubic centimeters1 corresponding to twenty grams of the earth1 are taken1 made slightly alkaline with ammonia1 acidified by a few drops of hydrochloric acid1 and after cooling treated with fifty cubic centimeters of the citrate solution and twenty-five cubic centimeters of the magnesia mixture4 ,the complete separation of the precipitate requires about forty-eight hours and shaking of the precipitate is not necessary4 #cgd4 ,estimation of total ,phosphoric ,acid in ,soils4--,in the method used at the ,halle ,station#bci twenty-five grams of the soil sample are boiled with twenty cubic centimeters of nitric acid and fifty cubic centimeters of concentrated sulfuric acid for half an hour4 ,with very clayey soils only half the quantity of the sample mentioned above is used in order to avoid the too great accumulation of soluble alumina4 ,the oxidation of the organic substances of the soils must be carried on at a moderate heat to avoid foaming4 ,during the boiling1 the flask is to be often shaken to prevent the soil constituents from accumulating too firmly at the bottom4 ,the total volume is finally made up to #ejj cubic centimeters4 ,for the estimation1 #ajj cubic centimeters of the solution1 corresponding to five 7or two and a half7 grams of the soil1 are taken4 ,in order to nearly completely saturate the acid1 the solution is treated with twenty cubic centimeters of twenty-four per cent ammonia1 care being taken that the precipitate of iron and alumina which is formed is again completely dissolved4 ,the solution is cooled and treated with fifty cubic centimeters of the citrate solution1 and then with twenty cubic centimeters of ammonia of above strength1 and precipitated with the magnesia mixture4 ,the filtration of the precipitate should not be made for at least forty-eight hours1 during which time the flask should be often shaken to prevent the attachment of ammonium magnesium phosphate to its sides and bottom4 ,a detailed description of the citrate method for estimating phosphoric acid will be found in the chapter devoted to this subject under fertilizers4 #cge4 ,french ,method for ,phosphoric ,acid4--,phosphoric acid is found in the soil principally in combination with alumina and iron oxid1 with organic matters1 or with lime and magnesia4 ,whatever may be the state in which it is found all the phosphoric acid1 with the exception of that which enters into the constitution of insoluble mineral particles1 can be brought into solution by acids and determined by some of the approved methods4 ,this method of solution1 therefore1 is capable of determining very accurately the total proportion of phosphoric acid in the soil1 but it is incapable of rendering account to us of the state in which the phosphorus is found and of its aptitude to be utilized by plants4 ,the estimation of soil phosphorus1 as recommended by the ,french ,commission1 is carried on in the following way3#bdj ,twenty grams of the earth are submitted to ignition in a muffle heated to the temperature of redness but not higher4 ,this calcination eliminates the organic materials1 whose intervention in subsequent reactions might be able to prevent the precipitation of a part of the phosphoric acid4 ,the calcined earth is placed in a capsule of about eleven centimeters diameter and saturated with water4 ,there is then added in small quantities1 as long as effervescence is produced1 nitric acid of #cf baum4 ,when the effervescence has ceased1 after thorough shaking and the addition of a new quantity of acid1 it will be found that the whole of the calcium carbonate in the soil has been decomposed4 ,it is necessary then to proceed to the solution of the phosphoric acid by adding twenty cubic centimeters of nitric acid and heating on the steam-bath for five hours1 shaking from time to time1 and avoiding complete desiccation4 ,at the end of this time the whole of the phosphoric acid has entered into solution4 ,it is taken up by warm water1 filtered1 and the insoluble residue washed with small quantities of boiling water4 ,but from the solution obtained1 which holds in addition to phosphoric acid1 some oxid of iron1 alumina1 lime1 magnesia1 etc41 it is necessary to separate the silica which has passed into solution4 ,for this purpose the mass is evaporated to dryness on a sand-bath1 heating toward the end of the operation with precaution and not allowing the temperature to pass beyond #aaj-abj4 ,in these conditions there is obtained a magma which sometimes remains quite sirupy when the earth is very highly impregnated with calcium carbonate1 but in which the silica is insoluble4 ,it is indispensable that it be eliminated wholly because it would introduce grave errors into the results1 as will be seen later on4 ,if the temperature be carried too high during the desiccation this silica would react upon the earthy salts and alkaline earths forming silicates and it would be found ultimately again in solution4 ,the application of a too high temperature would also render somewhat insoluble in nitric acid the iron and aluminum oxids1 and these would retain small quantities of phosphoric acid4 ,the desiccation1 therefore1 requires to be conducted with great precaution4 ,when it is accomplished there are placed in the capsule five cubic centimeters of nitric acid and five cubic centimeters of water1 and the whole heated on the sand-bath until the entire amount of iron oxid is dissolved1 that is to say1 until there is no ferruginous deposit persisting in the liquid4 ,the solution is then filtered and washed with small quantities of boiling water in such a way that the total volume of the filtrate will not exceed twenty-five to thirty-five cubic centimeters4 ,afterwards there are added twenty cubic centimeters of ammonium nitromolybdate and the whole is left at rest for twelve hours at the ordinary temperature4 ,at the end of this time the whole of the phosphoric acid is precipitated in the form of ammonium phosphomolybdate4 ,in order to be certain that an excess of nitromolybdate has been used in the precipitation1 which is indispensable to the total precipitation of the phosphoric acid1 a few cubic centimeters of the filtrate are removed by means of a pipette and are mixed with their own volume of the ammonium nitromolybdate4 ,if1 at the end of an hour or two1 no precipitate is formed the operation can be regarded as terminated4 ,in order to collect and weigh the ammonium phosphomolybdate some precautions are necessary4 ,two smooth filters are used1 one of which serves as a counter-weight for the other on the balance4 ,one of these filters is placed within the other and the phosphomolybdate is collected upon the inner filter4 ,the part of the phosphomolybdate adhering to the precipitating jar is detached by the aid of a stirring rod1 one of the ends of which is covered with a piece of rubber tubing4 ,the washing is accomplished with very small quantities of water containing five per cent of its volume of nitric acid4 ,when all of the precipitate is collected upon the filter and the washing is terminated a few drops of water are thrown upon the upper borders of the filters2 this is done to displace the acid liquor which has been used in washing4 ,the filters are then carried to the drying oven where they are dried at a temperature not exceeding #ij4 ,the application of a higher temperature would decompose the ammonium phosphomolybdate and lead to results which would be too low4 ,after the drying is completed the two filters are separated and placed upon the arms of the balance and the increase in weight corresponds to the ammonium phosphomolybdate4 ,this1 multiplied by the coefficient #j4jdc1 7see page #djd7 gives the quantity of phosphoric acid contained in the weight of the soil which has been employed4 ,the ammonium phosphomolybdate is pure if all the silica has been eliminated1 but if a part of that has remained in solution it would furnish an ammonium silicomolybdate whose weight would be added to that of the phosphomolybdate4 ,the elimination of the silica1 therefore1 should be made with the greatest care4 ,different processes have been proposed in order to determine the forms under which phosphoric acid should be regarded as most assimilable4 ,deherain has proposed acetic acid as a solvent for this purpose4 ,other scientists1 oxalic or citric acid1 and the ammonium oxalate or citrate4 ,the solubility of phosphoric acid in these different reagents gives some information in regard to its state1 but the relations which exist between this solubility and the assimilability of the acid have not yet been fixed4 ,preparation of the ,ammonium ,nitromolybdate4--,one hundred grams of molybdic acid are dissolved in #djj grams of ammonia with a density of ninety-five4 ,the mixture is filtered1 and the filtered liquor is received drop by drop in #a1ejj grams of nitric acid of one and two-tenths density1 constantly stirring4 ,this mixture is left standing for some days in an unexposed locality1 during which time a deposit is formed4 ,the clear part is decanted and used4 ,the above method of the ,french chemists unfortunately attempts to determine the phosphorus content of the soil by weighing the yellow precipitate and using an empirical factor for the calculation1 a factor which is probably too high4 ,experience has shown that at this point it is far more accurate to continue the process by dissolving the yellow precipitate1 and subsequently obtaining the phosphoric acid in combination with ammonia and magnesia1 or according to the process of ,pemberton the content of phosphoric acid in the yellow precipitate might be determined by titration4 ,in regard to the latter method which will be given in full under fertilizers1 it may be said that it has been found quite accurate by several analysts1 although it is difficult to see how a precipitate which is so variable in its constitution as to be estimated with little safety by weight may yet be capable of rather exact determination by titration4 #cgf4 ,petermann's ,method for the ,estimation of the ,phosphoric ,acid ,soluble in ,alkaline ,ammonium ,citrate4#bda--;,from twenty-five to fifty grams of the sample of soil are triturated with #ajj cubic centimeters of alkaline ammonium citrate and placed in a flask of #bej cubic centimeters capacity1 and allowed to digest for one hour at a temperature of from #ce-dj4 ,after cooling1 make up to the mark1 filter1 take #bjj cubic centimeters of the filtrate1 evaporate to dryness on a sand-bath in a platinum dish1 heat lightly at first1 and afterwards to a higher temperature4 ,take up the residue of the incineration with water and about two cubic centimeters of nitric acid1 heat a few minutes gently1 filter into a bohemian flask and precipitate with fifty cubic centimeters of ammonium molybdate solution1 and estimate the phosphoric acid in the usual way4 #cgg4 ,method of ,dyer for ,total and ,assimilable ,phosphoric ,acid4--,for the determination of phosphoric acid1 soluble in citric acid1 secured as described in paragraph #cbh1 #ejj cubic centimeters of the filtrate obtained1 corresponding to fifty grams of the soil1 are evaporated to dryness in a platinum dish1 gently ignited1 extracted with hydrochloric acid1 again evaporated1 ignited and extracted1 and the phosphoric acid determined as below in the method applied to the hydrochloric acid extract of the soil itself4 ,the total phosphoric acid is determined in each case in ten grains of the dried soil and also in twenty-five grams1 the mean of the two results being taken4 ,the numbers obtained in each case are1 however1 all but identical1 the difference in the duplicate percentages being in most cases only a small one in the third place of decimals4 ,the soil is incinerated and digested with hydrochloric acid1 and evaporated to dryness1 redigested with acid1 filtered1 and washed4 ,the filtrate and washings are concentrated to a small bulk1 and treated1 in the cold1 with excess of a solution of ammonium molybdate in nitric acid4 ,after standing forty-eight hours1 the liquor is decanted through a filter1 the precipitate washed several times by decantation1 first with dilute acid1 then with pure water in very small doses1 and finally transferred to the filter and washed free from excess of acid4 ,the ammonium phosphomolybdate is then dissolved in ammonia1 evaporated to dryness in a platinum capsule1 and dried to constant weight at #ajj4 ,the residue contains three and one-half per cent of its weight of phosphoric acid4 ,this is the method of ,hehner2 and for determining small quantities of phosphoric acid1 such as occur in soils or in solutions of iron and steel1 is in the opinion of ,dyer very much to be preferred to the old-fashioned method of conversion into magnesium ammonium phosphate4 ,the solubility of the yellow precipitate in the small quantity of wash-water used is in most cases negligible4 ,as a matter of fact1 the quantity of wash-water used in these analyses was found capable of dissolving only #j4jje gram of precipitate1 of which only #j4jjjag is phosphoric acid1 making an error of #j4jjag per cent on the soil if ten grams be used1 or of only #j4jjjf if twenty-five grams be used4 ,in the citric acid experiments the solution from fifty grams of soil is used1 when the error due to solubility of precipitate shrinks to #j4jjjc per cent4 ,the correction for this solubility is1 however1 made in each case4 ,it may be observed that the method of ,hehner is not applicable if the molybdic solution be added to a hot liquid1 since1 in that case1 some molybdic acid is sure to crystallize with the yellow precipitate4 ,moderate and careful warming to about #ce hastens precipitation1 but it is preferable1 when speed is not a special object1 to precipitate cold1 and leave the beaker standing at the laboratory temperature over night1 or longer if the quantity to be determined is very minute4 #cgh4 ,methods of ,berthelot and ,andr4--,the phosphorus in the soil may be found under three forms2 viz41 #a4 ,phosphoric acid in phosphates4 #b4 ,phosphoric acid in ethers which alkalies decompose slowly and oxidizing agents destroy with regeneration of phosphoric acid4 #c4 ,organic compounds or mineral compounds of phosphorus which are resolved by alkaline solutions with formation of phosphoric acid and which are not reduced to this state by the reagents employed in the wet way of decomposition except after a contact of indefinite length and uncertainty4 ,it is1 therefore1 seen that the employment of oxidizing agents for the valuation of phosphoric acid in soils and vegetables is not a very reliable procedure4 ,the same is true after incineration by which more or less phosphorus may be lost or rendered insoluble in acids4 ,the methods used by ,berthelot and ,andr for the estimation of these forms of phosphorus are as follows3#bdb ,total ,phosphorus4--,the sample is at first oxidized by a current of air near a red heat and the vapors are conducted over a column of sodium or potassium carbonate at the same temperature4 ,the combustion is finished in a current of pure oxygen4 ,all phosphorus compounds1 even those which are volatile1 are by this treatment converted into phosphoric acid4 ,the part of the acid held by the carbonate is to be determined with the non-volatile portions4 ,a less certain method of oxidation consists in mixing the material with potassium nitrate and carefully throwing it little by little into a red hot platinum crucible4 ,estimation of the ,phosphoric ,acid ,pre-existing as ,phosphates4--,the sample is treated with a cold dilute acid incapable of exercising an oxidizing or decomposing effect on the ethers4 ,the dissolved acid is precipitated and weighed in the usual way4 ,the precipitate first obtained should be ignited and the phosphoric acid taken up and reprecipitated4 ,this is necessary to remove any organic matter or silica which the first precipitate may contain4 ,estimation of ,ethereal ,phosphoric ,acid4--,the sample is boiled for some time with a non-oxidizing acid or with a concentrated solution of potash4 ,the phosphoric acid dissolved represents that which was present as phosphates and as ethers4 ,from this1 deduct that portion pre-existing as phosphates and the remainder represents the part derived from the ethereal compounds4 ,estimation of ,phosphorus in ,organic ,compounds and ,special ,minerals4--,from the total phosphoric acid deduct that found as phosphates and ethers4 ,the difference represents the quantity combined as noted in the caption4 ,illustration4 ,a sample of soil contained3 ,total phosphoric acid #j4bib per cent4 ---------- ,of this1 pre-existing as phosphoric acid #j4aji ,as ethereal phosphoric acid #j4jgd ,as organic phosphoric acid #j4aji ---------- ,sum #j4bib #cgi4 ,method ,used at the ,riga ,station4--,in the method pursued at the experimental station at ,riga#bdc the organic matter in the fine earth is first destroyed by igniting twenty-five grams in a muffle4 ,the ignited residue is placed in a #bej cubic centimeter erlenmeyer and digested with #aej cubic centimeters of ten per cent hydrochloric acid4 ,the digestion is continued for forty-eight hours with frequent shaking4 ,the filtrate is evaporated to dryness in a porcelain dish to separate any dissolved silica4 ,the residue is taken up with dilute hot nitric acid1 filtered1 and the phosphoric acid precipitated with ammonium molybdate4 ,the final weighing is made as magnesium pyrophosphate1 following the usual procedure in respect of precipitation and washing4 ,experiments show that approximately ninety-five per cent of the phosphoric acid are obtained by one extraction and five per cent by a second1 conducted exactly as the first4 ,thoms draws the following conclusions from a long series of determinations3 7#a7 ,for the simple purpose of determining the need of a soil for phosphorus fertilizer a single extraction with ten per cent hydrochloric acid is sufficient4 ,the difference between the first and second extraction2 viz41 five to six per cent is too small to be of any value from a practical point of view4 7#b7 ,a soil which has been ignited until organic matter is destroyed gives up to the hydrochloric acid solvent about fourteen per cent more phosphoric acid than a non-ignited sample would4 7#c7 ,the mean temperature in the flask during extraction on a steam-bath is #gd4 #chj4 ,method of ,hilgard4#bdd--,the weighed quantity of soil 7usually from three to five grams7 is ignited in a platinum crucible1 care being taken to avoid all loss4 ,the loss of weight after full ignition gives the amount of chemically combined water and volatile and combustible matter4 ,the ignited soil is now removed to a porcelain or glass beaker1 treated with four or five times its bulk of strong nitric acid1 digested for two days1 evaporated to dryness1 first over the water-bath and then over the sand-bath1 moistened with nitric acid1 heated and treated with water4 ,after standing a few hours on the water-bath it is filtered and the filtrate is evaporated to a very small bulk 7ten cubic centimeters7 and treated with about twice its bulk of the usual ammonium molybdate solution1 thus precipitating the phosphoric acid4 ,after standing at least twelve hours1 first at a temperature of about #ej1 it is filtered and washed with a solution of ammonium nitrate acidified with nitric acid4 ,the washed precipitate is dissolved on the filter with dilute ammonia water4 ,after washing the filter carefully1 the ammoniacal solution is treated with magnesia mixture1 by which the phosphoric acid is precipitated4 ,after allowing it to stand twenty-four hours it is filtered1 washed in the usual way1 dried1 ignited1 and weighed as magnesium pyrophosphate1 from which the phosphoric acid is calculated4 ,when a gelatinous residue remains on the filter after dissolving the phosphomolybdate with ammonia it may consist either of silica not rendered fully insoluble in the first evaporation1 or1 more rarely1 of alumina containing phosphate4 ,it should be treated with strong nitric acid1 and the filtrate with ammonium molybdate2 any precipitate formed is1 of course1 added to the main quantity before precipitating with magnesia solution4 #cha4 ,separation of ,phosphoric ,acid ,from ,iron and ,alumina4--,the following methods are suggested by ,wolff#bde for the complete separation of the phosphoric acid from the iron and alumina in soil analysis1 where large quantities of these bases are found in solution3 #a4 ,after the separation of the greater part of the iron and alumina the phosphoric acid is precipitated from the solution in nitric acid by molybdic acid4 ,the process is carried on as follows3 ,the acid extract is heated in a flask to boiling and the iron oxid completely reduced by the gradual addition of small particles of sodium sulfite4 ,while still warm the free acid is neutralized with soda-lye1 and ammonia added until the ferrous hydroxid and the aluminum hydroxid are completely separated4 ,acetic acid is now added in excess and until about four-fifths of the whole precipitate have passed again into solution4 ,then1 after boiling for a moment1 the whole is quickly filtered through a large filter with a cover1 and the contents of the filter finally washed slightly4 ,all the phosphoric acid is thus obtained in combination with some alumina and a very little iron4 ,nearly the whole of the iron and the larger part of the alumina1 by this precipitation1 are found in the filtrate and therefore cannot disturb the estimation of phosphoric acid in succeeding portions4 ,the filter is now filled with boiling water and a little nitric acid added4 ,the precipitate is dissolved and received in a beaker4 ,the precipitation of the phosphoric acid is then accomplished by ammonium molybdate in the presence of nitric acid4 ,after twenty-four hours all the phosphoric acid is thus precipitated and the precipitate is free from iron4 #b4 ,by the method of ,schulze#bdf the iron is completely1 and the alumina1 with the exception of a small quantity1 separated1 and the precipitation of the phosphoric acid is accomplished either by the addition of a small quantity of tartaric acid and afterwards magnesium sulfate1 or directly by means of ammonium molybdate4 ,the principle of the separation depends on the fact that when the hydrochloric acid is nearly neutralized with soda or ammonia1 and the solution boiled after treatment with ammonium formate1 the greater part of the alumina remains in solution4 ,the precipitate is quickly filtered1 washed with hot water1 dried1 taken from the filter and fused in a silver crucible with pure caustic alkali1 either soda or potash4 ,on solution and boiling with water1 the iron is completely separated from the phosphoric acid1 and from the small quantity of the alumina present the precipitation of the phosphoric acid can now be accomplished1 either by saturation of the alkaline solution with hydrochloric acid and the direct addition of the magnesia solution after the addition of a little tartaric acid and ammonia1 or after the addition of nitric acid by ammonium molybdate4 #chb4 ,estimation of ,phosphoric ,acid in ,muck and ,peat ,soils4--,the amount of phosphoric acid obtained by extraction with hydrochloric or sulfuric acid is markedly less in these soils than that obtained after the incineration of the sample1 as pointed out by ,schmoeger4#bdg ,this is due to the fact that the phosphoric acid is ordinarily combined in the form of nuclein4 ,extraction of the soils with ether shows that it is not present in the form of lecithin4 ,the nuclein products1 as is well known1 are decomposed by heating in presence of a liquid at a high temperature for some time4 ,the heating can either take place in an autoclave or in sealed glass tubes4 ,the method is as follows3 ,the sample of soil is thoroughly rubbed up in a mortar with water1 and then hydrochloric acid added until one gram of the water-free peat is suspended in about ten cubic centimeters of twelve per cent hydrochloric acid4 ,the sample is placed in a glass or porcelain vessel in an autoclave and heated to #adj-afj for ten hours4 ,the phosphoric acid is then determined in the extract in the usual way4 ,the percentage of phosphoric acid determined in this way is found to correspond to the amount determined by the incineration of the substance4 ,the total phosphoric acid is determined in peats by the incineration of the sample and the estimation of the phosphoric acid in the ash4 ,the phosphoric acid soluble in hydrochloric acid solution is determined by extracting a sample of the soil with twelve per cent hydrochloric acid in the usual way4 ,the difference between this and the total is calculated as phosphoric acid in organic compounds4 ,or the total phosphoric acid is determined by treating the soil with twelve per cent hydrochloric acid1 in the proportion of one gram of soil to ten cubic centimeters of the acid1 and the solution is placed in an autoclave and heated for ten hours to #adj-afj1 as above described4 ,the phosphoric acid is then determined by the usual method4 ,the difference between the total phosphoric acid as thus determined and the phosphoric acid soluble in hydrochloric acid is calculated as phosphoric acid in organic compounds4 #chc4 ,method of ,goss4--,on account of the length of time required to determine the phosphoric acid in soils by the usual methods1 ,goss#bdh has proposed the following modification which in his hands has given satisfactory results3 ,weigh ten grams of the air-dried soil1 which has been sifted through a one millimeter mesh sieve1 and transfer to a pear-shaped1 straight necked1 kjeldahl digestion flask1 which has been marked to hold #bej cubic centimeters4 ,add approximately seven-tenths gram of yellow mercuric oxid and twenty to thirty cubic centimeters of concentrated sulfuric acid1 as for the determination of nitrogen4 ,twenty cubic centimeters of acid are nearly always sufficient1 but in the case of unusually finely divided clay soils containing little or no sand it is necessary to use thirty cubic centimeters to prevent caking of contents of flask4 ,in doubtful cases twenty cubic centimeters of acid should first be added and at the end of five or ten minutes1 if contents show a tendency to cake1 ten cubic centimeters more should be introduced4 ,thoroughly mix the contents of the flask by shaking1 place on a suitable support over a burner1 boil for one hour1 cool1 add about #ajj cubic centimeters of water1 five cubic centimeters of concentrated hydrochloric acid1 and two cubic centimeters of concentrated nitric acid1 boil gently for two minutes to oxidize iron1 cool1 make up to volume1 and filter through a dry folded paper until perfectly clear4 ,in order to secure a clear filtrate it will usually be found necessary to pour the first portion of the filtrate back through the paper three or four times4 ,transfer #ajj cubic centimeters of the filtrate to an ordinary flask of about #dej cubic centimeters capacity1 add strong ammonia until a permanent precipitate forms1 then six or eight cubic centimeters of nitric acid to dissolve the precipitate1 and boil until clear4 ,in the case of many soils it is not absolutely necessary to oxidize with hydrochloric and nitric acids1 as a clear solution can be secured at this point without further oxidation4 ,in the case of some soils1 however1 and especially in subsoils1 the solution cannot be cleared up even by prolonged boiling with nitric acid1 but if the solution have been previously oxidized1 a clear solution can be secured without any difficulty whatever4 ,remove the flask from the lamp and after two minutes add seventy-five cubic centimeters of molybdate solution1 place the unstoppered flask in an open water-bath kept at a temperature of #hj for fifteen minutes1 shaking vigorously four or five times while in the bath2 then remove1 let stand ten minutes to allow precipitate to settle1 filter through a nine centimeter filter avoiding too strong a pressure at first1 wash the flask and precipitate thoroughly with ammonium nitrate solution1 place the flask in which the precipitation was made under the funnel1 shut off pump and close all valves to filtering jar to form an air-cushion and prevent too rapid filtration1 fill paper two-thirds full of hot water1 add a few cubic centimeters of strong ammonia1 aid solution1 if necessary1 by stirring precipitate with a small glass rod4 ,as pointed out by ,hilgard1 aluminum is sometimes carried down with the phosphoric acid upon precipitating with molybdate solution1 in which case some of the phosphoric acid will not be dissolved in the treatment with ammonia4 ,this will be indicated1 first1 by the appearance of a white precipitate upon dissolving the yellow precipitate in ammonia2 and1 second1 by the difficulty experienced afterward in washing4 ,if such a precipitate be present in any appreciable quantity1 proceed as follows3 ,after washing out all the ammoniacal solution in the usual manner1 place a small beaker under the funnel1 close all valves1 fill the filter one-third full of hot water1 add the same amount of concentrated hydrochloric acid1 proceed as if dissolving phosphomolybdate in ammonia1 and receive final solution and washings in flask used4 ,as soon as the yellow precipitate is dissolved open the valve to filtering jar but do not turn on the pump2 after the solution has all passed through rinse the filter once with a small amount of hot water2 after the last portion has passed through remove the flask and place a ,no4 #a lipped beaker under the funnel and heat the solution in the flask to boiling4 ,if the solutions have not been oxidized1 a blue color is sometimes present upon dissolving the yellow precipitate in ammonia4 ,this can be discharged by boiling the ammoniacal solution for a minute or two and shaking at the same time4 ,again pour the solution through the filter1 avoiding use of pump at first1 otherwise loss from spattering is likely to ensue1 wash out flask and filter with a small amount of hot water1 7the total filtrate should not exceed fifty cubic centimeters71 add hydrochloric acid to contents of beaker while hot1 until yellow color appears1 then add a few drops of ammonia until solution clears1 cool1 add fifty cubic centimeters of filtered magnesia mixture from a burette1 a drop at a time with constant stirring1 let stand fifteen minutes1 add twenty cubic centimeters of strong ammonia specific gravity nine-tenths1 let stand over night1 filter1 wash precipitate with dilute ammonia1 dry1 ignite intensely over blast-lamp for ten minutes1 cool in desiccator and weigh ,mg,p,o secured4 ,time of ,digestion4--,experience has shown that very little phosphoric acid is extracted from the sample by digestion with sulfuric acid after the first thirty minutes4 ,time ,required to ,precipitate ,phosphomolybdate4-- ,when the yellow precipitate is obtained according to the method of ,goss practically the whole of it will be thrown down in five minutes4 ,agreement with ,standard ,methods4--,comparative tests of the ,goss method against standard methods have shown that it gives almost identical results with them4 ,the variations were never more than #j4jb to #j4jc per cent4 ,while this method has not been sufficiently tried to receive unconditional recommendation it possesses merits which entitle it to the attention of analysts4 #chd4 ,estimation of the ,sulfuric ,acid4--,sulfuric acid is generally present in small proportions in soils4 ,since the plants have need of sulfur it is proper to inquire into the presence of the compound which is its principal source4 ,it is in combination with lime that sulfuric acid exists almost always4 ,in addition to this there is also some sulfur combined with the organic matter of the soil4 ,by digesting a soil for six hours with hot1 concentrated nitric acid the sulfates are dissolved1 and there is transformed into sulfuric acid an important part of the sulfur which is combined with the humic substances4 ,the quantity of soil to be operated upon should be about fifty grams4 ,after filtering and washing with hot water the filtered liquor is collected1 in the ,french ,commission method1#bdi in a flask and carried to boiling1 and five cubic centimeters of a saturated solution of barium chlorid or sufficient to be in slight excess are added4 ,the boiling is continued for some minutes and the flask is allowed to stand for twenty-four hours4 ,the filtrate is received upon a filter and washed with boiling water4 ,the filter is dried and incinerated1 allowed to cool1 and as there may have been a slight reduction of the sulfate a few drops of nitric acid are added and a drop of sulfuric acid4 ,it is now evaporated to dryness on a water-bath1 heated to redness for a few moments1 cooled and weighed4 ,the weight of the barium sulfate obtained multiplied by #j4cdcc1 gives the quantity of sulfuric acid obtained from the fifty grams of soil4 ,if it is desired to estimate only the sulfur which exists in the form of sulfate it is necessary to treat the soil with hydrochloric acid in a very dilute state1 heating for a few moments only and afterwards precipitate by barium nitrate4 ,if1 on the other hand1 it is desired to estimate the total sulfur which is sometimes of great interest1 it is necessary to employ the process of ,berthelot and ,andr4 #che4 ,method of ,berthelot and ,andr4--,sulfur may exist in the soil in three forms2 viz41 #a4 ,mineral compounds1 consisting generally of sulfates and sometimes of sulfids4 #b4 ,sulfur1 existing in ethereal compounds or their analogues1 as in urine4 #c4 ,organic compounds containing sulfur4 ,estimation of ,total ,sulfur4--,the principle on which this operation1 as described by ,berthelot and ,andr1 rests is that already described for phosphorus2 viz41 oxidation in a current of oxygen and passing the vapors over a column of alkaline carbonate at or near a red heat4#bej ,the ordinary methods of oxidation in the wet way give generally inexact results4 ,estimation of ,sulfur ,pre-existing as ,sulfates4--,the sample is treated with cold1 dilute hydrochloric acid4 ,the filtrate is treated with barium chlorid1 the precipitate collected1 dried1 ignited1 washed with a mixture of sulfuric and hydrofluoric acids to remove silica1 and afterwards weighed as barium sulfate4 ,estimation of ,sulfur as ,sulfids4--,the sample is distilled with dilute hydrochloric acid1 and the hydrogen sulfid produced is made to pass through an acidulated solution of copper sulfate in such a way as to transform the sulfur in the hydrogen sulfid into a sulfid1 which is afterwards collected and weighed in the usual way4 ,the use of a titrated solution of iodin is not advisable on account of the organic matter which may be present4 ,estimation of ,sulfur in ,ethereal ,compounds4--,these compounds can be decomposed by boiling with a solution of potash or concentrated hydrochloric acid4 ,the resulting sulfuric acid is precipitated with barium chlorid4 ,subtract from the sulfates thus obtained those pre-existing as sulfates2 the difference represents the sulfur present in ethers4 ,estimation of ,sulfur in ,other ,organic ,compounds4--,this is estimated indirectly by subtracting from the total sulfur that present as sulfates1 sulfids1 and ethers4 #chf4 ,method of ,von ,bemmeln4--,as ,von ,bemmeln#bea observes1 the estimation of sulfuric acid in soils presents a number of difficulties4 ,a small part of it can be present as sulfate insoluble in water4 ,in addition to this1 there is always some sulfur in the organic bodies present4 ,if the soil is extracted with water then the sulfuric acid can be estimated therein when only a trace of humus substance has gone into solution4 ,on the contrary1 if there is much humus substance in solution1 and also iron oxid1 as is the case when the extraction is made with hydrochloric acid1 then both of these must be removed1 otherwise the estimation is very inexact4 ,by fusing the residue of the solution with sodium carbonate and a little potassium nitrate the organic substance is destroyed1 and after treatment with water the iron oxid is separated4 ,if any sulfur has been dissolved in the organic substance present1 this is then oxidized to sulfuric acid4 ,the estimation of the sulfuric acid and of the sulfur1 therefore1 remains unsatisfactory4 ,in a sample of clay from ,java1 which was rich in calcium carbonate1 but which contained no basic iron sulfate1 there was found the following percentages of sulfuric acid3 ,exhausted in the cold with very weak hydrochloric acid1 #j4jd per cent2 the residue treated in the cold with concentrated hydrochloric acid1 the solution evaporated and fused with sodium carbonate and potassium nitrate1 #j4jg per cent2 again1 the residue treated with aqua regia to oxidize the sulfur1 the solution evaporated to dryness1 fused with sodium carbonate and potassium nitrate1 #j4ad per cent2 in all #j4be percent4 ,a sample of the same soil treated directly with aqua regia1 and then evaporated and fused as above1 gave two-tenths per cent sulfuric acid4 ,a sample of the same soil ignited in a crucible with sodium carbonate and potassium nitrate gave #j4af per cent of sulfuric acid4 ,the difference between #j4jd and #j4jg per cent can be attributed to the sulfur in the organic substance which was dissolved by the concentrated hydrochloric acid2 the quantity1 however1 is too small to draw any safe conclusion4 ,possibly it might have been that the very dilute hydrochloric acid did not dissolve all of the sulfate4 ,the quantity of sulfur combined in the organic substance in the above soil may be derived from the following equation2 viz41 7#j4b-j4jg7_/7hj7 #cb #j4je per cent of sulfur4 ,the estimation of the sulfur in a sample of soil from ,deli was carried on with still greater exactness by three different methods4 ,the quantities of hydrochloric acid1 nitric acid1 and sodium carbonate employed were measured or weighed1 and the minute content of sulfuric acid therein estimated and subtracted from the final results4 ,the methods employed were as follows3 7,a7 ,extraction with water and afterwards with very dilute hydrochloric acid4 7,b7 ,extraction with cold hydrochloric acid1 one part to three of water4 7,c7 ,extraction with aqua regia4 7,d7 ,ignition with sodium carbonate and potassium nitrate4 7,f7 ,ignition in a combustion tube with sodium carbonate in a stream of oxygen4 ,the percentages of sulfuric acid obtained by the different methods were as follows3 7,a7 #j4jeh per cent4 7,b7 #j4jgj 7,c7 #j4adj 7,d7 #j4abe 7,f7 #j4ajf #chg4 ,method of ,wolff4--,in regard to the sulfuric acid ,wolff calls attention to the fact that in soils which have been ignited1 a larger quantity of this acid is found than in soils containing humus4#beb ,this1 doubtless1 arises from the oxidation of the organic sulfur4 ,the following special method for determining the sulfuric acid is therefore proposed3 ,fifty grams of fresh air-dried soil are placed in a platinum dish with a concentrated solution of pure sodium nitrate4 ,after drying1 the heat is raised gradually to redness4 ,in this way the complete ignition of the humus present takes place4 ,after cooling1 the mass is diluted with hydrochloric acid1 with the addition of a little nitric acid1 and boiled4 ,in the solution1 the silicic acid is first separated and the sulfuric acid estimated in the usual way with barium sulfate4 #chh4 ,method of the ,italian ,chemists4--,the determination of the sulfuric acid is conducted as follows by the ,italian chemists3#bec ,the soil is completely extracted by diluted hydrochloric acid and the sulfuric acid precipitated in the solution with barium chlorid4 ,if a soil is very rich in calcium sulfate it should first be treated with a warm solution of sodium carbonate to decompose the calcium sulfate1 and the sulfuric acid determined in the solution after having added hydrochloric acid4 #chi4 ,estimation of the ,chlorin4--,the estimation of the chlorin is of great importance in certain cases4 ,when this element is lacking in the soil1 which1 however1 is rare1 certain plants appear to suffer from its absence4 ,the quality of the forage plants in particular is influenced by it2 but when the chlorids are too abundant1 which is a frequent case1 they prevent or arrest completely the progress of vegetation4 ,salty soils are1 in general1 completely sterile4 ,in the proportion of one pound in a thousand in the earth1 sodium chlorid is to be regarded as injurious4 ,it is necessary1 therefore1 in analysis to take account of two cases2 viz41 those of soils poor in chlorids and those of soils rich in chlorids4 ,for soils poor in chlorids the ,french method directs that#bed #bjj grams of the earth are to be washed on a filter with boiling water4 ,the liquor is evaporated to dryness and gently heated to a temperature inferior to redness in order to destroy the organic matter4 ,the residue is taken up by small quantities of water and to the filtered liquor the volume of which should not exceed forty to fifty cubic centimeters are added ten cubic centimeters of pure nitric acid and a sufficient quantity of silver nitrate to produce a complete precipitation4 ,the precipitate is vigorously shaken and allowed to stand for a few hours in a darkened locality4 ,the precipitate is collected upon a double filter and the silver chlorid1 after proper desiccation1 is weighed4 ,when the soil is rich in chlorids it is washed as has just been described upon a filter4 ,the wash-waters are made up to one liter and fifty cubic centimeters1 equivalent to ten grams of the soil1 are taken for analysis4 ,this quantity is treated exactly as described above4 #cij4 ,wolff's ,method of ,estimating ,chlorin in ,soils4#bee--,three hundred grams of the soil are treated with #ijj cubic centimeters of pure water containing a little nitric acid for forty-eight hours with frequent shaking4 ,four hundred and fifty cubic centimeters are then filtered and the clear liquid evaporated to #bjj cubic centimeters4 ,the chlorin is then precipitated with silver nitrate4 ,the quantity obtained1 corresponds to that found in #aej grams of the air-dried soil4 ,a second method1 ,mohr's1 is as follows3 ,fifty grams of the soil are placed in a platinum dish and moistened with a concentrated solution of potassium nitrate1 free from chlorin4 ,the mass is evaporated to dryness and gradually heated to a red heat4 ,after cooling it is moistened with water and washed into a beaker and the solid mass quickly separated4 ,the clear liquid is poured off and the residue again washed with water4 ,the clear liquid obtained is saturated with acetic acid1 carefully evaporated to dryness and after solution in water1 filtration and the addition of a little nitric acid1 the chlorin therein is precipitated by a silver nitrate solution1 and the precipitate collected and weighed as usual4 #cia4 ,method of ,petermann4#bef--;,chlorin in the soil is estimated at the ,gembloux station by digesting #a1jjj grams of the sample with two liters of distilled water with frequent shaking for thirty-six hours4 ,after allowing to stand for twelve hours with the addition of one gram of powdered magnesium sulfate to facilitate the deposition of suspended matter one liter of liquid is siphoned and evaporated in a platinum dish with the addition of a few drops of a solution of potassium carbonate free from chlorin and nitric acid4 ,the concentrated solution is filtered1 washed1 and made up to #bej cubic centimeters4 ,take #ajj cubic centimeters of the solution add some nitric acid and precipitate the chlorin with silver nitrate4 ,the rest of the solution is reserved for the estimation of nitrate4 #cib4 ,estimation of ,silicic ,acid4--,direct ,estimation4--,the sample of soil in the method of ,berthelot and ,andr#beg is mixed with two or three times its weight of pure sodium carbonate and fused in a silver crucible until complete decomposition has taken place4 ,the residue is dissolved in water and dilute hydrochloric acid4 ,the silicates are decomposed by this treatment and the solution is evaporated to dryness on the water-bath1 and when dry slightly heated4 ,the silicic acid 7silica7 is by this treatment rendered insoluble4 ,it is collected on a filter1 washed1 ignited1 and weighed4 ,the resulting compound should be mixed with ammonium fluorid and sulfuric acid1 and after the disappearance of the silica the residue should be dried and weighed4 ,the loss in weight represents the true silica4 ,the loss in weight should be corrected by calculating the sulfates of the alkalies back to oxids4 ,this correction can be neglected when the work has been carefully done1 and the washing of the original silica has been well performed4 ,indirect ,estimation4--,the total silica may be estimated indirectly by subtracting from the total weight of the sample the sum of the weights of the other constituents resulting from the separate estimation of each of them after decomposing the sample with hydrofluoric acid4 #cic4 ,simultaneous ,estimation of ,different ,elements4--,the operations and processes for the estimation of each of the elements have been described1 but it is often best to carry on an operation in such a way as to gain time by making a single decomposition upon a quantity of soil of some considerable magnitude1 and using the results of the solution for the determination of the different substances4 ,from the operations already described it will be easy to make a combination of methods by which all or nearly all the important constituents in a soil may be determined in a single sample4 ,of the various methods proposed1 that of the commission of the ,french agricultural chemists may be taken as a type4#beh ,in the case of the estimation of lime1 potash1 magnesia1 and sulfuric acid1 in which the operation is carried on in a soil which is not incinerated1 time may be saved by digesting a considerable quantity of the soil with concentrated nitric acid for a period of five hours4 ,it is best to take #ajj grams of the soil and increase proportionally the nitric acid4 ,the filtrate1 after washing1 is made up to one liter and thoroughly shaken4 ,from this amount of liquid1 portions are taken corresponding to the weights of soil upon which the operation for the determination of each of the constituents would be conducted4 ,for example1 for the estimation of lime in the case of a very calcareous earth1 ten cubic centimeters representing one gram of the original sample1 in the case of a soil poor in carbonates #ajj cubic centimeters representing ten grams1 and for the estimation of potash1 magnesia1 and sulfuric acid #bjj cubic centimeters1 representing twenty grams of the soil1 should be taken4 ,this method avoids frequent weighings of the earth and separate treatments thereof by the acid4 ,on the other hand1 in the same portion of the solution1 the different elements can be estimated4 ,for example1 for the estimation of the potash as has been indicated1 in the place of precipitating as a whole the sulfuric acid1 lime1 etc41 and of afterwards separating the magnesia in the sole aim of eliminating these bodies1 they can be collected separately and weighed1 thus securing at a single operation several determinations4 ,at the end1 some barium chlorid is added and if the barium sulfate is then collected and weighed1 the estimation of the sulfuric acid is effected4 ,to the filtrate there are afterwards added some ammonia and ammonium carbonate to precipitate1 at once1 the excess of barium and the iron and aluminum oxids1 the lime and the phosphoric acid4 ,this separation being effected the filtrate contains still the magnesia and the alkalies4 ,the first can be separated by carbonation by means of oxalic acid1 collected1 and weighed4 ,finally the potash itself can be estimated in the state of perchlorate4 ,it has thus been possible in the same suite of operations to estimate in a given quantity of the liquid1 the sulfuric acid1 the magnesia1 the lime1 and the potash4 #cid4 ,estimation of ,kaolin in ,soils4--,true kaolin is a hydrated aluminum silicate1 having the formula ,h,al,si,o4 ,this substance is1 even in concentrated hydrochloric acid1 almost completely insoluble4 ,it contains1 theoretically1 #ac4id per cent of water of combination4 ,the following methods1 due to ,sachsse and ,becker1#bei can be used for its determination4 ,estimation of the ,water of ,combination4--,heat from one to two grams of kaolin1 dried at #ajj1 for half an hour in a covered platinum crucible to a temperature which shows an incipient red heat when the crucible is partly protected from the daylight with the hand4 ,this treatment does not quite give the whole of the water of combination but nearly all of it4 ,a kaolin is changed by this treatment into a substance which is easily soluble in dilute hydrochloric acid4 ,estimation of the ,kaolin in ,impure ,kaolins4--,mineral kaolin1 or the kaolin obtained by silt analysis1 is dried at #ajj to constant weight4 ,it is then heated with strong hydrochloric acid until all the matters which will pass into solution have been dissolved4 ,the residual kaolin is then washed thoroughly with water and ignited for half an hour at a low red heat4 ,the residual mass is a second time extracted with hydrochloric acid until silica no longer passes into solution4 ,the soluble silica is then estimated in the usual way and calculated to kaolin4 ,the result will give the pure kaolin in the sample examined4 ,the estimation may also be made as follows3 ,two samples of the impure kaolin are taken and dried to constant weight at #ajj4 ,one is extracted with hydrochloric acid in the manner described above and the amount of silica determined4 ,the second is treated directly by ignition to low redness for half an hour1 dissolved in hydrochloric acid and the amount of silica determined4 ,the difference in the two percentages of silica corresponds to the silica equivalent to the pure kaolin4 ,statement of ,results4--,it is convenient to incorporate the data obtained by the above methods with the complete mass analysis of the silicate examined4 ,in the sample given below the analysis was made on a clay silt obtained with a velocity of two-tenths millimeter per second4 ,the mass analysis gave the following data3 ,loss on ignition #aj4jd ,si,o #ea4eb ,al,o #ag4ic ,fe,o #g4db ,ca,o #a4eg ,mg,o #f4bg ,k,o #d4a ,na,o #a4fa ,the loss on ignition was made up of the combined water and a trace of humus4 ,on gentle ignition only #g4eb per cent of water came off4 ,the examination of the non-ignited and the gently ignited silica by means of dilute hydrochloric acid1 gave the following data3 ,non-ignited4 ,gently ignited4 ,difference4 ,water #aj4jd #aj4jd ,insoluble residue #dj4 #cd4ed -#e4df ,al,o #i4jd #aj4 #j4if ,fe,o #e4if #g4bg #a4ca ,si,o #be4bg #bh4 #b4gc ,alkalies and alkaline earths #i4fi #aj4ae #j4df ,by a comparison of these data with those obtained by the mass analysis1 the following representation of the distribution of the various components in the clay is obtained3 #bc4eb per cent ,si,o in the form of quartz and undecomposed silicates4 #b4gc per cent ,si,o in the form of kaolin4 #be4bg per cent in the form of easily decomposable silicates and of the hydrates of ,si,o4 #g4ic per cent ,al,o in the form of undecomposed silicates4 #j4if per cent ,al,o in the form of kaolin4 #i4jd per cent ,al,o in the form of easily decomposed silicates and of hydrates4 #j4ae per cent ,fe,o in the form of undecomposed silicates4 #a4ca per cent ,fe,o in the form of kaolin4 #e4if per cent ,fe,o in the form of easily decomposable silicates and hydrates4 #c4dj per cent of alkalies and alkaline earths in the form of undecomposed silicates4 #i4fi per cent of alkalies and alkaline earths in the form of easily decomposable silicates4 #aj4jd per cent of water1 including a trace of humus4 ,collecting these results the following statement is obtained4 ,the clay analyzed contained3 #aj4jd per cent of water1 a trace of humus4 #ce4ae per cent of undecomposed silicates and quartz4 #e4jj per cent of kaolin4 #ej4bg per cent of easily decomposable silicates1 hydrates of ,si,o and hydroxids4 ,,estimation ,,of ,,nitrogen ,,in ,,soils4 #cie4 ,introductory ,considerations4--,the great economic and biologic value of nitrogen as a plant food renders its estimation in soils of especial importance4 ,it is necessary1 first of all1 to remember that the nitrogen present in soils may be found in three forms2 viz41 first1 in organic compounds1 second1 as ammonia1 and third1 as nitric or nitrous acid4 ,further than this each of these classes of nitrogen may be subdivided4 ,the organic nitrogen may be in a form easily nitrified and rendered available for plant food1 or it may be inert and resistant to nitrification1 as in humus1 or exist in an amid state4 ,the ammoniacal nitrogen may exist in small quantities as gaseous ammonia1 or be combined with mineral or organic acids4 ,as nitric or nitrous acid the nitrogen will be found combined with bases1 or perhaps in minute quantities as free acid1 in passing under the influence of the nitrifying ferment from the organic to the inorganic state4 ,to the latter state it must finally come before it is suited to absorption by plants4 ,in general1 far the largest part of soil nitrogen1 excluding the atmosphere diffused in the pores of the soil1 is found in the organic state and is derived from the dbris of animal and vegetable life and from added fertilizers4 ,as ammonia1 the nitrogen can only be regarded as in a transition state1 arising from the processes of decay1 or incomplete nitrification4 ,as nitric acid1 it is found as a completed product of nitrification1 or as the result of electrical action4 ,the processes of nitrification and the isolation and determination of the nitrifying organisms will be considered in a special chapter of this manual4 ,by reason of the great solubility of the nitrates1 and the inability of the soil to retain them1 there can never be a great accumulation of nitric acid in the soil save in localities deficient in rain-fall or in specially protected spots1 such as caves4 ,the nitric acid1 therefore1 produced in the soil passes at once into growing vegetation1 or is found eventually in the drainage waters4 ,the formation of ammonia in soil containing much vegetable matter is thought by ,berthelot and ,andr#bfj to be due to the progressive decomposition of amid principles under the influence of dilute acids or alkalies1 either in the cold or at an elevated temperature4 ,soils of the above description1 of themselves1 contain neither free ammonia nor ammoniacal salts1 and the ammonia which is found in the analysis of these soils comes from the reaction above indicated4 ,the ammonia which comes from these soils1 in place of what is given off to the surrounding atmosphere1 comes from the same class of decompositions1 and these decompositions1 in this case1 are effected by the water itself1 and by the alkaline carbonates of the soil4 ,the amid principles which are thus decomposed belong either to the class of amids proper1 derived by the displacement of hydrogen in ammonia by acids1 or to the class of alkalamids derived from nitrogenous bases1 both volatile and fixed4 ,among these alkalamids some are soluble in water and some insoluble1 and the decomposition of these last by acids or by alkalies may furnish bodies which themselves are either soluble or insoluble in water4 ,to determine the nature of the nitrogenous principles in a soil rather rich in humus1 ,berthelot and ,andr applied the following treatment3 ,a soil containing #ai4a grams of carbon and #a4fg grams of nitrogen per kilogram was first subjected to treatment1 at room temperature1 with a concentrated solution of potash4 ,by this treatment #ag4d per cent of the nitrogen content was set free under the form of ammonia4 ,one-quarter of this was obtained during the first three days2 one-eighth during the next three days4 ,afterward the action became much more feeble and was continued during forty days longer1 and the evolution of the gas was diminished almost proportionately to the time4 ,it appears from the above observations that the amid principles of the soil1 decomposable by potash1 belong to two distinct groups1 which are broken up with very unequal velocities4 ,the soil1 treated on the water-bath for three hours at #ajj with strong potash1 showed the following behavior in respect of its nitrogenous constituents3 ,nitrogen eliminated in the form of ammonia1 sixteen per cent2 nitrogen remaining in the part soluble in potash1 ten per cent2 nitrogen remaining in the part insoluble in potash1 seventy-four per cent4 ,treatment with ,acid4--,the nitrogenous compounds of the soil are also decomposed by dilute acids1 and often more rapidly than by the alkalies4 ,the method of treatment is substantially the same as that set forth above4 ,the decompositions effected either by alkalies or by acids tend in general to lower the molecular weights of the resulting products4 ,the prolonged action of alkalies at the temperature of boiling water rendered soluble1 after twenty-four hours of treatment1 #ic4f per cent of the organic nitrogen found in the vegetable mould4 ,by treating the earth successively with alkalies and acids #ie4e per cent of the total nitrogen were decomposed4 ,these experiments show how the insoluble nitrogen in humic compounds can be gradually rendered assimilable4 ,the action of vegetables is not assuredly identical with those which acids and alkalies exercise4 ,however1 both present certain degrees of comparison from the point of view of the mechanisms set in play by the earthy carbonates and carbon dioxid1 as well as by the acids formed by vegetation4 ,the reactions which take place naturally1 while they are not so violent as those produced in the laboratory1 make up by their duration what they lack in intensity4 ,for a more detailed study of the nature of the nitrogenous elements in soil the following method of treatment1 due to ,berthelot and ,andr1 is recommended3 ,treatment of the ,soil with ,alkalies4--#a4 ,reaction with cold1 dilute solution of potash4 ,take fifty grams of the sample1 dried at #aaj1 and mix with a large excess of ten per cent potash solution and place under a bell-jar containing standard sulfuric acid4 ,the mixture is left for a long time in order to secure as fully as possible the ammonia set free4 ,example3 ,fifty grams of a soil contained #j4jhad gram of nitrogen4 ,treated as above it gave the following quantities of nitrogen as ammonia3 ,nitrogen as ,ammonia4 ,after #c days #j4jjcd gram4 #f #j4jjed #aa #j4jjfe #ag #j4jjgh #be #j4jjic #da #j4jajg #df #j4jada ,it is seen that the action still continued after forty days4 ,in the space of forty days #ag4d per cent of the total nitrogen contained in the soil had been converted into ammonia by dilute potash4 ,according to the above observations the amid principles transformed into ammonia under the influence of dilute potash1 exist in groups which are acted on with very unequal rapidity4 #b4 ,reaction with hot dilute solution of potash4 ,take #bjj grams of the soil sample1 mix with one and one-half liters of dilute potash solution containing fifty grams of potash4 ,place in a flask and heat on boiling water-bath for six hours4 ,the flask is furnished with a stopper and tubes1 and a current of pure hydrogen is made to pass through the liquid1 having the double object of preventing any oxidizing effect from the air and of carrying away the ammonia which may be formed4 ,the escaping hydrogen and ammonia are passed into a bulb apparatus containing titrated sulfuric acid4 ,the sample of soil employed contained in #bjj grams1 #j4cbef gram of nitrogen4 ,there was obtained at the end of six hours' heating1 #j4jcff gram of nitrogen4 ,in other words1 #aa4bd per cent of the total nitrogen in the sample appeared as ammonia4 ,examination of ,residue4--,after the separation of the ammonia as above described1 pour the residue in the flask on a filter1 wash with hot water1 and determine nitrogen in filtrate and in solid matter on the filter by combustion with soda-lime4 ,the filtrate is1 of course1 first evaporated to dryness after being neutralized with sulfuric acid4 ,the insoluble part contained #j4jda gram of nitrogen1 i4 e41 #ab4hd per cent of the entire amount4 ,the soluble part contained #j4bdaa gram of nitrogen1 i4 e41 #gd4je per cent of the whole4 ,summary of ,data4--,in the sample analyzed the following data were obtained3 ,of the whole4 ,nitrogen as ammonia #aa4bd per cent4 in insoluble part #ab4hd soluble part #gd4je not determined #a4hg ------------ ,sum #ajj4jj ,the same experiment in which the heating on the water-bath was continued for thirteen hours gave the following data3 ,of the whole4 ,nitrogen as ammonia #af4jc per cent4 in insoluble part #i4ih soluble part #gd4ja ------------ ,sum #ajj4jj ,further ,treatment of ,matter ,insoluble in ,hot ,dilute ,potash4--,a portion of the insoluble portion from the last experiment was treated for thirteen hours longer under the same conditions with dilute hot potash4 ,the soluble and insoluble portions were determined as already described4 ,of the nitrogen insoluble after thirteen hours1 #fd4ba per cent remained insoluble after the second thirteen hours4 ,this fact shows that slow and progressive decomposition of the alkalamids in the soil occurs under the influence of hot dilute potash4 ,treatment of ,matter ,insoluble in ,hot ,dilute ,potash with ,hydrochloric ,acid4--,a part of the material insoluble in hot potash after thirteen hours is mixed with dilute hydrochloric acid1 in such proportion as to have one-fifth the weight of pure hydrochloric acid to the dry solid matter4 ,heat in flask on a boiling water-bath for thirteen hours4 ,determine the nitrogen in the insoluble residue4 ,example3 ,in the case given it was found that #ed4ia per cent of the nitrogen insoluble in dilute hot potash were dissolved by the hot hydrochloric acid4 ,this fact shows that insoluble nitrogen compounds contained in the soil are dissolved by dilute acids even more readily than by dilute alkalies at the temperature of boiling water4 ,several reactions appear to take place simultaneously when potash is brought into contact with the nitrogenous principles of arable earth4 ,some of these principles1 during the first period of the action become soluble and even form compounds which are not precipitable by acids4 ,when1 however1 the action of the potash is prolonged1 the dissolved bodies lose little by little a part of their nitrogen as ammonia or as soluble alkalamids4 ,they become thus changed either to compounds no longer soluble in the potash1 or to those insoluble in the solution when acidified4 ,these compounds1 it is true1 contain nitrogen1 but are poorer in this element and have a higher molecular weight1 or1 in other words1 are condensation products4 ,these last principles are not absolutely stable in the presence of potash1 but are decomposed much more slowly than the original principles from which they were derived4 ,in general1 it may be said that under the influence of alkalies on the nitrogenous principles of the soil there is a tendency to form two classes of bodies1 the one more soluble with a lower molecular weight1 the other less soluble with a higher molecular weight4 ,the inverse relation between solubility and condensation is in agreement with what is observed in similar reactions with organic bodies in general4 ,it certainly plays an important rle in the transformations which an arable soil undergoes1 either through the mild influences of the air and natural waters1 or the more energetic action of vegetables themselves4 ,the methods of estimating nitric nitrogen will be made the theme of a special study in connection with the chapter on nitrification4 ,there will be considered first1 therefore1 the methods of determining organic and ammoniacal nitrogen with only such incidental treatment of the methods for nitric nitrogen as the processes applicable to the other forms may contain4 #cif4 ,provisional ,methods of the ,association of ,official ,agricultural ,chemists4#bfa--,the nitrogen compounds in the soil are usually placed in three classes4 #a4 ,the nitrogen combined with oxygen as nitrates1 or nitrites1 existing as soluble salts in the soil4 #b4 ,the nitrogen combined with hydrogen as ammonia1 or organic nitrogen easily convertible into ammonia4 ,the ammonia may exist as salts1 or may be occluded by hydrated ferric or aluminum oxids and organic matter in the soil4 #c4 ,the inert nitrogen of the soil or the humus nitrogen4 ,active ,soil ,nitrogen4--,the material proposed for reducing the nitrates to ammonia1 and at the same time to bring ammonia salts and organic nitrogen into a condition for separation by distillation1 is sodium amalgam4 ,liquid sodium amalgam may be readily prepared by placing #ajj cubic centimeters of mercury in a flask of half a liter capacity1 covering the warmed mercury with melted paraffin1 and dropping into the flask at short intervals pieces of metallic sodium1 the size of a large pea 7taking care that the violence of the reaction does not project the contents from the flask71 till #f4ge grams of sodium have combined with the mercury4 ,the amalgam contains one-half per cent of sodium and may be preserved indefinitely under the covering of paraffin4 ,to estimate the active soil nitrogen1 weigh fifty grams of air-dried soil and place it in a clean mortar4 ,take #bjj cubic centimeters of ammonia-free distilled water1 rub up the soil with a part of the water to a smooth paste1 transfer this to a flask of one liter capacity1 washing the last traces of the soil into the flask with the rest of the water4 ,add twenty-five cubic centimeters of the liquid sodium amalgam and shake the flask so as to break the sodium amalgam into small globules distributed through the soil4 ,insert a stopper with a valve and set aside in a cool place for twenty-four hours4 ,pour into the flask fifty cubic centimeters of milk of lime1 and distill1 on a sand-bath1 #ajj cubic centimeters into a flask containing twenty cubic centimeters of decinormal sulfuric acid1 and titrate with decinormal soda solution1 using dimethyl-orange as indicator4 ,estimate the nitrogen of the ammonia found as active soil nitrogen4 ,if the ammonia produced is too small in amount to be readily estimated volumetrically1 determine the ammonia by nesslerizing the distillate4 ,estimation of ,nitrates in the ,soil4--,when it is desired to estimate separately the nitrates in the soil the following method may be used3 ,evaporate #ajj cubic centimeters of the soil extract to dryness on the water-bath1 dissolve the soluble portion1 of the residue in #ajj cubic centimeters of ammonia-free distilled water1 filtering out any insoluble residue1 place the solution in a flask and add ten cubic centimeters of liquid sodium amalgam1 insert stopper with valve1 set it aside to digest in a cool place for twenty-four hours1 add fifty cubic centimeters of milk of lime1 distill and titrate as above1 and estimate the nitrogen as ,n,o4 ,nesslerizing may be substituted for titration when the amount of nitrates is small4 ,an approximate estimation of the amount of nitrates will be of value in determining which method of estimation to use4 ,this may be done by evaporating a measured quantity of the soil extract1 say five cubic centimeters1 on a porcelain crucible cover on a steam-bath or radiator1 having first dissolved a minute fragment of pure brucin sulfate in the soil extract4 ,when dry pour over the residue concentrated sulfuric acid1 free from nitrates1 and observe the color reactions produced4 ,if the nitrate 7reckoned as ,,kno7 left upon evaporating the quantity of water taken does not exceed the two-thousandth part of a milligram1 only a pink color will be developed by adding the sulfuric acid2 with the three-thousandth part of a milligram1 a pink with faint reddish lines2 with the four-thousandth part1 a reddish color2 with the five-thousandth part1 a red color4 ,by increasing or diminishing the amount of soil extract evaporated to secure a color reaction of a certain intensity1 an approximate estimate may be made of the amount of nitrates present4 ,blank experiments to test the acid and the brucin sulfate will be required before confidence can be placed in such estimations4 ,total ,nitrogen of ,soils4--,the total nitrogen of soils may be determined by the usual combustion with soda-lime1 but this process is often unsatisfactory because of the large amount of material required when the organic matter or humus is small in amount4 ,a modification of the kjeldahl method is more easy to carry out and gives results equally satisfactory4 ,place twenty grams of soil in a kjeldahl flask1 and add twenty cubic centimeters of sulfuric acid 7free from ammonia7 holding in solution one gram of salicylic acid4 ,if the soil contain much lime or magnesia in the form of carbonate1 enough more sulfuric acid must be added to secure a strongly acid condition of the contents of the flask4 ,add gradually two grams of zinc dust1 shaking the contents of the flask to secure intimate mixture4 ,place the flask in a sand-bath and heat till the acid boils1 and maintain the boiling for ten minutes4 ,add one gram of mercury and continue the boiling for one hour1 adding ten cubic centimeters of sulfuric acid if the contents of the flask are likely to become solid4 ,cool the flask and wash out the soluble materials with #bjj cubic centimeters of pure water1 leaving the heavy earthy materials4 ,rinse the residue with #ajj cubic centimeters of water1 and add this to the first washings4 ,place this soluble acid extract in a liter digestion flask1 add thirty-five cubic centimeters of a solution of potassium sulfid1 and shake the flask to secure intimate mixture of the contents4 ,introduce a few fragments of granulated zinc1 pour in seventy-five cubic centimeters of a saturated solution of caustic soda1 connect the flask with a condenser and distill #aej cubic centimeters into a flask containing twenty cubic centimeters of acid1 using the same acid and alkali for titration used in the kjeldahl method under fertilizers4 ,enter the nitrogen found in this operation as total soil nitrogen4 ,the difference between the total soil nitrogen and the active soil nitrogen will express the inert nitrogen of the soil4 #cig4 ,hilgard's ,method4#bfb--,the humus determination will1 in the case of virgin soils1 usually indicate approximately the store of nitrogen in the soil1 which must be gradually made available by nitrification4 ,ordinarily 7outside of the arid regions7 the determination of ammonia and nitrates present in the soil is of little interest for general purposes1 since these factors will vary with the season and from day to day4 ,kedzie proposes to estimate the active soil nitrogen 7ammonia plus nitrates and nitrites7 by treatment of the whole soil with sodium amalgam and distillation with lime4 ,the objection to this process is that the formation of ammonia by the reaction of the alkali and lime upon the humus amids would greatly exaggerate the active nitrogen and lead to a serious overestimate of the soil's immediate resources4 ,the usual content of nitrogen in black soil-humus is from six to eight per cent in the regions of summer rains4 ,from late determinations it would seem that in the arid regions the usually small amount of humus 7often less than two-tenths per cent7 is materially compensated by a higher nitrogen percentage4 ,it thus becomes necessary to determine the humus nitrogen directly2 and this is easily done by substituting in the grandeau process of humus extraction potash or soda-lye for ammonia water1 and determining the nitrogen by the kjeldahl method in the filtrate4 ,the lye used should have the strength of four per cent in the case of potassium hydroxid1 three per cent in that of sodium hydroxid4 ,the black humus filtrate is carefully neutralized with sulfuric acid1 evaporated to a small bulk in a beaker or evaporating basin1 and the reduced liquid finally evaporated to dryness in the kjeldahl flask itself by means of a current of air4 ,the beaker or basin is washed either with some of the alkaline lye1 or1 after evaporation1 with warm concentrated sulfuric acid1 which is then used in the nitrogen determination in the usual way4 ,for the determination of nitrates in the soil it is1 of course1 usually necessary to use large amounts of material1 say not less than #ajj grams1 and1 according to circumstances1 five or more times that amount4 ,in the evaporated solution the nitric acid is best determined by the reduction method1 as ammonia4 ,usually the soil filtrate is clear and contains no appreciable amount of organic matter that would interfere with the determination2 yet in the case of alkaline soils 7impregnated with sodium carbonate7 a very dark colored solution may be obtained4 ,in that case the soil may advantageously be mixed with a few per cent of powdered gypsum before leaching2 or the gypsum may be used in the filtrate to discolor it by the decomposition of sodium carbonate and the precipitation of calcium humate4 ,the evaporated filtrate can then be used for the nitrate determination by either the kjeldahl1 griess1 or the nessler process1 which will1 of course1 include such portions of the ammoniacal salts as may have been leached out4 ,for the separate determination of these and of the occluded ammonia1 when desired1 it is probably best to mix the wetted soil intimately with about ten per cent of magnesium oxid and distill into titrated hydrochloric acid4 ,for general purposes1 however1 this determination is usually of little interest4 #cih4 ,mller's ,modified ,kjeldahl ,method4--,numerous difficulties1 as stated by ,mller1#bfc have attended the attempts to apply the kjeldahl method for the estimation of nitrogen to samples of soil1 and he has modified the method to some extent and made comparisons of the quantity of nitrogen by this modified method and by the soda-lime method4 ,the principal difficulty encountered by him has been in the regular heating of the mixture of fuming sulfuric acid and soil4 ,the particles of soil are deposited at the bottom of the flask and the result is that the bottom layers become overheated1 and1 being poor conductors of heat1 fail to transmit a sufficient quantity of heat to penetrate to the upper layers of the liquid to complete the reaction4 ,in order to avoid this difficulty ,mller heats his flask in a small stove formed with a straight vertical cylinder of iron or copper1 the upper end of which is covered with a sheet of iron pierced with a hole which allows the neck of the flask to pass through1 while the lower end is closed with a piece of sheet iron furnished on its upper surface with a layer of asbestos4 ,this cylinder of metal is surrounded with a second one1 concentric with the first through which passes a current of heated gases furnished by an ordinary bunsen4 ,by heating the flask in this stove or furnace an even distribution of the heat is secured to all parts of the mixture1 but the little drops of sulfuric acid1 which are condensed on the cold part of the neck1 sometimes lead to the fracture of the glass as they run down the sides of the flask to the hot portions4 ,to prevent the reflux of this condensed acid1 which only needs to be done near the end of the reaction1 when it is necessary to heat to a very high temperature1 the neck of the flask is bent at the point immediately above its emergence at the upper surface of the furnace1 and carried into a flask of about seventy-five cubic centimeters capacity1 which will receive the drops of sulfuric acid condensed during the operation4 ,the furnace has the following dimensions2 height1 twelve centimeters2 diameter of interior cylinder1 five and one-half centimeters2 diameter of exterior cylinder1 seven and one-half centimeters4 ,it is supported on a triangle of large iron wire and is heated by an ordinary bunsen1 or by a concentric bunsen1 according to the temperature which it is necessary to obtain4 ,the proportions which should be observed between the amount of earth employed and the sulfuric acid are about as follows3 ,of the dry earth1 fifteen grams2 of the fuming sulfuric acid1 thirty cubic centimeters4 ,there should also be added to the mixture about three-tenths of a gram of pure stearic acid1 or better1 benzoic acid4 ,when the soil to be analyzed does not contain carbonate1 the sulfuric acid should be added in two portions4 ,at first add about twenty cubic centimeters of the acid1 and after shaking it1 the other ten cubic centimeters1 running it in from a burette or a pipette in such a manner as to wash thoroughly the neck and sides of the flask4 ,if the earth contain carbonate1 however1 it is necessary to add the fuming acid in small portions of about five cubic centimeters at a time1 waiting each time until the disengagement of the gas caused by the previous addition has ceased4 ,a soil which contains from thirty to forty per cent of calcium carbonate should be carefully treated in a porcelain capsule with a slight excess of sulfuric acid1 pure and dilute4 ,the mixture is afterward to be evaporated to dryness upon a sand-bath and the residue heated in a drying oven to #aaj4 ,the mass is then pulverized1 introduced into the flask1 treated with three-tenths of a gram of benzoic acid and thirty cubic centimeters of fuming sulfuric acid1 and treated as indicated above4 ,in all cases it is necessary to continue the heating until the contents of the flask are colorless4 ,with soils containing considerable quantities of iron1 however1 a slight red color will probably be observed which will not interfere with the accuracy of the tests4 ,the heating should at first be gentle and the temperature afterward elevated little by little1 and finally the heat should be sufficiently great to distill about one and one-half cubic centimeters of sulfuric acid4 ,the operation lasts from twelve to thirteen hours4 ,as the reaction is terminated the cooled mass is taken up with water absolutely free from ammonia4 ,it is filtered into a flask1 and washed upon the filter until the volume of the filtered liquid is about #cej cubic centimeters4 ,afterward an excess of soda-lye1 at #ej baum is added1 then a few pieces of quartz to facilitate boiling4 ,the flask is then connected with a condenser1 the liquid distilled and received in a conical flask closed by a cork having two holes1 of which one permits the entrance of the end of the condenser1 and the other a glass tube which is connected with a small flask containing water1 the neck of the receiving flask being inclined toward the condenser to avoid the entrainment of any of the alkaline liquid which may be distilled4 ,the receiving flask rests upon two or three pieces of sheet iron and is heated with an ordinary burner1 and ebullition is perfectly regular4 ,from #agj to #ahj cubic centimeters of the liquid are distilled in from three and one-half to four hours4 ,the distilled liquid1 treated with a few drops of litmus1 is titrated by a solution of sulfuric or hydrochloric acid1 of which one cubic centimeter corresponds to #j4jja cubic centimeter of nitrogen4 #cii4 ,modification of the ,kjeldahl ,method by ,arnold and ,wedemeyer4#bfd--;,for the oxidizing liquid a mixture of three grams of benzoic acid with forty cubic centimeters of ,h,,so is employed4 ,after placing in the digestion flask with the nitrogenous body the whole is gently shaken for a few minutes to prevent clotting4 ,the temperature is then raised until acid vapors begin to come off1 when one gram of copper sulfate and one gram of mercuric oxid are added2 and after ten to fifteen minutes1 to avoid foaming1 ten to twenty grams of potassium sulfate4 ,the sublimate noticed on the walls of the flask is benzoic acid and does not interfere with the accuracy of the determination4 ,this method has given good results with the alkaline nitrates1 the nitrates of barium1 mercury1 silver1 lead1 and with strychnia1 ammonia1 pyridin1 azobenzol1 dinitrobenzol1 and picric acid4 #djj4 ,prevention of ,bumping ,during ,distillation4--,daffert has employed the modified kjeldahl method1 but found considerable difficulty in using the same owing to the violent bumping of the liquid in the distillation4 ,this was especially the case where the sample contained a large proportion of sand4 ,to overcome this annoyance and danger he devised the following process3#bfe ,fit into the mouth of a large-mouthed distillation flask a stopper having two perforations4 ,through one of the perforations pass the usual distillation tube1 through the other a similar tube connected with a supply of steam4 ,bring the contents to a brisk boil1 after which a small current of steam is turned on1 allowing the same to pass in a small stream throughout the distillation4 ,by this means1 not only is all danger from bumping avoided1 but the time required for the distillation shortened4 ,by the old method it usually requires from fifteen to twenty minutes1 whereas the former requires from six to ten minutes4 ,it is advisable to filter all samples of soils having a large proportion of sand4 #dja4 ,determination of ,organic ,nitrogen by the ,soda-,lime ,method4--,in the description of the method following1 the directions of the ,french ,commission of ,agricultural ,chemists have been taken as the basis of the analytical process4#bff ,this method is1 in this country1 almost superseded by the moist combustion process with sulfuric acid4 ,by reason of its long use1 however1 and because it is still regarded as the best method by the agricultural chemists of ,france1 ,italy1 and ,england1 it merits a full description4 ,it is recommended also by ,berthelot and ,andr1#bfg by the ,international ,congress of ,chemists1 held in ,paris in #ahhi1 by the ,italian chemists1 and by the official ,belgian method1#bfh in all cases where nitrates are not present in notable quantities4 ,the nitrogen which is found in soils in the organic state is transformed into ammonia when it is heated with soda-lime4 ,this reaction is the base of the process of analysis which has so long been used for this class of bodies4 ,the analytical process is conducted as follows3 ,a well-cleaned glass combustion tube1 closed at one end1 is used4 ,the length of the tube is from thirty-five to forty centimeters4 ,it is filled first to a depth of two centimeters with calcium oxalate2 afterwards to a depth of five centimeters with soda-lime in small fragments2 afterwards with the mixture to be analyzed2 viz41 of ten grams of the sample of soil1 or twenty grams if poor in nitrogen and organic matters1 with soda-lime reduced to a coarse powder4 ,this mixture should occupy a length of about twenty centimeters in the tube4 ,the soil and soda-lime are mixed in a mortar4 ,afterwards the mortar is rubbed with small quantities of soda-lime1 and this1 together with the copper boat which has been used in introducing the mixture1 is thoroughly washed with the soda-lime1 which is poured into the tube until it is filled to within four centimeters of its open extremity4 ,the open end of the tube is then closed with a wad of asbestos packed sufficiently tight to prevent the carrying off of the soda-lime by the gas which may be generated during the combustion4 ,the combustion should be commenced by heating the tube near the open extremity until it is red and carrying the heat progressively towards the part containing the soil mixed with the soda-lime4 ,an ordinary gas combustion furnace should be used and the heat graduated in such a way that the bubbles of gas pass off regularly and not too rapidly4 ,the gas is conducted into a bulb tube containing a decinormal standard sulfuric acid colored with litmus4 ,the combustion is continued until the whole of the organic material is decomposed1 care being taken not to raise the combustion tube above a low redness in order to avoid its softening4 ,at the end1 however1 the temperature of the combustion tube should be raised to a bright red1 and the part containing the calcium oxalate should be heated little by little for the purpose of evolving hydrogen1 which is used to drive out the last traces of ammonia4 ,after the combustion is completed1 and the last traces of ammonia driven out1 the standard acid which has received the evolved ammonia is removed1 the tube leading to it washed1 the wash-water collected with the rest of the liquid and titrated with a standard solution of lime-water1 the strength of which has previously been determined against standard sulfuric acid4 #djb4 ,preparation of the ,standard ,sulfuric ,acid4--,the sulfuric acid to be used in making the standard solutions should be previously boiled for half an hour in a platinum dish and allowed to cool in a desiccator4 ,it should contain #fa4be grams of sulfuric acid in one liter4 ,it is recommended that the flask which holds the sulfuric acid should be one which has been used for a long time for holding concentrated sulfuric acid1 in order to avoid any action of the alkali in the glass upon the acid after its strength has been determined4 ,the solution before described is of such strength as to have each cubic centimeter equivalent to one milligram of nitrogen4 ,for the estimation of the nitrogen in the soil a tenth normal solution should be used1 which is prepared by taking #ajj cubic centimeters of the normal solution1 described above1 and diluting to one liter4 ,preparation of the ,lime-,water4--,from #bjj to #cjj grams of slaked lime are placed in a closed flask of about five liters capacity4 ,this is filled with water and shaken frequently1 and left to deposit the matter in suspension4 ,the water which contains the saline particles which may have been present in the lime is then poured off4 ,fresh water is then poured on and the flask shaken from time to time4 ,to use this lime-water the clear part of it is decanted into a flask1 avoiding1 as much as possible1 access to the air4 ,the flask is closed with a cork carrying two tubes drawn out and bent at a right angle4 ,one of these serves for pouring off the water and the other serves for the entrance of the air4 ,these two tubes are themselves closed by means of a rubber tube carrying a pinch-cock4 ,the strength of the lime-water is fixed by titration with the decinormal standard sulfuric acid4 ,preparation of the ,soda-,lime4--,six hundred grams of slaked lime in fine powder are saturated with #cjj grams of caustic soda dissolved in #cjj cubic centimeters of water4 ,the whole is rubbed into a paste and introduced into a crucible which is heated to redness4 ,the contents of the crucible1 still hot1 are poured out1 and rapidly reduced to fragments in a copper mortar in such a manner as to have the pieces about the size of a pea1 and without having too much finely powdered soda-lime mixed with it4 ,while the matter is still hot it is placed in a flask and well-stoppered4 ,in order that this reagent should contain no nitrogen it is indispensable to use in its preparation materials which contain no trace of nitrates4 ,preparation of the ,calcium ,oxalate4--,in a small copper vessel place #ajj grams of oxalic acid and add gradually1 bringing it to boiling1 enough water to dissolve it4 ,afterwards place in the solution small portions of slaked lime in a state of powder1 constantly testing it until turmeric paper indicates that there is a little lime in excess4 ,it is then evaporated1 stirring vigorously on the open fire1 and the evaporation is finally finished on a steam-bath4 ,the dried material is placed in a flask and well-stoppered4 ,the oxalic acid which is used in this preparation should be free from every trace of nitrogen4 ,preparation of the ,litmus ,solution4--,five grams of litmus are placed in a flask with a flat bottom4 ,afterwards a few cubic centimeters of ammonia are added1 twenty five grams of crystallized sodium carbonate1 and ten cubic centimeters of water4 ,this mixture is left to digest for sometime1 with frequent stirring1 at a temperature of from #fj-hj4 ,the digestion is finished in about four or five days1 during which time1 at intervals1 a few drops of ammonia are added1 sufficient to maintain always the ammoniacal odor4 ,at the end of this time #bjj cubic centimeters of water are added and the digestion allowed to continue several days more1 still maintaining the solution alkaline with ammonia4 ,a slight excess of hydrochloric acid is added1 and the matter which is precipitated is received upon a filter where it is washed several times with cold water and allowed to dry at a low temperature4 ,for use1 from one to two grams of this dry precipitate are dissolved in #ajj cubic centimeters of alcohol1 and there is thus obtained a litmus solution of extreme sensibility4 #djc4 ,treatment of ,soil ,containing ,nitrates4--,nitrates exist in small quantities in all arable soils4 ,when treated for nitrogen by the soda-lime method above described1 a part of the nitric nitrogen is changed to the state of ammonia1 while another part escapes estimation altogether1 causing an error which it is important to point out4 ,when the soils contain only small quantities of nitrates this error is insignificant and does not affect sensibly the results1 but in the case of earths rich in nitrates it is necessary first to eliminate them before the determination of the nitrogen by the soda-lime method4 ,the operation is carried on as follows3 ,twenty grams of the soil are washed on a small funnel1 furnished with a plug of asbestos1 with small quantities of pure water1 in such a way as to cause thirty to forty cubic centimeters of water to pass through4 ,the whole of the nitrate is thus removed4 ,the soil is now dried and submitted to analysis by the soda-lime method as just described4 ,there are removed with the nitrate only small traces of organic nitrogen1 too small to influence the results of the analysis4 ,if1 however1 it is desired to remove altogether this slight cause of error1 evaporate the wash-waters1 above described1 to two or three cubic centimeters2 add a few drops of a concentrated solution of ferrous chlorid and as much hydrochloric acid1 and boil some minutes in order to drive off1 in the state of nitrogen dioxid1 all the nitric acid4 ,the residue is evaporated to dryness and contains the traces of organic nitrogen4 ,this is added to the soil which is to be treated by the soda-lime method4 #djd4 ,mller's ,method4--,the determination of nitrogen in the soil by soda-lime is carried on as follows by ,mller3#bfi ,fifteen grams of fine earth1 dried and mixed with a little sugar1 are mixed with thirty grams of soda-lime in powder4 ,the bottom of the combustion tube contains a little moist soda-lime1 which is heated at the end of the operation at the same time that a current of pure hydrogen is made to pass through it1 and the temperature of the tube is raised1 little by little1 to a distinct redness4 ,the contents of the receiving bulbs are distilled1 after the addition of water and soda1 in the same apparatus which served in the estimation of nitrogen1 by the kjeldahl method2 the determinations and titrations are made also under the same conditions4 ,blank determinations are also made under the same conditions to determine the amount of correction to be made by the two methods4 ,soda-lime1 heated with pure sugar1 gave #j4jjjb gram of nitrogen for a total weight of fifty-five grams of the soda-lime contained in the tube4 ,the fuming sulfuric acid gave #j4jjaa cubic centimeters of ammoniacal nitrogen for the volume of thirty cubic centimeters4 ,the numbers obtained by the kjeldahl method in general1 are lower than those obtained by the soda-lime method when no stearic or benzoic acid is used4 ,the numbers obtained when stearic acid alone was used were sometimes inferior to those obtained by the soda-lime method4 ,the numbers obtained when benzoic acid is used are1 in general1 about the same as those obtained by the soda-lime method4 ,it would seem that the double distillation1 outlined above1 for the kjeldahl method1 would not be necessary if due care were exercised in the first distillation4 ,this variation1 therefore1 seems to be unnecessary4 ,in the soda-lime method1 time would be saved by the reception of the ammonia in standard acid1 and its titration in the usual way1 unless a further purification of the nitrogenous products of the combustion by the final distillation be desired4 #dje4 ,volumetric ,determination of the ,nitrogen4--,instead of separating the nitrates1 the total nitrogen in the soil can be determined directly by the classic method of ,dumas1 which consists in bringing the whole of the nitrogen into a gaseous state and afterwards measuring its volume4 ,the following method illustrates the general principles of the determination3 ,a glass combustion tube closed at one end1 about one meter in length1 is selected4 ,in the bottom of this tube is placed some potassium bicarbonate in a crystalline form1 in small pieces1 filling the tube to a distance of about twenty centimeters4 ,afterwards copper oxid is placed to the depth of ten centimeters and finally a mixture of from twenty to thirty grams of the earth with thirty to forty grams of copper oxid in a fine state of subdivision1 and about ten grams of metallic copper obtained by reducing the copper oxid by hydrogen4 ,next the tube is filled with copper oxid to a depth of from twenty to twenty-five centimeters1 and afterwards with reduced copper to the depth of at least twenty-five centimeters1 and after this another layer of copper oxid of about five centimeters1 and finally a plug of asbestos4 ,the combustion tube is closed with a stopper carrying a glass tube of about ninety centimeters in length1 of which the extremity1 bent into the form of a 1 extends to a mercury trough4 ,the glass combustion tube is surrounded with brass gauze1 except that part which contains the potassium bicarbonate4 ,the beginning of the operation consists in heating the tube to decompose a part of the potassium bicarbonate1 until the whole of the apparatus is filled with carbon dioxid4 ,in order to determine that the whole of the air has been expelled and that the apparatus is entirely filled with carbon dioxid1 a part of the gas which is disengaged1 is received into a jar filled with mercury1 in which a little potash-lye has been placed4 ,if the gas is entirely absorbed by the potash1 so that there remain only unappreciable particles1 the tube can be regarded as completely free of air4 ,when assurance is given that the air is all out of the apparatus1 a jar of about #cjj cubic centimeters capacity1 filled with mercury and containing from thirty to forty cubic centimeters of a solution of potash of a density of #db baum1 is placed over the outlet tube4 ,the combustion is commenced by heating the anterior part of the tube1 avoiding the heating of the part containing the earth4 ,when the first part of the tube has reached the red stage the part containing the earth is gradually heated in order to obtain a gentle evolution of gas4 ,the temperature of the tube is carried to redness and the heating gradually carried back toward the closed extremity1 but avoiding raising the temperature of the part containing the potassium bicarbonate4 ,the red heat is continued as long as bubbles of gas are discharged into the reservoir4 ,when the evolution of gas has ceased the apparatus is again filled with carbon dioxid for the purpose of driving out the last traces of nitrogen1 by heating again the part of the tube containing the potassium bicarbonate4 ,the evolution of the carbon dioxid should be maintained for about fifteen minutes4 ,at the end of this time all the nitrogen will be found in the receiving jar4 ,sometimes a small quantity of nitrogen dioxid is formed incidentally in the operation4 ,after waiting for a quarter of an hour1 in order to permit all the carbon dioxid which may have escaped into the reservoir to be completely absorbed1 the receiving jar is carried to a water-basin and the mercury allowed gradually to escape2 its place being taken by the water4 ,the gas is then transferred into an azotometer where its volume and temperature are read in the usual way4 ,in order to absorb any nitrogen dioxid which may be admixed with the nitrogen itself1 a little crystal of ferrous sulfate is introduced4 ,the reservoir containing the nitrogen is carried to the mercury trough1 and the water which it contains is nearly all run out in such a way as to be replaced with mercury1 great care being exercised to avoid any escape of gas4 ,afterwards there is introduced over the mercury a crystal of ferrous sulfate and the azotometer is shaken until this crystal is dissolved by the water which it still contains4 ,it is then allowed to remain for twenty hours4 ,at the end of this time the nitrogen dioxid is absorbed and the volume of the gas is again read as before4 ,one-half only of the total loss should be subtracted1 since the volume of the nitrogen dioxid is twice the volume of the nitrogen itself4 ,for the practice of this method1 in connection with the use of a mercury pump1 the directions which will be given under fertilizers may be consulted4 #djf4 ,estimation of ,ammonia4--,ammonia exists ordinarily only in very small quantities in the soil1 since it is incessantly transformed into nitrate or diffused in the air4 ,nevertheless1 it is sometimes interesting to determine its quantity4 ,the method of determining the ammonia in soils is one of extreme delicacy on account of the small proportion therein1 and the difficulty of expelling it without at the same time converting some of the organic nitrogen into ammoniacal compounds4 ,the various methods employed for this purpose may be classified as follows3 #a4 ,treatment of the soil with soda-lye in the cold1 and the absorption of the ammonia given off by standard sulfuric acid4 #b4 ,the method of ,boussingault1 which consists in replacing the soda-lye with magnesia and distilling the ammonia at a boiling temperature1 absorbing the distillate in a standard acid4 #c4 ,a modification of the above method1 due to ,schloesing1 which consists first in extracting the ammonia by hydrochloric acid and subjecting the extract to distillation with magnesia4 #d4 ,the method of ,knop consists in treating the soil in a closed cylinder with soda-lye containing bromin4 ,the ammonia set free by the lye is decomposed in the presence of bromin into free nitrogen and hydrochloric acid4 ,the nitrogen is collected and measured in an azotometer4 ,the brom-soda-lye is prepared by dissolving #ajj grams of sodium hydroxid in #a1bjj cubic centimeters of water and adding twenty-five cubic centimeters of bromin4 #e4 ,the process described under #d1 as shown by ,baumann1#bgj does not give accurate results and it has been modified by him as follows3 ,two hundred grams of soil are treated with #ajj cubic centimeters of dilute hydrochloric acid 7one part acid and four of water7 free of ammonia2 #cjj cubic centimeters of ammonia-free distilled water are added and the whole digested for two hours with frequent stirring4 ,if a soil contain much calcium carbonate larger quantities of acid must be used4 ,two hundred cubic centimeters of the filtrate are placed in an evolution flask1 connected with an azotometer1 with five grams of freshly burned magnesia4 ,the mixture is then oxidized as follows3 ,ozone is generated by adding three parts by weight of sulfuric acid to one part of dry and powdered potassium permanganate4 ,a stream of air is drawn through the ozone generator by an aspirator1 and the ozone is conducted into a flask containing the hydrochloric acid extract of the soil and magnesia4 ,the oxidation is completed in about ten minutes4 ,the mixture is then brought into the evolution flask of the azotometer and the nitrogen set free and measured in the usual way4 ,it has been shown that if asparagin or glutamin be present in the soil they are decomposed by the soda-lye and the results obtained are too high4 ,it has been further proved that soils which contain a notable quantity of humus give1 with soda-lye in the cold1 a practically continuous evolution of ammonia4 ,moreover1 soils which are rich in humus and which have been treated by distillation with magnesia give1 on subsequent treatment with soda-lye1 considerable additional quantities of ammonia4 ,comparison of ,methods of ,estimating ,ammonia4--,baumann has determined the ammonia-nitrogen in various soils by the soda-lime method2 distillation of the hydrochloric acid extract with magnesia1 and the azotometric method modified as indicated above4 ,these methods will be designated as #a1 #b1 #c1 respectively in the following table4 ,,method4 #a4 #b4 #c4 ,ammonia-nitrogen in one kilogram of soil4 ------------ ------------ ------------ ,no4 of sample4 ,gram4 ,gram4 ,gram4 #a #j4jddh #j4jbbbg #j4jbgha #b #j4jafh #j4jaaje #j4jacbf #c #j4jccf #j4jagga #j4jbbad #d #j4jjef #j4jjddc #j4jjddc #e #j4jbhj #j4jbccg #j4jbhid #f #j4jaif #j4jabdc #j4jafgb ,from the above figures it is seen that the method usually attributed to ,schloesing gives uniformly higher numbers than either of the other processes1 while the third gives slightly higher values than the second4 #djg4 ,the ,magnesia ,distillation ,process4--,if a sample of soil be distilled directly with magnesia and water1 there is danger on the one side of not extracting all the ammonia1 by reason of the absorbing power of these bodies1 and on the other1 of transforming into ammonia the nitrogen of the organic matters4 ,it is therefore preferable to separate the ammonia from the soil in the form of chlorid1 and to subject this extract to distillation4 ,in fifty grams of the soil the humidity is determined by drying at #ajj until there is no further loss of weight4 ,the quantity of moisture being known1 #bjj grams of soil are taken and moistened with water1 and then there is added1 in small portions1 some dilute hydrochloric acid1 shaking frequently until the whole of the calcium carbonate present is decomposed4 ,the liquor should remain acid at the end of the operation1 but without containing a notable excess of acidity4 ,knowing beforehand the quantity of moisture contained in the #bjj grams1 water is added until the total quantity shall be equal to #ejj cubic centimeters4 ,the whole is then shaken and allowed to repose1 and filtered rapidly1 covering the funnel with a glass vessel and receiving the liquid which runs through in a flask with a narrow opening4 ,two hundred and fifty cubic centimeters of this liquor1 or mixture1 represent #ajj grams of earth of known humidity4 ,this quantity is introduced into a flask for determining the ammonia and five grams of calcined magnesia added4 ,before commencing the distillation1 assurance should be had that the magnesia has completely saturated the acid in excess1 and that the liquor is alkaline4 ,if1 by chance1 the liquor should be still acid it would be necessary to add sufficient magnesia in order that the reaction should be manifestly alkaline4 ,afterwards the distillation is begun and the ammonia is received in an appropriate vessel containing one-tenth normal sulfuric acid and titrated in the usual way1 or nesslerized4 ,inasmuch as the quantities of ammonia contained in the earth are generally very small it is necessary to be very particular in order to avoid errors4 ,the distilled water which is employed should be deprived of all traces of ammonia by prolonged ebullition1 and the hydrochloric acid should be distilled in the presence of a little sulfuric acid4 ,the treatment with hydrochloric acid is for the purpose of destroying the absorbing properties of the soil for ammonia1 and to permit this last to enter into solution as chlorid4 ,when there is need of very great precision it is convenient to make a blank operation with the hydrochloric acid and water which are employed1 in order to make a correction for the traces of ammonia which these reagents may contain4 #djh4 ,estimation of ,ammoniacal and ,amid ,nitrogen by the ,method of ,berthelot and ,andr4#bga--;,heat one hundred grams of earth for thirty hours on a steam-bath with about 4#ejj cubic centimeters of dilute hydrochloric acid 7fifteen grams of hydrochloric acid to #ejj cubic centimeters of water74 ,at the end of this time throw the contents of the flask on a filter and wash with hot water until acid reaction has ceased4 ,determine both the ammoniacal and amid nitrogen in the soluble1 and the total nitrogen in the insoluble portion1 the ammoniacal by distillation with magnesia1 and the amid and total with soda-lime4 ,example4 ,a soil contained #j4affi per cent total nitrogen4 ,of this there were obtained3 ,as ammoniacal nitrogen #ac4g per cent ,in the soluble part as amid nitrogen #ef4b ,in the insoluble part1 total nitrogen #bi4g -------- ,sum #ii4f ,treatment of the ,insoluble ,portion4--,treat the part insoluble in hydrochloric acid with a three per cent solution of potash on a steam-bath for thirty hours4 ,estimate the nitrogen remaining insoluble1 from which the part dissolved can be determined by difference4 ,the potash will dissolve usually about two-thirds of the remaining nitrogen4 ,about ninety per cent of the total nitrogen present in an arable soil will be rendered soluble by successive treatment with acid and alkali4 ,the reverse treatment will give practically the same result4 ,it is therefore immaterial1 from an analytical standpoint1 whether the acid or alkali be used first4 #dji4 ,estimation of ,volatile ,nitrogenous ,compounds ,emitted by ,arable ,soil4--,the following method1 due to ,berthelot and ,andr1#bgb may be practiced3 ,porcelain pots1 containing one kilogram of soil1 are placed under bell-jars of fifty liters capacity adjusted to glass dishes designed to receive the waters of condensation4 ,during the first period the pots are to be sprinkled from time to time1 during the duration of the experiment1 through the upper tubulature1 so as to prevent the soil from becoming dry4 ,the water is partly condensed on the sides of the bell-jar4 ,it is removed each week through the inferior tubulature1 treated with a little dilute sulfuric acid1 and preserved for further study4 ,a small vessel containing dilute sulfuric acid is placed near the porcelain pot for the purpose of collecting1 as far as possible1 the evolved ammonia4 ,during the second period the pots are not sprinkled1 the soil becomes dry and there is no longer any condensation of water on the walls of the bell-jar4 ,the two periods should include about five months1 from ,may to ,october4 ,at the end of the second period the following determinations are to be made3 #a4 ,the ammonia absorbed by the dilute sulfuric acid4 #b4 ,the ammonia set free by distillation with magnesia1 such as may have accumulated in the condensed water4 #c4 ,the organic nitrogen contained in the latter after elimination of the ammonia4 ,this is determined by adding a slight excess of acid1 evaporation to dryness1 and combustion with soda-lime1 or by moist combustion with sulfuric acid4 ,example3 ,earth ,employed4--,one kilogram of sandy clay containing total nitrogen1 #j4ji gram4 ,nitrogen in sprinkling water1 #j4jjjjdh gram4 ,nitrogen in ,exhaled ,products4-- ,,first ,,period4 ,,sprinkling4 ,ammoniacal nitrogen collected in the dilute sulfuric #j4jjjab gram4 acid ,ammoniacal nitrogen collected in the condensation waters #j4jjjab ,organic nitrogen in condensation waters #j4jjbbj ---------------- ,sum #j4jjbdd ,,second ,,period4 ,,no ,,sprinkling4 ,ammoniacal nitrogen in dilute sulfuric acid #j4jjjjjg gram4 condensed water #j4jjjjjg ,organic #j4jjjjdj ---------------- ,sum #j4jjjjed ,conclusions4--,the exhalation of nitrogenous compounds takes place with a certain relative activity1 about two milligrams in two months and a half1 as long as the soil is kept moist by sprinkling4 ,in the second period1 without sprinkling1 the exhalation is reduced to a mere trace4 ,the vessel containing the dilute sulfuric acid placed near the porcelain pot absorbs only about one-half of the ammoniacal nitrogen set free4 ,the nitrogen emitted under other forms than ammonia is1 in every instance1 greatly superior in quantity1 and this is the most important of the observed phenomena4 ,this is true at least with the kind of soil with which the experiment was made4 ,with arable soil containing twenty times as much nitrogen as the soil described above this order is reversed1#bgc the ammoniacal prevailing over the non-ammoniacal nitrogen volatilized4 ,these phenomena are doubtless greatly influenced in soil under culture by microbes1 and the lowest orders of vegetation to which are doubtless due the traces of non-ammoniacal volatile nitrogenous compounds1 a sort of vegetable ptomaines4 #daj4 ,general ,conclusions4--,in the light of our present knowledge concerning the methods of nitrogen determination in the soil in the form of organic compounds and ammonia1 moist combustion with sulfuric acid is to be preferred to the older soda-lime process4 ,for the nitrogen combined as ammonia1 the extraction of the sample with hydrochloric acid and subsequent distillation with an excess of freshly calcined magnesia1 are recommended4 ,for the study of the progressive decomposition of the nitrogenous compounds1 the various processes devised by ,berthelot and ,andr are the best4 ,the origin of the nitric acid in the soil1 the methods of studying the various nitrifying organisms1 and of estimating the nitric acid produced1 will form the subject of the next part4 ,,note4--,at the ,eleventh ,annual ,convention of the ,association of ,official ,agricultural ,chemists1 held in ,washington1 ,august #bc1 #bd and #be1 #ahid1 the following process of soil extraction was adopted as the official method3 ,preparation of the ,sample4--#ejj grams or more1 of the air-dried soil1 which may be either the original soil or that which has been passed through a sieve of coarser mesh1 are sifted upon a sieve with circular openings one-half millimeter in diameter1 rubbing1 if necessary1 with a rubber pestle in a mortar1 until the fine earth has been separated as completely as possible from the particles that are too coarse to pass through the sieve4 ,the fine earths thoroughly mixed and preserved in a tightly stoppered bottle from which the portions for analysis are weighed out4 ,the coarse part is weighed and may be subjected to further examination1 7as in ,bulletin #ch1 ,div4 of ,chem41 pp4 #fe1 #ge and #bjj47 ,it may sometimes be necessary to wash the soil through the one-half millimeter sieve with water1 in which case proceed as directed on pp4 #fe and #ge of the above ,bulletin4 ,the use of water is to be avoided whenever possible4 ,determination of ,moisture4--,heat two to five grams of the air-dried soil in a flat-bottomed1 tared platinum dish2 heat for five hours in a water-oven kept briskly boiling2 cover the dish1 cool in a desiccator1 and weigh4 ,repeat the heating1 cooling1 and weighing at intervals of two hours till constant weight is found1 and estimate the moisture by the loss of weight4 ,weigh rapidly to avoid absorption of moisture from the air4 ,an air-bath must not be used in this determination4 ,determination of ,volatile ,matter4--,the platinum dish and soil used to determine moisture are used also to determine volatile matter4 ,heat the dish and dried soil to full redness until all organic matter is burned away4 ,if the soil contain appreciable quantities of carbonates1 the contents of the dish1 after cooling1 are to be moistened with a few drops of a saturated solution of ammonium carbonate1 dried and heated to dull redness to expel ammonium salts1 cooled in the desiccator and weighed4 ,the loss in weight represents the organic matter1 water of combination1 ammonium salts1 etc4 ,extraction of ,acid-,soluble ,materials4--,in the following scheme for soil analysis it is intended to use the air-dried soil from the sample bottle for each separate investigation4 ,the determination of moisture1 made once for all on a separate portion of air-dried soil1 will afford the datum for calculating the results of analysis upon the soil dried at the temperature of boiling water4 ,it is not desirable to ignite the soil before analysis or to heat it so as to change its chemical properties4 ,the acid digestion is to be performed in a flask so arranged that the evaporation of acid shall be reduced to a minimum1 but to take place under atmospheric pressure and at the temperature of boiling water4 ,any flask resistant to acids is suitable1 but it is not necessary to use a condenser1 as a simple bohemian glass tube eighteen inches in length will answer the purpose of preventing loss of acid4 ,where it is not desired to determine sulfur trioxid1 an erlenmeyer fitted with a rubber stopper and hard glass tube will answer4 ,the flask must be immersed in the water-bath up to the neck or at least to the level of the acid and the water must be kept boiling continuously during the digestion4 ,in the following scheme1 ten grams of soil are taken1 this being a convenient quantity in most soils1 in which the insoluble matter is about eighty per cent4 ,if desired1 a larger quantity of such soil may be taken1 using a proportionately larger quantity of acid and making up the soil solution to a proportionately larger volume4 ,in very sandy soils1 where the proportion of insoluble matter is ninety per cent or more1 twenty grams of soil are to be digested with #ajj cubic centimeters of acid and the solution made up to #ejj cubic centimeters or a larger quantity may be used1 preserving the same proportions4 ,it is very important that the analyst assure himself of the purity of all the reagents to be used in the analysis of soils before beginning the work4 ,acid ,digestion of the ,soil4--,place ten grams of the air-dried soil in a #aej to #bjj cubic centimeter bohemian flask1 add #ajj cubic centimeters of pure hydrochloric acid of specific gravity #a4aae1 insert the stopper with condensing tube1 place in a water or steam-bath and digest for ten hours continuously at the temperature of boiling water1 shaking once each hour4 ,pour the clear liquid from the flask into a small beaker1 wash the residue out of the flask with distilled water on a filter adding the washings to the contents of the beaker4 ,the residue after washing until free of acid1 is to be dried and ignited as directed below4 ,add one or two cubic centimeters of nitric acid to the filtrate1 and evaporate to dryness on the water-bath1 finishing on a sand or air-bath to complete dryness2 take up with hot water and a few cubic centimeters of hydrochloric acid1 and again evaporate to complete dryness4 ,take up as before1 filter and wash thoroughly with cold water or with hot water slightly acidified at first with hydrochloric acid4 ,cool and make up to #ejj cubic centimeters4 ,this is solution 8,a40 ,the residue is to be added to the main residue and the whole ignited and weighed1 giving the insoluble matter4 ,the determination of the various components of the solution remains essentially as described in the provisional methods of the ,association which have already been given4 ,it is directed that all results of soil analysis be calculated on the basis of the sample dried to constant weight at the temperature of boiling water4 ,,authorities ,,cited ,,in ,,part ,,sixth4 ,footnote #ahi3 ,annales de ,chimie et de ,physique1 sixime serie1 ,tome #be1 pp4 #bib1 et seq4 ,footnote #aij3 ,l',analyse du ,sol1 p4 #ad4 #c4 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #ch1 ,s4 #caa4 ,footnote #aia3 ,bulletin #ch1 ,chemical ,division ,united ,states ,department of ,agriculture1 p4 #bja4 ,footnote #aib3 ,untersuchung ,landwirtschaftlich und ,gewerblich ,wichtiger ,stoffe1 ,s4 #ad4 ,footnote #aic3 ,vid4 op4 cit4 supra4 ,footnote #aid3 ,vid4 op4 cit4 #a4 ,footnote #aie3 ,vid4 op4 cit4 #c1 ,band #cg1 ,s4 #bgi4 ,footnote #aif3 ,journal of the ,chemical ,society1 ,september1 #ahhj1 p4 #fag4 ,footnote #aig3 ,wanklyn1 ,philosophical ,magazine1 ,series #e1 ,vol4 #e1 p4 #dff4 ,footnote #aih3 ,vid4 op4 cit4 #a4 ,footnote #aii3 ,trait d',analyse des ,matires ,agricoles1 p4 #adh4 ,footnote #bjj3 ,bulletin #ch1 ,division of ,chemistry1 ,united ,states ,department of ,agriculture1 pp4 #hd1 et seq4 ,footnote #bja3 ,encyclopedie ,chimique1 ,tome #d1 p4 #ahb4 ,footnote #bjb3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #cg1 ,s4 #bhj4 ,footnote #bjc3 ,vid4 op4 cit4 supra1 ,band #bh1 ,s4 #bbi4 ,footnote #bjd3 ,comptes rendus1 #ahij1 pp4 #bij1 et seq4 ,footnote #bje3 ,annales ,agronomiques1 #ahij1 p4 #eeh4 ,footnote #bjf3 ,bulletin #ac1 ,division of ,chemistry1 p4 #eij4 ,footnote #bjg3 ,bulletin de la ,socit ,chimique1 ,serie #c1 ,tome #b1 pp4 #dhc1 et seq4 ,footnote #bjh3 ,zeitschrift fr analytische ,chemie1 ,band #c1 ,s4 #afe4 ,footnote #bji3 ,petermann1 ,l',analyse du ,sol1 p4 #bj4 ,footnote #baj3 ,zeitschrift fr analytische ,chemie1 ,band #c1 ,s4 #ib4 ,footnote #baa3 ,journal of the ,chemical ,society1 ,march1 #ahid1 p4 #ada4 ,footnote #bab3 ,agricultural ,science1 ,january1 #ahid1 p4 #b4 ,footnote #bac3 ,american ,journal of ,science1 ,vol4 #g1 #ahgd1 p4 #bj4 ,footnote #bad3 ,geological and ,agricultural ,report of ,kentucky1 ,vol4 #c4 ,footnote #bae3 ,bulletin #ch1 ,division of ,chemistry1 p4 #gg4 ,footnote #baf3 ,op4 cit4 supra1 p4 #hc4 ,footnote #bag3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #cg1 ,s4 #caa4 ,footnote #bah3 ,zeitschrift fr analytische ,chemie1 ,band #c1 ,s4 #ib4 ,footnote #bai3 ,trait d',analyse des ,matires ,agricoles1 p4 #add4 ,footnote #bbj3 ,op4 cit4 #bh1 pp4 #bjb1 et seq4 ,footnote #bba3 ,op4 cit4 #bh1 pp4 #gg1 et seq4 ,footnote #bbb3 ,op4 cit4 #bb1 p4 #ba4 ,footnote #bbc3 ,manuscript communication to author4 ,footnote #bbd3 ,annales de la ,science ,agronomique1 ,huitime ,anne1 ,tome #a1 p4 #bgh4 ,footnote #bbe3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #cg1 ,s4 #caa4 ,footnote #bbf3 ,comptes rendus1 #ahij1 p4 #bhi4 ,footnote #bbg3 ,thoms1 ,zur ,werthschtzung der ,ackererde1 ,s4 #abj4 ,footnote #bbh3 ,le ,stazioni ,sperimentali ,agrarie ,italiane1 ,vol4 #af1 p4 #fgi4 ,footnote #bbi3 ,crookes' ,select ,methods in ,chemical ,analysis4 ,footnote #bcj3 ,chemiker ,zeitung1 ,band #ac1 ,s4 #acia4 ,footnote #bca3 ,annales de ,chimie et de ,physique1 serie sixime1 ,tome #ae1 p4 #cji4 ,footnote #bcb3 ,vid4 op4 cit4 #cg1 pp4 #bgj1 et seq4 ,footnote #bcc3 ,chemiker ,zeitung1 ,band #ac1 ,s4 #gbf4 ,footnote #bcd3 ,die ,agrikultur ,chemische ,versuchs-,station1 ,halle1 a_/,s41 ,s4 #hj4 ,footnote #bce3 ,comptes rendus1 ,tome #ajg1 pp4 #iii and #aaej4 ,footnote #bcf3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #da1 ,s4 #dec4 ,footnote #bcg3 ,bulletin de la ,socit ,chimique de ,paris1 #ahic1 p4 #cdc4 ,footnote #bch3 ,die ,agrikultur ,versuchs-,station1 ,halle1 a_/,s41 ,s4 #gj4 ,footnote #bci3 ,op4 cit4 supra41 ,s4 #fh4 ,footnote #bdj3 ,op4 cit4 #cg1 p4 #bfg4 ,footnote #bda3 ,l',analyse du ,sol1 p4 #bj4 ,footnote #bdb3 ,op4 cit4 #a1 pp4 #cjc1 et seq4 ,footnote #bdc3 ,op4 cit4 #dj1 ,s4 #aad4 ,footnote #bdd3 ,bulletin #ch1 ,division of ,chemistry1 p4 #hj4 ,footnote #bde3 ,zeitschrift fr analytische ,chemie1 ,band #c1 ,s4 #ib4 ,footnote #bdf3 ,chemisches ,centralblatt1 #ahfa1 p4 #c4 ,footnote #bdg3 ,berichte der deutschen chemischen ,gesellschaft1 ,band #bf1 ,s4 #chf4 ,footnote #bdh3 ,manuscript communication to author4 ,footnote #bdi3 ,op4 cit4 #cg1 p4 #bhe4 ,footnote #bej3 ,op4 cit4 #dd1 pp4 #cje1 et seq4 ,footnote #bea3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #cg1 ,s4 #bhd4 ,footnote #beb3 ,op4 et loc4 cit4 #eh4 ,footnote #bec3 ,op4 et loc4 cit4 #da4 ,footnote #bed3 ,op4 et loc4 cit4 #cg4 ,footnote #bee3 ,op4 et loc4 cit4 #eh4 ,footnote #bef3 ,l',analyse du ,sol1 p4 #ag4 ,footnote #beg3 ,op4 cit4 #dd1 p4 #cjh4 ,footnote #beh3 ,op4 cit4 #cg4 ,footnote #bei3 ,op4 cit4 #fd1 ,band #dj1 ,s4 #bea4 ,footnote #bfj3 ,bulletin de la ,socit ,chimique1 ,may1 #ahia1 pp4 #fdc1 et seq4 ,footnote #bfa3 ,bulletin #ch1 ,division of ,chemistry1 p4 #bjd4 ,footnote #bfb3 ,bulletin #ch1 ,division of ,chemistry1 p4 #ha4 ,footnote #bfc3 ,op4 cit4 #dd1 ,march1 #ahia1 pp4 #cic1 et seq4 ,footnote #bfd3 ,op4 cit4 #eh1 ,band #ca1 ,s4 #ebe4 ,footnote #bfe3 ,relatorio ,annual do ,instituo ,agronomico do ,estado de ,san ,paulo 7,brazil71 #ahib1 p4 #ajg4 ,footnote #bff3 ,op4 cit4 #cg1 pp4 #bec1 et4 seq4 ,footnote #bfg3 ,op4 cit4 #dd1 ,tome1 #be1 pp4 #bii1 et seq4 ,footnote #bfh3 ,petermann1 ,l',analyse du ,sol1 p4 #ag4 ,footnote #bfi3 ,op4 et4 loc4 cit4 #gf4 ,footnote #bgj3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #cc1 ,ss4 #bdg1 et seq4 ,footnote #bga3 ,op4 cit4 #dd1 ,tome #be1 pp4 #cbg1 et seq4 ,footnote #bgb3 ,op4 cit4 #dd1 ,tome #be1 pp4 #ccj1 et seq4 ,footnote #bgc3 ,op4 et loc4 cit4 supra4 ,,part ,,seventh4 ,,the ,,origin ,,and ,,estimation ,,of ,,oxidized ,,nitrogen ,,in ,,soils1 ,,rain ,,and ,,drainage ,,waters4 #daa4 ,introductory ,considerations4--,the estimation of oxidized nitrogen in the soil would properly find a place in the preceding part2 but on account of the late progress in our knowledge of the source of this indispensable and costly plant food it has become necessary to give it especial attention4 ,the present part will1 therefore1 be devoted to a brief statement of our present knowledge in respect of the origin of oxidized nitrogen1 a description of the nitrifying ferments and methods for their isolation and determination and finally the most approved methods of estimating the ammonia1 nitrous1 and nitric acids formed thereby both in the soil and the waters pertaining thereto or proceeding therefrom4 ,it is scarcely necessary to caution the reader not to consider this part in any sense a treatise on the bacteria active in soil chemistry4 ,its object is rather to place in the hands of the soil analyst data which will enable him to intelligently study the soil phenomena depending on these organisms and to determine the extent and character of their biological and chemical functions4 ,these are matters which1 up to the present time1 have found no place in manuals dedicated to agricultural analysis4 #dab4 ,organic ,nitrogen in the ,soil4--,with the exception of the small quantities of nitric acid added to the soil directly by rain water1 the whole of the supply of this substance is derived from the products of the oxidation of nitrogenous bodies4 ,these products are either stored as the results of past nitrification or are formed synchronously with their consumption by the growing plant4 ,nitrogenous compounds are present as organic vegetable or animal remains and as humus4 ,all vegetable and animal material deposited in or on the soil contains more or less of these proteid or nitrogenous matters while the amount of nitric acid supplied in this way is probably represented entirely by the quantity in the organism of the plant or animal and unabsorbed at the time of its death4 ,in other words it is not demonstrated that nitrates or nitrites are in any sense a special product of plant growth save in the case of nitrifying organisms themselves which are supposed to be of a vegetable nature4 ,animal organisms do not in any sense assimilate nitric nitrogen4 ,with most plants1 the quantity of proteid nitrogen which they can deliver to the soil is in no case greater than the sum of organic and nitric nitrogen supplied in their food and they can therefore be regarded only as the carriers and conservers of this substance4 ,on the other hand there are some plants notably those belonging to the leguminous family which permit of the development on their rootlets of colonies of bacteria which have the faculty of rendering atmospheric nitrogen available for plant growth4 ,whether or not there exist plants other than the micro-organisms mentioned which are capable of directly oxidizing and fixing atmospheric nitrogen is still an unanswered question4 ,it is not probable1 however1 that the difficult task of oxidizing atmospheric or free nitrogen would be accomplished in nature in only one way4 ,in fact it has already been established that organisms do exist which are capable of oxidizing free nitrogen in a manner wholly independent of other plant life and to produce weighable quantities of nitric acid when developed in media of mineral matters and pure carbohydrates to which free nitrogen has access4 ,it is1 therefore1 fair to assume that the fixation of free nitrogen is a function of chemical activity quite independent of ordinary plant life and that the leguminous plants take no further part in this process than that of providing in their radical development a favorable nidus for the growth of the nitrifying organism4 ,by the action of denitrifying organisms a portion of the nitrogen of nitric acid is constantly restored to a free state1 a far larger portion1 perhaps1 than is fixed in the atmosphere itself by the action of electricity4 ,were it not1 therefore1 for the activity of the nitrifying ferments the stores of nitrogen available for growing plants would constantly become less4 ,instead of this being the case1 however1 it is probable that the contrary is true and that1 by a wise system of agriculture1 the total nitrogen at the disposal of plants may become greater and greater in quantity4 #dac4 ,development of ,nitric and ,nitrous ,acids in ,soils4--,owing to the solubility of nitrates there can be but little accumulation of them in soils in those countries where there is any considerable amount of rain-fall4 ,on the other hand in arid regions there may be found extensive deposits of nitrates4 ,the occurrence of a certain quantity of nitrates in the soil1 however1 is essential to the growth of plants4 ,until within a few years little was known of the origin of nitric acid in the soil4 ,the presence of nitrates in drainage waters was well established1 likewise the consumption of nitric acid by the growing plant1 but the method of its supply was unknown4 ,in a general way it was said that the nitric acid came from electrical action and the oxidation of the albuminous bodies in the soil1 but without specifying the manner in which this change takes place4 ,the researches of ,schloesing and ,mntz1 of ,springer1 ,winogradsky1 ,frankland1 ,warington and others have demonstrated the fact that this oxidation is caused by means of bacteria and that the nitrates formed can be consumed and destroyed by other species of this organism4 ,in the one case the process has been called nitrification and in the other denitrification4#bgd ,the influence of these low organisms both in producing fertility in a soil and maintaining it in a state of fertility is of the highest importance4 #dad4 ,conditions ,necessary for ,nitrification4--,in order to properly understand the reasons for many of the steps in investigating a soil for nitrifying organisms1 it will be useful to state the general conditions on which nitrification depends4 ,the nitrifying organism1 like every other one1 first of all feels the necessity for food4 ,in general1 food which is given to microbes of all kinds consists of some organic matter together with the addition of mineral substances necessary to growth4 ,these substances in general are phosphoric acid1 potash1 and lime4 ,of these articles of bacterial food phosphoric acid seems to be the most important4 ,with the nitrifying organisms1 however1 it has been found that the organic matter can be omitted4 ,in fact1 as will be seen further on1 the omission of organic matter supplies the best condition for the proper isolation of the organisms4 ,in other words some forms of the nitrifying organisms have the property of subsisting wholly on mineral substances1 i4 e41 are true vegetables4 ,the presence of oxygen is also necessary to the growth of the common nitro-organisms4 ,in an atmosphere deprived of oxygen or in which the oxygen is reduced to a very low percentage1 the process of nitrification is retarded or stopped as the oxygen diminishes or disappears4 ,the presence of a base with which the nitrous or nitric acid formed may unite is also essential to the proper conduct of the process4 ,for this reason the nitrification should take place in a solution which is feebly alkaline or in the presence of a base which can be easily decomposed so that no acidity can take place4 ,calcium carbonate is a base well suited to favor the nitrifying process and its presence in a soil favors the rapid oxidation of proteid matter4 ,the mistake must not be made1 however1 of supposing that an excess of alkali would favor nitrification4 ,the contrary is true4 ,a slight excess of alkali may prevent nitrification altogether when it is due to the common organisms present in an arable soil4 ,it may be that in soils charged with alkali a different organism exists which is capable of exercising its functions when the alkali is in excess4 ,the temperature to which the nitrifying body is subjected is also a matter of importance4 ,the nitrifying organisms have the property of remaining active at lower temperatures than most bodies of their class4 ,on the contrary their action is retarded and destroyed by high temperatures4 ,the most favorable temperature for nitrification is about that of blood heat2 viz41 #cg4 ,at #ej the organism shows very little activity and at #ee its activity ceases altogether4 ,nitrification1 however1 according to ,warington1 cannot be started in a solution if the initial temperature is #dj4 ,desiccation has the same retarding influence on nitrification that a high temperature has4 ,even thoroughly air-drying a soil may destroy its nitrifying qualities4 ,darkness is also necessary to the proper progress of nitrification4 ,in a strong light1 the activity of the organism is very much diminished or destroyed altogether4 ,a bright light like sunshine may even stop nitrification which has set in4 #dae4 ,effect of ,potassium ,salts on ,rate of ,nitrification4--,dumont and ,crochetelle have described some experiments to determine the effect of potassium salts alone and in combination with lime on nitrification4#bge ,soil rich in vegetable mold 7#ah4e per cent of humus and #j4bi per cent of lime7 was treated with varying amounts of potassium sulfate and carbonate and kept for twenty days at #be4 ,in the untreated soil the amount of nitric acid produced was twenty-five parts per million4 ,when potassium carbonate was applied in quantities of from one-tenth to six per cent the amount of nitric acid increased from forty-seven parts per million to #dch parts when four and one-half per cent of the potassium salt were used4 ,larger quantities caused a decrease in the amount of nitric acid produced4 ,very little effect1 on the contrary1 was produced by the action of potassium sulfate4 ,when one-half per cent was employed the quantity of nitric acid formed rose to fifty parts per million1 while with quantities as high as five per cent it fell below the normal2 viz41 twenty-five parts per million4 ,when calcium carbonate was added to the soil in conjunction with potassium sulfate there was a marked increase in the amount of nitrogen oxidized4 ,the activity of potassium sulfate in promoting nitrification is therefore increased by the presence of the calcium salt1 potassium carbonate and calcium sulfate being formed4 #daf4 ,production of ,nitrous and ,nitric ,acids4--,in the following pages the study of the methods of isolating the nitrous and nitric ferments will be considered as one process1 the final isolation of the two classes of bodies being the result of their synchronous cultivation in appropriate media4 ,the special process of the production of ammonia by oxidation is not so well-known1 and will therefore be described in brief4 ,it is now generally conceded that the action of the nitrous organism is precedent to that of the nitric1 but the two processes go on so nearly together as to prevent the accumulation of any large quantities of the lower salt in the soil4 ,whether or not the formation of ammonia precedes that of nitrous acid is still a subject for experimental demonstration4 ,chemically1 both nitrous acid and ammonia may be produced by the reduction of nitric acid4 ,in nature1 the reverse of this process may be the customary method4 #dag4 ,production of ,ammonia in the ,soil by the ,action of ,microbes4--,it is highly probable that organic nitrogen in the soil in passing into the form of nitric acid exists at some period of the process in the form of ammonia4 ,marchal has isolated and studied some of these ammonia-making bacteria4#bgf ,bacillus mycoides is the most active of these organisms4 ,it occurs constantly in surface soils and is present in the air and in natural waters4 ,in decomposing albumen it produces a strongly alkaline solution due to ammonium carbonate4 ,organic carbon1 during this process1 is converted chiefly into carbon dioxid1 but small quantities of formic1 propionic1 and butyric acids are also produced4 ,any organic sulfur which is present is converted into acid4 ,no hydrogen or nitrogen is eliminated in a free state4 ,while slight alkalinity is favorable to the development of this bacterium1 yet it may be propagated in a feeble sulfuric acid solution when the acid is less than one per cent4 ,the greatest activity of this organism is manifested at #cj4 ,below #e and above #db no ammonia is produced4 ,the bacillus will not develop in an atmosphere of hydrogen or carbon dioxid1 except in solutions of organic matter and nitrate4 ,in addition to its action on egg albumen it decomposes other proteid bodies as well as leucin1 tyrosin1 creatin1 and asparagin4 ,it1 however1 does not oxidize urea1 nor does it develop in solutions of ammonium salts and nitrates1 except as mentioned above4 ,when soluble carbohydrates are present1 acids are formed4 ,it is concluded from these experiments that the final oxidation of organic nitrogenous matter is preceded by its conversion into ammonium carbonate4 #dah4 ,summary of ,statements4--,all nitrogenous matters which would be naturally present in the soil may become subject to nitrification when the proper conditions are supplied4 ,munro has also succeeded in nitrifying ethylamin1 thiocyanates1 and gelatin1 urea1 asparagin1 and the albuminoids of milk and rapeseed4 ,the products of nitrification are ammonia1 nitrous or nitric acid1 carbon dioxid1 and water4 ,the ammonia and nitrous acid may not appear in soils as the final products of nitrification1 as the nitric organism attacks the latter at once and converts it into nitric acid4 ,nitrous acid and ammonia may also be produced in soils as one of the retrograde steps in denitrification4 ,to summarize the conditions necessary for nitrification it may be said that first1 the proper material must be supplied2 viz41 an organic or inorganic nitrogenous compound capable of oxidation4 ,in the second place1 the medium must be faintly alkaline1 the temperature must not be too high1 the nitrifying organisms must have abundant food1 and the process must take place in the dark4 #dai4 ,order of ,oxidation4--,it is quite definitely determined that activity of the ammoniacal and nitrous organisms is the first step in the process1 since the nitric organism appears to have no power whatever to oxidize proteid compounds2 while1 on the other hand1 the nitrous organism can not1 in any case1 complete the conversion of nitrous into nitric acid4 ,the conditions which permit certain organisms to oxidize free nitrogen have not been definitely determined4 ,the presence of such bodies in the tubercles attached to the rootlets of certain leguminous plants has been established4 ,lately1 ,winogradsky has isolated from the soil a nitrifying organism which is capable of converting free nitrogen into forms suited to nourish plant growth4 ,this organism is cultivated in dextrose with careful exclusion of all nitrogen1 save that which exists in the air carefully freed of every trace of ammonia or oxidized nitrogen4 ,under the influence of the growth of this organism the sugar undergoes a butyric fermentation1 and nitrogen in an oxidized form is assimilated in an amount apparently equal to about one five-hundredth of the sugar consumed4 ,this result leads ,warington#bgg to remark that it is a fact of extraordinary interest1 both to the physiologist and chemist1 that a vegetable organism should be able to acquire from the air all the nitrogen it needs4 #dbj4 ,the ,nitrification of ,ammonia4--,the same organism which converts organic nitrogen into nitrous acid acts also on ammonia and its compounds with a similar result4 ,in fact1 the formation of ammonia may be regarded as one of the stages on the road from albuminoid to nitric nitrogen4 ,data have been collected by ,schloesing on the nitrification of ammonia taking place in arable soil1 tending to show that this phenomenon is accomplished without appreciable loss of nitrogen in the gaseous state4#bgh ,this1 however1 does not hold good when the quantity of ammonium carbonate introduced into the earth is largely increased4 ,in two experiments1 conducted by ,schloesing1 with a larger quantity of ammonium carbonate1 the loss of nitrogen was very notable4 ,in certain conditions the production of nitrous acid may take place1 and it is interesting to know whether the appearance of nitrites has any influence on the disengagement of free nitrogen4 ,in order to determine this question a solution of calcium nitrite was prepared by decomposing silver nitrite with calcium chlorid4 ,from the results of the experiments made it was seen that the nitrites were only the results of a retarded and partially incomplete nitrification4 ,they are1 moreover1 thus an obstacle to the normal work of the nitrifying organisms4 ,it is also established that when they are present a disengagement of gaseous nitrogen takes place1 whether the nitrites are formed during the progress of the experiment1 or whether they were originally present4 ,however1 it is not best to say that the nitrites themselves have been the cause of the disengagement of the nitrogen4 ,it may happen that the disengagement of the nitrogen and the presence of nitrites are simply simultaneous and due to one and the same cause4 ,the destruction of nitrates in the midst of reducing agents furnishes1 according to the nature of these bodies and the circumstances1 nitrous acid1 nitrogen dioxid1 nitrogen protoxid1 free nitrogen1 and even ammonia4 ,this destruction of nitrates and the appearance of oxids of nitrogen and of free nitrogen are more likely to be due to the presence of a separate denitrifying ferment as pointed out by ,springer than to have arisen in the manner mentioned above by ,schloesing4 ,in the present state of our knowledge1 moreover1 we can hardly regard the presence of nitrites as an obstacle to complete nitrification4 ,on the other hand1 it seems to be well established that the production of nitrites or ammonia is a necessary step between organic nitrogen and nitric acid4 #dba4 ,occurrence of ,nitrifying ,organisms4--,according to the observations of ,schloesing and ,mntz the nitrifying organisms are widely distributed4#bgi ,arable soil containing considerable humus seems to be the medium in which they grow most freely and in which they accomplish their most important functions4 ,sewage waters are also rich in nitrifying ferments1 and1 in fact1 all waters containing organic matter4 ,they are also found in running waters but not in great numbers4 ,they affect chiefly the surface of bodies1 and especially are found on the bottom of culture-flasks4 ,these authors have not found the nitrifying organisms in normal air4 ,they could not seed sterilized flasks by admitting air freely4 ,the absence of these ferments from the air is explained by reason of their sensitiveness to desiccation4 ,the method used by ,schloesing and ,mntz for the separation of the organism consisted in the preparation of original and subcultures in sterilized solutions containing nitrifiable matters4 ,the proof of isolation was assumed when a given subculture contained only one kind of organism as seen with the microscope4 ,the appearance of this organism1 as described by the authors1 was that of the later isolations by ,warington and ,winogradsky1 but the method used could hardly now be regarded as decisive4 #dbb4 ,determination of ,nitrifying ,power of ,soils4--,in studying the distribution of the nitrifying organisms in a soil the general method of procedure is based on the production of nitrification in a convenient solution by the organisms present in a given sample of soil4 ,if the solution seeded with the given portion of soil remain unaffected1 it will show that there were no nitrifying organisms present in the seed used4 ,on the other hand1 the vigor of the nitrifying process when once it is started1 may be taken as an evidence of the number and activity of the organisms in the soil1 a sample of which was used for seed4 #dbc4 ,composition of the ,culture ,medium4--,the solution recommended by ,warington for the culture and isolation of the nitrifying ferments has the following composition3 ,ammonium chlorid #hj milligrams4 ,sodium potassium tartrate #hj ,potassium phosphate #dj ,magnesium sulfate #bj calcium carbonate about #bjj ,pure bacteria-free water to make one liter4 #dbd4 ,apparatus and ,manipulation4--,the experiments are conducted in short1 wide-mouthed bottles4 ,the initial volume of the solution in each bottle is #ajj cubic centimeters1 and the bottle should be of such size as to give a depth of liquid of from three to five centimeters4 ,the neck of the bottle is closed with a plug of cotton and this is protected from dust by tying over it a cap of filter paper4 ,arranged in this way1 filtered air has free access to the solution4 ,the bottle with the solution thus protected is placed in a water-oven and kept near the temperature of boiling water for six to eight hours to destroy any organisms present4 ,when cool1 the solution is ready for use4 ,the calcium carbonate used should be prepared by precipitation and added in a moist state4 ,the calcium carbonate solution should be added after the sterilization of the liquid1 the precipitated carbonate being boiled just before it is added4 ,preparation of ,seed4--,the seed employed to start the nitrification should be a small quantity of fresh soil1 usually about one-tenth of a gram4 ,if a previously nitrified solution be used for seed it should be thoroughly shaken and about one cubic centimeter of the solution removed for seeding the new bottle4 ,in introducing the nitrifying liquor into the bottle the plug should be lifted slightly and a small pipette inserted by means of which the liquor is added4 ,the operation should be carried on in a room perfectly free from dust and to which no one but the operator has access4 ,the greatest care should be exercised to prevent any particles of matter entering the solution except that which is purposely added4 ,in withdrawing the liquor from the nitrifying solution cotton wool should be pressed around the top of the pipette so that the entering air may be filtered before admission to the interior of the bottle4 ,the pipette which is used should be kept in boiling water until it is required for use4 ,after use it should be washed and replaced in boiling water until again required4 ,after seeding1 the bottles should be placed in a dark cupboard and exposed to the ordinary temperature of the laboratory4 ,if a higher or stated temperature be desired1 the bottle should be placed in a metal box the temperature of which can be regulated to any degree4 ,test of the ,commencement of ,nitrification4--,the beginning of the nitrification can be determined in a solution by testing it with diphenylamin4 ,one cubic centimeter of the solution withdrawn as above indicated1 is placed in a small beaker1 a drop of solution of diphenylamin sulfate in sulfuric acid added1 and then two cubic centimeters of concentrated sulfuric acid and the contents of the beaker well shaken4 ,the development of a violet-blue color shows the presence of nitric or nitrous acid4 ,this test will detect one part of nitric nitrogen in twenty million of water4 ,determining the ,progress of ,nitrification4--,the progress of nitrification is determined by repeated examinations for ammonia by nesslerizing1 and for nitrous acid with metaphenylenediamin4 ,each experiment is made with five cubic centimeters of the solution withdrawn as above indicated and placed in test-tubes1 always of the same size4 ,the reaction with the nessler solution is then made by adding it in the usual way4 ,the colorations are recorded as1 trace1 small1 moderate1 considerable1 large1 and abundant4 ,if the change produced by the organism consisted in the formation of nitrites only1 the ammonia in the original solution would fall from large to trace1 while the nitrous acid would increase from trace to large4 ,if the nitrification consisted in the production of nitrates only1 the ammonia would diminish without any corresponding production of nitrous acid4 ,in mother solutions which contain ammonium carbonate instead of sulfate1 it should not be forgotten that the ammonia might gradually disappear owing to the volatilization of the carbonate without any corresponding production of free nitrites or nitrates4 ,the complete disappearance of the ammonia in the above experiments shows the completion of the process4 #dbe4 ,to ,determine the ,distribution of the ,nitrifying ,organism in the ,soil4--,the principle on which the determination of the distribution of the nitrifying organism in the soil depends1 rests upon seeding the growth solutions with samples of soil taken at different depths and carefully protected from the time of sampling until the time of seeding from any admixture of accidental organisms4 ,the method of ,warington is the simplest and best to follow4#bhj ,the samples of soil are taken by digging a pit of convenient depth usually from eight to ten feet4 ,a fresh surface is then cut on one of the sides of the pit at the spot selected for sampling4 ,this surface is scraped with a freshly ignited platinum spatula4 ,the spatula should then be washed1 re-ignited1 and cooled1 and a small portion of the soil1 at the depth required1 detached with the spatula and transferred at once into one of the growth bottles already described4 ,the growth solution best suited for the purpose contains four cubic centimeters of urine per liter4 ,each bottle should also contain some freshly precipitated calcium carbonate4 ,in sterilizing urine solutions the calcium carbonate should be added before the heating instead of afterwards4 ,the quantity of soil taken for each seeding should be about one-tenth of a gram4 ,inasmuch as the cotton stopper has to be lifted to introduce the soil1 opportunity is given for the entrance of any organisms floating in the air4 ,experience1 however1 has shown that air free from soil dust very seldom contains nitrifying organisms4 ,the seeded bottles are placed in a dark cupboard of moderate temperature as already described4 #dbf4 ,sterilized ,urine ,solution4--,the sterilized urine solution used for the determination of the distribution of the nitrifying organisms in the soil1 is made by taking four cubic centimeters of healthy urine1 diluting to one liter1 adding some freshly precipitated calcium carbonate1 stoppering with cotton wool and heating for several hours at the boiling temperature of water4 ,as a result of ,warington's experiments it was shown that the nitrifying organism in the soil did not exist1 at least in portions of one-tenth of a gram1 to a greater depth than eighteen inches4 ,in only one case was nitrification produced from a sample of soil taken at a greater depth and this may have been due to the accidental introduction of organisms from other sources4 ,it may be assumed that any long delay in the commencement of nitrification under favorable conditions1 implies the presence of a very limited quantity of organisms in the solution4 ,thus a comparative study of the period of incubation and the progress of nitrification in solutions seeded with soils taken at different depths or at different places1 becomes a fair index of the number and vitality of the nitrifying organisms contained therein4 #dbg4 ,depth to ,which ,micro-,organisms are ,found4--,koch states that at the depth of about one meter1 the soil is nearly free from every kind of bacteria4#bha ,these observations have been corroborated by ,pumpelly and ,smyth who find that no infection of a bacterial nature is produced in a sterilized solution from samples of clay taken at the depth of nine feet below the surface4#bhb ,it is evident from the nature of the experiments above described that the nitrifying processes go on almost exclusively in those portions of the soil which are subject to cultivation1 while in the subsoil and below the processes of nitrification are either retarded or arrested4 ,any stores of nitrogenous matter1 therefore1 in an insoluble state1 resting in the subsoil1 are preserved from oxidation and consequent waste until such time as they may be removed to near the surface4 #dbh4 ,isolation of the ,nitrous and ,nitric ,organisms in the ,soil4--,the action of the organisms which produce nitrification either in form of nitrites or nitrates1 having been thoroughly established1 and the method of testing the soil therefor given1 it remains to describe a method by means of which these organisms in the soil may be isolated and obtained in a state of purity4 ,the difficulties attending this process are extremely great on account of the similarity of the two organisms4 ,all earlier attempts to make pure cultures of the two separate organisms were attended with but little success4 ,according to ,winogradsky the method of culture on gelatin so long practiced is not to be relied upon4#bhc ,it is very difficult to eliminate by this process the organisms which grow rapidly in gelatin and which mature their colonies in two or three days1 but where they require eight or ten days to produce a colony the method is successful4 ,in fact1 by the gelatin process as it was at first practiced1 a good deal was owing to chance1 but sometimes by a happy accident a pure nitro-bacterium might be isolated4 ,formerly it was considered that a liquid could be regarded as sterile if it gave no growth upon gelatin4 ,it has1 however1 now been demonstrated that a liquid may contain large numbers of nitro-bacteria and still produce no growth upon gelatin4 ,however1 for the organisms which accompany the nitro-bacteria in soils1 it is regarded as certain that if no growth on gelatin is produced by them they are absent4 ,therefore in the case of a solution which has been seeded with a soil1 if it can be brought to such a state as to produce no growth on gelatin1 it may be safely assumed that it contains no bacterial organisms save those which are capable of producing nitrites or nitrates4 ,therefore if such a solution produce nitrification and at the same time no growth upon gelatin1 it may be considered as a proof of the isolation of the nitro-organisms from all others4 ,this method was also worked out independently by ,mr4 and ,mrs4 ,frankland4#bhd ,winogradsky says further he confesses that he has advanced these views only provisionally and without being convinced of their infallibility4 ,strictly speaking1 the proof of seeding gelatin is not sufficient alone because the absence of growth can not be regarded as the exclusive privilege of the nitro-bacteria4 ,such might be the case sometimes for an accidental mixture of microbes1 introduced with any given sample of soil into the cultures1 but the criterion is not absolute4 ,microbes1 for example1 of a sulfurous or ferruginous nature may be cited1 for which the gelatin layer is not only unfavorable but even fatal4 ,it may thus happen that there may be eliminated from the solution all that will grow upon gelatin without freeing it from some special kinds of cultures1 refractory like the nitro-bacteria1 but which might reappear if they should be resown in some favorable nutritive solution4 ,on account of this fault in the process1 ,winogradsky has been impressed with the necessity of bringing out a better method4 ,in using the gelatin media it is necessary to find the one that is suited to nourish these organisms1 which would evidently be the way promising the greatest success4 ,this having been found1 and those organisms which produce colonies being easily recognizable1 a great step towards the solution of the problem will have been made and the more so as the medium would be at the same time absolutely unfavorable to other forms of microbes4 ,on account of the slow degree of development of the nitro-organisms1 all others would probably have opportunity to grow and strengthen to their exclusion1 unless these interfering organisms could be completely removed4 #dbi4 ,the ,culture ,solution4--,the culture-solution1 first proposed by ,winogradsky1 had the following composition3 ,to ten grams of gelatin or one part of agar-agar in #ajj cubic centimeters of water add potassium phosphate1 one-tenth of a gram2 magnesium sulfate1 five-hundredths of a gram2 calcium chlorid1 trace2 and sodium carbonate1 half a gram4 ,the solution being sterilized in the usual way by heating1 there are added to it a few cubic centimeters of a sterilized solution containing two-tenths per cent of ammonium sulfate4 ,such a solution has been proved to be very favorable to nitro-organisms4 ,nevertheless the experiments with such solutions gave no definite results and they were abandoned4 ,the non-success of this method led ,winogradsky to adopt a nitrifying solution which absolutely excluded all organic substances4 ,instead of using an animal or vegetable gelatinous substance he used one of a mineral nature1 first proposed by ,graham and ,khne4#bhe ,two of these gelatinous mineral substances were considered2 viz41 the aluminum hydroxid and the hydrate of silica4 ,the latter was chosen4 #dcj4 ,preparation of the ,mineral ,gelatinous ,solution4--,the soluble glass which is found in commerce is generally of a thick1 sirupy consistence4 ,it is first diluted with three times its volume of water4 ,one hundred cubic centimeters of this liquid are poured with constant stirring into fifty cubic centimeters of dilute hydrochloric acid and the mixture placed in a dialyzer4 ,it is useless to employ a standard solution of silica4 ,all that is necessary is to submit to dialysis a liquid with an excess of acid and sufficiently dilute not to be exposed to the danger of being spontaneously gelatinized in the dialyzer4 ,the dialyzer is left for one day in running water and two days in distilled water1 often renewed4 ,the solution is then ready for use4 ,this is the case when it is no longer rendered turbid on the addition of silver nitrate1 showing that the hydrochloric acid has been entirely extracted4 ,the solution is then to be sterilized by boiling1 and preserved in a glass flask closed with a plug of cotton4 ,more recent instructions by ,winogradsky for preparing the gelatinous silica recommend dialyzing the soluble glass after treatment with hydrochloric acid in a parchment tube4#bhf ,the proportions of silicate and acid are #ajj cubic centimeters of the silicate solution 7#a4jf specific gravity7 and #ajj cubic centimeters of hydrochloric acid 7#a4a specific gravity74 ,with a dialyzing tube placed two days in running water and one day in distilled water frequently changed it will be found that the acid is completely removed4 ,one hundred cubic centimeters of the residual liquor giving no reaction for hydrochloric acid are concentrated to twenty cubic centimeters4 ,when cold there is added one cubic centimeter each of a solution of ammonium sulfate and of sodium carbonate1 together with corresponding quantities of the other nutrient salts commonly employed4 ,the ammonium sulfate should never exceed two to two and a half1 and the sodium carbonate four parts per thousand4 ,to the flask containing the above substances is added one drop of the seed-liquor1 which may be a soil water or a drop from some previous culture4 ,the flask is shaken and the mixture poured into a low circular glass dish which is covered by one slightly larger in diameter 7,petri double dish74 ,to the liquid in the dish is added a drop of a cold saturated solution of common salt1 and it is then stirred with a platinum spatula4 ,the addition of the salt greatly favors the setting of the jelly4 ,the jelly may set in from two to three hours1 but a longer time secures better results in the end4 ,in employing these preparations as seed1 after the organisms have grown1 it is absolutely necessary to use the isolated cellules and not the aggregated masses 7zogl74 ,the latter are rarely free of foreign germs which adhere to their gelatinous envelope4 ,since the zogl can not be broken up by any artificial means it is necessary to await their spontaneous disintegration in order to separate the mobile monads4 ,the opalescence of the culture-liquid is a sure index of this separation4 ,the particles of mineral gelatin to be used as seed for nitrifying are best taken as follows3 ,a glass tube is drawn out immediately preceding the operation1 until the end is as fine as a hair4 ,the surface of the mineral gelatin is magnified by means of a dissecting microscope magnifying #hj to #ajj1 to the proper degree and the preparation table is so arranged as to give a perfect support to the right hand which should hold the filament of glass4 ,the smallest colony is then pricked with the needle and the end of the glass is broken and dropped into the flask which is to be seeded4 ,the seed is thus selected in as small a particle as may be desired1 only a few cells1 but it can always be ascertained with certainty that some of the particles have been obtained by this operation4 ,the method of cultivation on mineral jelly is considered by ,winogradsky an important resource in the study of the nitrifying organisms4 ,it removes the chief difficulties heretofore existing in discovering and characterizing these organisms among the innumerable micro-organisms of the soil4 ,the long series of cultures necessary to separate the organisms are rendered nugatory4 ,by directly introducing a little of the earth into the silicic jelly the active organisms in nitrification can be at once discovered4 ,it is preferable1 however1 as indicated below1 to previously produce a nitrification in an aqueous solution by a trace of earth and to take from it the seed for impregnating the solid medium4 ,in order to show at once a proof of its nitrifying character1 it is only necessary to take a small bit of the mineral jelly1 the size of a grain of rye1 and to throw it into a little sulfuric acid which has been treated with diphenylamin4 ,there is at once formed a blue spot equal in intensity to a saturated solution of anilin blue4 ,in regard to the growths which nitro-organisms make in a medium of the kind described1 they are far from being so marked as are those produced by ordinary micro-organisms4 ,a nitro-bacterium is not capable of the energy of growth which is recognized for the greater number of microbes4 ,the colonies contained in the gelatin always remain small4 ,the largest among them are just visible to the naked eye like white points4 ,along the striae1 on the contrary1 there is formed quite a thick white crust4 ,to the naked eye1 in general1 there is nothing very characteristic in the formation of colonies in a medium of this nature4 ,but this impression changes altogether when the placques are examined with a low magnifying power4 ,the colonies1 especially those of the interior surface1 reveal then an aspect so curious as to be well remembered when once seen4 ,this mineral gelatin1 as has already been noticed1 is very unfavorable to the growth of microbes other than nitro-bacteria and becomes altered only under the action of the air4 ,if the placques be carefully preserved from desiccation the culture of these organisms can be continued for several weeks4 ,although they do not seem to increase1 the colonies1 as well as the jelly1 are still in a good condition at the end of that time4 ,nevertheless the expectation that this medium would prevent the formation of any foreign organism has not been realized4 ,some of the organisms which accompany the nitro-bacteria in soil1 also grow upon the silicic jelly2 but they do not form colonies1 properly so-called1 and their growth is extremely slow4 ,they generally make their appearance before the nitro-bacteria and spread exclusively upon the surface in form of white spots1 so transparent that without careful examination they would not be discovered4 ,having reached a certain size the spots do not change during entire weeks4 ,this circumstance renders the operations of isolation somewhat delicate1 but does not prevent them4 #dca4 ,preparation and ,treatment of the ,solution to be ,nitrified4--,the organisms having been grown on the siliceous gelatin in the manner described they are tested for their nitrifying power as follows3 ,the mineral solution which is to be nitrified with the above preparation is composed of ammonium sulfate1 four-tenths gram2 magnesium sulfate1 half a gram2 potassium phosphate1 one-tenth gram2 calcium chlorid1 trace2 sodium carbonate1 six-tenths to nine-tenths gram2 and distilled water1 #ajj cubic centimeters4 ,the sulfates with the calcium chlorid on the one hand1 and the phosphate and carbonate on the other1 are dissolved separately and the two solutions sterilized separately and mixed after cooling4 ,the seeding is then done as described above4 #dcb4 ,isolation of the ,nitrous and ,nitric ,organisms4--,instead of proceeding immediately to the isolation of special organisms in the soil1 the preliminary period of purification is prolonged by ,winogradsky by allowing the free growth to take place of all the organisms which can be maintained in the ordinary medium4#bhg ,the composition of the culture solution employed is as follows3 ,distilled water1 #a1jjj parts2 potassium phosphate1 one part2 magnesium sulfate1 half a part2 calcium chlorid1 trace4 ,each flask receives besides this some magnesium carbonate1 freshly washed with boiling water and added in slight excess4 ,the flasks thus charged are sterilized1 and after sterilization there are added two cubic centimeters of a solution of two per cent of ammonium sulfate1 which1 when added to fifteen or twenty cubic centimeters of liquid give from two to two and a half parts per thousand4 ,they are then seeded with soil4 ,the reasons for this preliminary treatment are as follows3 ,first1 all the observations upon the enfeeblement of the oxidizing power of these organisms have been made upon cultures seeded simply by the fresh soil1 and in cultures derived therefrom4 ,in the second place1 the existence of the two forms1 one nitrous and the other nitric1 prevents at once the isolation of a single organism4 ,samples of soil from ,europe1 ,africa1 ,asia1 ,australia1 and ,america1 were used for seed for the experiments4 ,first1 the cultures were made by seeding with a small quantity of each of these samples of soil1 and each one of these cultures served as a point of departure for a series of subcultures4 ,the temperature of the cultures should be kept constantly at #cj4 ,the method of following the nitrification adopted by ,winogradsky is essentially that of ,warington1 the percentage of ammonia remaining at any time being determined by nesslerizing4 ,to detect the presence of nitric acid the nitrous acid is decomposed by boiling with ammonium chlorid in excess1 or with urea1 and then diphenylamin is used as a reagent4 ,by treatment with ammonium chlorid and boiling1 the ammonium nitrite is resolved into free nitrogen and water as indicated by the equation ,,nh,,no ,n #b;,h,o4 ,or the total oxidized nitrogen may be estimated by the ,schloesing method or by any of the standard methods hereafter given4 ,the nitrous acid is then determined by potassium permanganate and the nitric acid by difference4 ,a great difference is to be noted between freshly taken earth and that which has been kept for a long while1 especially when sealed4 ,with fresh earth taken near the surface a mere trace is sufficient to produce nitrification4 ,with samples of earth which have been kept for a long while and thoroughly dried1 several grams must be added in order to secure perfect nitrification4 ,the period of incubation with the samples of earth ranges from three to twenty days4 ,the beginning of the phenomenon is revealed by the appearance of nitrous acid1 of which the quantity is increased very rapidly1 but in the end it disappears and is transformed into nitric acid4 #dcc4 ,statement of the ,results4--,the method of stating the results of examination of soils for nitrifying organisms is illustrated by the following example3 ,soil from ,zurich4 ,the culture was seeded on the #aath of ,october1 one gram of soil being taken4 ,on the #bjth of ,october the nitrous acid had reached its maximum of intensity and there was no ammonia left4 ,on the #bith of ,october the nitrous acid remained almost stationary and there was hardly any nitric acid present4 ,on the #ast of ,november the reaction for nitrous acid began to decrease4 ,on the #eth of ,november the reaction for nitric acid was very intense4 ,on the #aath of ,november the nitrous acid had all disappeared except a mere trace4 ,the above order of phenomena was observed with all the samples of soil tried1 from which it is concluded with certainty that nitrifying organisms transplanted directly from their natural medium in the soil into a liquid easily nitrifiable produce at once nitrous acid in abundance4 ,the phenomenon of nitrification is divided into two periods therefore1 of which the first is devoted to the production of nitrites1 and the second consists in the oxidation of the nitrites1 and this does not commence until the total disappearance of the ammonia4 ,occasionally the formation and oxidation of the nitrites practically go on together1 but never equally1 the oxidation of the nitrites being always sensibly behind their formation4 #dcd4 ,method for ,subcultures4--,from the mother cultures described above1 ,winogradsky makes subcultures as follows3 ,the solution to be nitrified is prepared as in the mother cultures4 ,the seeding is accomplished by adding a small quantity of the liquor of the mother culture after shaking4 ,subcultures can be made in this way to the seventh generation4 ,in respect of the oxidation of the nitrites the results may be entered as negative if they have not disappeared at the end of two months4 ,to determine whether the process of oxidizing the nitrites is in progress or not the total nitrous acid is estimated1 and the process repeated at the end of eight or ten days4 ,should there be no diminution of the nitrous acid within this time it may be considered that the further oxidizing action is not taking place4 #dce4 ,use of a ,solid ,medium4--,it may be justly claimed that the action of nitrifying organisms in a liquid is not to be compared with their action in a solid medium1 such as a soil which is their natural habitat4 ,it might be1 therefore1 that the inability of the nitrous organism to produce nitrates is due to the nature of the medium in which it is cultivated4 ,winogradsky in order to determine this question cultivated the organism in a solid medium of two kinds1 first a silicate gelatin impregnated with an ammonium salt and second in sterilized earth4 ,the silicate jelly is prepared as follows3 ,mix a jelly of silica containing some ammonium sulfate with sterilized soil4 ,the seeding is done with one of the subcultures which no longer has the power of producing nitrates4 ,in the case of the jelly the seeding is accomplished as follows3 ,a minute drop of a culture liquid is taken with a capillary glass tube and applied in striae to different parts of the solid jelly2 or a minute drop of the culture liquid may be mixed with the jelly before solidification4 ,the ,petri dishes in which these cultures are made can be preserved in a moist atmosphere and thus the desiccation be easily prevented for a long time4 ,from time to time small pieces of the jelly as large as a pea can be taken and tested for the progress of nitrification4 ,results4--,the nitrous reaction1 both in the prepared jelly and in sterilized soil1 will appear in a few days4 ,at the end of from seven to twelve days it will have attained its maximum intensity and will then remain stationary indefinitely4 ,sterilized soil has no power to generate the nitric from the nitrous ferment4 ,the two organisms are1 therefore1 of different species4 ,after a few generations the power of producing nitrates seems to be lost although the nitrous ferment may still be active4 ,this suppression of the power to oxidize the nitrites is not due to any pernicious influence of the culture-medium but to the condition of the successive solutions at the time of taking the seeding samples4 #dcf4 ,microscopic ,examination4--,a small particle of the deposit in the culture-liquid is spread on a glass slide and dried4 ,there is then added a drop of very dilute perfectly transparent malachite green solution4 ,malachite green is ,bittermandellgrn1 or tetramethyldiamidotriphenylcarbinol4 ,use the zinc chlorid double salt or oxalate4 ,in about half a minute it is washed and colored by a very dilute solution of gentian violet which is left to act for some time4 ,the cells then appear distinctly colored on a colorless background4 ,in examining in this way nitrous cultures under a moderate enlargement there are seen particles of material covered with scattered groups and massive zogl composed of cells which are1 doubtless1 identical4 ,by their round or roundish forms1 by their relative size and especially by their numbers and uniformity they are at once distinguished from the other vegetations which are generally of a purely bacillus shape4 ,with the exception of some shreds of mycelium coming from some oidium in the soil the microscope reveals nothing but the organisms described4 ,the microscopic appearance#bhh of the nitrous ferment is shown in ,fig4 #fi4 ,illustration3 ,figure #fi4 7,upper figure47 ,nitrous ferment prepared by ,winogradsky from soil from ,cito4 ,figure #gj4 7,lower figure47 ,nitric ferment prepared by ,winogradsky from soil from ,cito4 ,the general conclusions of ,winogradsky are3 #a4 ,each soil possesses but one organism capable of oxidizing ammonia4 #b4 ,soils from one locality have always the same kind of nitrifying ferment4 #c4 ,soils from different and distant countries contain nitrifying organisms which differ from one another in some respects so much so that it may be necessary to distinguish a few species or even genera in these bodies4 #dcg4 ,isolation of the ,nitric ,ferment in ,soils4--,the principle of the separation of this ferment as described by ,winogradsky rests upon the fact that in culture solutions of a mineral nature free from ammonia the nitrous ferment will not grow1 whereas if nitrite or nitrous acid be present the nitric ferment will grow4#bhi ,in a few generations1 therefore1 the nitrous ferment will be entirely eliminated4 ,solution employed3 ,distilled water #a1jjj grams4 ,potassium phosphate #a gram4 ,magnesium sulfate #j4e ,calcium chlorid trace4 ,potassium nitrite #j4bb gram4 ,to culture-flasks containing #ajj cubic centimeters of the above mixture after sterilization about one-tenth gram of fresh soil is added4 ,in favorable conditions the nitrous acid will disappear in about fifteen days4 ,subcultures are made by seeding fresh portions of the sterilized solution with one or two cubic centimeters of the mother culture4 ,the operation is continued until the nitrous ferment is eliminated4 ,the organisms in the deposit in the culture-flasks are then subjected to microscopic examination in the manner already described for the nitrous ferment2 or proceed as follows3 #dch4 ,culture on ,solid ,media4--,take a liquid which has been employed in the culture of a nitrous ferment and evaporate to one third of its bulk4 ,gelatinize the residue by adding double its volume of the silicic acid solution prepared as already directed4 ,the jelly is placed in the glass vessels usually employed4 ,the seeding may be done with a few drops of a culture-liquid containing the nitric ferment as obtained above4 ,the first reaction will appear in from eight to ten days4 ,in about forty-five days the nitrous acid in the jelly will have entirely disappeared4 ,two classes of colonies are noticed under the microscope4 ,the first to appear are small colonies which never extend beneath the surface of the jelly4 ,in cultures seeded with these colonies there is no oxidation of nitrous acid4 ,the second class of colonies extends into the interior of the jelly4 ,they are much larger than the first1 of a yellowish-gray color and not spherical but rather lenticular in shape4 ,cultures seeded with these colonies will lose their nitrous acid in about ten days or two weeks4 ,the growth of these organisms in a liquid scarcely merit the name of cultures4 ,the naked eye can usually distinguish no form of vegetation4 ,the liquid remains clear1 the surface is free from any film1 no flocks are deposited4 ,colored and examined in the microscope the organisms found are so puny as to make doubtful their oxidizing power4 ,there is an apparent contradiction between the powerful chemical action that these organisms can produce and their apparent deficiency in physical properties4 ,these organisms are best found by cultivating them in a very limpid solution4 ,the bottoms of the culture boxes will be found covered with an extremely tenuous gelatinous deposit communicating to the glass a feeble grayish-blue tint4 ,the culture bottle is inclined and the bottom scratched with a recently drawn-out capillary tube4 ,the colonies rise in the tube together with a little of the liquid4 ,the colonies are dried1 mounted1 and colored as already described and when examined with the microscope are found to be composed exclusively of masses of an organism of extreme minuteness4 ,the organism remains attached so firmly to the bottom of the culture bottle that it can be washed several times with pure water without danger of detachment and thus rendered more pure4 ,in old cultures which are sustained by new additions of nitrite an extremely transparent pellicle on the bottom of the flask can be distinguished4 ,by shaking the liquid some fragments may be detached and made to float through the fluid4 ,with a little care and patience these flocks can be captured1 mounted1 and colored4 ,since they show the nitric organism in its natural state their preparations are of the greatest interest4 ,the best preparations are made by coloring with malachite green and gentian violet and then coloring again hot with magenta4 ,afterwards the preparation is washed with warm water at #ej-fj which takes almost the whole of the color from the gelatinous matter4 ,the cells are then clearly presented colored a reddish violet on a rose background4 ,these organisms#bij are shown in figure #gj4 ,the figure shows the cells united by a gelatinous membrane and grouped in small dense masses composed often of a single layer of organisms4 ,the cells are generally elongated1 rarely regularly spherical or oval4 ,their mean length does not exceed half a micromillimeter and their thickness is from two to three times less4 ,the difference in form of the nitrous and nitric ferments is very marked and leaves no doubt of the existence of these two forms which are as distinct as could be desired in microbic discrimination4 #dci4 ,dilution ,method of ,warington4--,the method pursued by ,warington in preparing pure cultures of the nitrifying ferment is based on the well-known principle of dilution which may be expressed as follows3#bia ,in a liquid containing bacterial ferments dilution may be practiced until a drop of the liquid may be taken which will contain no more than a single organism of any one kind4 ,if now proper solutions be seeded with single drops of this solution1 some of them may give colonies of pure cultures of any given organism4 ,the solution to be nitrified employed by ,warington had the following composition3 ,water #ajjj parts4 ,ammonium carbonate #j4be ,ammonium chlorid #j4ej ,potassium phosphate #j4jd ,magnesium sulphate #j4jb ,calcium sulphate #j4jb ,the ammonium chlorid is added to prevent the precipitation of magnesium and calcium phosphates4 ,the solution is kept in wide-mouthed1 stoppered bottles to prevent the loss of ammonium carbonate1 the bottles being only half full4 ,about #ajj cubic centimeters are taken for each experiment4 ,these bottles are sterilized and seeded with fresh soil in the ordinary way4 ,they are then covered with paper caps and placed in a dark cupboard at a constant temperature of #bb4 ,special ,media4--,a quantity of arable soil is exhausted of nitrates by washing with cold water under pressure4 ,the soil is then boiled with water and filtered4 ,the clear amber-colored solution obtained may be used instead of water in the above formula4 ,solid ,media4--7#a7 ,ordinary ten per cent gelatin made with beef broth and peptone4 7,p7 7#b7 ,a ten per cent urine solution solidified with six per cent of gelatin4 7,u7 7#c7 ,a solution of one gram of asparagin1 one-half gram sodium acetate1 one-half gram potassium phosphate1 two-tenths gram magnesium sulfate1 two-tenths gram calcium sulfate1 and one liter of water solidified with six per cent gelatin4 7,as7 ,other solid media may also be employed for the purpose of favoring1 as much as possible1 the growth of the nitrifying organisms4 ,the first culture in the ammonium carbonate solution given above1 is always made by seeding with a little unmanured arable soil4 ,subcultures are seeded from this mother culture by seeding new solutions with a few drops of the original4 ,in all cases tried by ,warington the subcultures produced only nitrous fermentation while the original cultures produced the nitric fermentation4 #ddj4 ,microscopic ,examination4--,the microscopic examination of the organisms formed is conducted as follows3 ,the cover glasses for microscopic objects are placed at the bottom of the culture-flask1 the cover glasses being previously sterilized4 ,at the end of the nitrification the liquid is removed with a pipette and the flask containing the cover glasses dried at #ce4 ,the cover glasses are then removed and stained4 ,the microscopic appearance of the organisms obtained by the previous cultures showed masses of corpuscles usually of oval shape and having a length generally exceeding one micromillimeter4 ,an immersion objective giving a magnification of #hjj diameters is suitable for this work4 ,other forms of organisms are also met1 the whole series being characterized as follows3 7#a7 ,the corpuscles already mentioned4 ,larger ones are frequently rough in outline resembling masses of siliceous sea-sand4 ,the smaller oval corpuscles are regular in form4 7#b7 ,some very small circular organisms often appearing as mere points and staining much more plainly than the preceding4 7#c7 ,a few slender bacilli1 staining faintly4 ,all the cultures obtained by the above method give abundant growth on gelatin4 #dda4 ,trials with the ,dilution ,method4--,one part of the third subculture in the ammonium carbonate solution described above1 is mixed with #ejj parts of thoroughly boiled water and one drop from a sterilized capillary tube is added to each of five bottles containing the sterilized ammonium carbonate solution4 ,in ,warington's experiments one of the five bottles was found to have nitrified after forty-one days4 ,after ninety-one days two more were nitrified4 ,two bottles did not nitrify at all4 ,all three solutions which nitrified gave growths on gelatin4 ,the growths took place more speedily on gelatin ,u and ,as than on ,p4 ,the organisms obtained on gelatin were seeded in appropriate liquid media but no nitrification was obtained4 ,a subculture from solution ,no4 #b of the first dilution mentioned above1 was diluted to one one-thousandth1 one ten-thousandth1 one one-hundred-thousandth1 and one one-millionth4 ,each of these dilutions was used for seeding with five sterilized solutions of ammonium carbonate1 using the method of seeding above described4 ,at the end of #aij days not one of these solutions had nitrified4 ,warington supposed that the cause of failure in the method just mentioned might be due to the alkalinity of the ammonium carbonate4 ,while this solution could be seeded in the ordinary way with fresh earth it might be that the faint alkalinity which it presented might prevent it altogether from action when the nitrifying agent was reduced to a few organisms4 ,he therefore changed the solution to one of the following composition3 ,water #a1jjj parts4 ,ammonium chlorid #j4jb part4 ,potassium phosphate #j4jf ,magnesium sulfate #j4jc ,calcium sulfate #j4jc ,the solution was divided in twenty stoppered bottles which were half filled4 ,the bottles were divided into four series1 ,a1 ,b1 ,c1 ,d1 each one consisting of five bottles1 and these were respectively seeded with one drop from dilutions to one one-thousandth1 one ten-thousandth1 one one-hundred-thousandth1 and one one-millionth of a second subculture of ,no4 #c in the first dilution series4 ,after #aae days1 nitrification had occurred in ten of the bottles4 ,the other ten did not nitrify at all4 ,each of the nitrifying solutions was spread on gelatin1 ,p and ,u being employed4 ,growth took place far more easily on gelatin ,u than on gelatin ,p4 ,of the ten nitrified solutions there were three which gave no growth on gelatin ,u1 either when spread on the surface or introduced into the substance of the jelly4 ,there were therefore secured nitrifying solutions which did not contain organisms capable of growing on gelatin4 ,the supposition is therefore fair that they were pure nitrifying organisms4 ,these fresh1 pure organisms had the faculty of converting ammonia into nitrous acid only and not into nitric acid4 ,with the organisms thus prepared a number of solutions of potassium nitrite containing phosphates and other mineral ingredients were seeded4 ,in no case was any loss of nitrite found1 which is proof that the solution contained no organisms capable of oxidizing nitrous acid4 ,the organisms prepared as above1 have the power of nitrifying organic substances containing nitrogenous bodies4 ,the organism isolated as described and examined under the microscope is seen to contain two forms4 ,the first one is nearly spherical in shape1 the corpuscles varying in size from mere points to a diameter of one micromillimeter4 ,the form is very striking and easily stained4 ,the second form is oval-shaped and attains a length distinctly exceeding one micromillimeter4 ,sometimes it is a regular oval and sometimes it is egg-shaped4 ,this form is stained less easily than the preceding or spherical form4 #ddb4 ,method of ,staining4--,the method of staining employed is as follows3 ,a drop of the culture-liquid is placed on a glass slide and mixed with the filtered stain by means of a wire4 ,a cover glass is placed on the drop and allowed to stand for half an hour4 ,it is then pressed down on the slide and the liquid which exudes wiped off and hollis glue run around the cover glass4 ,in this way the organism is stained in its own culture-fluid and can be seen in its true form without any possibility of the destruction of its shape by drying4 ,the plate is bright and clear though colored4 ,if the preparation is to be mounted in balsam a drop of the culture is dried in the center of a cover glass4 ,it is then placed for some minutes in dilute acetic acid to remove matter which would cause turbidity4 ,the cover glass with its contents is then washed1 dried1 and stained for some hours in methyl violet4 #ddc4 ,classification of ,nitrifying ,organisms4--,the names proposed by ,winogradsky for the various organisms are the following3 ,for the general group of microbes transforming ammonia into nitric acid1 ,nitro-bacteria4 ,for the nitrous ferments of the ,old ,world ,genus1 ,nitrosomonas3 ,species1 ,nitrosomonas europaea4 ,nitrosomonas javanensis4 ,for the nitrous microbes of the ,new ,world3 ,genus1 ,nitrosococcus4 ,species1 not determined4 ,for the nitric ferment3 ,genus1 ,nitrobacter4 #ddd4 ,nitrification in ,sterilized ,soil4--,the process of nitrification in sterilized soil1 when seeded with pure cultures1 is determined as follows3 ,preparation of ,sample4--,the fresh sample of arable soil is freed from pebbles and vegetable dbris and reduced to as fine a state of subdivision as is possible in the fresh state4 ,it is placed in quantities of about #hjj grams in large crystallizing dishes4 ,one dish is set aside for use in the natural state1 and the other1 hermetically closed1 is placed in a sterilizing apparatus and subjected to the action of steam for two and a half hours4 ,this treatment is repeated three times on as many successive days4 ,seeding of ,sample4--,each of the two dishes is moistened with fifty cubic centimeters of pure water containing #ejj milligrams of ammonium sulfate4 ,the sterilized portion is then seeded with a preparation of the pure nitrous ferment1 produced as before described4 ,the seed is prepared by filtering a few cubic centimeters of the nitrous culture liquid through asbestos4 ,the asbestos is well washed and then thrown into a flask containing a few cubic centimeters of sterilized water and well shaken4 ,the water carrying the filaments of asbestos is poured drop by drop on the surface of the soil in as many places as possible4 ,the two dishes of soil are kept at an even temperature of #bj in a dark place4 ,winogradsky found that1 treated in this way1 the unsterilized soil produced only nitrates1 while the sterilized portions produced only nitrites4#bib #dde4 ,variation of the ,determinations4--,to vary the conditions of the experiment ,winogradsky uses twelve flasks of the erlenmeyer shape1 four having bottoms twelve centimeters in diameter1 and eight of them five centimeters in diameter4 ,in each of the four large flasks are placed #ajj grams of fresh soil1 and in each of the eight small flasks twenty-five grams4 ,the eight small flasks are designated a1 b1 c1 d1 and a1 b1 c1 d1 and the four large flasks ,a1 ,b1 ,c1 ,d4 ,the flasks a1 b1 c1 d1 and a1 b1 c1 d1 are placed in a stove at #cj for several days before use1 while ,a1 ,b1 ,c1 and ,d1 are kept at #bb-bc for the same length of time4 ,the soil in the small flasks is1 therefore1 somewhat drier than that in the large ones4 ,the flasks are treated as follows3 a1 a1 ,a1 contain the soil as prepared above for control4 b1 b1 ,b1 are sterilized at #ace and seeded with a drop of the pure nitrous culture4 c1 c1 ,c1 sterilized as above and seeded with a little of the unsterilized earth4 d1 d1 ,d1 sterilized as above and seeded with pure nitrous and pure nitric cultures4 ,after sterilization there was added to the small flasks two cubic centimeters of a twenty per cent sterilized ammonium sulfate solution1 and to the large ones six cubic centimeters4 ,at the end of a month or six weeks the contents of the flasks are thrown on a filter and washed with cold water until a drop of the filtrate gives no blue color with diphenylamin4 ,the respective quantities of nitrite and nitrate are then determined in the filtrates by the usual processes1 which will be fully described further along4 #ddf4 ,sterilization4--,one of the chief requisites for success in the bacteriological investigation of soils is found in the thoroughness of the sterilizing processes4 ,the value of cultures depends chiefly on the care with which the introduction of foreign germs is prevented4 ,in the following description a mere outline of the method of sterilization is presented1 while those who wish to study more carefully the details of the process are referred to the standard works on bacteriology4 #ddg4 ,sterilization of the ,hands4--,it is important that the hands of the operator handling apparatus and materials for bacteriological work should be sterilized4 ,the sterilization may be accomplished in the following way3 ,the nails should be cut short and thoroughly cleaned with soap and brush4 ,the hands are thoroughly washed in hot water with soap4 ,after washing in hot water the hands should be washed in alcohol and ether4 ,they are then dipped in the sterilizing solution4 ,this liquid may consist of a three per cent solution of carbolic acid1 which is the one most commonly employed4 ,a solution of corrosive sublimate1 however1 is perhaps the best disinfectant4 ,it should contain from one to two parts of the crystallized salt to #a1jjj parts of water4 ,it has lately been advised to use the sublimate in an acid solution4 ,acetic acid or citric acid may be employed1 but hydrochloric acid is recommended as the best1 in a preparation of one-half part per #a1jjj4 ,for stronger solutions of sublimate containing more than a half per cent1 equal quantities of common salt should be added4 ,the solution should be made with sterilized water4 ,after dipping the hands in the sterilizing solution they should be dried with a napkin taken directly from a sterilizing oven1 where it has been kept for some time at the temperature of boiling water4 ,where only ordinary work in bacteriology is contemplated this sterilization of the hands is not necessary4 ,it is practiced chiefly in antiseptic surgery4 #ddh4 ,sterilizing ,apparatus4--,with platinum instruments the most effective and easiest way for sterilizing is to hold them in the flame of a bunsen until they are red hot4 ,steel and copper instruments can not be treated in this way without injury4 ,they are best sterilized by submitting them to dry heat in a drying oven at a temperature of #aej-afj for two hours4 ,glass and porcelain apparatus can be sterilized best in the same way4 ,all apparatus and materials employed should be used in a space as free as possible from dust1 so that any germs which might be carried in the dust can be excluded from the apparatus in transferring it from one place to another4 #ddi4 ,methods of ,applying ,heat4--,sterilization by means of heat may take place in several ways4 ,first4 ,submitting the ,materials to ,dry ,heat ,without ,pressure4--,the temperature in sterilization of this kind may vary from the temperature of boiling water at sea-level to #afj obtained by an oil-bath or by an air-oven4 ,second4 ,sterilization in a ,liquid ,under ,pressure4--,this form of sterilization may be effected by sealing the liquid in a strong vessel and submitting it to the required temperature4 ,if the temperature required be greater than that of boiling water the vessel can be immersed in a solution of some mineral salt which will raise the boiling-point4 ,third4 ,sterilization in ,steam ,under ,pressure4--,this method of sterilization consists in placing the body in a proper receptacle in vessels to which the steam can have access and then admitting steam from a boiler at any required pressure4 ,in the case of small apparatus1 such as the autoclave1 the steam can be generated in the apparatus itself4 ,the variety of apparatus used in the above method of sterilization is very great1 but all the forms of apparatus employed depend upon the principles indicated4 #dej4 ,the ,sterilizing ,oven4--,the apparatus for sterilization by means of hot1 dry air usually consists of a double-walled vessel made of sheet-iron1 usually with a copper bottom4 ,the apparatus is shown in ,fig4 #ga4 ,the temperature is controlled by means of a thermometer1 ,t1 and the gas-regulator1 ,r4 ,this is one of the ordinary gas-regulators by means of which the amount of gas supplied to the lamp is increased if the temperature should fall1 and diminished if it should rise above the required degree4 ,the best form of the sterilizing ovens is provided with a means for circulating the hot air so that the temperature may be made uniform throughout the mass4 ,this can be accomplished by introducing a mechanical stirrer1 or by the movement of the air itself4 ,illustration3 ,,figure #ga4 ,,sterilizing ,,oven4 ,between the walls of the vessel may be placed water1 provided the temperature of sterilization be that of boiling water4 ,if it should require a higher temperature than boiling water1 a solution of salt can be added until the required temperature is reached1 or the space between the two walls may be left vacant and hot air made to circulate around the oven4 ,the exterior of the oven1 except at the bottom where the lamp strikes the copper surface1 should be protected by thick layers of asbestos or other non-conducting material4 ,to avoid danger of flying filaments1 this covering should be coated with some smooth paint which will leave an even surface not easily abraded4 #dea4 ,sterilization with ,steam at ,high ,pressure4--,the apparatus used for this is commonly called an autoclave and is shown in ,fig4 #gb4 ,the top is movable and held in place by the clamp1 a1 which is fixed by the screw worked by the lever1 b4 ,the vessel itself is double-jacketed and the pressure is obtained from water in the vessel heated by means of the lamp1 c4 ,the actual steam pressure is indicated by the index d4 ,the safety-valve1 e1 allows any excess of steam to escape above the amount required for the maintenance of the pressure4 ,this1 however1 is best regulated by the lamp4 ,the outer jacket permits the heat from the lamp to circulate around the inner pressure vessel1 and the holes near the top1 oo1 are for the escape of the heated gases4 ,enough water is placed in the bottom of the inner pressure vessel to supply all the aqueous vapor necessary to produce the required pressure and still leave some water in excess4 ,illustration3 ,,figure #gb4 ,,autoclave ,,sterilizer4 ,the materials to be sterilized are held on the shelves of the stand and the vessels may be of various kinds according to the nature of the material to be sterilized4 ,the vessels containing the material being covered1 the steam does not come in actual contact with it4 ,at the end of the operation the safety-valve must not be opened to allow the escape of the steam1 otherwise the remaining water would be rapidly converted into vapor and would be projected over the materials on the shelves4 ,the lamp should be extinguished and the apparatus allowed to cool4 ,the autoclave is not only useful for sterilizing purposes but can be made of general use in the laboratory where heat under pressure1 as in the estimation of starch1 etc41 is required4 ,these two forms of apparatus are sufficient to illustrate the general principles of sterilization by hot air and steam4 ,there are1 however1 many variations of these forms designed for special use in certain kinds of work4 ,for full descriptions of these1 reference is made to catalogues of bacteriological apparatus4 #deb4 ,arnold's ,sterilizing ,apparatus4--,a very simple and cheap steam sterilizer has been devised by ,arnold4 ,illustration3 ,,figure #gc4 ,,arnold',s ,,sterilizer4 ,water is poured into the pan or reservoir1 ,b1 ,fig4 #gc1 whence it passes through three small apertures into the shallow copper vessel1 ,a4 ,it is there converted into steam by being heated with any convenient lamp1 and rises through the funnel in the center to the sterilizing chamber4 ,here it accumulates under moderate pressure at a temperature of #ajj4 ,the excess of steam escapes about the cover1 becomes imprisoned under the hood1 ,e1 and serves to form a steam-jacket between the wall of the sterilizing chamber and the hood4 ,as the steam is forced down from above and meets the air it condenses and drips back into the reservoir4 ,such an apparatus as this is better suited to commercial purposes1 as the sterilizing of milk1 than for scientific uses4 #dec4 ,thermostats for ,culture ,apparatus4--,it is important in the culture of micro-organisms that the temperature should be kept constant during the entire time of growth4 ,inasmuch as some operations continue for as much as three months it is necessary to have special forms of apparatus by means of which a given temperature1 during the time specified1 can be maintained4 ,this is secured by means of an oven with an automatic temperature regulator1 practically built on the principle of the hot air sterilizing oven already described4 ,the essential principles of construction are1 however1 that the regulator for the temperature should be delicate and that the non-conducting medium surrounding the apparatus should be as perfect as possible1 so that the variations in temperature from changes in the exterior temperature1 are reduced to a minimum4 ,this delicacy is secured by introducing a drop of chloroform-ether into a confined space over the mercury of the regulating apparatus4 ,the doors of the chamber are double1 the interior one being of glass so that the exterior door can be opened for inspection of the progress of the bacterial growth without materially interfering with the interior temperature4 ,a convenient form is shown in ,fig4 #gd4 ,illustration3 ,,figure #gd4 ,,lautenschl,,ger',s ,,thermostat4 ,the apparatus figured1 is oval in shape1 although circular or other forms are equally as effective4 ,the arrangement of the lamp1 a1 thermometers1 t t t1 and gas-regulator1 g1 and the double doors1 d d1 is shown in the engraving and does not require further description4 ,the usual temperatures for cultures range from #bb to #ce1 and the apparatus once set at any temperature will remain fixed with extremely minute variations for an indefinite time4 ,the apparatus possesses a heat zone which1 by the arrangement of the regulator1 is kept absolutely constant4 ,the space between the walls of the apparatus being filled with water1 the temperature is maintained even in every part4 ,the apparatus1 as constructed1 is independent not only of the surrounding temperature within ordinary variations1 but also of the pressure of the barometer4 ,three thermometers are employed to determine the temperature of the heating zone1 the water space and the inner space4 ,the arrangement of the gas-regulator is of an especial kind1 as mentioned above1 by means of which the consumption of gas is reduced to a minimum4 ,this apparatus can be regulated to suit the character of the work4 #ded4 ,microscopic ,apparatus ,required4--,any good microscope1 capable of accurate observation1 of high power1 may be used for the bacteriological observations necessary to soil analysis4 ,preference should be given to the patterns adapted to receive any additional accessories which may be subsequently required for advanced work4 ,the stage1 in addition to being fitted with a sliding bar1 should have a large circular or horseshoe opening to facilitate focusing operations4 ,a mechanical stage is a desirable acquisition if really well made1 but a plain stage is preferable for many purposes4 ,a rackwork1 centering sub-stage is essential for advanced work1 and in the absence of the more complete form1 there should at least be a fitting beneath the stage to take the diaphragm and condenser4 ,an iris diaphragm will be found more useful than any other kind in practice1 since the size of the opening can be increased very gradually at will4 ,one of the best lamps is known as the paraffin lamp and is fitted with a half-inch wick4 ,this will give even more light than is actually required1 and a steady flame1 perfectly under control1 may be obtained4 ,for the minute details to be observed in high-grade microscopic work1 such as is required in the bacteriological examination of soils1 reference must be had to the standard works on bacteriology and microscopy4 #dee4 ,general ,conclusions4--,the nitrogenous food of plants is provided in several ways2 viz41 7#a7 ,by the nitrogen brought to soil in rain and snow4 ,this nitrogen is chiefly in the form of ammonia and nitric acid4 ,the nitrogen gas in solution in rain water has no significance as a plant food4 7#b7 ,by the action of certain anaerobic organisms herding in the rootlets of leguminous plants1 free nitrogen may be oxidized and put into form for assimilation4 7#c7 ,by the action of certain organisms on nitrogenous compounds pre-existing in the soil1 ammonia1 nitrous acid1 and finally1 nitric acid1 are produced4 ,it is believed that the plant organism1 unaided by the activity of a micro-organism1 is unable to assimilate nitrogen unless it be fully oxidized to nitric acid4 7#d7 ,there exist micro-organisms capable of acting directly on free nitrogen independent of other plant growth1 but the significance of this possible source of plant food is1 at the present time1 unknown4 7#e7 ,the micro-organisms of importance to agriculture may be isolated and developed to the exclusion of other organisms of a similar character4 ,this isolation is best accomplished in culture-media consisting essentially of a mineral gelatin to which is added only pure carbohydrates and the necessary mineral nourishment4 7#f7 ,the nitrifying ferments consist probably of several species1 of different geographic distribution4 ,different types of soils probably have nitrifying organisms of different properties4 ,this is illustrated by the fact that nitrification is accomplished in dry alkaline soils under conditions in which the ordinary nitrifying organisms would fail to develop4 7#g7 ,the study of typical soils in respect of the kind1 activity1 and vigor of their nitrifying organisms has become as important a factor in soil analysis as the usual determination of physical and chemical composition4 ,,determination ,,of ,,nitric ,,and ,,nitrous ,,acids ,,in ,,soils4 #def4 ,classification of ,methods4--,the minute quantities in which highly oxidized nitrogen exists in soils render the operations of its quantitative estimation extremely delicate4 ,on the other hand1 the easy solubility of these forms of combination and the absence of absorptive powers therefor1 in the soil1 render the separation of them from the soil a matter of great ease4 ,it is possible1 therefore1 to secure all the nitrates and nitrites present in a large quantity of earth in a solution which can be concentrated under proper precautions to a volume convenient for manipulation4 ,the method of this extraction is the same for all the processes of determination4 ,the methods of analysis suited to soil extracts1 as a rule1 may also be used in the determination of the same compounds in rain1 drainage1 and sewage waters1 and for the qualitative and quantitative control of the progress of nitrification4 ,the various processes employed may be classified as follows3 #a4 ,the conversion of the nitrogen into the gaseous state and the determination of its volume directly4 ,this is accomplished by combustion with copper oxid and metallic copper4 #b4 ,the conversion of the nitrogen into nitric oxid and the volumetric determination thereof4 ,the decomposition of a nitrate with ferrous chlorid in the presence of free hydrochloric acid is an instance of this type of methods4 #c4 ,the oxidation of colored organic solutions and the consequent disappearance of the characteristic color1 or its change into a different tint4 ,the indigo and indigotin processes are examples of this method4 #d4 ,the production of color1 in a colorless or practically colorless solution1 by the treatment thereof with the nitrate in presence of an acid which decomposes it with the liberation of oxidizing compounds4 ,the depth of color produced is compared with that formed by a known quantity of a pure nitrate solution until the two colorations are alike4 ,the methods depending on the use of carbazol or acid phenol sulfate illustrate this class of reactions4 #e4 ,the conversion of the nitrogen into ammonia by moist combustion with sulfuric acid in the presence of certain organic compounds1 e4 g41 salicylic acid1 and the collection of the ammonia in standard acid1 the excess of which1 is determined by titration4 #f4 ,the reduction of nitrates to ammonia by nascent hydrogen and the recovery of the ammonia produced by distillation and collection in standard acid4 #g4 ,the reduction of nitrates by electrolytic action and the collection of the ammonia as above4 #h4 ,the decomposition of nitrates with the quantitative evolution of a different element1 and the direct or indirect measurement of the evolved substance4 ,the quantitative evolution of chlorin on treating a nitrate with hydrochloric acid1 the collection of the chlorin in potassium iodid1 and the determination of the iodin set free1 form a process belonging here4 #deg4 ,relative ,merit of ,methods4--,the processes mentioned in the classifications embraced under numbers 7#a7 and 7#e7 of the preceding schedule are sufficiently described in the paragraphs devoted thereto1 under soil and fertilizers4 ,in practice at the present time it is rare to determine the nitrogen in nitrates by the copper oxid method4 ,the more rapid and equally exact processes of colorimetric comparison or reduction by nascent hydrogen are in all respects to be preferred4 ,the indigo methods among the colorimetric processes are not so much in use now as those which depend on the development of a color4 ,lawes and ,gilbert considered them far inferior to the ,schloesing method4 ,the developed color methods are especially delicate and are to be preferred in all cases where the detection of the merest traces of nitrates is desired4 ,where nitrates are present in considerable quantities the reduction method with nascent hydrogen is to be preferred over all others4 ,in all these cases the judgment of the analyst must be exercised4 ,the particular method to be employed in any given case can not be determined save by the intelligent discrimination of the operator4 #deh4 ,the ,extraction of ,nitric ,acid from the ,soil4--,the easy solubility of nitric acid and of nitrates in water is taken advantage of in the separation of these bodies from the soil4 ,a convenient quantity1 usually about #a1jjj grams of the fine soil1 is taken for the extraction4 ,instead of freeing the soil entirely from water1 it is better to determine the amount of water in the air-dried or prepared sample1 and base the calculation on #a1jjj grams of the water-free soil4 ,all samples of soil1 when taken for the purpose of examining for nitrates1 should be rapidly dried to prevent the process of nitrification from continuing after the sample is taken4 ,for this purpose the soil should be placed in a thin layer in a warm place1 #ej-fj1 until air-dried4 ,it still contains in this case a little moisture but not enough to permit nitrification to go on4 ,one thousand grams of soil prepared as above are treated with #b1jjj cubic centimeters of distilled water1 free of nitric acid1 and allowed to stand for forty-eight hours with frequent shaking4 ,one thousand cubic centimeters of the extract are then filtered1 corresponding to #ejj grams of the dry soil4 ,a small quantity of pure sodium carbonate should be added to the filtrate which is then evaporated on a water-bath to a volume of about #ajj cubic centimeters4 ,should a precipitate be formed during evaporation it should be separated by filtration1 the filter washed thoroughly1 and the filtrate again evaporated to a volume of #ajj cubic centimeters4 ,in taking a soil for the determination of nitrates1 it is well to extend the sampling to a considerable depth4 ,if the sample be taken only to the depth of nine inches1 it should be in dry weather when the nitrates are near the surface4 ,the temperature at which a soil is dried has also an influence on the quality of nitric nitrogen remaining after desiccation4 ,if a wet soil be dried at #ajj1 the nitrates present will suffer partial decomposition4 ,this is probably due to deoxidation by organic matter present4 ,on the other hand1 ordinary air-drying affords opportunity for continued nitrification1 thus increasing the residuum of oxidized nitrogen4 ,the above method is essentially that followed by ,warington at ,rothamstead4 ,the method of drying practiced at ,rothamstead1 in order to secure results as nearly accurate as possible is the following3#bic ,the soil is broken up directly after it is taken from the field1 and spread on trays in layers one inch deep4 ,the trays are then placed in a room at #ee4 ,the drying is completed in twenty-four hours4 ,after drying1 stones and roots are removed1 and the soil is finely powdered and placed in bottles4 ,for extracting the nitrates1 a funnel is prepared by cutting off the bottom from a bottle four and a half inches in diameter4 ,a nicely fitting disk of copper gauze is placed in the bottom of this funnel1 and this is covered with two filter papers1 the upper one having a slightly greater diameter than the lower4 ,the paper is first moistened1 and then from #bjj to #ejj grams of the dry powdered soil introduced4 ,the funnel is connected with the receiving flask of a filter pump1 and pure water poured on the soil until it is thoroughly saturated4 ,the water is then added in small quantities4 ,when the filtrate amounts to #ajj cubic centimeters the process may be discontinued1 since all the nitrates in the soil will be found in this part of the filtrate4 ,the extract obtained above is evaporated to convenient bulk for the determination of nitric nitrogen4 ,,the ,,nitric ,,oxid ,,process4 #dei4 ,method of ,schloesing4--,the processes for estimating nitrogen by combustion with copper oxid and by moist combustion with sulfuric acid have both been used for the determination of the quantity of nitrogen existing in a highly oxidized state4 ,these processes will be fully discussed under the head of fertilizers4 ,in the case of soil extracts1 drainage waters1 etc41 it will be sufficient to discuss1 for the present1 only those processes adapted especially to a quick and accurate estimation of oxidized nitrogen4 ,the principle of the method of ,schloesing depends on the decomposition of nitrates in the presence of a ferrous salt and a strong mineral acid4#bid ,the nitrogen in the process appears as nitric oxid1 the volume of which may be directly measured1 or it may be converted into nitric acid and titrated by an alkali4 ,the typical reactions which take place are represented in the following equation3 #f;,fe,cl #b,,kno #h;,h,cl #c;,fe,cl #b,k,cl #d;,h,o #b,,no4 #dfj4 ,schloesing's ,modified ,method4--,the ,schloesing method as now practiced by the ,french chemists is conducted in the apparatus shown in ,fig4 #ge4bie ,the carbon dioxid is generated by the action of the hydrochloric acid in ,f on the fragments of marble in ,a4 ,after passing the wash-bottle the gas enters the small tubulated retort1 ,c1 which contains the nitrate in solution4 ,for ordinary soils #ajj grams are placed in an extraction flask1 plugged with cotton1 and a layer of the same material is placed over the soil for the purpose of securing an even distribution of the extracting liquid4 ,this liquid is distilled water containing in each liter one gram of calcium chlorid4 ,the purpose of using the calcium chlorid is to prevent the soil from becoming compacted which would render the extraction of the nitrate difficult4 ,the extracting liquid is allowed to fall drop by drop from a mariotte bottle until the filtrate amounts to #ejj cubic centimeters4 ,this volume is concentrated on a sand-bath until it is reduced to ten or fifteen cubic centimeters when it is transferred to a flat-bottomed dish and the evaporation finished over steam1 care being taken not to allow the temperature to exceed #ajj4 ,illustration3 ,,figure #ge4 ,,schloesing',s ,,apparatus ,,for ,,nitric ,,acid4 ,another and more rapid method for dissolving the nitrate1 may also be practiced4 ,in a flask holding about one liter1 place #bbj grams of the soil and #ffj cubic centimeters of distilled water and shake vigorously1 or enough water to make #ffj cubic centimeters together with the moisture remaining in the air-dried sample taken4 ,all the nitrates pass into solution4 ,throw the contents of the flask into a filter and take #fjj cubic centimeters of the filtrate which will contain all the nitrates in #bjj grams of the sample taken4 ,this filtrate is evaporated as described above4 ,in the flat dish containing the dried nitrates1 pour three or four cubic centimeters of ferrous chlorid solution and stir with a small glass rod until complete solution of the nitrate takes place4 ,by means of a small funnel the solution is poured into ,c1 and the capsule and funnel are well rinsed with two cubic centimeters of hydrochloric acid4 ,the washing is repeated three times as above described1 and once with one cubic centimeter of water1 which is added cautiously so as to form a layer over the surface of the heavier liquid4 ,the tubulated flask is then connected with the carbon dioxid apparatus1 previously freed from air1 and the gas allowed to flow evenly until the whole of the apparatus is completely air-free4 ,the other details of the method are essentially the same as those adopted by the ,commission of ,french ,agricultural ,chemists which will be given below4 #dfa4 ,the ,french ,agricultural ,method4--,the ,schloesing method as practiced by the ,french agricultural chemists is very slightly different from the procedure just described4#bif ,the process with soils is carried on as follows3 ,five hundred grams of the soil are taken and introduced into a flask of about two liters capacity and shaken thoroughly with a liter of distilled water4 ,the whole of the nitrates of the soil is thus passed into solution4 ,the solution is filtered and #djj cubic centimeters of the filtrate are taken1 which correspond to #bjj grams of the soil4 ,this liquid is evaporated in a flask1 adding a fragment of paraffin to prevent foaming1 until its volume is reduced to fifteen or twenty cubic centimeters4 ,it is afterwards transferred through a filter into a capsule with a flat bottom in which the evaporation is finished on a steam-bath1 taking care that the temperature does not exceed #ajj4 ,an important precaution is1 not to allow the contact of the water with the soil to be too prolonged1 to avoid the reduction of the nitrates which could take place under the influence of the denitrifying organisms which are developed with so great a rapidity in moist earth4 ,the apparatus in which the transformation of the nitrates into nitric oxid takes place is essentially that already described 7,fig4 #ge74 ,the carbon dioxid generator is connected by means of a rubber tube and a small wash-bottle to the small retort in which the reaction takes place1 and from which the exit tube leads to a mercury trough4 ,the gas which is disengaged is received under a jar drawn out to a fine point in its upper part1 which carries about fifteen cubic centimeters of potash solution containing two parts of water to one of potash4 ,the operation is conducted as follows3 ,into the small capsule which contains the dried matter1 three or four cubic centimeters of ferrous chlorid are poured4 ,by means of a stirring rod the residue sticking to the sides of the capsule is detached with care and all the matter is thus collected in the bottom4 ,by means of a small funnel the contents of the capsule are introduced into the retort4 ,about two cubic centimeters of hydrochloric acid are used for washing out the materials and this acid is also introduced into the retort4 ,the washing with hydrochloric acid is repeated three or four times1 and finally the apparatus is washed with one cubic centimeter of water1 which is also poured in by the small funnel with great care1 so that this water may form a layer over the surface of the liquid4 ,the apparatus is now connected and filled completely with carbon dioxid4 ,since it is necessary that this gas should be completely free of air1 the flask1 which generates it1 is first filled with the acidulated water from the acid flask1 and the air is thus almost totally displaced by the liquid4 ,the evolution of carbon dioxid gas which follows1 completely frees the apparatus from air4 ,when this is accomplished the retort is connected with the rest of the apparatus and the gas allowed to pass for about two minutes until the air is completely driven out of all the connections4 ,the current is arrested for a moment by pinching the rubber tube which conducts the carbon dioxid into the retort1 and the vessel which is to receive the gas is then placed over the delivery-tube1 this vessel being filled with mercury and a strong solution of potash4 ,the communication between the retort and the carbon dioxid flask is broken and the flask is heated slightly by means of a small lamp4 ,the first bubbles of gas evolved should be entirely absorbed by the potash4 ,this will be an indication of the complete absence of the air4 ,when the liquid is in a state of ebullition the nitrogen dioxid is set free4 ,the boiling is regulated in such a way that the evolution is regular and the liquid of the retort may not1 by a too violent boiling1 pass into the receiver4 ,the boiling is continued until the larger part of the liquid is distilled and only three or four cubic centimeters remain in the retort4 ,at this time a few bubbles of carbon dioxid are allowed to flow through in order to cause to pass into the receiver the last traces of nitric oxid4 ,the gas received is left for some minutes in contact with the potash4 ,afterward in a small flask1 ,g1 the neck of which is drawn out to a fine point1 and carrying a bulb-tube1 ,h1 and a piece of rubber tubing1 there are boiled twenty-five or thirty cubic centimeters of water for five or six minutes in order to drive all the air out of the flask1 and while the boiling is continued the rubber tubing is fastened to the drawn-out part of the jar containing the nitric oxid4 ,within the rubber tubing the drawn-out point is broken and the vapor of water is forced into the jar and drives before it the solution of potash which has filled the capillary part of the drawn-out tube4 ,as soon as the point is broken1 the boiling of the flask is stopped and by its cooling the nitric oxid passes into it4 ,it is necessary to press the rubber tubing with the fingers in order that the passage of the gas into the flask be not too rapid4 ,as the solution of potash rises in the bell-jar which contains the nitric oxid near to the point where the rubber tubing covers its drawn-out portion1 the fingers are removed and a clamp put in their place4 ,there still remains a little nitric oxid in the flask and to drive this out it is necessary to introduce five or six cubic centimeters of pure hydrogen1 which are allowed to pass over into the receiving flask1 by releasing the clamp in the same way as the nitric oxid4 ,the hydrogen being introduced in successive portions1 finally carries all the nitric oxid into the flask without allowing any of the potash to enter4 ,the flask containing the nitric oxid is now connected with a reservoir of oxygen4 ,the oxygen is allowed to enter1 bubble by bubble1 by means of cooling the flask by immersion in water4 ,the transformation of nitric oxid into nitric acid is not entirely complete for twenty-four hours4 ,it is necessary1 therefore1 to wait that long after the introduction of the oxygen before determining the amount of nitric acid produced4 ,the contents of the flask are placed in a titration-jar1 the flask being washed two or three times and a few drops of tincture of litmus being added4 ,the nitric acid is then determined by a standard solution of calcium hydroxid or some other standard alkali4 ,from the titration the content of nitric acid is calculated4 ,the ,french ,committee further suggests that this method may be modified in the way of making it more rapid by collecting the nitric acid in a graduated tube filled with mercury and containing some potash4 ,the volume of the gas is determined and the pressure of the barometer and the temperature observed1 and the usual calculations made to reduce the volume to zero and to a pressure of #gfj millimeters of mercury4 ,each cubic centimeter of nitric oxid thus measured corresponds to #b4dag milligrams of nitric acid4 ,the presence of organic matter does not interfere with the determination of nitric acid by either of the methods given above4 #dfb4 ,modification of ,warington4--,the method of procedure and description of apparatus used1 as employed by ,warington1 are as follows3 ,the vessel in which the reaction takes place is a small tubulated receiver1 ,a 7,fig4 #gf71 about four centimeters in diameter1 mounted and connected as shown in the illustration4 ,the delivery-tube dips into a jar of mercury in a trough containing the same liquid4 ,the long supply funnel-tube a is of small bore1 holding in all only one-half cubic centimeter4 ,the connecting tube ,f1 carrying a clamp1 is also of small diameter and serves to connect the apparatus with a supply of carbon dioxid4 ,illustration3 ,,figure #gf4 ,,warington',s ,,apparatus ,,for ,,nitric ,,acid4 ,in practice1 the supply-tube a is first filled with strong hydrochloric acid and carbon dioxid passed through the apparatus until the air is all expelled4 ,this is indicated when a portion of the gas collected over the mercury1 is entirely absorbed by caustic alkali4 ,at this point the current of carbon dioxid is stopped by the clamp ,c1 and a bath of calcium chlorid1 ,b1 heated to #adj is brought under the bulb ,a1 until the latter is half immersed therein4 ,the temperature of the bath is maintained by a lamp4 ,by allowing a few drops of hydrochloric acid to enter the receiver1 the carbon dioxid is almost wholly expelled4 ,the end of the delivery-tube is then connected with the tube1 ,t1 filled with mercury1 and the apparatus is ready for use4 ,the nitrate1 in which the nitric acid is to be determined1 in a dry state1 is dissolved in two cubic centimeters of the ferrous chlorid solution 7one gram of iron in ten cubic centimeters71 one cubic centimeter of strong hydrochloric acid is added1 and the whole is then introduced into the receiver through the supply-tube1 being followed by successive rinsings with hydrochloric acid1 each rinsing not exceeding one-half cubic centimeter4 ,the contents of the receiver are1 in a few moments1 boiled to dryness2 a little carbon dioxid is admitted before dryness is reached1 and again afterwards to drive over all remains of nitric oxid4 ,in the recovered gas the carbon dioxid is first absorbed by caustic potash1 and afterwards the nitric oxid by ferrous chlorid4 ,all measurements of the gas are made in ,frankland's modification of ,regnault's apparatus4 ,the carbon dioxid should be as free as possible from oxygen4 ,the carbon dioxid generator is formed of two vessels1 the lower one consisting of a bottle with a tubule in the side near the bottom2 this bottle is supported in an inverted position and contains the marble from which the gas is generated4 ,the upper vessel consists of a similar bottle standing upright and containing the hydrochloric acid required to act on the marble4 ,the two vessels are connected by a glass tube passing from the side tubule of the upper vessel to the inverted mouth of the lower vessel4 ,the acid from the upper vessel thus enters below the marble4 ,carbon dioxid is generated and removed at pleasure by opening a stop-cock attached to the side tubule of the lower vessel thus allowing hydrochloric acid to descend and come in contact with the marble4 ,a good ,kipp's generator of any approved form may also be used instead of the simple apparatus1 above described4 ,the fragments of marble used are previously boiled in water in a strong flask4 ,after boiling has proceeded for some time1 a rubber stopper is fixed in the neck of the flask and the flame removed4 ,boiling will then continue for some time in a partial vacuum4 ,the hydrochloric acid is also well boiled and has dissolved in it a moderate quantity of cuprous chlorid4 ,as soon as the acid has been placed in the upper reservoir1 it is covered by a layer of oil4 ,the apparatus being thus charged is at once set in active work by opening the stop-cock of the marble reservoir2 the acid descends1 enters the marble reservoir1 and the carbon dioxid produced drives out the air4 ,as the acid reservoir is kept on a higher level than the marble reservoir1 the latter is always under internal pressure1 and leakage of air from without1 into the apparatus1 cannot occur4 ,the presence of the cuprous chlorid in the hydrochloric acid not only insures the removal of dissolved oxygen1 but affords an indication to the eye of the maintenance of this condition4 ,while the acid remains of an olive tint1 oxygen is absent2 but should the color change to a blue-green1 more cuprous chlorid must be added4 ,all the reagents employed should be previously boiled4 ,in order to secure absolute freedom from air1 the following modifications on the above process have been adopted by ,warington3 ,the apparatus having been mounted as described1 the funnel-tube attached to the bulb retort is filled with water1 and the apparatus connected with the carbon dioxid generator4 ,carbon dioxid is then passed through the apparatus until a moderate stream of bubbles rises in the mercury trough4 ,the stop-cock is left in this position1 and the admission of gas is controlled by the pinch-cock4 ,the bath of calcium chlorid is so adjusted as to cause the bulb retort to be almost entirely submerged1 and the temperature of the bath is kept at #acj to #adj4 ,small quantities of water are next admitted into the bulb and expelled as steam in the current of carbon dioxid1 the supply of this gas being shut off before the evaporation is entirely completed1 so as to leave as little carbon dioxid as possible in the apparatus4 ,previous to very delicate experiments it is advisable to introduce through the funnel-tube a small quantity of potassium nitrate1 ferrous chlorid1 and hydrochloric acid1 rinsing the tube with the latter reagent4 ,any trace of oxygen remaining in the apparatus is then consumed by the nitric oxid formed2 and after boiling to dryness and driving out the nitric acid with carbon dioxid1 the apparatus is in a perfect condition for a quantitative experiment4 #dfc4 ,preparation of the ,materials to be ,analyzed4--,according to ,warington1 soil extracts may be used without other preparation than concentration4 ,vegetable juices which coagulate when heated1 require to be boiled and filtered or else evaporated to a thin sirup1 treated with alcohol1 and filtered4 ,a clear solution being thus obtained1 it is concentrated over a water-bath to a minimum volume in a beaker of small size4 ,as soon as cool1 it is mixed with one cubic centimeter of a cold saturated solution of ferrous chlorid and one cubic centimeter of hydrochloric acid1 both reagents having been boiled and cooled immediately before use4 ,in mixing with the reagents1 care must be taken that bubbles of air are not entangled1 which is apt to occur with viscid extracts4 ,the quantity of ferrous chlorid mentioned is amply sufficient for most soil extracts1 but it is well to use two cubic centimeters in the first experiment1 the presence of a considerable excess of ferrous chlorid in the retort being thus insured4 ,with bulky vegetable extracts more ferrous chlorid should be employed4 ,to the sirup from twenty grams of mangel-wurzel sap1 five cubic centimeters of ferrous chlorid and two cubic centimeters of hydrochloric acid are usually added4 #dfd4 ,measurement of the ,gas4--,the measurement of the gas was for some time conducted by the use of concentrated potash for absorbing the carbon dioxid1 and ferrous chlorid for absorbing the nitric oxid4 ,the use of the ferrous chlorid1 however1 was found to introduce a source of error4 ,the treatment of the gas with oxygen and pyrogallol over potash has therefore been substituted by ,warington for its absorption by ferrous chlorid4 ,the chief source of error attending the oxygen process lies in the small quantity of carbon monoxid produced during the absorption with pyrogallol2 this error becomes negligible if the oxygen be only used in small excess4 ,the amount of oxygen employed can be regulated by the use of ,bischof's gas delivery-tube4 ,this may be made of a test-tube having a small perforation half an inch from the mouth4 ,the tube is partly filled with oxygen over mercury1 and its mouth is then closed by a finely perforated stopper made from a piece of wide tube and fitted tightly into the test-tube by means of a covering of rubber4 ,when this tube is inclined1 the side perforation being downwards1 the oxygen is discharged in small bubbles from the perforated stopper1 while mercury enters through the opening4 ,using this tube1 the supply of oxygen is perfectly under control and can be stopped as soon as a fresh bubble ceases to produce a red tinge on entering4 ,warington concludes his description by stating that in the reaction proposed by ,schloesing the analyst has a means of determining a very small quantity of nitric acid with considerable accuracy1 even in the presence of organic matter2 but to accomplish this1 the various simplifications consisting in the omission of the stream of carbon dioxid1 and the collection of the gas over caustic soda must be abandoned1 and special precautions must be taken to exclude all traces of oxygen from the apparatus4 #dfe4 ,spiegel's ,modification4--,spiegel noticed inaccuracies in the results of the ferrous chlorid method of estimating nitric acid when carbon dioxid is used1 which sometimes amounted to three per cent of the nitric acid present in the sample4 ,the following suggestions are made by him for the improvement of the process3#big ,as regards the use of carbon dioxid in the operation1 the first difficulty consists in obtaining it entirely free from air4 ,by the use of small pieces of marble1 which1 before being placed in the ,kipp apparatus1 are kept for a long while in boiling water1 a product is obtained which1 after thirty minutes of moderate evolution1 leaves only a trace of unabsorbed gas in contact with potash-lye4 ,the apparatus used is illustrated in ,fig4 #gg4 ,illustration3 ,,figure #gg4 ,,spiegel',s ,,apparatus ,,for ,,nitric ,,acid4 ,a is a round flask of about #aej cubic centimeters capacity1 furnished with a well-fitting rubber stopper provided with two holes1 one for the entrance of the funnel-tube ,b and the other for the delivery-tube ,c4 ,the tube ,b ends about two centimeters above the bottom of ,a and carries a bulb-shaped funnel at its top capable of holding about fifty cubic centimeters4 ,the gas-tube ,d is ground into the bulb of ,b as shown in the figure4 ,after the flask had been filled with the solution to be examined1 carbon dioxid is conducted through ,d and the flask is heated to boiling until the gas which escapes through ,c no longer contains any air4 ,the measuring tube is brought over the end of the delivery-tube ,c1 in the usual manner1 but not shown in the figure4 ,in the funnel of ,b are placed twenty cubic centimeters of previously prepared and boiled ferrous chlorid solution and this liquid is allowed to flow partly into ,a by lifting slightly the gas-tube1 ,d4 ,about forty cubic centimeters of concentrated1 boiled hydrochloric acid are afterwards added to it in the same way4 ,as soon as the liquid in the flask ,a is again boiling1 the stream of carbon dioxid is shut off and allowed to flow again only towards the end of the operation1 when the contents of the flask are reduced almost to dryness4 ,as will be seen from the above directions no unboiled liquids of any kind are to be used as reagents in the apparatus described4 ,if the flask ,a were made much smaller the efficiency of this apparatus would be increased4 ,it appears to have few1 if any1 advantages over ,warington's process4 #dff4 ,schulze-,tiemann ,method4--,the modification of ,schulze-,tiemann in the ferrous salt method consists chiefly in the omission of the use of carbon dioxid1 and in the simplified form of apparatus1 which permits rapid work and gives1 also1 according to some authorities1 very exact and reliable results4#bih ,the extract1 representing #ejj grams of the fine soil1 is reduced by evaporation to #ajj cubic centimeters and placed in a glass flask1 ,a 7,fig4 #gh71 of #ejj cubic centimeters capacity4 ,the flask is closed with a rubber stopper1 carrying two bent glass tubes which pass through it4 ,the tube a b c is drawn out into a point at a and reaches about two centimeters below the surface of the rubber stopper4 ,the tube e f g passes just to the lower surface of the rubber stopper4 ,the two tubes mentioned are connected1 by means of rubber tubes and pinch-cocks1 with the tubes d and h4 ,the pinch-cocks at c and g must be capable of closing the tubes air-tight4 ,the end of the tube g h passes into a crystallizing dish1 ,b1 and is bent upward to a point passing two to three centimeters into the measuring tube ,c4 ,the point within the tube is covered with a piece of rubber tubing4 ,the measuring tube ,c is divided into tenths of a cubic centimeter1 and together with the crystallizing dish ,b1 is filled with a ten per cent solution of boiled soda-lye1 which is obtained by dissolving #ab4i parts of sodium hydroxid in #ajj parts of water4 ,illustration3 ,,figure #gh4 ,,schulze-,,tiemann',s ,,nitric ,,acid ,,apparatus4 ,the liquid which is to be examined for nitric acid1 the pinch-cocks being opened and the tube g h not dipping into the crystallizing dish1 is boiled for one hour in order to drive the air out of the flask ,a4 ,the end of the tube e f g h is then brought into the crystallizing dish containing the sodium hydroxid solution so that the steam escaping from the flask ,a1 escapes partly through the tube b c d1 and partly through the tube f g h1 not allowing1 however1 the bubbles to enter the measuring tube ,c4 ,to determine whether the air is all expelled1 the pinch-cock at g is closed and the soda-lye will thereupon rise to g in case no air interferes4 ,it is best to close the tube at g first with the thumb and finger and then the rise of the soda-lye to that point can be determined by the impulse felt4 ,the tube is then firmly closed by means of the pinch-cock g4 ,the rest of the steam is allowed to escape through the tube a b c d1 and the evaporation is continued until the contents of the flask are evaporated to about ten cubic centimeters4 ,the flask into which the tube c d dips1 is filled with freshly boiled water4 ,the lamp is removed from the flask ,a1 the pinch-cock is closed1 whereupon the tube c d becomes filled with the freshly boiled water4 ,the measuring tube ,c1 filled with freshly boiled soda-lye is closed with the thumb and brought into the dish ,b1 care being taken that no bubble of air enters4 ,it is placed over the end of the tube g h4 ,the pressure of the external air will now flatten the rubber tubes at c and g4 ,the flask at the end of c d holding freshly boiled water is then replaced with one filled with a nearly saturated solution of ferrous chlorid containing some hydrochloric acid4 ,the flask containing the ferrous chlorid solution should be graduated so that the amount which is sucked into the flask ,a can be determined4 ,the pinch-cock c is opened and from fifteen to twenty cubic centimeters of the ferrous chlorid solution allowed to flow into ,a4 ,the end of the tube c d is then placed in another flask containing strong hydrochloric acid1 and the latter allowed to flow into the tube in small quantities at a time until all the ferrous chlorid is washed out of the tube b c d into ,a4 ,at the point b there is sometimes formed a little bubble of hydrochloric acid in the state of gas1 which by heating the flask ,a completely disappears4 ,the flask ,a is next warmed gently until the rubber tubes at the pinch-cocks begin to assume their normal condition4 ,the pinch-cock at g is now replaced by the thumb and finger1 and as soon as the pressure within the flask ,a is somewhat stronger1 caused by the nitric oxid gas evolved from the mixture1 it is allowed to pass through the tube e f g h and escape into the measuring cylinder ,c4 ,by a manipulation of the finger and thumb at g1 it is possible to prevent regurgitation of the sodium hydroxid into ,a1 and at the same time to relieve the pressure of the nitric oxid in ,a1 which would be difficult to do by means of the pinch-cock alone4 ,the boiling of the liquid is continued until there is no longer any increase of the volume of gas in the measuring cylinder ,c4 ,after the end of the operation the tube g h is removed from the dish ,b and the measuring tube ,c is closed by means of the thumb while its end is still beneath the surface of the soda-lye1 and it is shaken until all traces of any hydrochloric acid1 which may have escaped absorption1 are removed4 ,it is then placed in a large glass cylinder filled with water at the temperature at which the volume of gas is to be read4 ,after being kept at this constant temperature for about half an hour the volume of the nitric oxid can be read4 ,for this purpose the measuring cylinder ,c is sunk into the water of the large cylinder until the level of the liquids within and without the tube is the same4 ,the usual correction for pressure of the atmosphere1 as determined by the barometer1 and for the tension of the aqueous vapor at the temperature at which the reading is made1 is applied4 ,the correction is made by means of the following formula3 ,v 7,v #bgc 7,b f77 77#bgc t7 #gfj7 ,in this formula ,v denotes the volume of the gas at the temperature of zero1 and at #gfj millimeters barometric pressure2 ,v the volume of the gas as read at the barometric pressure observed1 ,b1 and the temperature observed1 t1 while f denotes the tension of the aqueous vapor in millimeters of mercury pressure at the observed temperature t4 ,the tension of the aqueous vapor at temperatures from zero to #bf1 expressed in millimeters of mercury1 is given in the following table3 ,temp4 ,tension in mm4 mercury4 #j #d4f #a #d4i #b #e4c #c #e4g #d #f4a #e #f4e #f #f4i #g #g4d #h #h4j #i #h4e #aj #i4a #aa #i4g #ab #aj4d #ac #aa4a #ad #aa4i #ae #ab4g #af #ac4e #ag #ad4d #ah #ae4c #ai #af4c #bj #ag4d #ba #ah4e #bb #ai4f #bc #bj4i #bd #bb4b #be #bc4e #bf #be4j ,from the gas volume reduced by the above formula the nitric acid is calculated as follows3 ,one cubic centimeter of nitric oxid weighs at #j and #gfj millimeters barometric pressure #a4cdc milligrams4 ,since two molecules of ,,no 7molecular weight sixty7 correspond to one molecule of ,n,o 7#ajh7 we have the following equation3 #fj 3 #ajh #a4cdc 3 x4 ,whence x #b4dag milligrams1 the weight of nitric acid corresponding to one cubic centimeter of nitric oxid4 ,illustration3 ,,figure #gi4 ,,de ,,konick',s ,,apparatus4 ,illustration3 ,,figure #hj4 ,,end ,,of ,,delivery-,,tube4 #dfg4 ,de,konick's ,modification of ,schloesing's ,method4--,this modification consists in an arrangement of the gas delivery-tube1 whereby the regurgitation of the water in the measuring burette into the evolution flask is prevented by a device for sealing the delivery-tube with mercury4#bii ,the apparatus is arranged as shown in ,fig4 #gi4 ,the flask in which the decomposition takes place is provided with a long neck1 into which a side tube is sealed and bent upwards1 carrying a small funnel attached to it by rubber tubing4 ,the piece of rubber tubing carries a pinch-cock1 by means of which the solution containing the nitrate and hydrochloric acid can be introduced into the flask4 ,the small gas delivery-tube is arranged as shown in the figure1 and carries at the end next the burette a device shown in ,fig4 #hj4 ,the cork represented in this device has radial notches cut in it1 so as to permit of a free communication between the water in the burette and in the pneumatic trough4 ,the open end of the burette1 when the apparatus is mounted ready for use1 rests on the notched surface of the cork1 and the end of the delivery-tube is placed in the crystallizing dish resting on the bottom of the pneumatic trough4 ,the end of the delivery-tube1 as indicated1 has fused onto it a vertical tube open at both ends and six to seven centimeters in length1 and carrying the notched cork already described4 ,the crystallizing dish in the bottom of the pneumatic trough is filled with mercury until the point of union of the delivery-tube with the vertical end is sealed to the depth of a few millimeters4 ,as the gas is evolved it bubbles up through the mercury into the measuring tube and the displaced water passes out through the notches in the cork4 ,should any back pressure supervene the mercury at once rises in the delivery-tube which is of such a length as to prevent its entrance into the flask4 ,the operation can then be carried on with absolute safety4 ,to make an estimation there are placed in the flask about forty cubic centimeters of ferrous chlorid solution containing about #bjj grams of iron to the liter1 and also an equal volume of hydrochloric acid of one and one-tenth specific gravity4 ,the side tube is also filled up to the funnel with the acid4 ,the contents of the flask are boiled until all air is expelled1 which can be determined by holding a test-tube filled with water over the end of the delivery-tube4 ,the solution containing the nitrate is next placed in the funnel1 the pinch-cock opened and the liquid allowed to run into the flask by means of the partial vacuum produced by stopping the boiling and allowing the mercury to rise in the delivery-tube4 ,all the solution is washed into the flask by successive rinsings of the funnel with hydrochloric acid1 being careful to allow no bubble of air to enter4 ,the contents of the flask are again raised to the boiling-point and the nitric oxid evolved collected in the nitrometer4 ,the solution examined should contain enough nitrate to afford from sixty to eighty cubic centimeters of gas4 ,without refilling the flask1 from eight to nine determinations can be made by regenerating the ferrous chlorid by treatment with zinc chlorid4 ,care must be exercised not to add the zinc chlorid in excess1 otherwise ammonia and not nitric oxid will be produced4 ,the side tube and funnel must also be carefully freed from zinc chlorid by washing with hydrochloric acid4 #dfh4 ,schmidt's ,process4--,in the case of a water1 or the aqueous extract of a soil1 according to the content of nitric acid1 from fifty to one hundred cubic centimeters are evaporated to thirty cubic centimeters1 and the residue sucked into the generating flask of the apparatus1 ,fig4 #ha1 and1 with the rinsings with distilled water1 evaporated again to from twenty to thirty cubic centimeters1 and the flask then connected1 as shown in the figure1 to a ,schliff measuring apparatus1 ,b4#cjj ,this apparatus is previously filled to i with mercury1 and the bulb g connected with k by a rubber tube4 ,illustration3 ,,figure #ha4 ,,schmidt',s ,,apparatus4 ,the apparatus is then filled with a twenty per cent1 previously boiled and still warm1 caustic soda solution until the bulb g is partially filled when raised a little above the cock h4 ,then h is closed and g held1 by an appropriate support1 on about the same level with h4 ,the cock at b is then closed and e opened4 ,meanwhile the ebullition in the flask is continued1 and the air bubbles rising in the ,schliff apparatus are removed1 from time to time1 by carefully opening h and raising g4 ,when bubbles no longer come over1 the cock at e is closed and at b opened1 and the steam issuing at a is conducted through a mixture of ferrous chlorid and strong hydrochloric acid to free it1 as far as possible1 from air4 ,when the contents of the flask have been evaporated to about five cubic centimeters1 b is closed and the lamp at once removed4 ,by carefully opening b about ten cubic centimeters of a mixture of ferrous chlorid and hydrochloric acid are allowed to enter the flask1 when b is closed and the flask slowly heated until the positive pressure is restored4 ,the pinch-cock e is then opened and the contents of the flask evaporated nearly to dryness4 ,the cock e is again closed and the flame removed4 ,another quantity 7fifteen cubic centimeters7 of ferrous chlorid and hydrochloric acid solution is sucked into the flask and the process of distillation repeated1 whereby the whole of the nitric oxid is collected in h4 ,the nitric oxid evolved is measured in the usual way and calculated to nitric acid1 one cubic centimeter of nitrogen dioxid being equal to #b4dag milligrams of nitric acid4 #dfi4 ,merits of the ,ferrous ,chlorid ,process4--,the possibility of an accurate determination of nitrates2 by decomposition with a ferrous salt in presence of an excess of acid1 has been established by many years of experience and by the testimony of many analysts4 ,the method is applicable especially where the quantity of nitrate is not too small and when organic matter is present4 ,in the case of minute quantities of nitrate1 however1 the process is inapplicable and must give way to some of the colorimetric methods to be hereafter described4 ,in respect of the apparatus modern practice has led to the preference of that form which does not require the use of carbon dioxid for displacing the air4 ,steam appears to be quite as effective as carbon dioxid and is much more easily employed4 ,that form of apparatus should be used which is the simplest in construction and has the least cubical content4 ,the measurement of the evolved gas is most simply made by collecting over lye in an azotometer1 reading the volume1 noting the reading of the barometer and thermometer and then reducing to standard conditions of pressure and temperature by the customary calculations4 ,where a very strong lye is used the tension of the aqueous vapor may be neglected4 ,while every analyst should have a thorough knowledge of the ferrous chlorid method and the principles on which it is based it can not be compared in simplicity to the later methods with pure nitrates which are based on the conversion of the nitric acid into ammonia by the action of nascent hydrogen4 ,in accuracy1 moreover1 it does not appear to have any marked advantage over the reduction methods4 #dgj4 ,mercury and ,sulfuric ,acid ,method4--,this simple and accurate method of determining nitric acid in the absence of organic matter is known as the ,crum-,frankland process4#cja ,the method rests on the principle of converting nitric acid into nitric oxid by the action of mercury in the presence of sulfuric acid4 ,the operation as at first described is conducted in a glass jar eight inches long by one and a half inches in diameter filled with mercury and inverted in a trough containing the same liquid4 ,the nitrate to be examined1 in a solid form1 is passed into the tube together with three cubic centimeters of water and five of sulfuric acid4 ,with occasional shaking1 two hours are allowed for the disengagement of the gas1 which is then measured4 #dga4 ,warington's ,modification4--,a graduated shaking tube is employed which allows the nitrate solution and oil of vitriol to be brought to a definite volume4 ,the nitrate solution1 with rinsings1 is always two cubic centimeters and enough sulfuric acid is added to increase the volume to five cubic centimeters4 ,the sulfuric acid should give no gas when shaken with distilled water4 ,any gas given off in the apparatus before shaking1 is not expelled but is included in the final result4 ,the persistent froth sometimes noticed where some kinds of organic matter are present1 is reduced by the addition of a few drops of hot water through the stop-cock of the apparatus4 ,the nitric oxid is finally measured in ,frankland's modification of ,regnault's apparatus4 ,this method1 accurate for pure nitrates1 unfortunately fails in the presence of any considerable amount of organic matter4 ,according to ,warington's observations the presence of chlorids is no hindrance to the accurate determination of both nitric and nitrous acids by the mercury method4 ,this simplifies the operation as carried on by ,frankland who directs that any chlorin present1 be removed before the determination of the nitric acid is commenced4 #dgb4 ,noyes' ,method4--,in the analyses made by ,noyes for the ,national ,board of ,health1 the ,crum-,frankland method was employed4#cjb ,the apparatus used was essentially that which is now known as ,lunge's nitrometer and it will be described in the next paragraph4 ,no correction is made by ,noyes for the tension of aqueous vapor in the measurement of the nitric oxid because of the moderate dilution of the sulfuric acid by the liquid holding the nitric compounds in solution4 ,the chlorin was not removed from the dry residue of the evaporated water as its presence in moderate quantity does not interfere with the accuracy of the process4 ,in order to obtain the amount of nitrogen in the form of nitrates1 the total volume of nitric oxid must be diminished by that due to nitrites present1 which must be determined in a separate analysis4 ,the method of manipulation is given in the following paragraph4 ,illustration3 ,,figure #hb4 ,,lunge',s ,,nitrometer4 #dgc4 ,lunge's ,nitrometer4--,the apparatus employed by ,noyes1 in a somewhat more elaborate form1 is known as ,lunge's nitrometer4#cjc ,this apparatus is shown in ,fig4 #hb4 ,it consists of a burette1 a1 divided into one-fifth cubic centimeters4 ,at its upper end it is expanded into a cup-shaped funnel attached by a three-way glass stop-cock4 ,below1 the burette is joined to a plain tube1 b1 of similar size1 by means of rubber tubing4 ,the apparatus is first filled with mercury through the tube b1 the stop-cock being so adjusted as to allow the mercury to fill the cup at the top of a4 ,the cock is then turned until the mercury in the cup flows out through the side tube carrying the rubber tube and clamp4 ,the three-way cock is closed1 and the solution containing the nitrate placed in the cup4 ,by lowering the tube b and opening the cock the liquid is carefully passed into a1 being careful to close the cock before all the liquid has passed out of the cup4 ,by repeated rinsings with pure concentrated sulfuric acid1 every particle of the nitric compound is finally introduced into a1 together with a large excess of sulfuric acid4 ,the total volume of the introduced liquid should not exceed ten cubic centimeters4 ,the mixture of the mercury1 nitric compound1 and sulfuric acid is effected by detaching a from its support1 compressing the rubber connection between a and b1 placing a nearly in a horizontal position1 and quickly bringing it into a vertical position with vigorous shaking4 ,after about five minutes the reaction is complete1 and the level of the liquids in the two tubes is so adjusted as to compensate for the difference in specific gravity between the acid mixture in a and the mercury in b2 in other words1 the mercury column in b should stand above the mercury column in a one-seventh of the length of the acid mixture in a4 ,this secures atmospheric pressure on the nitric oxid which has been collected in a4 ,the measured volume of nitric oxid should be reduced to #j and #gfj millimeters barometric pressure4 ,each cubic centimeter of nitric oxid thus obtained corresponds to #a4cdc milligrams ,,no2 #b4dag milligrams ,n,o2 #d4eba milligrams ,,kno2 #a4gja milligrams ,n,o2 #b4hbj milligrams ,,hno2 and #c4hje milligrams ,na,n,o4 #dgd4 ,lunge's ,improved ,apparatus4--,lunge has lately improved his apparatus for generating and measuring gases and extended its applicability4#cjd ,the part of it designed to measure the volume of a gas is the same in all cases4 ,for generating the gas1 the apparatus varies according to the character of the substance under examination4 ,the measuring apparatus is shown in ,fig4 #hc4 ,it is composed essentially of three tubes1 conveniently mounted on a wooden holder with a box base for securing any spilled mercury4 ,the support is not shown in the illustration4 ,the tubes ,a1 ,b1 ,c1 are mutually connected by means of a three-way tube and rubber tubing with very thick walls to safely hold the mercury without expansion4 ,in the middle of the measuring tube ,a1 is found a bulb of seventy cubic centimeters capacity4 ,above and below the bulb the tube is divided into tenths of a cubic centimeter1 and its diameter is such1 viz41 #aa4c millimeters1 that each cubic centimeter occupies a length of one centimeter4 ,the upper end of ,a is closed with a glass cock with two oblique perforations1 by means of which communication can be established at will1 either through e with the apparatus for generating the gas1 or through d with the absorption apparatus1 or the opening be completely closed4 ,illustration3 ,,figure4 #hc4 ,,lunge',s ,,improved ,,apparatus4 ,the volume of air under the observed conditions which would measure exactly #ajj cubic centimeters at #j and #gfj millimeters pressure of mercury1 is calculated by the formula ,v 7#ajj7bgc t7#gfj7_/7bgc7;b f772 where t equals observed temperature1 b the barometric pressure less the correction noted above and f the tension of the vapor of water under existing conditions4 ,for example3 ,let the temperature be #ah ,barometric reading #gee ,correction for t #b ,corrected barometer #gec ,vapor of water tension #af ,then ,v 7#ajj7bgc #ah7gfj7_/7bgc7gec #af77 #aji4i4 ,this indicates that #aji4i cubic centimeters of air would occupy a volume of #ajj cubic centimeters when subjected to standard conditions4 ,the tubes ,a1 ,b1 and ,c are filled with mercury of which about two and a half kilograms will be required4 ,by means of the leveling tube ,b1 the stopper in ,c being opened1 the mercury in ,c is brought exactly to #aji4i cubic centimeters4 ,the stopper in ,c is then closed1 mercury poured into ,d1 which is then closed with a rubber stopper1 carrying a small glass tube as indicated in the figure4 ,the leveling tube ,b serves to regulate the pressure on the gas in ,a and this is secured by depressing or elevating it as the case may require4 ,the tube for reducing the volume to standard conditions of temperature and pressure1 viz41 #j and #gfj millimeters of mercury1 is shown in ,c4 ,in its narrow part which has the same internal diameter as ,a it is graduated into tenths of a cubic centimeter4 ,the upper end of ,c is furnished with a heavy glass neck ,d surmounted by a glass cup4 ,in the neck is placed a ground-glass stopper1 carrying a groove below1 which corresponds to a similar groove above in the side of the neck whereby communication can be established at will between the interior of ,c and the exterior4 ,the joint is also sealed by pouring mercury into ,d as is shown in the figure4 ,when the stopper is well ground and greased the reduction tube may be raised or lowered as much as may be necessary without any danger of escape or entrance of gas4 ,to determine the position of the reduction tube ,c the reading of the barometer and thermometer at room temperature is taken4 ,from the reading of the barometer subtract one millimeter if the temperature be below #ab1 two millimeters at a temperature from #ab to #ai1 three from #bj to #be1 and four above #be4 ,when a gas has been introduced into the measuring tube ,a it is brought to the volume which it would assume under standard conditions by adjusting the tube ,c in such a way as to bring the level of mercury in ,c and ,a to the same point and the level of the mercury in ,c is exactly at #ajj cubic centimeters4 ,the gas in ,a is then at the volume which it would occupy under standard conditions and this volume can be directly read4 ,this adjustment is secured by moving the tubes ,b and ,c up or down4 ,if gases are to be measured wet1 a drop of water should be put on the side of the upper part of ,c1 and1 if dry1 of sulfuric acid1 before the adjustment for temperature and pressure4 #dge4 ,method of ,manipulation4--,by the action of mercury in the presence of sulfuric acid1 the nitrogen in nitrates1 nitrites1 nitrosulfates1 nitroses1 nitrocellulose1 nitroglycerol1 and the greater number of explosives1 may be obtained and measured as nitric oxid4 ,the nitrogen compounds are decomposed in the apparatus shown in ,fig4 #hd4 ,to make an analysis1 the apparatus is filled with mercury1 through ,f1 until the two openings in the cock and i are entirely occupied with that liquid4 ,the cock h is then closed1 and the nitrogen compound1 in solution1 introduced through g1 care being taken that no air enters g when ,f is depressed and h opened to admit the sample4 ,the funnel g is washed several times with a few drops of sulfuric acid1 which are successively introduced into ,g4 ,the total liquid introduced should not exceed ten to fifteen cubic centimeters1 of which the greater part should be sulfuric acid4 ,the rubber tube connecting ,g and ,f is carefully closed with a clamp and ,g violently shaken for a few minutes until no further evolution of nitric oxid takes place4 ,in shaking1 the apparatus should be so held as to prevent the escape of the mercury from the small tube i by keeping it closed with the finger or drawing over it a rubber cap4 ,illustration3 ,,figure #hd4 ,,lunge',s ,,analytic ,,apparatus4 ,after the evolution of the gas has ceased1 the tube e1 ,fig4 #hc1 is brought into contact with i1 ,fig4 #hd1 and the two are joined by a tight-fitting piece of rubber tubing in such a way as to exclude any particle of air4 ,the tube ,f1 ,fig4 #hd1 is lifted and ,b and ,c1 ,fig4 #hc1 depressed4 ,on carefully opening the cocks h and b and bringing i and e into union1 the gas is passed from ,g into ,a4 ,when all the gas has entered ,a and the acid mixture from ,g has reached b the latter is closed1 and also h4 ,the apparatus ,g is disconnected and removed4 ,the gas in ,a is then reduced to normal conditions by manipulating the reduction tube ,c in the manner already described4 ,the gas in ,a is measured dry by reason of having been generated in presence of rather strong sulfuric acid4 ,consequently1 for this operation the adjustment of the volume of gas in ,c should be made in contact with a drop of strong sulfuric acid4 ,in order to make the readings1 a quantity of material must be taken which will give less than thirty or from #ajj to #adj cubic centimeters of nitric oxid4 ,the quantities of the different compounds of nitric acid corresponding to the number of cubic centimeters of nitric oxid1 measured under standard conditions1 are shown in the following table3 ,,corresponding ,,to ------------------------ ------------------------ ------------------------ ,cubic ,weight in ,n,o in ,,hno in ,na,n,o in centimeters milligrams4 milligrams4 milligrams4 milligrams4 of ,,no4 #a #a4cdc #a4gja #b4hbj #c4hje #b #b4fhb #c4djb #e4fdj #g4faj #c #d4jbi #e4ajc #h4dfj #aa4dae #d #e4cgb #f4hjd #aa4bhj #ae4bbj #e #f4gae #h4ejf #ad4ajj #ai4jbe #f #h4jeh #aj4bjf #af4ibj #bb4hcj #g #i4dja #aa4ijg #ai4gdj #bf4fce #h #aj4gdd #ac4fjh #bb4efj #cj4ddj #i #ab4jhg #ae4cji #be4chj #cd4bde #dgf4 ,utility of the ,method4--,where it is desirable that the nitric oxid method be used1 and at the same time heating be avoided1 the decomposition of a nitrate by means of metallic mercury and sulfuric acid affords a convenient and accurate procedure4 ,but1 as a rule1 there is no objection to the application of the lamp1 and in such cases the mercury method appears to have no advantage over the ferrous chlorid process4 ,nevertheless1 in the hands of a skilled worker the results are reliable1 and the process is a quicker one1 on the whole1 than by distillation with ferrous chlorid and hydrochloric acid4 ,this method1 however1 can not be recommended as in any way superior to the reduction methods to be hereinafter described4 ,,estimation ,,of ,,nitric ,,acid ,,by ,,oxidation ,,of ,a ,,colored ,,solution4 #dgg4 ,method of ,boussingault4--,the process for the estimation of nitric acid by the decoloration of a solution of indigo is due originally to ,boussingault4#cje ,in this method the extract1 obtained by washing slowly #bjj grams of soil until the filtrate amounts to #cjj cubic centimeters1 is evaporated until its volume is no greater than two or three cubic centimeters1 and it is transferred to a test-tube1 with washings1 and again evaporated in the tube until the volume is not greater than that last mentioned4 ,a few drops of solution of indigo are added1 and then two cubic centimeters of pure hydrochloric acid2 the whole is then heated4 ,as the color of the indigo disappears more is added4 ,when the color ceases to fade1 the liquid in the test-tube is concentrated by boiling4 ,if concentration fail to destroy the blue or green color1 another one-half cubic centimeter of hydrochloric acid is introduced4 ,the reaction is completed when neither concentration nor fresh addition of hydrochloric acid destroys the excess of indigo present4 ,the color produced by a small excess of indigo is a bright sap-green2 this tint is the final reaction sought4 ,the small excess of indigo necessary to produce a green color is deducted in every experiment4 ,when more than mere traces of organic matter are present1 ,boussingault advises that the nitric acid be first separated by distillation and then reduced by the indigo solution4 ,for this purpose the concentrated solution of the nitrate1 two or three cubic centimeters1 is placed in a small tubulated retort with two grams of manganese dioxid in fine powder4 ,the retort is next half filled with fragments of broken glass1 over which is poured one cubic centimeter of concentrated sulfuric acid4 ,the retort is heated carefully by means of a small flame1 which is kept in motion so as to successively come in contact with all parts of the bottom of the retort4 ,the distillate is received in a graduated test-tube which is kept cool4 ,the distillation is continued until the vapors of sulfuric acid begin to appear4 ,the apparatus is allowed to cool1 the stopper of the retort removed1 two cubic centimeters of water introduced1 and the distillation again made until fumes of sulfuric acid are again seen4 ,the distillation with water is made twice in order to remove every trace of nitric acid from the retort4 ,the distillate is neutralized with a solution of potassium hydroxid and concentrated to two cubic centimeters1 and the nitric acid estimated in the manner already described4 ,the manganese dioxid used should be previously well washed and the sulfuric must be free of nitric acid4 ,preparation of the ,indigo ,solution4--,fifty grams of indigo in fine powder are digested for twenty-four hours1 at #dj1 in a liter of distilled water4 ,the water is then poured off and replaced with a fresh supply4 ,after the second decantation the residue is treated with #gej cubic centimeters of equal parts of water and pure concentrated hydrochloric acid and boiled for an hour4 ,after cooling1 the undissolved portion is collected on a filter and washed at first with hot1 and afterwards with cold water1 until the filtrate is no longer colored and is free of acid4 ,the dried residue is treated with ether under a bell-jar1 or in a continuous extraction apparatus1 until the ether is only of a faint blue tint4 ,the fifty grams of indigo at first taken will give about twenty-five grams of the purified article1 which1 however1 will still leave a little ash on combustion4 ,solution in ,sulfuric ,acid4--,five grams of the purified indigo are placed in a flask having a ground-glass stopper1 treated with twenty-five grams of fuming sulfuric acid1 and allowed to digest two or three days at a temperature of from #ej to #fj4 ,from seventy to #bjj drops of the solution thus made are placed in #ajj cubic centimeters of water for use in the process4 ,standardization of the ,indigo ,solution4--,the solution as prepared above is standardized by a solution of one gram of pure potassium nitrate in #a1jjj cubic centimeters of distilled water4 ,the oxidation of the indigo solution is accomplished as described above4 ,for this strength of standard nitrate solution two cubic centimeters are taken corresponding to two milligrams of potassium nitrate4 ,the indigo solution for this strength should have only twenty drops of the sulfuric acid solution of indigo to #ajj cubic centimeters of water4 ,if twenty grams of potassium nitrate are taken for #a1jjj cubic centimeters of the standard solution then #bjj drops of the sulfindigotic acid should be used to #ajj cubic centimeters of water4 #dgh4 ,method of ,marx4--,as usually practiced1 the indigo method is conducted according to the variation described by ,marx4#cjf ,there are required for the process the following reagents and apparatus3 a4 ,a solution of pure potassium nitrate containing #a4hgbd grams per liter4 ,one cubic centimeter of the solution is equivalent to one milligram of nitric anhydrid 7,n,o74 b4 ,a solution of the best indigo carmine in water which should be approximately standardized by solution in the manner described hereafter1 and then diluted so that six to eight cubic centimeters equal one milligram of nitric acid4 c4 ,chemically pure sulfuric acid of specific gravity #a4hdb1 perfectly free from sulfurous and arsenious acids and nitrogen oxids4 d4 ,several thin flasks of about #bjj cubic centimeters capacity4 e4 ,a small cylindrical measure holding fifty cubic centimeters and divided into cubic centimeters4 f4 ,a ,mohr's burette divided into tenths of a cubic centimeter4 g4 ,a twenty-five cubic centimeter pipette or another burette4 h4 ,a five cubic centimeter pipette divided into cubic centimeters or half cubic centimeters4 i4 ,a measuring flask of #bej cubic centimeters capacity4 ,preliminary ,trial4--,twenty-five cubic centimeters of the sample are transferred to a flask2 the fifty cubic centimeter measure is filled with sulfuric acid and the burette with indigo solution4 ,the sulfuric acid is added to the sample all at once1 shaken for a moment1 and the indigo run in as quickly as possible with shaking until a permanent greenish tint is produced4 ,if the sample do not require more than twenty cubic centimeters of indigo solution of the above strength1 it can be titrated directly1 otherwise it must be diluted with a proper quantity of pure water1 and subjected again to the preliminary trial4 ,the ,actual ,titration4--7#a7 ,twenty-five cubic centimeters of the sample properly diluted if necessary1 are measured and poured into a flask1 and as much indigo as was used in the preliminary trial1 is added2 a quantity of sulfuric acid1 equal in volume to the liquid in the flask1 is added all at once1 the mixture shaken1 and indigo solution run in quickly out of the burette until the liquid remains permanently of a greenish tint4 7#b7 ,the last experiment is repeated as often as may be necessary adding to the water at first half a cubic centimeter less indigo than the total quantity used previously1 afterwards proceeding as in 7#a7 until the final test shows too little indigo used4 7#c7 ,from the rough titration of the indigo1 calculate the amount of potassium nitrate solution corresponding with the indigo solution used in 7#b71 multiply the result by ten1 transfer this quantity of the standard nitrate solution to a #bej cubic centimeter flask1 fill with pure water to the mark1 and titrate twenty-five cubic centimeters of this fluid with indigo as in 7#b74 ,if the quantity of indigo solution used is nearly the same as that required in 7#b71 its exact value may be calculated1 but if it is not1 another nitrate solution may be made up in the #bej cubic centimeter flask1 more closely resembling the sample in strength1 and the titration with the indigo solution must be repeated4 7#d7 ,if the water contain any considerable amount of organic matter1 it must first be destroyed by potassium permanganate4 ,in this case1 the estimation of the organic matter and nitric acid may be conveniently combined4 ,the use of permanganate in the above case is likely to introduce an error as has been shown by ,warington4 ,the method therefore can not be recommended in the presence of organic matter4 #dgi4 ,method of ,warington4--,the modification of the indigo method as used by ,warington1 applicable only in absence of organic matter1 is the one chiefly employed in ,england4#cjg ,instead of the ordinary indigo of commerce1 indigotin is used4 ,the normal solution of the coloring matter is made of such a strength as to be equivalent to a solution of potassium nitrate containing #j4ad gram of nitrogen per liter4 ,where large quantities of the coloring matter are to be used it is advisable to prepare it about four times the strength given above and then dilute it as required4 ,four grams of sublimed indigotin will furnish more than two liters of the color solution4 ,the solution is prepared as follows3 ,four grams of indigotin are digested for a few hours with five times that weight of ,nordhausen sulfuric acid1 diluted with water1 filtered1 and made up to a volume of two liters4 ,the strength of the indigotin solution is determined with a solution of potassium nitrate of the strength mentioned above4 ,the process is performed as follows3 ,from ten to twenty cubic centimeters of the standard nitrate solution are placed in a wide-mouthed flask of about #aej cubic centimeters capacity4 ,a portion of the indigotin solution is next added1 such as will be deemed sufficient for the process1 and the whole is well mixed4 ,strong sulfuric acid is next measured out from a burette into a test-tube1 in volume equal to the united volumes of the nitrate solution and indigotin4 ,the whole of the sulfuric acid is then poured as quickly as possible1 into the solution in the flask and rapidly mixed1 and the flask transferred to a calcium chlorid bath1 the temperature of which should be maintained at #adj4 ,it is essential to the success of the operation that the sulfuric acid should be mixed with the greatest rapidity4 ,it should be poured in at once and the whole well shaken without waiting for the test-tube containing the acid1 to drain4 ,the flask should be covered by a watch-glass while it is held in the bath4 ,as soon as the larger part of the indigotin is oxidized the flask in the bath should be gently rotated4 ,with very weak solutions of nitrate it may be necessary sometimes to keep the flask in the bath for five minutes4 ,when the indigo color is quickly discharged it shows the presence of nitric acid in considerable excess and a considerably larger quantity of indigo must be taken in the next experiment4 ,the experiments are continued until just the quantity of indigo necessary to consume the nitric acid is taken1 the amount of indigo being in very slight excess1 not exceeding one-tenth cubic centimeter of the indigo solution used4 ,the tint produced by the small excess of indigo remaining is best seen by filling the flask with water4 ,on substances of approximately known strength about four experiments are usually necessary to determine the amount of indigo to be taken1 but with unknown substances a larger number may be necessary4 ,usually in determinations of this kind it is directed to use double the volume of sulfuric acid mentioned above4 ,in this case not only is the quantity of indigo oxidized much greater than with a smaller portion of acid1 but the prejudicial effect of organic matter is also greater than when the smaller quantity of acid is employed4 ,an indigo solution standardized as above is strictly to be used for a solution of nitrate of the strength employed during the standardization4 ,the quantity of indigo oxidized in proportion to the nitric acid present diminishes as the nitrate solution becomes more dilute4 ,instead of determining this during each series of experiments it may be estimated once for all and a table of corrections used4 ,the following table is based upon experimental determinations3 ,strength of ,indigo ,difference ,nitrogen ,difference ,difference niter required1 between corresponding between the in the solution cubic amounts of to one cubic nitrogen nitrogen used4 centi- indigo1 centimeter of values1 values for a meters4 cubic indigo1 gram4 gram4 difference centi- of one cubic meters4 centi- meter in the amount of indigo1 gram4 ,normal #aj4jj #j4jjjjcejjj #h4ga #a4bi #j4jjjjceafa #j4jjjjjjafa #j4jjjjjjabe #g4dc #a4bh #j4jjjjceccj #j4jjjjjjafi #j4jjjjjjacb #f4ad #a4bi #j4jjjjcefbg #j4jjjjjjbih #j4jjjjjjbca #d4hf #a4bh #j4jjjjcfjjh #j4jjjjjjcha #j4jjjjjjbih #c4eg #a4bi #j4jjjjcfgfc #j4jjjjjjgef #j4jjjjjjehf #b4bi #a4bh #j4jjjjchbji #j4jjjjjadde #j4jjjjjaabi #a4jj #a4bi #j4jjjjdcgej #j4jjjjjeeda #j4jjjjjdbie ,the table is used as follows3 ,suppose that twenty cubic centimeters of water under examination have required #e4cf cubic centimeters of indigo solution for the oxidation of the nitric acid contained therein4 ,by inspection of the table it is seen that this number is five-tenths cubic centimeter above the nearest quantity given2 viz41 #d4hf cubic centimeters4 ,from the last column in the table it is found that the correction for five-tenths cubic centimeter of indigo solution is #j4jjjjjjadi cubic centimeter1 being half that for the one cubic centimeter given in the table4 ,this is to be subtracted from the unit value in nitrogen given in the first 8gram0 column of the table2 viz41 #j4jjjjcfjjh4 ,it is thus seen that the #e4hf cubic centimeters of indigo solution are equivalent to #j4jjjjcehei gram of nitrogen per cubic centimeter4 ,the water under examination1 therefore1 contains nine and six-tenths parts of nitrogen as nitric acid per million4 ,attention must also be paid in standardizing indigo solutions to the initial temperature of the solutions4 ,a rise in the initial temperature will be attended by a diminution in the quantity of indigo oxidized4 ,experiments with a room temperature of #aj and a room temperature of #bj1 being the initial temperatures of the experiments1 showed that at the higher temperature the amount of indigo consumed was about five per cent less when the strong solutions of nitrate were employed4 ,the indigo solution should1 therefore1 be standardized at the same temperature at which the determinations are made4 ,if twenty cubic centimeters of the standard nitrate solution employed be used in setting the indigo solution1 this standard will enable the operator to determine nitric acid up to #ag4e parts of nitrogen per million in water or soil extracts4 ,the presence of an abundance of chlorids in the water under examination tends to diminish the content of nitric acid found1 and also tends to introduce an error1 which is sometimes of a plus and sometimes of a minus quantity1 according to the strength of the nitric acid present4 ,the reaction is shortened in weak solutions by the presence of chlorids1 and the quantity of indigo consumed is consequently increased4 ,the error introduced by chlorids is usually of an insignificant nature4 ,on account of the interference of organic matters with the reaction of indigo it is not of much use in the examination of nitrates washed out of soils1 although in some cases the results may be quite accurate4 ,this method must1 therefore1 be considered as applicable1 in general1 to waters or soil extracts which contain little or no organic matter4 ,in analytical work pertaining particularly to agriculture1 the use of the indigo method for determining nitric acid has been largely employed1 both in the analyses of soil extracts and drainage and irrigation waters4 ,the method1 however1 can hardly survive as an important one in such work in competition with more modern and speedy processes of analysis4 ,,determination ,,of ,,nitric ,,nitrogen ,,by ,,reduction ,,to ,,ammonia4 #dhj4 ,classification of ,methods4--,when nitrogen is present in a highly oxidized state1 e4 g41 as nitric acid1 it may be quickly and accurately estimated by reduction to ammonia4 ,this action is effected by the reducing power of nascent hydrogen1 and this substance may be secured in the active state by the action of an acid or alkali on a metal1 or by means of an electric current4 ,the processes depending on the use of a finely divided metal in the presence of an acid or alkali have come into general use within a few years1 and are now employed generally instead of the more elaborate estimations depending on the use of copper oxid or indigo4 ,the typical reaction which takes place in all cases is represented by the following equation3 #b;,,hno #h;,h #b,,nh #f;,h,o4 ,the method will be considered under three heads2 viz41 #a4 ,reduction in an alkaline solution2 #b4 ,reduction in an acid solution2 #c4 ,reduction by means of an electric current4 ,in the first class of processes the reduction and distillation may go on together4 ,in the second class the reduction is accomplished first and the distillation effected afterwards1 with the addition of an alkali4 ,in the third class of operations the reduction is accomplished by means of an electric current and the ammonia subsequently obtained by distillation1 or determined by nesslerizing4 ,these processes may be applied to rain and drainage waters1 and to soil extracts4 ,on account of the ease with which the analyses are accomplished1 the short time required and the accuracy of the results1 the reduction methods for nitrates have already commended themselves to analysts1 and are quite likely to supersede all others for practical use where weighable quantities of nitrates are present4 ,for the minute traces of nitrates found in rain and drainage waters1 and in some soil extracts1 the reduction method may also be applied1 but in these cases the ammonia which is formed must be determined by colorimetry 7nesslerizing7 and not by distillation4 ,the processes about to be described are especially applicable to the examination of soils and waters rich in nitrates4 ,,reduction ,,in ,,alkaline ,,solutions4 #dha4 ,provisional ,method of the ,association of ,official ,agricultural ,chemists4#cjh-- ,extraction of the ,nitrates4--,place one kilogram of the dried soil1 calculated to water-free substance1 on a percolator of glass or tin4 ,moisten the soil thoroughly with pure distilled water1 and allow to stand for half an hour4 ,add fresh portions of pure distilled water until the filtrate secured amounts to one liter4 ,if the first filtrate be cloudy before use it may be refiltered4 ,qualitative ,test for ,nitrates4--,evaporate five cubic centimeters of the soil extract in a porcelain crucible1 having first dissolved a small quantity of pure brucin sulfate therein4 ,when dry1 add to the residue a drop of concentrated sulfuric acid free of nitrates4 ,if the nitrate calculated as potassium nitrate does not exceed the two-thousandth part of a milligram only a pink color will be developed2 with the three-thousandth part of a milligram a pink color with reddish lines2 with the four-thousandth part of a milligram a reddish color2 with the five-thousandth part of a milligram a distinct red color4 ,estimation of the ,nitrates4--,evaporate #ajj cubic centimeters of the soil extract to dryness on a steam-bath4 ,dissolve the soluble portions of the residue in #ajj cubic centimeters of ammonia-free distilled water1 filtering out any insoluble residue4 ,place the solution in a flask1 add ten cubic centimeters of sodium amalgam1 stopper the flask with a valve which will permit the escape of hydrogen1 and allow to stand in a cool room for twenty-four hours4 ,add fifty cubic centimeters of milk of lime and titrate the ammonia produced by distillation1 with standard acid and estimate as nitrogen pentoxid4 ,where the amount of ammonia is small1 nesslerizing may be substituted for titration4 ,preparation of ,sodium ,amalgam4--,place #ajj cubic centimeters of mercury in a flask of half a liter capacity2 warm until paraffin will remain melted over the surface2 drop successively in the paraffin-covered mercury1 pieces of metallic sodium of the size of a pea until #f4ge grams have united with the mercury4 ,the amalgam contains then #j4e per cent of metallic sodium and may be preserved indefinitely under the covering of paraffin4 #dhb4 ,method of the ,experiment ,station at ,mckern4#cji--,the principle of this reaction is based on the reducing action exercised by nascent hydrogen on a nitrate1 the hydrogen being generated by the action of soda-lye on a mixture of zinc dust and finely divided iron4 ,ten grams of nitrate are dissolved in #ejj cubic centimeters of water4 ,of this solution twenty-five cubic centimeters1 corresponding to one-half gram1 are placed in a distillation flask of about #djj cubic centimeters capacity1 #abj cubic centimeters of water added1 and about five grams of well-washed and dried zinc dust and an equal weight of reduced iron4 ,to the solution are added eighty cubic centimeters of soda-lye of #cb ,b4 ,the flask is then connected with the condensing apparatus and the distillation carried on synchronously with the reduction1 the ammonia being collected in twenty cubic centimeters of titrated sulfuric acid4 ,the distillation is continued from one to two hours1 or until #ajj cubic centimeters have been distilled1 and the remaining sulfuric acid is titrated in the usual way4 ,soil extracts and sewage waters should be concentrated until they have approximately the proportion of nitrates given above4 #dhc4 ,method of ,devarda4--,the inconvenience due to slow action and other causes1 arising from the use of pure metals in the reduction of nitrates to ammonia1 has been overcome1 to some extent1 by ,devarda1 by use of an alloy1 in a state of fine powder1 consisting of aluminum1 copper1 and zinc4#caj ,the alloy consists of forty-five per cent of aluminum1 fifty per cent of copper1 and five per cent of zinc4 ,in dissolving1 the copper is left in a finely divided state1 which is a great help in distillation in preventing bumping4 ,the analytical process is carried out as follows3 ,the solution containing the nitrate1 in quantity equivalent to about one-half gram of potassium nitrate1 is placed in a flask having a capacity of about one liter1 and diluted with sixty cubic centimeters of water and five cubic centimeters of alcohol1 and then forty cubic centimeters of caustic potash solution added of specific gravity one and three-tenths4 ,from two to two and one-half grams of the alloy1 described above1 are introduced1 and the flask attached to a condenser with a receiver containing standard acid4 ,the connection between the flask and the condenser is made by means of a tube having on the limb next the flask a bulb filled with glass beads to prevent the contents of the flask splashing over into the receiver1 and on the other limb another bulb to prevent the acid in the receiver finding its way into the distillation flask1 should regurgitation occur4 ,when the flask has been thus connected with the condenser it is gently heated for half an hour1 at the end of which time the evolution of hydrogen will have slackened or ceased1 and then the distillation is begun1 at first cautiously1 until the zinc of the alloy has completely dissolved1 and then more vigorously1 the time necessary being about twenty minutes from the time when the contents of the flask begin to boil4 ,the distillate is caught in standard acid and the ammonia determined by backward titration in the ordinary way4 ,it is to be noted that the strength of the alkali used is of importance1 as if it be too strong1 the action on the alloy is unduly vigorous at the beginning of the operation1 and if too weak1 the contents of the flask have to be heated overmuch1 the result in both cases being the formation of a fine spray of caustic solution1 which is very difficult to stop1 even with complicated washing attachments to the distilling flask4 ,the test analyses on pure nitrates are satisfactory4 ,this method has been used with satisfaction in the laboratory of the ,department of ,agriculture1 but does not appear to have any special advantage over the process of ,ulsch1 to be described further on4 #dhd4 ,variation of ,stoklassa4--,stoklassa has subjected the method of ,devarda to a comparative test with the following methods3#caa #a4 ,wagner's ,schloesing-,grandeau method4 #b4 ,lunge's nitrometer method4 #c4 ,stutzer's method4 ,illustration3 ,,figure #he4 ,,stoklassa',s ,,nitric ,,acid ,,apparatus4 ,the reduction takes place in a copper erlenmeyer1 ,a1 ,fig4 #he1 in which1 in addition to the solution containing the nitrate1 are placed #bjj cubic centimeters of water1 forty cubic centimeters of potassium hydroxid solution of #cc ,b41 five cubic centimeters of alcohol1 and finally two and one-half grams of the finely powdered ,devarda alloy4 ,the distillate passes through a tube1 ,b1 filled with glass pearls and into the condenser ,d1 through the bulbs1 ,c ,c4 ,after the flask is connected with the distilling apparatus1 it is gently warmed and the reduction is ended in about twenty minutes4 ,the ammonia which is formed is then distilled into ,e1 containing the standard acid1 ,s1 requiring about twenty minutes more4 ,the comparative results given1 show that the ,devarda method is equally as accurate as any of the other methods mentioned1 giving practically theoretical results4 ,in so far1 however1 as speed of an analysis1 is concerned the first place is awarded to the ,lunge nitrometer method1 with which a complete analysis can be made in from thirty to forty minutes4 ,in the second rank1 so far as speed is concerned1 the ,devarda method is recommended4 ,all the methods give accurate results4 #dhe4 ,method of ,sievert4#cab--,two grams of potassium or sodium nitrate are dissolved and made up to #a1jjj cubic centimeters4 ,fifty cubic centimeters of the solution are placed in a #fjj cubic centimeter flask and diluted with fifty cubic centimeters of water1 and from eighteen to twenty grams of caustic alkali added4 ,after the alkali is dissolved1 seventy-five cubic centimeters of ninety-six per cent alcohol are added and a few pieces of bone-black to prevent foaming4 ,from ten to fifteen grams of zinc or iron dust are then added to the flask which is closed and connected with a tube holding about #bjj cubic centimeters1 which contains about ten cubic centimeters of normal sulfuric acid4 ,this tube is kept cool by being immersed in water4 ,the whole mixture is now allowed to stand for three or four hours and then the alcohol is distilled slowly and the ammonia formed by the reduction of the nitrates is carried over with it4 ,the distillation lasts for about two hours4 ,the contents of the tube are carefully rinsed into a dish and the excess of sulfuric acid titrated with one-fourth normal soda-lye4 ,for soil extracts and substances containing unknown quantities of nitric acid1 a preliminary test will indicate approximately the amount thereof1 and this will be an indication for the quantity to be used in the analysis4 ,the method of ,stutzer differs from the foregoing in the substitution of aluminum dust instead of iron or zinc4#cac ,the reducing power of aluminum1 however1 varies greatly according to the method in which the metal has been prepared4 ,pure aluminum prepared by the electric method1 reduces the nitric acid much less vigorously than the metal prepared by the older methods of fusion with sodium4 ,for this reason the method of ,stutzer is not to be preferred to that of ,sievert4 ,,reduction ,,in ,,an ,,acid ,,solution4 #dhf4 ,variation of the ,sodium ,amalgam ,process4--,this method is described by ,monnier and ,auriol4#cad ,illustration3 ,,figure #hf4 ,,variation ,,of ,,the ,,sodium ,,amalgam ,,process4 ,the principle of the operation depends on the reduction of the dissolved nitrate by titrated sodium amalgam in presence of an acid1 and the estimation of the quantity of nitric acid present from the deficit in the volume of hydrogen4 ,the apparatus employed is conveniently mounted as shown in ,fig4 #hf4 ,the brass vessel ,a is movable by means of the cord on the pulley ,b1 in such a way as to be fixed at any required altitude4 ,it is filled with water and connected by a rubber tube to the cooling tube ,d4 ,within the cooling tube there is a graduated cylinder open at its lower end4 ,its upper end is connected directly with the apparatus ,c4 ,the cooling tube ,d has a small side tube1 c1 near its upper end1 by means of which the air can enter or escape when the position of ,a is changed4 ,the apparatus ,c1 in which the reaction takes place1 is a glass cylinder4 ,its upper end is continuous with the tube provided with the stop-cocks a and b4 ,one arm of the permits connection with the graduated measuring tube by means of a rubber union4 ,the lower end of ,c is closed with a large hollow ground-glass stopper1 carrying a small receptacle within1 so that it forms two separate water-tight compartments1 open at the top4 ,the sodium amalgam is prepared as follows3 ,in a clay crucible are heated #djj grams of mercury1 and1 little by little1 with constant stirring1 four grams of dry sodium are added4 ,when cold1 the amalgam is placed in a burette1 having a ground-glass stopper1 and covered with petroleum4 ,the strength of the amalgam is established in the following manner4 ,a small glass thimble1 ground even at the top1 is filled with the amalgam and struck off even with a ground-glass straight edge4 ,in this way the same quantity of amalgam is taken for each test4 ,this measured portion of the amalgam is placed in the inner vessel of the glass stopper to ,c4 ,ten cubic centimeters of water1 containing sixty centigrams of tartaric acid1 are placed on the outer ring of the glass stopper1 which is then inserted1 well oiled1 in ,c1 closing it air- and water-tight4 ,the tartaric acid solution also carries a piece of litmus paper1 so that its constant acidity may be insured4 ,the vessel ,a is then fixed in a position which brings the water in the graduated burette and tube ,d exactly to the #j mark4 ,the cock a is next closed1 b opened1 and ,c is inverted until all the amalgam is poured into the solution of tartaric acid4 ,the evolved hydrogen mixed with the air contained in the apparatus1 is passed into the graduated burette4 ,after fifteen minutes1 the reaction is ended4 ,the water level within and without the graduated tube is restored and the volume of gas evolved noted and reduced by the usual tables to #j and #gfj millimeters pressure of the barometer4 ,an amalgam prepared as above will give about three cubic centimeters of hydrogen for each gram4 ,the thimble should hold from twelve to fifteen grams4 ,the estimation of nitric acid should be made in a solution containing about one-tenth per cent of nitrate4 ,ten cubic centimeters are taken1 to which six-tenths gram of tartaric acid is added1 and placed in the outer part of the glass stopper4 ,the rest of the process is conducted exactly as described above4 ,the deficit in hydrogen is calculated to nitrogen pentoxid4 ,the reduction by sodium amalgam is not so convenient a form of estimating nitric acid as many of the other forms of using nascent hydrogen4 ,as practiced by calculating from the deficit of hydrogen1 however1 it has some advantages by reason of the fact that no heating is required4 ,the presence of organic neutral bodies1 or even those of an acid nature1 like humus1 does not1 therefore1 interfere with the work4 ,likewise1 mineral bodies in solution1 which are not reduced by nascent hydrogen1 do not interfere with the accuracy of the reaction4 #dhg4 ,method of ,schmitt4--,in the method of ,schmitt forty cubic centimeters of glacial acetic acid are placed in a flask of #fjj cubic centimeters content1 and fifteen grams of a mixture of zinc and iron dust added4#cae ,to this a quantity of the solution containing the nitrate1 representing about half a gram of the pure nitrate1 is added with constant shaking1 in portions which do not evolve hydrogen too rapidly4 ,after about fifteen minutes when the evolution of nitrogen has somewhat diminished1 an additional fifteen grams of the metal dust are added4 ,if the contents of the flask should become thick they can be diluted with thirty cubic centimeters of water4 ,the reduction is complete in from thirty to forty minutes4 ,the contents of the flask are now saturated with enough soda-lye not only to neutralize the excess of acetic acid1 but to keep the zinc hydroxid also in solution4 ,for this purpose about #bjj cubic centimeters of soda-lye of #a4be specific gravity are necessary4 ,the ammonia is obtained by distillation into standard acid in the usual way4 #dhh4 ,method of ,ulsch4--,in practice the method of ,ulsch has come into general use4#caf ,for the determination of nitrogen by this method half a gram of saltpeter or four-tenths gram of sodium nitrate is taken and dissolved in twenty five cubic centimeters of water1 in a flask with a content of about #fjj cubic centimeters4 ,five grams of iron reduced by hydrogen1 and ten cubic centimeters of sulfuric acid diluted with two volumes of water are then added to the flask4 ,to avoid mechanical losses during the evolution of hydrogen a pear-shaped glass stopper is hung in the neck of the flask4 ,after the first violent evolution of hydrogen has passed1 the flask is slowly heated until in about four minutes it is brought to a gentle boil4 ,the boiling is continued for about six minutes when the reduction is complete4 ,about fifty cubic centimeters of water are then added2 also an excess of soda-lye and a few particles of zinc and the ammonia is distilled and collected in standard acid in the usual way4 ,the method of ,ulsch can also be applied1 according to ,fricke1 to the analysis of nitrates contained in drinking and drainage waters1 and it is regarded by him as one of the best methods to be employed in such investigations4#cag ,the method of ,ulsch in this laboratory has given entirely satisfactory results1 and is generally used in preference to other methods in cases where a considerable quantity of nitrates is present4 ,it is based on the following reactions3 #b,,kno ,h,,so ,k,,so #b;,,hno #b;,,hno #h;,h #b,,nh #f;,h,o #b,,nh ,h,,so 7,,nh7,,so4 ,,reduction ,,by ,,the ,,electric ,,current4 #dhi4 ,method of ,williams-,warington4--,from the losses which naturally occur during the evaporation of water1 even with all the precautions noted1 ,warington was led to try some method for the determination of nitrates and nitrites in waters without previous concentration4#cah ,the reduction of these bodies by the copper-zinc couple formed the basis of these experiments1 and they resulted in the following method of manipulation1 which is based on a process devised by ,williams4#cai ,the method consists in boiling rapidly one liter of the rain water in a retort1 with a little magnesia previously raised to a low red heat and then washed1 until #bej cubic centimeters have distilled over4 ,the residue is then made up to #hjj cubic centimeters1 transferred to a wide-mouthed1 stoppered bottle supplied with strips of copper and zinc forming electric couples1 and set aside1 at a constant temperature of from #ba-bd1 for three days4 ,a measured portion of the solution is then distilled1 and the ammonia determined in the distillate by nesslerizing4 ,this plan has two advantages3 ,first1 the ammonia1 as well as the nitrogen as nitrates and nitrites1 can be determined in the course of the same operation and in the same sample of water4 ,for this purpose it is only necessary to fit the retort to an efficient condenser and to remove all ammonia from the apparatus by boiling distilled water in the retort before introducing the rain water4 ,the distillate of #bej cubic centimeters from the rain water1 as described above1 is well mixed and the ammonia determined1 in from twenty-five to one hundred cubic centimeters thereof1 diluted to #aej cubic centimeters with ammonia-free water4 ,second1 the nitrogen1 as nitrates and nitrites1 is determined directly and alone2 the error of the determination is as small as nesslerizing admits of1 since it is possible1 if necessary1 to distill #fjj cubic centimeters of the boiled rain water corresponding to #gej cubic centimeters of the original1 and thus obtain a full amount of ammonia for determination1 even when the rain water has been poor in nitrates4 ,the determination of nitric nitrogen1 in a given sample1 by the above method gave a mean quantity of product of #j4afb part per million1 while the determination1 in the same lot of samples1 by the modified ,schloesing method gave #j4abe part per million4 ,this result confirms the supposition that in the complete evaporation necessary to the manipulation of the ,schloesing method there is a loss of nitrogen4 ,the amount of nitrogen as nitrates and nitrites in the rain water at ,rothamstead1 for the twelve months ending ,april #a1 #ahhh1 was found1 by the ,schloesing method1 to be #j4fad pound per acre1 the total rain-fall being #ba4if inches4 ,for the year ending ,april #a1 #ahhi1 by the copper-zinc method1 it amounted to #j4iag pound per acre1 the total rain-fall being #bi4bg inches4 ,the amounts found in other localities are quite different from the above1 as for instance1 the mean of seven stations in ,germany for thirteen years1 beginning in #ahfd1 showed #aj4ah pounds of nitrogen per acre4 ,the average amount for ten years at the observatory of ,mont ,sauris1 near ,paris1 showed #ab4cf pounds of nitrogen per acre4 ,the average for three years at ,lincoln1 as determined by ,professor ,g4 ,gray1 shows one and six-tenths pounds of nitrogen per acre per annum4 ,at ,tokio1 in ,japan1 ,kellner found1 for one year1 #a4jb pounds per acre4 #dij4 ,determination of the ,ammonia4--,the method used at ,rothamstead is to make one determination of ammonia in the whole of the distillate obtained1 the strength of which is regulated by varying the amount introduced into the retort1 so that it shall be equal to about two cubic centimeters of the standard ammonia solution4 ,a #aej cubic centimeter cylinder is first filled with the rain water1 and fifty cubic centimeters of nessler reagent added4 ,the depth of tint indicates what quantity of rain water will be required for distillation4 ,this having been determined1 the appropriate volume of the rain water1 provided it do not exceed #fjj cubic centimeters1 is placed in the retort described above1 and the distillation continued until the #aej cubic centimeter cylinder is filled4 ,the titration is made in the usual way4 #dia4 ,preparation of the ,copper-,zinc ,couple4--,for #hjj cubic centimeters of boiled rain water1 prepared as described1 six strips of zinc foil1 four inches long by one and a quarter inches wide1 are taken and bent at right angles along their center to obtain stiffness4 ,the couple is cleansed and coated by washing in a series of five beakers containing1 respectively1 dilute solution of sodium hydroxid1 very dilute sulfuric acid1 a three per cent solution of copper sulfate1 ordinary distilled water1 and distilled water free from ammonia4 ,through these five beakers the zinc foil is successively passed4 ,it is rinsed both after the alkali and the acid4 ,but after the copper has been deposited1 the strips are simply drained and carefully placed in the distilled water1 it being difficult to rinse without removing the copper4 ,the couples should be entirely submerged when placed in the rain water4 ,the strips should remain in the copper sulfate solution long enough to be well covered with copper4 #dib4 ,substitution of an ,aluminum-,mercury ,couple for ,copper-,zinc4--,ormandy and ,cohen have proposed to use an aluminum-mercury couple for the copper-zinc in the process described above4#cbj ,this couple acts more quickly than the copper-zinc1 and the results are equally as accurate4 ,nitrites are reduced in about one hour by this apparatus1 while the zinc-copper couple of ,gladstone and ,tribe requires about six times as long4 ,aluminum foil1 free of grease1 should be used4 ,the foil should be heated over a bunsen just before amalgamation4 ,the clean1 very thin foil is coated with mercury by shaking with a concentrated solution of mercuric chlorid4 ,it should be prepared immediately before use4 ,the amalgamated foil is introduced into the sample of water to be analyzed1 and left until all the aluminum is converted into oxid4 ,the presence of the oxid favors the prevention of bumping during the subsequent distillation4 ,the distilled ammonia1 collected in dilute acid1 is determined by nesslerizing1 the free ammonia in the sample having been previously determined4 ,the increase in ammonia is due to nitrates or nitrites reduced by the couple4 ,,iodometric ,,estimation ,,of ,,nitric ,,acid ,,in ,,nitrates4 #dic4 ,method of ,de ,koninck and ,nihoul4--,this process is applicable only in the absence of organic bodies and other reducing agents4 ,the principle on which it rests1 as applied by ,mc,gowan1 is as follows3#cba ,when a fairly concentrated solution of a nitrate is warmed with an excess of pure1 strong hydrochloric acid1 the nitrate is completely decomposed1 and the production of nitrosyl chlorid and chlorin is quantitative4 ,the reaction1 as shown by ,tilden1 is represented by the following equation3#cbb ,,hno #c;,h,cl ,n,o,cl ,cl #b;,h,o4 ,one molecule of nitric acid thus yields two atoms of chlorin and one molecule of nitrosyl chlorid capable of setting free three atoms of iodin4 ,the iodin can be estimated in the usual manner by titration with sodium thiosulfate4 ,the nitrosyl chlorid is decomposed by the potassium iodid1 nitric oxid escaping4 ,the apparatus employed is shown in ,fig4 #hg4 ,a is a small1 round-bottomed flask1 into the neck of which a glass stopper1 x1 is accurately ground 7with fine emery and oil74 ,the capacity of the bulb is about forty-six cubic centimeters1 and the length of the neck1 from x to y1 ninety millimeters4 ,the first condenser is a simple tube1 slightly enlarged at the foot into two small bulbs4#cbc ,the length from a to b is #cjj millimeters1 from b to c #ahj millimeters1 and from e to f thirty millimeters4 ,the capacity of the bulb ,b is twenty-five cubic centimeters1 and the total capacity of the two bulbs and tube1 up to the top of ,c1 forty-one cubic centimeters4 ,this condenser is immersed1 up to the level of c1 in a beaker full of water4 ,d is a geissler bulb apparatus1 ,e is a calcium chlorid tube1 filled with broken glass1 which acts as a tower and g is a small funnel1 attached by rubber and clip to the branch tube h4 ,between the tube i and the wash-bottle for the carbon dioxid is placed a short piece of glass tubing1 s1 containing a strip of filter paper1 slightly moistened with iodid of starch solution4 ,this tube s is really hardly necessary1 as no chlorin escapes backwards if a moderate current of carbon dioxid is kept passing1 but it serves as a check4 ,a glance at the joints o1 p1 and q1 which are of narrow india-rubber tubing1 is sufficient to show that1 by using this arrangement1 practically no rubber is exposed to the action of the chlorin4 ,the tiny piece of rubber tubing at the joint o may be done away with1 the narrower tube there being accurately ground into the wider one2 this makes the condensing apparatus practically perfect4 ,illustration3 ,,figure #hg4 ,,mcgowan',s ,,apparatus ,,for ,,the ,,iodometric ,,estimation ,,of ,,nitric ,,acid4 ,the actual operation is performed in the following manner3 ,the evolution flask is washed and thoroughly dried1 and the nitrate 7say1 about #j4be gram of potassium nitrate7 is tapped into it from the weighing tube4 ,two cubic centimeters of water are now added1 and the bulb is gently warmed1 so as to bring the nitrate into solution1 after which the stopper of the flask is firmly inserted4 ,about fifteen cubic centimeters of a solution of potassium iodid 7one in four7 are run into the first condensing tube1 any iodid adhering to the upper portion of the tube being washed down with a little water1 and five cubic centimeters of the same solution1 mixed with eight to ten cubic centimeters of water1 are sucked into the geissler bulbs whilst the glass in the tower ,e is also thoroughly moistened with the iodid4 ,the geissler bulbs should be so arranged that gas only bubbles through the last of them1 the liquid in the others remaining quiescent4 ,all the joints having been made tight the carbon dioxid is turned on briskly and passed through the apparatus until a small tubeful collected at l1 over caustic potash solution1 shows that no appreciable amount of air is left in it4 ,the small outlet tube l1 is now replaced by a calcium chlorid tube1 filled with broken glass which has been moistened with the above-mentioned iodid solution1 and closed by a cork through which an outlet tube passes1 the object of this trap tube being to prevent any air getting back into the apparatus4 ,the brisk current of carbon dioxid is continued for a minute or two longer1 so as to practically expel all the air from this last tube4 ,the stream of gas is now stopped for an instant1 and about fifteen cubic centimeters of pure concentrated hydrochloric acid1 free from chlorin1 run into ,a through the funnel g 7into the tube of which it is well to have run a few drops of water before beginning to expel the air from the apparatus71 and ,a is shaken so as to mix its contents thoroughly4 ,a slow current of carbon dioxid is now again turned on 7one to two bubbles through the wash-bottle per second71 and ,a is gently warmed over a burner4 ,it is a distinct advantage that the reaction does not begin until the mixed solutions are warmed1 when the liquid becomes orange-colored1 the color again disappearing after the nitrosyl chlorid and chlorin have been expelled4 ,the warming should be very gentle at first in order to make sure of the conversion of all the nitric acid1 and also because the first escaping vapors are relatively very rich in chlorin2 afterwards the liquid in ,a is briskly boiled4 ,a very little practice enables the operator to judge as to the proper rate of warming4 ,when the volume of liquid in ,a has been reduced to about seven cubic centimeters 7by which time it is again colorless7 the stream of carbon dioxid is slightly quickened and the apparatus allowed to cool a little4 ,the burner is now set aside for a few minutes1 and two cubic centimeters more of hydrochloric acid1 previously warmed in a test-tube1 run in gently through g2 there is no fear either of the iodid solution running back1 or of any bubbles of air escaping through y if this is done carefully4 ,this is a precautionary measure1 in case a trace of the liberated chlorin might have lodged in the comparatively cool liquid in the tube h4 ,the carbon dioxid is once more turned on slowly and the liquid in ,a is boiled again until it is reduced to about five cubic centimeters4 ,it is now only necessary to allow the apparatus to cool1 passing carbon dioxid all the time1 after which the contents of the condensers are transferred to a flask and titrated with thiosulfate4 ,at the end of a properly conducted experiment1 the glass in the upper part of tower ,e should be quite colorless and there should be only a mere trace of iodin showing in the lower part of the tower1 while the liquid in the last bulb of the geissler apparatus ought to be pale yellow4 ,during the operation1 the stopper of ,a and the various joints can be tested from time to time by means of a piece of iodid of starch paper1 and before disjointing it is well to test the escaping gas 7say at m7 in the same way1 to make sure that all nitric oxid has been thoroughly expelled4 ,the method is capable of giving accurate results1 but it can not be preferred to the reduction or colorimetric processes4 #did4 ,method of ,gooch and ,gruener4--,the principle on which this method rests depends on the decomposition of a nitrate in presence of a hot saturated solution of manganous chlorid and hydrochloric acid in an atmosphere of carbon dioxid4#cbd ,the products of decomposition are passed into a solution of potassium iodid and the liberated iodin is titrated with standard sodium thiosulfate4 ,the products of the reaction are chlorin1 nitric oxid1 and possibly nitrosyl chlorid1 and under proper precautions the iodin set free is quantitively proportional to the weight of nitrate decomposed4 ,the manganous mixture is acted on slowly at ordinary temperatures1 but on heating1 the nitrate is decomposed with the formation of a higher manganese chlorid and nitric oxid4 ,when the heat is continued a sufficient length of time the chlorin from the higher chlorids is evolved and only manganous chlorid remains4 ,during the heating the color of the solution passes from green to black and at the end the green color is restored4 ,the apparatus employed is shown in ,fig4 #hh4 ,illustration3 ,,figure #hh4 ,,apparatus ,,of ,,gooch ,,and ,,gruener4 ,a plain pipette bent as is shown in the figure serves as the generating flask and for the attachment on the one hand to the carbon dioxid apparatus and on the other to the system of absorption bulbs for containing the potassium iodid4 ,the latter should be glass1 sealed to the evolution bulb of the pipette to prevent the action of the evolved gases on organic materials4 ,the point of the potassium iodid apparatus is drawn out so as to be pushed well into the second receiver1 being held in place by a piece of rubber tubing4 ,the third tube acts simply as a trap to exclude the air from the absorption apparatus4 ,the first receiver contains in solution three grams1 the second two1 and the third one gram of potassium iodid4 ,during the reaction the first receiver is kept cool by immersion in water4 ,before connecting the apparatus with the carbon dioxid generator the solution of manganous chlorid and afterwards the nitrate solution are drawn into the bulb of the pipette by gentle suction4 ,after connecting the apparatus the current of carbon dioxid is started and kept up until all the air is expelled4 ,heat is then applied to the bulb of the pipette and the distillation continued until all the liquid has passed over4 ,at the end of the reaction the contents of the receivers are united by disconnecting the apparatus from the carbon dioxid generator and passing water through the pipette4 ,the introduction of the manganous chlorid into the mixture does not interfere with the titration of the iodin4 ,this is accomplished in the usual way with sodium thiosulfate using starch as an indicator4 ,the quantity of material used should contain about the amount of nitric acid that is found in two-tenths of a gram of potassium nitrate4 ,this method1 so similar to the preceding1 is somewhat less complex1 and1 to that extent1 preferable to it4 ,,estimation ,,of ,,nitric ,,acid ,,by ,,colorimetric ,,comparison4 #die4 ,delicacy of the ,method4--,the remarkable delicacy of those methods of chemical analysis1 which depend on the production of a pronounced color1 which can be compared with that produced by a known quantity of a given substance1 has been long illustrated by the nesslerizing process for the estimation of ammonia4 ,by such methods minute qualities of substances can be quantitively determined with great accuracy1 when they would escape all effort for their estimation by gravimetric methods4 ,processes based on this principle are1 therefore1 peculiarly applicable to the detection and estimation of oxidized nitrogen in waters and soil extracts1 whether they be present as nitric1 nitrous1 or ammoniacal compounds4 ,in the following paragraphs will be given with sufficient detail for the needs of the analyst1 the principles and practice of the colorimetric comparison methods which have been approved as best by the experience of analysts4 ,these methods are applicable especially to cases in which only minute quantities of the substances looked for are present1 and where celerity of determination is especially desirable4 ,they are1 therefore1 of especial value in the analysis of rain1 drainage1 and irrigation waters1 and of soil extracts poor in oxidized nitrogen4 #dif4 ,hooker's ,method4--,the quantitive action depends upon the deep green coloration given by nitric acid1 when dissolved in sulfuric acid and carbazol4#cbe ,other oxidizing bodies1 such as iron1 chlorin1 bromin1 chromic acid1 etc41 give the same reaction1 but not in such a prominent manner4 ,such bodies with the exception of chlorin and iron1 are not often found in waters4 ,in the application of the process1 iron1 if present in quantities greater than one-tenth part per one hundred thousand1 must be removed4 ,chlorids also1 even when present in very small quantities1 interfere with the delicacy of the reaction and must be removed4 ,easily destructible organic matter tends to lower the result1 but not materially1 unless present in large excess4 ,calcium carbonate and sulfate1 soda1 and other alkalies1 in the quantities in which they are usually present in water1 do not affect the result4 ,the following reagents are required3 #a4 ,concentrated sulfuric acid4 #b4 ,an acetic acid solution of carbazol2 diphenylimid1 7,c,h_/,c,h_/ ,,nh47 #c4 ,a sulfuric acid solution of carbazol4 #d4 ,standard solutions of potassium nitrate4 #e4 ,a solution of aluminum sulfate4 #f4 ,a solution of silver sulfate4 #a4 ,the sulfuric acid1 used for all purposes in the process1 should be entirely free from nitrogen oxids4 ,it may be readily tested by dissolving in it a small quantity of carbazol4 ,if the solution be at first golden-yellow or brown1 the acid is sufficiently pure2 if it be green or greenish1 another and better sample must be taken4 ,it is essential also that the specific gravity of the acid be fully #a4hd1 and it is well to ascertain that this is really the case4 #b4 ,the acetic acid solution of carbazol is prepared by dissolving six-tenths gram in about ninety cubic centimeters of strongest acetic acid1 by the aid of gentle heat4 ,it is allowed to cool1 and is then made up to #ajj cubic centimeters by the further addition of acetic acid4 ,the exact strength of this solution1 is of no material importance to the success of the process1 and the above proportions have been selected principally because they are convenient4 ,the solution will remain unchanged for several months4 ,the use of this solution merely facilitates the preparation of that next described1 which will not keep1 and has1 consequently1 to be freshly prepared for each series of determinations4 #c4 ,the sulfuric acid solution of carbazol is easily made in a few seconds1 but it is advisable to allow it to stand from one and one-half to two hours before using4 ,it is prepared by rapidly adding fifteen cubic centimeters of sulfuric acid1 to one cubic centimeter of the above-described acetic acid solution4 ,this quantity usually suffices for from two to three nitrate estimations4 ,when freshly prepared it is golden-yellow or brown2 it changes gradually1 however1 and in the course of one and one-half or two hours it becomes olive-green4 ,this change is probably due to traces of oxidizing agents1 which occur in the sulfuric and acetic acids1 and which1 although not present in sufficient quantity to act immediately1 gradually bring about the reaction described4 ,the greenish color does not interfere with the process1 as might at first be supposed2 on the contrary1 the solution is not sensitive to small quantities of nitric acid until it has undergone the change to olive-green1 and it is for this reason1 that it should be prepared about two hours before required for use4 ,this solution may be thoroughly depended on for six hours after preparation4 ,the intensities of color produced by the more concentrated solutions of nitrates after this time1 gradually approach each other and become ultimately the same4 #d4 ,the standard solutions of potassium nitrate are very readily prepared4 ,the solutions which are to be compared directly with the waters examined1 may be prepared as required1 but if many determinations are to be made with a variety of waters1 it will be found best to prepare a complete series1 differing from each other by #j4jb part nitrogen in #ajj1jjj4 ,this series may include solutions containing quantities of nitrogen in #ajj1jjj parts1 represented by all the odd numbers from #j4jc up to #j4ci4 ,it will be found convenient to prepare them in quantities of #ajj cubic centimeters at a time1 from a stock solution of potassium nitrate which contains #j4jjjja gram nitrogen1 or #j4jjjjde nitric acid in one cubic centimeter4 ,each cubic centimeter of this solution1 when diluted to #ajj cubic centimeters1 represents #j4ja nitrogen in #ajj1jjj1 and consequently if it is desired to make a solution containing #j4ce part nitrogen in #ajj1jjj1 thirty-five cubic centimeters are taken and made up to #ajj cubic centimeters1 and so on4 ,the solution of potassium nitrate 7b7 is best prepared from a stronger one 7a7 containing #j4jjja gram nitrogen to the cubic centimeter1 or #j4gbad gram potassium nitrate to the liter2 #ajj cubic centimeters of 7a7 made up to one liter give the solution 7b74 ,it is obvious that the series of solutions1 above described1 could be made directly from 7a71 but by first making 7b71 greater accuracy is secured4 #e4 ,for purposes which will be presently described1 a solution of aluminum sulfate is required1 containing five grams to the liter4 ,the salt used must be free from chlorin and iron2 and the solution should give no reaction when tested with carbazol4 #f4 ,the solution of silver sulfate is required for the removal of chlorin from the water or soil extract to be examined4 ,it is prepared by dissolving #d4cidc grams of the salt in pure distilled water and making up to one liter4 ,the sulfate is preferably obtained by dissolving metallic silver in pure sulfuric acid4 ,the solution should be tested with carbazol in the same way as will be presently described for water2 if perfectly pure1 no reaction will be obtained4 ,as silver sulfate is often prepared by precipitation from the nitrate1 it is very apt to contain nitric acid1 and consequently1 if the source of the salt be unknown1 this test should on no account be omitted4 ,the analytical process is carried on as follows3 ,two cubic centimeters of the water are carefully delivered by means of a pipette into the bottom of a test-tube2 four cubic centimeters of sulfuric acid are added1 and the solution thoroughly mixed by the help of a glass rod4 ,the test-tube is then immersed in cold water1 and when well cooled1 one cubic centimeter of the sulfuric acid solution of carbazol is added1 and the whole again mixed as before4 ,the intensity of the color is now observed1 and a little experience enables a fairly good opinion to be formed of the quantity of nitric acid present4 ,suppose that the water be roughly estimated to contain about #j4ae part nitrogen per #ajj1jjj2 in such a case solutions of potassium nitrate containing #j4aa1 #j4ae1 #j4ai part nitrogen are selected from the series4 ,two cubic centimeters are taken from each1 and treated1 side by side1 with a fresh quantity of the water1 precisely as described for the preliminary experiment1 the various operations being performed as nearly simultaneously as possible with each of the samples1 and under precisely similar conditions4 ,two or three minutes after the carbazol has been added1 the intensity of the color of each is observed4 ,if that given by the water is matched by any of the standard solutions1 the estimation is at an end4 ,similarly1 if it falls between two of these1 the mean may be taken as representing the nitrogen present in cases in which great accuracy is not required4 ,if this be done1 the maximum error will be #j4jb part nitrogen1 or #j4ji part nitric acid per #ajj1jjj4 ,if greater exactness be required1 or it be found that the color given by the water is either darker or lighter than that given by all the standard solutions1 a new trial must be made4 ,in such a case the water must be again tested simultaneously with the solutions with which it is to be compared4 ,this is rendered necessary principally for the reason that the shade of the solutions to which the carbazol has been added is apt to change on standing4 ,hence it is desirable that the water1 and the standard potassium nitrate with which it is to be compared1 should have the carbazol added at as nearly the same time as possible4 ,when finally the color falls between that given by any two consecutive members of the standard potassium nitrate series1 the estimation may be considered at an end1 and the mean of these solutions taken as representing the nitrogen present4 ,the greatest neatness should be observed in all steps of the analysis4 ,the quantity of water operated upon is so small that if the greatest care be not exercised throughout1 sources of error may be readily introduced4 ,the test-tubes should be rinsed out with nitrate-free water before being used and then dried4 ,the tint should be determined by looking through the tube and not through the length of the column of liquid4 ,influence of ,nitrites4--,if the quantity of nitrous acid in the water is known a correction can be applied for nitrates by deducting one-fifth of the number found for nitrites when estimated as nitrates4 ,influence of ,iron4--,although ferrous salts give no reaction with carbazol1 nitrates are apt to be overestimated in their presence4 ,oh the other hand1 ferric compounds1 like other oxidizing agents1 may give a characteristic green color with carbazol4 ,in all cases when iron is present in any considerable quantity it is best to remove it by rendering the water slightly alkaline1 evaporating to dryness1 and redissolving the soluble residue until the solution reaches the original volume4 ,influence of ,chlorids4--,the presence of chlorids furnishes by far the most serious source of error in the process by intensifying the action of the nitric acid4 ,if1 however1 nitrates be absent chlorids give no reaction with carbazol4 ,the chlorids are removed by a standard silver sulfate solution1 the quantity of chlorids present having been first determined by a standard silver nitrate solution4 ,for this purpose an ordinary sugar flask can be employed marked at #ajj and #aaj cubic centimeters4 ,this flask is filled to the #ajj cubic centimeter mark with the water to be examined2 the necessary quantity of silver sulfate is added and then two cubic centimeters of the solution of aluminum sulfate1 previously described1 and the contents of the flask brought up to #aaj cubic centimeters by the addition of pure distilled water4 ,the whole is shaken up and filtered1 the first portion of the filtrate being rejected4 ,the aluminum sulfate by reacting with the carbonates usually present in the water and producing the precipitation of alumina1 facilitates the removal of the precipitated silver chlorid4 ,the above-described method on account of its delicacy is not well suited to aqueous solutions of soils except where the quantity of nitric nitrogen present is extremely minute4 ,hooker also first suggested the use of diphenylamin for detecting the presence of nitrates1#cbf a method afterwards worked out by ,spiegel4#cbg ,in the variation of the method as practiced by ,rideal the standard potassium nitrate and the pure sulfuric acid mentioned below are required1 and in addition1 the following reagents3#cbh 7a7 ,silver sulfate solution containing #d4cide grams per liter4 7b7 ,aluminum sulfate solution free from chlorids and iron1 five grams per liter4 7c7 ,carbazol solution2 six-tenths gram carbazol dissolved in glacial acetic acid and made up to #ajj cubic centimeters with the glacial acid4 ,for use1 one cubic centimeter of this solution is withdrawn by a pipette and mixed with fifteen cubic centimeters of pure redistilled sulfuric acid4 ,the process is carried out as follows3 ,to #ajj cubic centimeters of water the amount of chlorin which has been previously ascertained is removed by the silver sulfate solution4 ,two cubic centimeters of the aluminum sulfate are added and the whole made up to a convenient volume1 say about #aaj cubic centimeters4 ,the liquid is filtered and two cubic centimeters of the filtrate taken for an estimation of nitrates4 ,to the two cubic centimeters are added four cubic centimeters of concentrated sulfuric acid and the mixture cooled4 ,one cubic centimeter of the carbazol solution in sulfuric acid is added and a bright green color appears in a few moments1 if nitrates are present4 ,comparison is made with solutions of standard potassium nitrate4 #dig4 ,phenylsulfuric ,acid ,method4--,rideal also proposes a variation of the method described by ,hooker1 which consists in the substitution of phenylsulfuric acid for carbazol4#cbi ,the solutions required are3 7a7 ,a standard solution of potassium nitrate containing #j4gbae gram of the pure crystallized salt in a liter of water4 7b7 ,phenylsulfuric acid1 7acid phenyl sulfate17 prepared by dissolving fifteen grams of pure crystallized phenol in #ib4e cubic centimeters of pure1 redistilled sulfuric acid free from nitrates and diluted with seven and one-half cubic centimeters of water4 ,the process is conducted as follows3 ,a known volume of water1 from twenty-five to one hundred cubic centimeters1 according to its richness in nitrates1 is evaporated to dryness in a porcelain dish1 one cubic centimeter of phenylsulfuric acid added then one cubic centimeter of pure water and three drops of strong sulfuric acid and the mixture gently warmed4 ,a yellow color shows the presence of nitrates4 ,dilute to about twenty-five cubic centimeters with water and add ammonia in slight excess4 ,pour into a narrow nessler tube and add the washings and make up to #ajj cubic centimeters4 ,imitate the color of the solution with the standard potassium nitrate treated with the same reagents4 ,the phenylsulfuric acid should be prepared some time before use1 as the fresh solution imparts a greenish tint to the yellow of the ammonium picrate formed4 #dih4 ,variation of ,leffmann and ,beam4--,the phenyl sulfate process1 as described by ,leffmann and ,beam1 is conducted as follows3#ccj ,solutions ,required4--,acid phenyl sulfate3 #ah4e cubic centimeters of strong sulfuric acid are added to one and one-half cubic centimeters of water and three grams of pure phenol4 ,preserve in a tightly-stoppered bottle4 ,standard potassium nitrate3 #j4gbb gram of potassium nitrate1 previously heated to a temperature just sufficient to fuse it1 is dissolved in water1 and the solution made up to #ajjj cubic centimeters4 ,one cubic centimeter of this solution will contain #j4jjja gram of nitrogen4 ,analytical ,process4--,a measured volume of the water is evaporated just to dryness in a platinum or porcelain basin4 ,one cubic centimeter of the acid phenyl sulfate is added and thoroughly mixed with the residue by means of a glass rod4 ,one cubic centimeter of water1 and three drops of strong sulfuric acid are added1 and the dish gently warmed4 ,the liquid is then diluted with about twenty-five cubic centimeters of water1 ammonium hydroxid added in excess1 and the solution made up to #ajj cubic centimeters4 ,the reactions are3 ,acid phenyl sulfate4 ,trinitrophenol 7picric acid74 ,,hc,h,,so #c;,,hno ,,hc,h7,,no7,o ,h,,so #b;,h,o4 ,ammonium picrate4 ,,hc,h7,,no7,o ,,nh,,ho ,,nh,c,h7,,no7,o ,h,o4 ,the ammonium picrate imparts to the solution a yellow color1 the intensity of which is proportional to the amount present4 ,five cubic centimeters of the standard solution of potassium nitrate are similarly evaporated in a platinum dish1 treated as above1 and made up to #ajj cubic centimeters4 ,the color produced is compared to that given by the water1 and one or the other of the solutions diluted until the tints of the two agree4 ,the comparative volumes of the liquids furnish the necessary data for determining the amount of nitrate present1 as the following example will show3 ,five cubic centimeters of standard nitrate are treated as above1 and made up to #ajj cubic centimeters1 representing #j4jjje gram nitrogen4 ,suppose #ajj cubic centimeters of water similarly treated are found to require dilution to #aej cubic centimeters before the tint will match that of the standard2 then #ajj 3 #aej 33 #j4jje 3 #j4jjge i4 e41 the water contains seven and one-half milligrams of nitrogen as nitrate per liter4 ,the ammonium picrate solution keeps very well1 especially in the dark4 ,a good plan1 therefore1 is to make up a standard solution equivalent to1 say1 ten milligrams of nitrogen as nitrate per liter1 to which the color obtained from the water may be directly compared4 ,the results obtained by this method are quite accurate4 ,care should be taken that the same quantity of acid phenyl sulfate be used for the water and for the comparison liquid1 otherwise different tints instead of depths of tints are produced4 ,with subsoil and other waters probably containing much nitrates1 ten cubic centimeters of the sample will be sufficient for the test1 but with river and spring waters1 twenty-five to one hundred cubic centimeters may be used4 ,when the organic matter is sufficient to color the residue1 it will be well to purify the water by addition of alum and subsequent filtration1 before evaporating4 ,the method may also be used to determine small quantities of nitrates in aqueous extracts of soils when the quantity is too small for estimation by the ferrous chlorid or reduction processes4 #dii4 ,variation of ,johnson4--,the ammonium picrate method has given very satisfactory results as practiced by ,johnson1 who varies the process as described below4#cca ,the standard solution of potassium nitrate is prepared by dissolving #j4gbae gram of the pure salt in a liter of distilled water4 ,dilute #ajj cubic centimeters of this solution to one liter with distilled water4 ,ten cubic centimeters of this dilute solution contain nitrogen equivalent to one part as nitrates in #ajj1jjj4 ,the ,solution of ,acid ,phenyl ,sulfate4--,this is prepared by pouring two parts by measure of pure crystallized phenol liquefied by hot water into five parts by measure of pure concentrated sulfuric acid and digesting the whole in the water-bath for eight hours4 ,after cooling1 add one and one-half volumes of distilled water and one-half volume strong hydrochloric acid to each volume of the above mixture4 ,the analytical processes are carried on as follows3 ,ten cubic centimeters of the water under examination and ten cubic centimeters of the standard potassium nitrate are placed in small beakers and put near the edge of a hot plate4 ,when nearly evaporated they are put on the top of the water-bath and left there until completely dry4 ,the residue1 in each case1 is then treated with one cubic centimeter of the acid phenyl sulfate and the beakers placed on the top of the water-bath4 ,in good water1 a red color ought not to appear for about ten minutes4 ,after standing about fifteen minutes1 the beakers are removed1 the contents of each washed successively into #ajj cubic centimeter flasks1 about twenty cubic centimeters of #j4if per cent4 ammonia added1 and the #ajj cubic centimeters made up by the addition of water and the yellow liquid transferred to the nessler glass and the tints appropriately compared4 #ejj4 ,estimation of ,nitric in ,presence of ,nitrous ,acid4--,the detection of nitrous in presence of nitric acid can be accomplished by the method proposed by ,griess1 as described further on1 through the development of azocolors1 with metaphenylenediamin and other bodies1 which are not produced under similar conditions by nitric acid4 ,the detection and estimation of nitric in the presence of nitrous acid1 however1 is not so easy4 ,lunge and ,lwoff propose brucin for this purpose1 which1 contrary to most authorities1 does not give the red-yellow color with nitrous acid4#ccb ,the reagent is prepared by dissolving two-tenths gram of brucin in #ajj cubic centimeters of sulfuric acid1 pure and concentrated4 ,it is almost impossible to prepare a sulfuric acid which does not give a trace of color with brucin2 but with the purest acids this trace may be neglected4 ,a solution of nitrate is also prepared containing #j4ja milligram of nitrogen as nitric acid in one cubic centimeter4 ,it is made by dissolving #j4jgba gram of pure potassium nitrate in #ajj cubic centimeters of distilled water1 and diluting ten cubic centimeters thereof with pure concentrated sulfuric acid to #ajj cubic centimeters4 ,both solutions are conveniently preserved in burettes with glass stop-cocks4 ,the liquid to be tested for nitric acid should be mixed with sulfuric acid in such a way that the mixture will have a specific gravity of one and seven-tenths4 ,if the liquid to be tested is water1 this concentration is reached by adding three times its volume of the strong acid4 ,for the comparison of colors1 cylinders of colorless glass are employed1 marked at fifty cubic centimeters4 ,they should be about twenty-four centimeters high and extend about ten centimeters above the mark4 ,there is placed in the cylinder one cubic centimeter of the solution of nitrate in sulfuric acid1 and the same quantity of the brucin mixture1 and it is filled to the mark with pure sulfuric acid4 ,the contents of the cylinder are poured into a flask and warmed at from #gj-hj1 until the final yellow tint is secured1 and then poured into the cylinder again4 ,the liquid to be tested is treated in exactly the same way4 ,the tints are then equalized by pouring out a part of the contents of the deeper colored cylinder1 taking account of the volume1 and filling up with pure concentrated sulfuric acid4 ,in this manner the content of nitric acid in the liquid under examination can be compared directly with the solution of potassium nitrate of known strength4 ,the coloration is distinctly produced with #j4ja milligram in fifty cubic centimeters of liquid1 at least three-fourths of which must be sulfuric acid4 #eja4 ,piccini ,process4--,the method proposed by ,piccini may also be used4#ccc ,about five cubic centimeters of the nitrite solution are placed in a small beaker1 some pure urea dissolved therein and a few drops of sulfuric acid1 and then held in boiling water for three minutes4 ,the nitrous acid is thus completely destroyed4 ,ammonium chlorid may be substituted for urea4 ,the reaction is given on page #dgh4 ,the nitric acid present is then determined by diphenylamin or other suitable reagents4 ,diphenylamin reacts both with nitrous and nitric acids1 producing a violet tint4 ,warington calls attention to a slight difference1 however1 in its deportment with these two acids4 ,when the solution of the reagent is not too strong a drop of it produces but little turbidity when added to water or to a solution containing nitric acid4 ,when1 however1 nitrous acid is present1 a cream-colored turbidity is produced4 ,the violet color also appears at once on adding sulfuric acid when a nitrite is present1 while in the case of nitrates1 more sulfuric acid is required1 except when the solution is very strong4 ,in this connection1 it must not be forgotten that in heating nitrites with urea or ammonium chlorid in the presence of a slight excess of sulfuric acid a trace of nitric acid may be formed4 ,,estimation ,,of ,,nitrous ,,acid ,,by ,,colorimetric ,,comparison4 #ejb4 ,application of the ,method4--,the most minute traces of nitrous acid may be detected by colorimetric methods and the determination of the quantity present may be approximated with great exactness by comparison with a solution of a nitrite of known strength4 ,especially in following the progress of nitrification is this method1 in some of its forms1 of essential importance4 ,in delicacy and celerity it has the same advantages as the colorimetric methods for the determination of nitric acid4 #ejc4 ,metaphenylenediamin ,method4--,this process depends upon the development of a yellow color in water containing nitrous acid on the addition of a reagent containing metaphenylenediamin2 m-,c,h7,,nh74 ,this variety of the phenylenediamins is readily obtained from common dinitrobenzene4 ,it melts at #fc and boils at #bhg4 ,in order to preserve the reagent in shape for use it should be prepared in the following manner3 ,dissolve two grams of the chlorid in ten cubic centimeters of ammonia1 and place the solution in a glass-stoppered flask4 ,to this solution are added five grams of powdered animal-black1 and the whole vigorously shaken4 ,after allowing to settle1 the shaking is repeated at intervals of an hour1 three or four times1 and the flask then allowed to remain at rest for twenty-four hours4 ,the supernatant liquid is generally sufficiently decolorized by this treatment4 ,if not1 the shaking and subsidence must be repeated until a completely colorless liquid is obtained4 ,the solution can be kept1 indefinitely1 in contact with the animal-black4 ,aqueous and alcoholic solutions of the salt can not be kept4 ,the test is applied by mixing five drops of the reagent with five cubic centimeters of sulfuric acid4 ,the mixture must be colorless4 ,to the mixture add #ajj cubic centimeters of the water to be tested1 and heat on the water-bath for five minutes4 ,a yellow coloration indicates the presence of nitrous acid4 ,the metaphenylenediamin test is fairly satisfactory in perfectly colorless waters and aqueous extracts4 ,many waters and soil extracts1 however1 have a yellowish tint1 and this interferes in a marked way with a proper judgment of the yellow triaminazobenzol developed in the application of the above test4 ,the decoloration of such waters by means of sodium carbonate or hydroxid and alum1 is a matter of some difficulty and not wholly without action on the nitrites which may be present4 ,the method1 therefore1 is inferior to the one next described4 #ejd4 ,sulfanilic ,acid and ,naphthylamin ,test for ,nitrous ,acid4--,a very delicate test for the presence of nitrous acid1 first described by ,griess1 is the coloration produced thereby in an acid solution of sulfanilic acid and naphthylamin4#ccd ,sulfuric or acetic acid may be used as the acidifying agent1 preferably the latter4 ,the solutions are prepared as follows3 7#a7 ,dissolve one-half gram of sulfanilic acid in #aej cubic centimeters of dilute acetic acid4 7#b7 ,boil one-tenth gram of naphthylamin with twenty cubic centimeters of water1 decant the colorless solution from the residue and acidify it with #aej cubic centimeters of dilute acetic acid4 ,the two solutions may at once be mixed and preserved in a well-stoppered flask4 ,the action of light on the mixture is not hurtful1 but air should be carefully excluded because of the traces of nitrous acid which it may contain4 ,whenever the mixed solutions show a red tint it is an indication that they have absorbed some nitrous acid4 ,the red color may be discharged and the solution again fitted for use by the introduction of a little zinc dust1 and shaking4 ,the water1 or aqueous solution of a soil1 to be tested for nitrites1 in portions of about twenty cubic centimeters1 is treated with a few cubic centimeters of the mixed reagent and warmed to #gj-hj4 ,if nitrous acid1 in the proportion of one part to one million be present1 the red color will appear in a few minutes4 ,if the content of nitrous acid be greater1 e4 g41 one part in one thousand1 only a yellow color will be produced1 unless a greater quantity of the reagent be used4 ,leffmann and ,beam recommend the following method of conducting the determinations4#cce ,solutions required3 ,naphthylammonium ,chlorid4--,saturated solution in water free from nitrites4 ,it should be colorless2 a small quantity of animal charcoal allowed to remain in the bottle will keep it in this condition4 ,paraamidobenzene ,sulfonic ,acid 7,sulfanilic ,acid74--,saturated solution in water1 free from nitrites4 ,hydrochloric ,acid4--,twenty-five cubic centimeters of concentrated pure hydrochloric acid added to seventy-five cubic centimeters of water1 free from nitrites4 ,standard ,sodium ,nitrite4--#j4bge gram pure silver nitrite is dissolved in pure water1 and a dilute solution of pure sodium chlorid added until the precipitate ceases to form4 ,it is then diluted with pure water to #bej cubic centimeters and allowed to stand until clear4 ,for use1 ten cubic centimeters of this solution are diluted to #ajj4 ,it is to be kept in the dark4 ,one cubic centimeter of the dilute solution is equivalent to #j4jjjja gram of nitrogen4 ,the silver nitrite is prepared in the following manner3 ,a hot concentrated solution of silver nitrate is added to a concentrated solution of the purest sodium or potassium nitrite available1 filtered while hot and allowed to cool4 ,the silver nitrite will separate in fine needle-like crystals1 which are freed from the mother-liquor by filtration with the aid of a filter pump4 ,the crystals are dissolved in the smallest possible quantity of hot water1 allowed to cool and crystallize1 and again separated by means of the pump4 ,they are then thoroughly dried in the water-bath1 and preserved in a tightly-stoppered bottle away from the light4 ,their purity may be tested by heating a weighed quantity to redness in a tared1 porcelain crucible and noting the weight of the metallic silver4 ,one hundred and fifty-four parts of silver nitrite leave a residue of #ajh parts of silver4 ,analytical ,process4--,one hundred cubic centimeters of the water are placed in one of the color-comparison cylinders1 the measuring vessel and cylinder having previously been rinsed with the water to be tested4 ,by means of a pipette1 one cubic centimeter each of the solutions of sulfanilic acid1 dilute hydrochloric acid1 and naphthylammonium chlorid is dropped into the water in the order named4 ,it is convenient to have three pipettes for this test1 and to use them for no other purpose4 ,in any case the pipette must be rinsed out thoroughly with nitrite-free water each time before using1 as nitrites1 in quantity sufficient to give a distinct reaction1 may be taken up from the air4 ,one cubic centimeter of the standard nitrite solution is placed in another clean cylinder1 made up with nitrite-free water to #ajj cubic centimeters and treated with the reagents1 as above4 ,in the presence of nitrites a pink color is produced1 which1 in dilute solutions1 may require half an hour for complete development4 ,at the end of this time the two solutions are compared1 the colors equalized by diluting the darker1 and the calculation made as explained under the estimation of nitrates4 ,the following are the reactions3 ,paraamidobenzene ,nitrous acid4 ,paradiazobenzene sulfonic acid4 sulfonic acid4 ,c,h,,nh,,hso ,,hno ,c,h,n,,so #b;,h,o4 ,naphthylammonium ,azoalphaamidonaphthalene parazobenzene chlorid4 sulfonic acid4 ,c,h,n,,so ,c,h,,nh,cl ,c,h7,,nh7,,nnc,h,,hso ,h,cl4 ,the last named body gives the color to the liquid4 ,the method pursued by ,tanner1 in the preparation of the reagent1 is as follows3 ,sulfanilic acid is prepared by mixing thirty grams of anilin slowly1 with sixty grams of fuming sulfuric acid1 in a porcelain dish4 ,the brown1 sirupy liquid formed is carefully heated until quite dark in color1 and until the evolution of sulfurous fumes is noticed4 ,after cooling1 the thick1 semi-fluid mass is poured into half a liter of cold water and allowed to stand for some hours4 ,the liquid portion is then decanted from the nearly black undissolved crystalline mass4 ,to the residue half a liter of hot water is added and allowed to stand until cold1 and the liquid again decanted4 ,the undissolved portion is then treated with one liter of hot water and filtered4 ,the filtrate is treated with animal charcoal to decolorize it1 and allowed to stand for twenty-four hours and again filtered1 the filtrate diluted to #a1ejj cubic centimeters and used as required4 ,this solution tends to turn pink on keeping1 and thus its color interferes with the delicacy of the test1 and a small amount of animal-char is kept in a small bottle containing the portion for immediate use1 and this bottle is filled1 from time to time1 from the larger one4 ,the solution of naphthylamin hydrochlorate is made with one gram of the salt dissolved in #ajj cubic centimeters of water4 ,the solution is to be occasionally filtered1 and not more than #ajj cubic centimeters should be prepared at a time4 ,the analytical operations are carried on as follows3 ,a standard solution of pure potassium nitrite1 made from the silver salt in distilled water perfectly free from nitrites1 is placed in a color-glass1 similar to those used in the nessler reaction1 together with a second glass containing the water to be tested4 ,these glasses should be marked to hold #ajj cubic centimeters at the same depth4 ,to each of the tubes a few drops of pure hydrochloric acid are added and two cubic centimeters of the sulfanilic solution4 ,afterwards1 to each tube are added two cubic centimeters of the solution of naphthylamin hydrochlorate1 and it is allowed to stand for twenty minutes1 at the end of which time the color should be fully developed4 ,each tube is covered by a piece of glass in order to prevent access of air4 ,it is unnecessary to add that the standard solutions of nitrite of different strength should be employed until the one is found which resembles1 as nearly as possible1 the color developed in the sample of water under examination4 #eje4 ,lunge and ,lwoff's ,process for ,nitrous ,acid4--,the reaction of nitrous acid with naphthylamin1 first described by ,griess1 may be made reliable1 quantitatively1 by proceeding as below3#ccf ,boil #j4ajj gram of pure white naphthylamin for fifteen minutes with #ajj cubic centimeters of water1 add five cubic centimeters of glacial acetic acid1 or its equivalent of dilute acid1 and afterwards one gram of sulfanilic acid dissolved in #ajj cubic centimeters of hot water4 ,the mixture is kept in a well-closed flask4 ,a slight red tint in the mixture is of no significance1 inasmuch as this completely disappears when one part of it is mixed with fifty parts of the liquid to be examined4 ,if the coloration be very strong it can be removed by adding a little zinc dust4 ,one cubic centimeter of this reagent will give a distinct coloration with #j4jja milligram of nitrous nitrogen in #ajj cubic centimeters of water4 ,the analysis is conducted in cylinders of white glass marked at fifty cubic centimeters4 ,one cubic centimeter of the above reagent is placed in each of two cylinders with forty cubic centimeters of water and five grams of solid sodium acetate4 ,in one of the cylinders is placed one cubic centimeter of a normal solution of a nitrite prepared by dissolving #j4jdic gram of pure sodium nitrite corresponding to ten milligrams of nitrogen in #ajj cubic centimeters of water1 and adding ten cubic centimeters of this solution to ninety cubic centimeters of pure sulfuric acid4 ,this secures a normal solution of nitrosylsulfuric acid1 of which each cubic centimeter corresponds to #j4ja milligram of nitrogen4 ,in the other cylinder is placed one cubic centimeter of the solution to be examined1 and the contents of both cylinders are well mixed so that the nitrous acid in a nascent state may act on the reagent4 ,the colors are compared after any convenient period1 but1 as a rule1 after five minutes4 ,the chief improvement made by ,lunge and ,lwoff on the method of ,griess is in keeping the reagent in a mixed state ready for use1 by means of which any nitrous impurities in the components thereof are surely indicated4 ,its advantage over the method of ,ilosvay#ccg consists in using the comparative normal nitrite solution as nitrosylsulfuric acid1 in which state it is much more stable4 #ejf4 ,estimation of ,nitrous ,acid with ,starch as ,indicator4--,the method of procedure1 depending on the blue color produced in a solution of starch in presence of a nitrite and zinc iodid when treated with sulfuric acid1 is not of wide application on account of the interference produced by organic matter4 ,the soil extract or water is treated in a test-tube1 with a few drops of starch solution and some zinc iodid1 to which is added some sulfuric acid4 ,the decomposition of the nitrite is attended with the setting free of an equivalent amount of iodin which gives a blue coloration to the starch solution4 ,the depth of the tint is imitated by treating a standard solution of nitrite in a similar way until the proper quantity is found1 which gives at once the proportion of nitrite in the sample examined4 ,this process1 however1 is scarcely more than a qualitative one4 #ejg4 ,estimation of ,nitrites by the ,method of ,chabrier4--,in order to make the estimation of the evolved nitrous acid more definite by the iodin method1 ,chabrier has elaborated a plan for titrating it with a reducing agent4#cch ,the substance chosen for this purpose is sodium hyposulfite4 ,in point of fact1 it is not the nitrous acid which is attacked by the hyposulfite1 but the equivalent amount of free iodin representing it4 ,in the case of a soil where the quantity of nitrites is usually very small1 it is well to take as much as one kilogram4 ,the extraction should be made rapidly1 with water1 free of nitrites1 in order to avoid any reducing action on the nitrates which may be present4 ,in the case of water1 from five to ten liters should be evaporated to a small volume4 ,the concentration should take place in a large flask1 rather than in an open dish1 in order to avoid any possibility of the absorption of nitrites produced by combustion4 ,when the volume has been reduced to about #ajj cubic centimeters it is transferred to a small flask and the concentration continued until only ten or fifteen cubic centimeters are left4 ,the residue is filtered into a woulff bottle1 ,f1 ,fig4 #hi1 of about #ajj cubic centimeters capacity4 ,one of the side tubulures carries a burette1 ,b1 containing five per cent sulfuric acid1 the other one filled with a hyposulfite solution of known strength4 ,the middle tubule serves to introduce a glass tube through which carbon dioxid or illuminating gas passes for the purpose of driving out the air from the solution and the flask4 ,if carbon dioxid be used it should be generated by the action of sulfuric acid on marble4 ,the cork holding this is furnished with a slot or valve to permit the exit of the air and the excess of the gas4 ,before inserting the middle stopper1 a few cubic centimeters of potassium iodid solution and a few drops of thin starch paste are added1 the potassium salt being always used in excess of the nitrite supposed to be present4 ,illustration3 ,,figure #hi4 ,,method ,,of ,,chabrier4 ,after the air has all been expelled from the flask the analytical process is commenced1 the carbon dioxid current being slowly continued4 ,at first1 a few drops of the dilute sulfuric acid are allowed to flow into the flask4 ,as soon as the liquid is colored blue a sufficient quantity of the thiosulfate solution is added to discharge the color4 ,the successive addition of acid and thiosulfate is continued until another portion of the acid fails to develop the blue color1 thus indicating that all the nitrite has been decomposed4 ,from the volume of thiosulfate used the quantity of nitrite is calculated4 ,the ,thiosulfate ,solution4--,the thiosulfate solution is conveniently prepared1 when a large number of analyses is to be made1 by dissolving twenty-five grams of pure crystallized sodium thiosulfate in #ajj cubic centimeters of water and diluting any convenient part thereof to #ajj or #a1jjj cubic centimeters1 according to the supposed strength of nitrite solution under examination4 ,for fixing the strength of the solution dissolve #c #cdh grams of pure iodin in a solution of potassium iodid and make the volume up to one liter4 ,each cubic centimeter of this solution corresponds to one milligram of nitrous acid4 ,a given volume of the iodin solution is titrated against the thiosulfate1 but it is best not to add the starch paste until the greater part of the iodin has been removed4 ,the starch paste is then added and the titration continued until the blue color has been discharged4 ,ten cubic centimeters of the iodin solution is a convenient quantity for the titration and the thiosulfate should be diluted by adding to ten cubic centimeters of the solution mentioned above1 #iij cubic centimeters of water4 ,each liter of this dilute solution contains two and a half grams of the sodium thiosulphate4 ,example4--,let us suppose that it has required #ba4c cubic centimeters of thiosulfate to absorb ten cubic centimeters of the iodin solution2 further that ten liters of water have been evaporated and titrated as described above1 and that the volume of thiosulfate employed was #ac4h cubic centimeters4 ,from this is derived the following formula3 7#ac4h #aj7_/7ba4c7 #f4dh milligrams of nitrous acid2 or #j4fdh milligram per liter4 #ejh4 ,estimation of ,nitrous ,acid ,by ,coloration of ,solution of ,ferrous ,salt4--,this method1 due to ,picini is based on the production of the well-known brown color formed by the action of nitric oxid on a ferrous salt4#cci ,the nitrite is decomposed by heating with acetic acid while nitrates thus treated do not develop the reaction4 ,the tint produced is imitated as above by testing against a standard solution of nitrite4 ,ferrous chlorid is to be preferred to other ferrous salts for the above purpose4 ,the process should be carried on in solutions free of air4 #eji4 ,estimation of ,nitrous ,acid ,by ,decomposition with ,potassium ,ferrocyanid4--,the method of ,schaeffer was first described in #ahea1 but little attention has been paid to it since4 ,the method has lately been brought into notice again by ,deventer4#cdj ,the reaction depends upon the decomposition of nitrous acid by potassium ferrocyanid in the presence of acetic acid with the formation of potassium ferricyanid and acetate1 and nitric oxid4 ,the reaction is expressed by the following equation3 #b,k,fe,cy #b;,,hno #b;,c,h,o ,k,fe,cy #b,,kc,h,o #b,,no #b;,h,o4 ,illustration3 ,,figure #ij4 ,,schaeffer',s ,,nitrous ,,acid ,,method4 ,a eudiometer with a glass stop-cock is arranged as shown in ,fig4 #ij4 ,the lower part of the eudiometer is closed with a rubber stopper carrying a glass tube which ends in the pan f as shown at e4 ,the eudiometer is filled to the stop-cock with a solution of potassium ferrocyanid of about fourteen per cent strength4 ,the dish f is also filled up to the height indicated in the figure with the same solution4 ,the solution of nitrite is used in such quantities that the nitric oxid evolved will occupy a space of about twenty cubic centimeters4 ,the whole eudiometer should contain about fifty-seven cubic centimeters4 ,the nitrite solution is added to the eudiometer by means of a funnel1 a4 ,the vessel containing it is washed out with a little water and then with acetic acid and finally with a few cubic centimeters of strong potassium ferrocyanid solution4 ,the last fluid flows through the solution of nitrite and acetic acid and thus mixes it with the solution already in the eudiometer4 ,the liquids reacting on each other float together on the strong ferrocyanid solution and each one of them is at once pressed downward by the gases which are evolved4 ,when the evolution of gas becomes slower the apparatus should be shaken for about twenty minutes1 moving it back and forth without taking the bottom of it out of the dish4 ,when there is no longer any evolution of gas1 water is added through a slowly1 until the heavy potassium ferrocyanid solution is almost completely driven out of the eudiometer4 ,the opening of the tube at e is then closed with the thumb1 the apparatus is taken out of the dish1 shaken for some time in a vertical direction and again placed in the dish4 ,water of any required temperature is now allowed to flow through the jacket1 g1 h1 until the temperature is constant1 when the volume of nitric oxid is read4 ,the whole experiment can be performed in less than an hour4 ,operating in this way1 at the end there is in the eudiometer a liquid which is not very different from water and one whose coefficient of solubility for nitric oxid is practically the same as that of water4 ,the gas volume read is to be corrected for temperature1 pressure1 tension of the aqueous vapor1 height of the water column in the eudiometer1 and1 after the end of the calculation1 five per cent of the volume of water remaining in the eudiometer is to be added to the volume of gas obtained4 ,this is to compensate for the volume of the gas absorbed by the water4 ,the method gives good quantitive results4 #eaj4 ,method of ,collecting ,samples of ,rain ,water for ,analysis4--,warington collects rain water in a large leaden gauge having an area of #j4jja of an acre4#cda ,of the daily collection of rain1 dew1 and snow water1 an aliquot part amounting to a gallon for each inch of precipitation is placed in a carboy2 at the end of each month the contents of the carboy are mixed1 and a sample taken for analysis4 ,in the carboy receiving the rain for nitric acid estimation a little mercuric chlorid is placed each month with the view of preventing any change of ammonia into nitric acid4 ,it may be doubted1 however1 if this precaution is necessary1 as the rain water thus collected always contains a very appreciable amount of lead2 and experiments have shown that on the whole1 rain water more frequently gains than loses ammonia by keeping4 ,preparation of the ,sample4--,the method first employed by ,warington was to concentrate ten pounds of the rain water in a retort1 a little magnesia being used to decompose any ammonium nitrite or nitrate present4 ,concentration by evaporation in the open air1 and especially over gas1 results in a distinct addition to nitrites present4 ,when concentrated to a small bulk1 the water is filtered and evaporated to dryness in a very small beaker4 ,the nitrogen as nitrates and nitrites is then determined by means of the methods already described4 ,,determination ,,of ,,free ,,and ,,albuminoid ,,ammonia ,,in ,,rain ,,and ,,drainage ,,waters ,,and ,,soil ,,extracts4 #eaa4 ,nessler ,process4--,the quantities of free ammonia in rain and most drainage waters are minute1 but may reach considerable magnitude in some sewages4 ,by reason of these minute proportions1 gravi- and volumetric methods are not suitable for its quantitive determination4 ,recourse is therefore had to the delicate colorimetric reaction first proposed by ,nessler4 ,this reaction is based on the yellowish-brown coloration produced by ammonia in a solution of mercuric iodid in potassium iodid4 ,the coloration is due to the formation of oxydimercuric ammonium iodid1 ,,nh,hg,,oi1 and takes place between the molecule of free ammonia and the mercuric iodid dissolved in the alkaline potassium iodid as represented by the following equation3 ,hg--,o--,hg--,i ,hg _/ _/ ,o #b;,h,n #b,o ,,nh,i ,h,o _/ ,hg--,o--,hg--,i ,,hg ,nessler ,reagent4--,dissolve thirty-five grams of potassium iodid in #ajj cubic centimeters of water4 ,add to this solution gradually a solution of seventeen grams of mercuric chlorid in #cjj cubic centimeters of water until a permanent precipitate of mercuric iodid is formed4 ,add now enough of a twenty per cent solution of sodium hydroxid to make #ajjj cubic centimeters4 ,the mixed solutions1 at room temperature1 are treated with additional mercuric chlorid until the precipitate formed1 after thorough stirring1 remains undissolved4 ,this precipitate is then allowed to subside1 and when the supernatant liquid is perfectly clear1 it is decanted or filtered through asbestos and kept in a well-stoppered bottle in a dark place4 ,the part in use should be transferred to a smaller bottle as required4 ,the solution should be made for a few days before using1 since its delicacy is increased by keeping4 ,the nessler reagent should show a faint yellow tint4 ,if colorless it is not delicate1 and shows the addition of an insufficient quantity of mercuric chlorid4 ,when properly prepared1 two cubic centimeters of the reagent poured into fifty cubic centimeters of water containing #j4je milligram of ammonia will at once develop a yellowish-brown tint4 ,preparation of ,ammonia-,free ,water4--,to pure distilled water add pure1 recently-ignited sodium carbonate1 from one to two grams per one liter1 and distill4 ,when one-fourth of the whole has passed over1 the distillate may be regarded as free from ammonia2 fifty cubic centimeters of the following distillate should give no reaction with the nessler reagent4 ,the distillation should be continued until the residual volume in the retort is about one-fourth of the original1 and the distillate free of ammonia is carefully preserved in close glass-stoppered bottles previously washed with ammonia-free water4 ,pure water1 free of ammonia may also be obtained by distilling with sulfuric acid4 ,comparative ,solution of ,ammonium ,chlorid containing #j4jjjja gram ,ammonia in one cubic centimeter4--,dissolve #c4ae grams ,h,n,cl in ammonia-free water and make the volume up to one liter4 ,take ten cubic centimeters of the above solution and dilute to #ajjj with water1 free from ammonia4 ,solution containing #j4jjjja gram ,nitrogen in one cubic centimeter4--,dissolve #c4hb grams ,h,n,cl in water1 free from ammonia and dilute with same to #ajjj cubic centimeters4 ,dilute ten cubic centimeters of the above solution to #ajjj4 ,the ,distillation4--,any kind of suitable retort or flask connected with a good condenser may be used4 ,the capacity of the retort should be from #gjj to #a1jjj cubic centimeters4 ,the retort and condenser preferred by ,leffmann and ,beam are shown in ,fig4 #ia4 ,any good lamp may be used in which the flame is under complete control4 ,the gauze burner shown in the figure is easily controlled and distributes the heat evenly over the surface of the retort thus diminishing the danger of fracture4 ,the apparatus having been previously rinsed with distilled water receives #ejj cubic centimeters of the liquid to be tested for ammonia1 together with a few pieces of recently ignited pumice stone to prevent bumping and five cubic centimeters of the twenty percent sodium carbonate solution to render its contents alkaline4 ,the water is raised to the boiling-point and with gentle ebullition fifty cubic centimeters of distillate collected4 ,the distillate is conveniently collected in a color-comparison cylinder of thin white glass and flat bottom1 about two and a half centimeters in diameter1 and marked at fifty and one hundred cubic centimeters4 ,two cubic centimeters of the nessler reagent are added and if ammonia be present a yellowish-brown color will be developed1 the intensity of which is matched by taking portions of the ammonium chlorid solution1 diluting to fifty cubic centimeters with pure water and treating with the same quantity of the nessler reagent4 ,the process is repeated until a distillate is obtained which gives no reaction for ammonia4 ,the sum of the quantities obtained in the several distillates gives the total amount of ammonia in the #ejj cubic centimeters of the water taken4 ,in most cases practically all the ammonia is obtained in three or four portions of the distillate4 ,illustration3 ,,figure #ia4 ,,retort ,,for ,,distilling ,,ammonia4 ,albuminoid ,ammonia4--,the residue from the process just described is employed for the purpose of determining the albuminoid ammonia4 ,two hundred grams of potassium hydroxid and eight grams of potassium permanganate are dissolved in #a1jjj parts of distilled water4 ,fifty cubic centimeters of the solution are placed in a porcelain dish with #ajj cubic centimeters of distilled water and evaporated to fifty cubic centimeters4 ,this liquid is placed in the retort and the distillation resumed and continued until an ammonia-free distillate is obtained4 ,the total albuminoid ammonia is determined by taking the sum of the quantities in the several distillates4 #eab4 ,nessler ,reagent of ,ilosvay4--,to secure greater delicacy in nesslerizing1 ,ilosvay uses a reagent prepared as follows3#cdb ,dissolve two grams of potassium iodid in five cubic centimeters of water1 heat the solution gently1 and add three grams of mercuric iodid4 ,after the solution is cooled1 add an additional portion of three grams of the mercury salt1 and then twenty cubic centimeters of water1 and wait until the precipitation is complete4 ,after filtering1 there are added to the filtrate from twenty to thirty cubic centimeters of a twenty per cent solution of potassium hydroxid4 ,only the limpid supernatant liquid is used in the analytical work4 ,with this reagent1 ,ilosvay has been able to detect #j4jb milligram of ammonia in #aaj cubic centimeters of water4 ,,authorities ,,cited ,,in ,,part ,,seventh4 ,footnote #bgd3 ,comptes rendus1 ,tome #hd1 pp4 #cja1 et seq4 ,journal of the ,chemical ,society1 7,transactions71 #ahgh1 p4 #dd2 #ahgi1 p4 #dbi2 #ahhd1 p4 #fcg4 ,american ,chemical ,journal1 ,vol4 #d1 p4 #deb4 ,proceedings of the ,american ,association for the ,advancement of ,science1 ,vol4 #da1 p4 #aje4 ,annales de l',institut ,pasteur1 ,tome #d1 pp4 #bah1 #beg1 #gfj2 ,tome #e1 p4 #ib4 ,footnote #bge3 ,comptes rendus1 ,tome #aah1 p4 #fjd4 ,footnote #bgf3 ,bulletin de la ,academie royale de ,belgique1 #c1 ,tome #be1 p4 #gbg4 ,journal of the ,chemical ,society1 7,abstracts71 ,june1 #ahid1 p4 #bdh4 ,footnote #bgg3 ,chemical ,news1 ,oct4 #ac1 #ahic1 p4 #agf4 ,footnote #bgh3 ,comptes rendus1 ,tome #aji1 p4 #hhc4 ,footnote #bgi3 ,op4 cit4 supra1 ,tome #hi1 pp4 #hia1 et seq4 ,footnote #bhj3 ,journal of the ,chemical ,society1 7,transactions71 ,vol4 #de1 pp4 #fde1 et seq4 ,footnote #bha3 ,jahresbericht der ,agricultur ,chemie1 #ahha1 ,s4 #dc4 ,footnote #bhb3 ,annual ,report of the ,british ,board of ,health1 #ahhc4 ,footnote #bhc3 ,annales de l',institut ,pasteur1 #ahia1 ,s4 #ic4 ,footnote #bhd3 ,philosophical ,transactions of the ,royal ,society of ,london1 ,vol4 #aha1 7#ahij74 ,footnote #bhe3 ,zeitschrift fr ,biologie1 ,band #i1 ,s4 #agb4 ,footnote #bhf3 ,archives de ,science ,biologique ,st4 ,petersbourgh1 ,tome #a1 p4 #acca4 ,footnote #bhg3 ,annales de l',institut ,pasteur1 #ahia1 pp4 #eha1 et seq4 ,footnote #bhh3 ,op4 cit4 supra1 #ahia1 ,plate #ah1 ,fig4 #b4 ,footnote #bhi3 ,op4 cit4 supra1 #ahia1 pp4 #eie1 et seq4 ,footnote #bij3 ,op4 cit4 supra1 #ahia1 ,plate #ah1 ,fig4 #a4 ,footnote #bia3 ,journal of the ,chemical ,society1 7,transactions71 #ahia1 pp4 #dih1 et seq4 ,footnote #bib3 ,annales de l',institut ,pasteur1 #ahia1 pp4 #fje1 et seq4 ,footnote #bic3 ,journal of the ,chemical ,society1 7,transactions71 #ahhb1 p4 #ceg4 ,footnote #bid3 ,annales de ,chimie et de ,physique1 #ahed1 ,tome #dj1 p4 #dgi4 ,zeitschrift fr analytische ,chemie1 #ahgj1 ,s4 #bd2 #ahgg1 ,s4 #bia4 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #ab1 ,s4 #afd4 ,journal of the ,chemical ,society1 7,transactions71 #ahhj1 p4 #dfh2 #ahhb1 p4 #cde2 #ahhi1 p4 #ecg4 ,footnote #bie3 ,encyclopedie ,chimique1 ,tome #d1 p4 #aea4 ,footnote #bif3 ,annales de la ,science ,agronomique1 #ahia1 pp4 #bfc1 et seq4 ,footnote #big3 ,berichte der deutschen chemischen ,gesellschaft1 ,band #bc1 ,s4 #acfa4 ,footnote #bih3 ,zeitschrift fr analytische ,chemie1 ,band #i1 ,s4 #bd1 #dja4 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #i1 ,s4 #i4 ,berichte der deutschen chemischen ,gesellschaft1 ,band #f1 ,s4 #ajch4 ,footnote #bii3 ,zeitschrift fr analytische ,chemie1 ,band #cc1 ,s4 #bjj4 ,footnote #cjj3 ,apotheker ,zeitung1 #ahia1 ,band #e1 ,s4 #bhg4 ,footnote #cja3 ,sutton's ,volumetric ,analysis1 #c;d edition1 p4 #caf4 ,warington1 ,journal of the ,chemical ,society1 7,transactions71 #ahgi1 p4 #cgf4 ,footnote #cjb3 ,report of the ,national ,board of ,health1 #ahhb1 p4 #bha4 ,footnote #cjc3 ,berichte der deutschen chemischen ,gesellschaft1 ,band #aa1 ,s4 #dcb4 ,footnote #cjd3 ,bulletin de la ,socit ,chimique1 #c1 ,tomes #aa-ab1 p4 #fbe4 ,footnote #cje3 ,encyclopedie ,chimique1 ,tome #d1 p4 #aed4 ,footnote #cjf3 ,zeitschrift fr analytische ,chemie1 ,band #g1 ,s4 #dab4 ,fresenius1 ,quantitative ,analysis1 ,grove's translation1 special part1 p4 #aah4 ,footnote #cjg3 ,journal of the ,chemical ,society1 7,transactions71 #ahgi1 pp4 #egh1 et seq4 ,footnote #cjh3 ,bulletin #ch1 ,department of ,agriculture1 ,division of ,chemistry1 p4 #bjd4 ,footnote #cji3 ,die ,landwirtschaftlichen ,versuchs-,stationen1 ,band #da1 ,s4 #afe4 ,footnote #caj3 ,chemiker ,zeitung1 #ahib1 ,band #af1 ,s4 #aieb4 ,footnote #caa3 ,zeitschrift fr angewandte ,chemie1 #ahic1 ,s4 #afa4 ,footnote #cab3 ,chemiker ,zeitung1 #ahhi1 ,no4 #ae4 ,footnote #cac3 ,vid4 op4 cit4 #ch1 #ahij1 ,s4 #fie4 ,footnote #cad3 ,archives de la ,socit ,physique de ,genve1 ,tome #ca1 p4 #ceb4 ,footnote #cae3 ,chemiker ,zeitung1 #ahij1 ,s4 #adaj4 ,footnote #caf3 ,chemisches ,centralblatt1 #ahij1 ,band #b1 ,s4 #ibf4 ,footnote #cag3 ,vid4 op4 cit4 #ch1 #ahia1 ,s4 #bda4 ,footnote #cah3 ,vid4 op4 cit4 #cd1 #ahhi1 p4 #ech4 ,footnote #cai3 ,op4 cit4 supra1 #ahha1 p4 #ajj4 ,footnote #cbj3 ,op4 cit4 supra1 ,vol4 #eg1 p4 #haa4 ,footnote #cba3 ,op4 cit4 supra1 #ahia1 pp4 #ecj1 et seq4 ,footnote #cbb3 ,op4 cit4 supra1 #ahgd1 p4 #fcj1 and #ahhe1 p4 #hf4 ,footnote #cbc3 ,sutton's ,volumetric ,analysis1 #dth edition1 p4 #ajc4 ,footnote #cbd3 ,american ,journal of ,science1 ,vol4 #dd1 p4 #aag4 ,footnote #cbe3 ,american ,chemical ,journal1 ,vol4 #aa1 p4 #bdi4 ,footnote #cbf3 ,journal of the ,franklin ,institute1 ,vol4 #abg1 p4 #fa4 ,footnote #cbg3 ,zeitschrift fr ,hygiene1 ,band #b1 ,s4 #afc4 ,footnote #cbh3 ,chemical ,news1 #ahhi1 ,nov4 #bi1 #bfa4 ,footnote #cbi3 ,vid4 op4 cit4 supra1 p4 #ea4 ,footnote #ccj3 ,examination of ,water for ,sanitary and ,technical ,purposes1 p4 #bh4 ,footnote #cca3 ,chemical ,news1 #ahij1 ,jan4 #aj1 p4 #ae4 ,footnote #ccb3 ,zeitschrift fr angewandte ,chemie1 #ahid1 ,heft #ab1 ,s4 #cdg4 ,footnote #ccc3 ,journal of the ,chemical ,society1 7,abstracts71 #ahia1 p4 #dhi4 ,footnote #ccd3 ,zeitschrift fr analytische ,chemie1 ,band #ah1 ,s4 #eig4 ,zeitschrift fr angewandte ,chemie1 #ahhi1 ,s4 #fff4 ,bulletin de la ,socit ,chimique1 #c1 ,tome #b1 p4 #cdg4 ,footnote #cce3 ,op4 cit4 #eg1 p4 #cj4 ,footnote #ccf3 ,zeitschrift fr angewandte ,chemie1 #ahid1 ,s4 #cdi4 ,footnote #ccg3 ,bulletin de la ,socit ,chimique1 #c1 ,tomes #aa-ab1 p4 #bah4 ,footnote #cch3 ,encyclopedie ,chimique1 ,tome #d1 p4 #bfb4 ,footnote #cci3 ,peligot1 ,trait de ,chimie ,analytique applique ,agriculture1 p4 #bfa4 ,footnote #cdj3 ,berichte der deutschen chemischen ,gesellschaft1 #ahic1 ,s4 #ehi4 ,footnote #cda3 ,journal of the ,chemical ,society1 #ahhi1 p4 #ecg4 ,footnote #cdb3 ,op4 cit4 #fd1 p4 #baf4 ,,note4--,on page #aeh1 paragraph #agb1 third line1 insert1 8and determining matters dissolved therein10 after 8flow40 ,,part ,,eighth4 ,,special ,,examination ,,of ,,waters1 ,,vegetable ,,soils1 ,,and ,,unusual ,,soil ,,constituents4 #eac4 ,further ,examination of ,waters4--,having described in the preceding part the approved methods of determining the oxidized nitrogen in waters and soil extracts there remains to be considered the examination of waters for other substances of importance to agriculture4 ,rain waters add practically nothing to the soil but nitric acid and ammonia1 and1 therefore1 demand no further discussion here4 ,in drainage and sewage waters1 in addition to the oxidized nitrogen1 there may be sufficient quantities of phosphoric acid and potash to make their further analysis of interest4 ,but by far the most practical point to be considered is in the case of waters used for irrigation purposes where the continued addition to the soil of mineral matters may eventually convert fertile fields into barren wastes4 ,in irrigated lands there is practically no drainage and the whole of the water is removed by superficial evaporation4 ,it is easily seen how these mineral matters tend to accumulate in that part of the soil in which the rootlets of plants seek their nourishment4 #ead4 ,estimation of ,total ,solid ,matter4--,the total solid contents of a sample of water are determined by evaporating a known volume or weight to dryness and weighing the residue4 ,for comparative purposes a given volume of water may be taken if the solid contents do not exceed four grams in a ,united ,states gallon4 ,the water should be measured at a temperature of about #ae4e4 ,where the content of mineral matter is greater it is best to weigh the water and calculate the solid contents to parts per one hundred thousand4 ,for practical purposes in the ,united ,states it is customary to state the content of solid matter in grains per gallon4 ,since1 however1 the gallon has so many different values it is always necessary to indicate what particular measure is meant4 ,in ordinary spring and well waters the volume to be used is conveniently taken at #ajj cubic centimeters4 ,to avoid calculation a volume in cubic centimeters corresponding to some decimal part of a gallon in grains may be taken and the weight in milligrams will then be equivalent to the grains per gallon4 ,thus in the imperial gallon which contains #gj1jjj grains of distilled water at #ae4e1 seventy cubic centimeters may be taken4 ,if the residue weigh twenty-five milligrams the water contains twenty-five grains of solid matter per gallon4 ,the ,united ,states gallon at #ae4e contains #eh1cjd grains of distilled water4 ,in this case #eh4c cubic centimeters should be used1 or double this amount and the weight in milligrams be divided by two4 ,the evaporation may be made in a platinum1 porcelain1 or aluminum dish1 preferably with a flat bottom2 ,the dish does not need to hold the whole volume at once1 but the water may be added from time to time as the evaporation continues4 ,the dish1 however1 should1 as a rule1 hold not less than #ajj cubic centimeters4 ,the evaporation is best conducted over a steam-bath1 and after the complete disappearance of the liquid the heating should be continued until the residue is perfectly dry4 ,in the case of mineral waters highly impregnated with inorganic salts1 a smaller volume or weight may be taken1 and greater care must be exercised in drying the residue4 ,for the purpose of qualitively determining the percentage of special ingredients1 quantities of the water should be taken inversely corresponding to the content of the ingredient desired4 ,in general1 it will not be necessary to evaporate the sample to complete dryness1 but only to concentrate it to a volume convenient for the application of the analytical process4 ,where a complete quantitive analysis of the solid residue is desired1 a sufficient quantity of the water is evaporated to give a weighable amount of the least abundant ingredient4 ,the total solid content of the water having been previously determined1 the actual weight or volume of the water taken to obtain the above residue is of no importance4 #eae4 ,estimation of the ,chlorin4--,the chlorin in the solid residue from a sample of water may be determined directly by dissolving the soluble salts in distilled water1 to which enough nitric acid is added to preserve the solution slightly acid4 ,after filtering and washing1 silver chlorid is added1 little by little1 with constant shaking until a further addition of the reagent produces no further precipitate4 ,the beaker or flask should be placed in a dark place1 on a shaking apparatus which is kept in motion until the precipitate has entirely settled in a granular state4 ,the silver chlorid is then collected on a gooch1 washed free of all soluble matter1 dried at #aej and weighed4 ,if the precipitate be ignited to incipient fusion1 a porcelain gooch should be used4 ,a more convenient method is to determine the chlorin directly in the water1 or1 where the quantity is too minute1 after proper concentration1 volumetrically by means of a titrated solution of silver nitrate1 using potassium chromate as indicator4 ,as soon as the chlorin has all united with the silver1 any additional quantity of the silver nitrate will form red silver chromate1 the permanent appearance of which indicates the end of the reaction4 ,this process is especially applicable to water1 which in a neutral state contains no other acids capable of precipitating silver4 ,the chromate indicator does not work well in an acid solution4 #eaf4 ,solutions ,employed4--,a quantity of pure silver nitrate1 about five grams1 is dissolved in pure water and made up to a volume of one liter4 ,for determining the actual strength of the solution1 #j4hbd gram of pure sodium chlorid is dissolved in water and the volume made up to half a liter4 ,twenty-five cubic centimeters of this solution are placed in a porcelain dish1 and a few drops of the solution of potassium chromate added4 ,the silver nitrate solution is allowed to flow into the porcelain dish from a burette graduated to tenths of a cubic centimeter4 ,the red color produced as each drop falls1 disappears on stirring as long as there is any undecomposed chlorid4 ,finally a point is reached when the red color becomes permanent1 a single drop in excess of the silver nitrate being sufficient to impart a faint red tint to the contents of the dish4 ,the solution of potassium chromate is prepared by dissolving five grams of the salt in #ajj cubic centimeters of water4 ,silver nitrate solution is added until a permanent red precipitate is produced1 which is removed by filtration1 and the filtrate is employed as the indicator as above described4 ,water with any considerable quantity of chlorin can be treated directly with the reagents2 when the percentage of chlorin is low1 previous concentration to a convenient volume is advisable4 ,in waters containing bromids and iodids these halogens would be included with the chlorin estimated as above4 ,for agricultural purposes such waters have little importance4 ,in the case of soluble carbonates capable of precipitating silver this action can be prevented by acidifying the water with nitric acid and afterwards removing the excess of acid with precipitated calcium carbonate4 ,in this reaction ,mc,elroy recommends the use of ,congo paper1 which is not affected by the carbon dioxid but is turned blue as soon as an excess of nitric acid is added4 ,after the addition of the calcium carbonate the mixture should be boiled to expel carbon dioxid4#cdc ,irrigation waters from natural sources or derived from sewage rarely contain enough chlorin to make their use objectionable4 ,on the other hand1 when water is obtained for this purpose from artesian wells it may often contain a quantity of chlorin which will eventually do more harm to the arable soil than the water will do good4 #eag4 ,carbon ,dioxid4--,free carbon dioxid in water has no significance in respect of its use for irrigation purposes4 ,such waters1 however1 are usually of a highly mineral nature and thus are justly open to suspicion when used for farm animals and on the field4 ,the presence of free carbon dioxid as has already been pointed out in paragraph #db1 gives to water1 one of its chief sources of power as an agent for dissolving rocks and ultimately forming soil4 ,the estimation of the total free carbon dioxid in a sample of water issuing from a spring or well is a matter of some delicacy by reason of the tendency of this gas to escape as soon as the water reaches the open air and is relieved from the natural pressure to which it has been subjected4 ,the actual quantity of the gas remaining in solution at any given time is determined as follows3 #ajj cubic centimeters of the water are placed in a flask with three cubic centimeters of a saturated solution of calcium and two of ammonium chlorid4 ,to this mixture is added forty-five cubic centimeters of a titrated solution of calcium hydroxid4 ,the flask is stoppered1 well shaken1 and set aside for twelve hours to allow the complete separation of the calcium carbonate formed4 ,when the supernatant liquid is perfectly clear an aliquot part thereof1 from fifty to one hundred cubic centimeters1 is removed and titrated with decinormal acid with phenacetolin or lacmoid as an indicator4 ,from the quantity of calcium hydroxid remaining unprecipitated the amount which has been converted into carbonate can be determined by difference4 ,the difference between the quantity of calcium hydroxid originally present in the solution and that remaining after the above treatment multiplied by the factor #j4jjbb will give the weight of carbon dioxid present in the water in a free state or in excess of that present as normal carbonates4 ,,unusual ,,constituents ,,of ,,soil4 #eah4 ,boric ,acid4--,boron1 while not regarded as an essential plant food1 is yet found quite uniformly in the ashes of a large number of plants4 ,it may1 therefore1 be of some interest to the agricultural analyst to determine the amount of it which may be present in a soil extract or mineral water4 ,for this purpose the following method due to ,gooch may be employed4#cdd ,to one liter of the water supposed to contain boric acid add enough sodium carbonate to produce distinct alkalinity4 ,after evaporation to dryness acidify the residue with hydrochloric acid1 apply a piece of turmeric paper and dry at a moderate heat4 ,the usual brown-red tint will reveal the presence of boric acid4 ,the quantitive estimation of the acid is accomplished as follows3 ,one or more liters of the water rendered alkaline as above are evaporated to dryness4 ,with the aid of as small a quantity as possible of acetic acid the dry residue is transferred to a distillation flask and condenser arranged as shown in ,fig4 #ib4 ,about one gram of recently ignited pure lime1 cooled in a desiccator and weighed accurately1 is introduced into the flask at the bottom of the condenser and slaked by a few cubic centimeters of water4 ,when the flask is attached1 the terminal tube of the condensing apparatus should dip into the lime-water in the flask4 ,the heating-bath is partly filled with paraffin at a temperature of about #abj4 ,the paraffin-bath is raised so that the entire bulb of the flask is immersed therein and the distillation continued until all the liquid has been distilled4 ,the bath is removed and after cooling somewhat1 ten cubic centimeters of methyl alcohol are introduced by means of the stoppered funnel-tube and the process of distillation repeated4 ,this operation with methyl alcohol is repeated five times4 ,the boric acid passes off with the distillate and is found in the flask below the condenser as calcium borate4 ,the contents of the distillation flask are evaporated to dryness and ignited conveniently in the same crucible in which the lime was burned4 ,the increase in weight represents the quantity of boric anhydrid1 ,b,o obtained4 ,illustration3 ,,figure #ib4 ,,gooch',s ,,apparatus ,,for ,,boric ,,acid4 #eai4 ,method ,of ,moissan4--,the principle of the method of ,gooch1 which has just been described1 is applied by ,moissan in a slightly modified manner4#cde ,in this method the generating flask is made smaller than in the ,gooch apparatus1 and the funnel at the top is oval and provided with a ground-glass stopper4 ,it is closed at the bottom with a glass stop-cock1 and the slender funnel-tube enters through a rubber stopper and ends about the middle of the bulb of the flask4 ,the delivery-tube is longer than in ,fig4 #ia1 and is bent upward at its middle part in the form of an obtuse angle4 ,the receiving flask is connected with the condenser by means of a tube-shaped funnel1 which prevents any regurgitation into the generating flask4 ,the receiving flask also has attached to it a three-bulb potash absorption tube1 through which all vapors escaping from the receiving flask must pass4 ,the bulbs contain a five per cent solution of ammonia4 ,the receiving flask should be placed in a crystallizing dish and kept surrounded with ice-water4 ,the boron which is to be estimated should be in the form of boric acid4 ,this can readily be accomplished by treating the residue to be analyzed with nitric acid in a sealed tube4 ,the mixture is introduced into the generating flask1 washing with a little nitric acid1 and evaporated to dryness4 ,the heat is removed1 and1 by means of the funnel1 ten cubic centimeters of methyl alcohol added1 and distillation is renewed4 ,this operation with methyl alcohol is repeated four times1 taking care to distill to dryness in each case before the addition of a fresh quantity of alcohol4 ,afterwards1 there is introduced into the apparatus one cubic centimeter each of distilled water and nitric acid and the distillation again carried to dryness4 ,the treatment with methyl alcohol1 as described above1 is then repeated three times4 ,to determine whether all the boric acid have passed over1 the receiving flask at the bottom of the condenser is disconnected and a drop of the alcohol taken from the end of the condensing tube by means of a filament of filter paper4 ,on burning1 the flame should not show any trace of green4 ,in case a green color is observed1 the distillation with nitric acid and methyl alcohol must be repeated4 ,the ammonia in the potash bulbs serves to arrest any of the vapors carrying boric acid which might escape from the receiving flask4 ,the contents of the bulbs are to be mixed with the liquid in the receiving dish1 and the whole poured onto a known weight of recently ignited calcium oxid contained in a platinum dish1 and the mixture briskly stirred4 ,if the liquid be very acid the platinum dish should be kept in ice-water to prevent heating4 ,after fifteen minutes the liquid usually becomes alkaline1 and it is then evaporated at a temperature below the boiling-point of methyl alcohol 7#ff74 ,the mass1 after the methyl alcohol has disappeared1 is dried at a gradually increasing temperature1 and finally1 the dish is ignited over a blast1 at first covered and afterwards open4 ,the dish is covered and weighed and again ignited until constant weight is obtained4 ,the lime used should be specially prepared by igniting calcium nitrate incompletely1 and reigniting a portion of this to constant weight just before beginning each analysis4 ,the calcium oxid is then obtained in a perfectly fresh state4 ,it should be employed in considerable excess1 for each half gram of boric acid at least eight grams of the lime4 ,the operation is tedious but the results are quite accurate4 ,,special ,,treatment ,,of ,,muck ,,soils4 #ebj4 ,general ,considerations4--,deposits of muck which are to be used as soil for cultural purposes1 or marsh lands1 containing large quantities of organic matter1 require a special treatment in addition to the general principles of examination illustrated in the previous pages4 ,these soils1 essentially of an organic origin1 do not permit of the same treatment either chemical or physical as is practiced with soils of a mineral nature4 ,for instance1 it would be useless to attempt a silt analysis with organic soils1 and the extraction of them with hydrochloric acid for the purpose of determining the materials passing into solution would prove of little utility4 ,the object of the examination is not only to obtain knowledge of the ultimate constitution of the sample1 but also1 and this is the practical point1 to gain some idea of its stores of plant food and of the proper steps necessary to secure a supply of the deficient nutrients4 ,the final analytical processes for the estimation of the constituents of a muck or vegetable soil are the same as those already given1 but the preliminary treatment is radically different4 #eba4 ,sampling4--,first of all the geologic and meterologic conditions of the muck formations must be determined as nearly as possible4 ,it is fair to presume that these formations are of comparatively recent origin1 in fact that they are still in progress4 ,the geologic formation in the vicinity of the deposit should be noted4 ,information should be given in respect of the character of the water1 whether running or stagnant1 fresh1 salt1 or brackish1 and changes of level to which it is subject1 should be noted4 ,it should be particularly stated whether the vegetable growth contributing to the formation be subject to frost or freezing4 ,the character of the growth is to be carefully noted1 and observation made of any changes in vegetation due to drainage preparatory to cultivation4 ,it is to the original vegetation that the chief vegetable accretions in the muck must be accredited4 ,in all cases1 for purposes of comparison1 some samples must be taken from parts of the field which have not been under cultivation or fertilization4 ,the original properties of the muck can thus be determined and compared with the portions which have been changed under cultivation4 ,if the vegetation in different parts of the field vary it is an indication that the muck is not homogeneous1 and in such cases all the different kinds must be separately sampled4 ,any alluvial deposit should be carefully separated from the muck found in situ1 for the two layers are radically different in nature4 ,the sampling should be made by digging a pit1 if possible to the bottom of the muck formation1 and taking the samples at depths of one foot from one or all of the sides4 ,the samples from sections of even depth are to be mixed and about five kilograms of the well-mixed sample preserved4 ,blocks of the unbroken and unshattered material should also be taken from each section for the purpose of determining permeability to water and air4 ,all living vegetable matter should be as fully as possible removed before the sampling begins4 ,the nature of the subsoil must be observed1 and it should be stated whether it be sand1 clay1 limestone1 etc4 ,fresh samples should be taken at various depths for the purpose of determining the content of moisture in the manner described in paragraph #fe4 ,the tubes used are made sharp at the end to be inserted in the soil1 and so arranged as to cut cylinders of soil a trifle smaller than their interior diameter4 ,by this means the sample slips easily into its place4 ,the same care and judgment must be used in taking these samples as are required in the case of common soils4 ,illustration4--,samples of muck soil taken at ,runnymede1 ,florida4 7a7 ,formation4 ,littoral fresh-water lacustrine deposits1 varying from a few inches to four feet in depth1 and from a few feet to half a mile in width4 7b7 ,vegetation before drainage4 ,saw grass 7,cladium ,mariscus or effusum74 7c7 ,principal present vegetation 7see pages #ei-fj74 7d7 ,kinds of ,soil4--,the muck shows two distinct colors1 black and brown4 ,the vegetation1 however1 seems to be the same in both cases4 ,the black muck has the appearance of being more thoroughly decomposed4 7e7 ,geologic ,formation4--,this portion of the ,florida peninsula is covered generally with sand due to marine submergence during recent geologic periods4 ,the forest growth is pine4 ,the drainage from the pine land is towards the muck deposits4 ,the pine land lies from four to ten feet higher than the surface of the muck and is much less subject to frost4 #ebb4 ,water ,content4--,the capacity of a muck soil for retaining water is very great4 ,in a moist state these soils are heavy and apparently quite firm4 ,when dry they are light and fluffy and unsuited to hold the rootlets of plants4 ,saturated to their greatest capacity they hold considerably more than their own weight of water4 ,attention has already been called to the danger of drying such samples at a high temperature4 ,as in most cases of drying exposure at the temperature of boiling water until a constant weight is obtained is a perfectly safe way4 ,it is hard to say what comes off in addition to water at a higher temperature4 ,all that comes off even at the temperature of boiling water is not water4 ,the method of determination usually employed in this laboratory is the following3 ,from four to five grams of the material are spread as evenly as possible over the flat bottom of a circular aluminum dish1 about seven centimeters in diameter4 ,the dish is exposed for three hours at the temperature of boiling water and then kept for two hours in an air-bath at #aaj4 ,at the end of this time constant weight is obtained4 ,additional drying at #aaj for five hours1 usually gives no further loss of volatile matter4 ,the dish should be covered during weighing on account of the hygroscopicity of the residue4 ,when well sampled the dry matter thus obtained serves as the basis of calculation for the general analytical data4 ,results4--,samples of muck soil taken in brass tubes in ,march during the dry season had the following contents of moisture3 ,matter volatile at #aaj1 per cent4 ,taken near the surface #fa4fj one foot below the surface #hd4ce two feet #ha4eb ,it is thus seen that the normal content of moisture in such a soil during the dry season1 exclusive of the top layer1 is about eighty per cent4 #ebc4 ,organic ,carbon and ,hydrogen4--,the organic carbon and hydrogen in muck soils are determined on the carefully dried sample by combustion with copper oxid4 ,this process gives not only the quantities of these bodies combined as humus1 but also those in a less advanced state of decomposition and present as fatty bodies or resins4 ,the method employed is given on pages #cai-bj4 ,results4--,the data obtained on a sample of muck soil from ,florida are as follow3 ,per cent4 carbon4 ,per cent4 hydrogen4 ,one foot from surface #eg4fg #d4dh ,two feet #dg4jg #e4ae ,three #h4eb #j4ec ,the last sample was largely mixed with sand1 the muck at the point when it was taken not being quite three feet deep4 #ebd4 ,total ,volatile and ,organic ,matter and ,ash4--,the ignition of the sample should be very carefully conducted at the lowest possible temperature4 ,about five grams of the air-dried sample or double that amount of the moist sample should be taken4 ,in the latter case the calculations should be made on the basis of the dry material4 ,the ignition should be continued with frequent stirring with a platinum wire until all organic matter is destroyed4 ,at the same time in a large dish one or more kilograms of the sample should be ignited in order to secure an ash for analysis4 ,the ash should be quickly weighed to avoid absorption of moisture4 #ebe4 ,sulfur4--,the sulfur present in muck is combined either in an organic form or with iron4 ,it may be estimated by the method of ,fleischer4#cdf ,from five to ten grams of the sample are ignited carefully in a hard glass tube in a stream of air or better of oxygen4 ,the sulfur compounds escape as sulfuric or sulfurous acid4 ,the combustion is carried on in the apparatus shown in ,fig4 #ic4 ,illustration3 ,,figure #ic4 ,,apparatus ,,for ,,determining ,,sulfur4 ,the end of the tube ,a1 next to ,b1 is lightly stopped with a plug of glass wool1 the substance introduced and held in place by a second plug of glass wool next to ,c4 ,a is connected to the working flask ,c1 containing water1 as is shown in the illustration4 ,the chief object of the flask is to control the rate of aspiration of the air or oxygen4 ,a is also connected with the bulb-tube ,b1 as shown in the figure4 ,b contains potash-lye1 free of sulfur4 ,on the top of ,b is placed a drying tube filled with glass pearls1 moistened with potash-lye4 ,this is connected with the aspirator by a small bulb-tube bent at right angles1 as indicated4 ,the bulb of this tube contains a little neutral litmus solution1 which must suffer no change of color during the progress of this analysis4 ,the tube1 thus arranged1 is placed in a combustion furnace and gradually heated to redness1 beginning with the part next to ,b4 ,a moderate stream of air or oxygen is passed through the tube during the operation4 ,any product of the combustion collecting in the tube before reaching ,b1 is driven into ,b by careful heating4 ,at the end of the combustion the contents of ,b are acidified with hydrochloric acid1 and treated with bromin to convert the sulfurous into sulfuric acid4 ,the excess of bromin is afterwards removed by boiling1 and the sulfuric acid precipitated by barium chlorid and estimated in the usual way4 ,the total sulfuric acid having thus been determined1 the sample is extracted with water and the sulfuric acid estimated in the residue4 ,the sulfuric acid in a muck which is injurious to vegetation is classified by ,fleischer1 as follows3 7#a7 ,free sulfuric acid4 7,the residue which is obtained by calculation as sulfates of the bases in the water extract47 7#b7 ,the sulfuric acid contained as copperas 7calculated from the iron oxid content of the aqueous extract74 7#c7 ,sulfuric acid arising from the oxidation of pyrites 7calculated from the sulfuric acid obtained by treatment of the water-extracted sample74 ,a better idea of the distribution of the sulfur in the sample can be obtained by estimating it according to the method given in paragraph #che4 #ebf4 ,phosphoric ,acid4--,the method for determining the phosphorus in muck is given in paragraph #chb4 ,the process given in #cgh may also be used4 ,the method of extraction with hydrochloric acid is wholly unreliable as a means of determining the available phosphoric acid in muck4 ,there are some vegetable soils which contain so much iron and lime that the whole of the acid ordinarily used would be consumed thereby4 ,this fact has been clearly pointed out by ,wiklund in determining the phosphoric acid in a large number of peaty soils4#cdg ,his experiments1 were made with acid of only four per cent strength4 ,in some cases1 however1 it may be found useful to determine the quantity of phosphoric acid which can be extracted with hydrochloric acid1 and afterwards to separate the humus and determine the content of phosphoric acid therein4 #ebg4 ,humus4--,in this laboratory the humus is estimated by the method of ,huston and ,mc,bride1 as given in paragraph #cab4 ,in samples so rich in organic matter the method of ,grandeau does not give as good results4 ,often more than half the weight of the dry substance is soluble in ammonia after treatment with acid4 ,the nitrogen in the original sample and the separated humus should be estimated by moist combustion with sulfuric acid in the usual manner4 #ebh4 ,the ,mineral ,contents of ,humus4--,the material obtained by precipitating the alkaline extract of a vegetable earth with an acid does not consist alone of oxygen1 carbon1 hydrogen1 and nitrogen4 ,the complex molecules which make up this mixture contain certain quantities of iron1 sulfur1 and phosphorus in an organic state4 ,these bodies are left as inorganic compounds on ignition1 provided there is enough of base present to combine with all the acid elements4 ,much of the sulfur and phosphorus1 however1 in these compounds might be lost by simple ignition4 ,in such cases moist oxidation of these bodies must be practiced1 or the gases of combustion passed over bodies capable of absorbing the oxidized materials in order to detect and determine them4 ,the proper methods of accomplishing this have already been pointed out for vegetable soils1 and the same processes are applicable in the case of extracted and precipitated humus4 ,another proof that both phosphorus and sulfur are present in humus in an organic state is found in the fact pointed out by ,eggertz and ,nilson1 that the ash of muck soils is always richer in sulfuric and phosphoric acids than the solution obtained therefrom by hydrochloric acid4#cdh ,in a sample of muck examined by them there was found in the ash #a4df per cent ,,so1 and in the acid extract only #j4je per cent ,,so2 and in the ash #j4c per cent ,p,o1 while in the extract only #j4jd per cent ,p,o4 #ebi4 ,combustion of the ,humus4--,the percentage composition of the extracted humus can be determined1 after drying to constant weight1 by combustion with copper oxid4 ,there is little use in trying to assign definite chemical formulas to any of the components of the complex which we call humus4 ,some of the supposed formulas have been given on pages #fa and #fb4 #ecj4 ,ether ,extract4--,most peaty soils1 when very dry1 are not easily moistened with water4 ,this is due to a superficial coating of fatty or resinous bodies which prevents the water from reaching the muck particles4 ,in such cases water will pass between the particles and percolate to a considerable depth1 but without wetting4 ,this oily matter can be removed by treating the dry material with ether in any approved extraction apparatus4 ,for the separation of the more purely fatty bodies1 light petroleum may be used1 while the total of such matters is extractable with sulfuric ether4 ,the extracted bodies should be examined to determine their nature1 whether fatty1 resinous1 or of other materials soluble in ether4 ,the quantity of this material in some muck soils is remarkably high4 ,in a ,florida muck1 examined in this laboratory1 #ah4ie per cent in the air-dried substance1 which contained still #da4hc per cent of water1 or about #cb4e per cent of the water-free material were found to be soluble in ether4 ,the color of the ether extract may be almost black1 showing the extraction of a part of the humus or coloring matter in the muck4 ,this extractive coloring matter may also be a partial oxidation product of the original chlorophyl of the plant4 #eca4 ,further ,examination of the ,ether ,extract4--,the ether extract should be first treated with petroleum ether1 unless this substance be used first in extraction4 ,afterwards1 it is to be exhausted with strong alcohol1 and the quantities of material soluble in the three reagents separately determined4 ,the nitrogen is further to be determined in the several extracts1 and1 for control1 in the residue of the muck4 ,the method of procedure practiced in this laboratory is to first extract the sample with petroleum ether1 which will yield any free fat acids1 fats1 or oils1 waxes1 and possibly some resinous matter4 ,a weighed portion of the sample1 about two grams1 is extracted quantitively by one of the methods which will be described in the second volume of this manual4 ,from two to five kilograms of the sample are then extracted in bulk for the purpose of securing a sufficient quantity of the material to use for further analysis4#cdi ,in each case the petroleum is followed by pure ether1 and in this way the chlorophyl1 resins1 etc41 are obtained4 ,this extract is examined also for its several proximate constituents4#cej ,the treatment with ether is followed by extraction with absolute alcohol for the removal of tannins and other glucosides1 resins insoluble in ether1 etc41 and the extract subjected to the usual examination4#cea ,instead of absolute alcohol a spirit of ninety-five per cent strength1 or even of eighty per cent1 may be used4 ,the final residue should be subjected to the usual determination for nitrogen1 volatile matter1 ash1 etc41 in the manner already described4 ,the large amount of resinous and other matters soluble in petroleum and ether1 which is found in the ,florida muck soils1 is probably due to the proximity of pine forests1 the dbris of which1 sooner or later1 find their way to these littoral deposits4 ,considerable portions of organic humic acids and even humus itself1 may also be removed by ether and alcohol and in every case nitrogen should be determined in these extracts4 ,,rare ,,constituents ,,of ,,soils4 #ecb4 ,estimation of ,copper4--,the natural occurrence of copper in many vegetables has acquired additional significance by reason of its relation to added copper in canned peas and other preserves4 ,formerly1 copper was not regarded1 in any sense1 as a plant food4 ,even now it can scarcely be considered as more than an accidental and non-essential constituent of vegetable matter4 ,it is by no means certain1 however1 that copper may not be1 in some sense1 in organic combination1 as phosphorus and sulfur often are4 ,it is said1 also1 to be found in certain animal organisms1 notably in the oyster4 ,in the estimation of copper in soils1 there is first made a hydrochloric acid solution of the sample4 ,the solution is treated with well-washed hydrogen sulfid until well saturated4 ,the precipitate is collected at once on a gooch1 and washed with water containing the precipitating reagent4 ,the filtrate is dried1 gently ignited or roasted1 and dissolved in aqua regia4 ,after evaporating to dryness on a steam-bath1 water and hydrochloric acid are added1 and the copper reprecipitated in the manner described above4 ,if zinc be present in the sample the solution should be made very strongly acid with hydrochloric before the treatment with hydrogen sulfid1 otherwise some zinc may be carried down with the copper4#ceb ,if lead be present it is also precipitated with the copper and can be separated as described below4 ,in the filtrate from the solution in nitric acid after the second precipitation the copper is precipitated as hydroxid by potash1 collected in a porcelain gooch1 dried1 ignited1 and weighed as ,cu,o4 ,or the copper may be secured as sulfate and estimated electrolytically in the manner described in volume second for the gravimetric estimation of sugar4 #ecc4 ,estimation of ,lead4--,if the soil contain lead this metal will be thrown down with the copper as sulfid in the manner described above4 ,in this case the mixed sulfids are dissolved in nitric acid1 diluted with water1 filtered1 and washed4 ,the filtrate is treated with sulfuric acid in considerable excess1 and evaporated until all the nitric acid has passed off and the sulfuric acid begins to escape4 ,after cooling1 water is added and the lead sulfate collected on a porcelain gooch and washed with water containing sulfuric acid4 ,finally it is washed with alcohol1 dried1 ignited1 and the lead weighed as ,pb,s,o4 #ecd4 ,estimation of ,zinc4--,if zinc be present in the hydrochloric acid extract of a soil it may be estimated as carbonate after freeing it carefully of iron4 ,the principal part of the iron should first be separated in the usual way by sodium acetate4 ,in the warm solution 7acid with acetic7 the zinc is precipitated by hydrogen sulfid in excess4 ,the beaker in which the precipitation takes place should be left covered in a warm place at least twelve hours4 ,after collecting the zinc sulfid on a filter it is washed with water saturated with hydrogen sulfid4 ,in order to free the zinc from every trace of iron it is better to dissolve the precipitate in hot dilute hydrochloric acid and reprecipitate as above1 and1 after boiling with some potassium chlorate1 saturate it with ammonia4 ,any remaining trace of iron is precipitated as ferric hydroxid while the zinc remains in solution4 ,the ferric hydroxid is separated by filtration and the filtrate1 after acidifying with acetic1 is treated with hydrogen sulfid as above4 ,the zinc sulfid is dissolved again in hot hydrochloric acid1 oxidized with potassium chlorate1 the acid almost neutralized with soda and the zinc precipitated as carbonate with the sodium salt4 ,after precipitation1 the contents of the beaker are boiled until all free carbon dioxid is expelled1 the carbonate collected on a filter1 washed with hot water1 dried1 ignited1 and weighed as ,zn,o4 #ece4 ,estimation of ,boron4--,boron has been found in the ashes of many plants and agricultural products4 ,whether or not it be an essential or only accidental constituent of plants has not been determined4 ,its occurrence in the soil1 nevertheless1 is a matter which the agricultural chemist can not overlook4 ,the boron should be dissolved from the soil by gently heating with dilute nitric acid followed by washing with hot water4 ,boiling should be avoided on account of the volatility of boric acid4 ,in the solution thus obtained1 concentrated on a bath at a moderate temperature to a convenient volume1 the boron is to be estimated by the method given in paragraphs #eah and #eai4 ,,authorities ,,cited ,,in ,,part ,,eighth4 ,footnote #cdc3 ,bulletin #ac1 ,chemical ,division1 ,department of ,agriculture1 p4 #ajba4 ,footnote #cdd3 ,sanitary and ,technical ,examination of ,water1 p4 #fj4 ,footnote #cde3 ,bulletin de la ,socit ,chimique1 #c1 ,tomes #aa-ab1 p4 #iee4 ,footnote #cdf3 ,anleitung zur ,wissenschaftlichen ,bodenuntersuchung1 ,s4 #abf4 ,footnote #cdg3 ,mitteilungen ber die ,arbeiten der ,moor ,versuchs-,station in ,bremen2 dritter ,bericht1 ,s4 #edj4 ,footnote #cdh3 ,biedermann's ,centralblatt1 #ahhi1 ,s4 #ffd4 ,footnote #cdi3 ,dragendorff's ,plant ,analysis1 translation by ,greenish1 pp4 #h1 et seq4 ,footnote #cej3 ,vid4 op4 cit4 supra1 pp4 #ca1 et seq4 ,footnote #cea3 ,vid4 op4 cit4 #g1 pp4 #ch1 et seq4 ,footnote #ceb3 ,journal fr praktische ,chemie1 ,band #gc1 ,s4 #bda4 ,,note4--,on page #eeg1 paragraph #ejj1 ninth line1 read 8red-yellow0 instead of 8blue40 ,,index4 ,a ,absorption1 cause in soils1 #aai determination1 #bhg of heat1 by soils1 #aae water1 by soils1 determination1 #acf-adc ,acetic acid1 solvent for soils1 #cdd ,acid phenyl sulfate1 reagent for nitric acid1 #eed1 #eee soluble materials1 extraction1 #dee ,adobe1 analyses1 #eh soils1 #eg ,aeolian rocks1 #ch ,air1 absorption1 #bhf action1 #ea ,albuminoid ammonia1 estimation1 #egb ,alkali salts1 composition1 #ef ,alkalies and alkaline earths1 estimation1 #chd ,alkaline soils1 #ec-ee ,alumina1 estimation1 #ced1 #ceg1 #cfb ,aluminum1 #ag -mercury couple for nitric acid1 #edb microchemical examination1 #bff ,ammonia1 determination of free and albuminoid1 #egj-egc estimation1 #ddh-deb formation in soils1 #dbi magnesia distillation process1 #dej nitrification1 #dff production1 by microbes1 #dfd ,ammonium chlorid1 solvent for soils1 #cdc ,apocrenic acid1 #fb ,apparatus for soil sampling1 #hb-hf ,aqueous rocks1 #cb-ch vapor absorption1 #bhc1 #bhd ,armsby1 soil absorption1 #aba ,assimilable phosphoric acid1 method of ,dyer1 #daj ,atomic masses1 table1 #c ,atwater1 fish nitrogen1 #ad ,authorities cited in ,part ,eighth1 #eic ,fifth1 #cjj ,first1 #fc1 #fd ,fourth1 #bgi-bha ,second1 #ic1 #id ,seventh1 #egc-ege ,sixth1 #def-deh ,third1 #afi1 #agj ,b ,bacteria1 action1 #ej ,barium1 #bc microchemical examination1 #bfe ,barus1 theory of flocculation1 #agg-ahj ,beaker elutriation1 comparison with ,hilgard's method1 #bci method1 comparison with ,schloesing's1 #bda ,belgian methods for soil extracts1 #cfa-cfc ,bennigsen1 method of silt analysis1 #aid ,berlin-,schne method1 #aid ,bernard1 calcimeter1 #cci ,berthelot and ,andr1 determination of residual water1 #cjh method of water determination1 #cje nature of nitrogen in soils1 #dcj-dcd odoriferous matters in soils1 #ig phosphoric acid in soils1 #daa ,bigelow1 solubility of digestion vessels1 #cdh ,boric acid1 #ehj1 #eha ,boron1 #ag estimation1 #eic ,boussingault and ,lewey1 method of determining absorption1 #bij method for nitric acid1 #ebd-ebf ,braun's separating liquid1 #bga ,bron's method1 #bgb ,brewer1 chemical action1 #agg ,brgger's apparatus1 #bgf ,brucin1 reagent for nitric acid1 #eeg ,bulk analysis1 #cfe-cfg ,c ,calcium1 #ah microchemical examination1 #bfd ,caldwell1 preliminary treatment of soil samples1 #hh ,capillary attraction1 determination1 #ade movement of water1 #aec ,carbazol1 reagent for nitric acid1 #edh ,carbon1 #e comparison of methods for estimating1 #cba dioxid1 diffusion in soils1 #big estimation in water1 #egi in soils1 apparatus for estimating1 #bic occurrence in soils1 #bhi solvent for soils1 #cdc estimation of organic1 #cae oxidation with chromic acid1 #caf permanganate1 #cah ,carbonates1 ,belgian method1 #cdb deficiency in soils1 #cdj estimation1 #ccg ,carnot1 method for manganese1 #cig phosphoric acid1 #djc ,chabrier1 method for nitrous acid1 #efe ,chemical analysis of soils1 #cja-ege order of examination1 #cjb preliminary considerations1 #cja elements in soils1 #b ,chevreul1 ammonium phosphate in guanos1 #g ,chile1 nitrate deposits1 #ae1 #af ,chlorin1 #f estimation1 #dbb in water1 #egg ,mohr's method1 #dbd ,petermann's method1 #dbd ,wolff's method1 #dbc ,citric acid1 solvent for soils1 #cdd ,clarke1 relative abundance of elements1 #bc ,classification of soils1 #eb ,clay1 chemical nature1 #bcb colloidal1 #bca mechanical determination1 #bdb properties1 #bbc separation1 #bcj suspension1 #agf ,clayey soils1 effect of boiling on texture1 #bdd-bdf elutriation1 #bci ,cleavage of soil particles1 #bfb ,coefficient of evaporation1 determination1 #add-adf ,cohesion and adhesion of soils1 #aaf1 #aag ,colloidal clay1 estimation1 #bca ,color of rocks1 #ca soil1 determination1 #ig ,colorimetric comparison1 delicacy1 #edh1 #eei ,compact soils1 #ij ,conductivity of soils1 #aae ,copper1 estimation1 #eia -zinc couple for nitric acid1 #edj1 #edb ,crenic acid1 #fa ,crum-,frankland process1 #eah ,crystal angles1 measurement1 #bei ,culture media1 composition1 #dfh1 #dgc1 #dgd1 #dgf1 #dgi1 #dha1 #dhc1 #dhd1 #dhf solid1 #dgi1 #dha ,d ,darton1 ,florida phosphates1 #i ,davidson1 origin of ,florida phosphates1 #g ,decay of rocks1 #dc-eb ,deherain1 measurement of percolation1 #afg-afi ,desiccator1 drying1 #cji ,devarda's method for nitric acid1 #ecd variation of ,stoklassa1 #ece ,diffusion of gases1 general conclusions1 #bii ,dietrich's elutriator1 #bji ,digestion of soil1 #def vessels1 #cdg ,dilution method1 experiments1 #dhc1 #dhe ,diphenylimid1 reagent for nitric acid1 #edi ,diphenylamin1 reagent for nitric acid1 #eec ,distillation1 prevention of bumping1 #dda ,dobeneck1 method of determining absorption1 #bhg-bij ,drainage1 influence on porosity1 #acb ,durham1 clay suspension1 #agf ,dyer1 citric acid solution1 #cdd ,dyer1 method for assimilable phosphoric acid1 #daj ,e ,earth worms1 action1 #di ,eldridge1 ,florida phosphates1 #aj ,elements1 different1 simultaneous estimation1 #dbe relative abundance1 #bc ,elutriating tube1 #bcf ,eruptive rocks1 #da1 #db ,estimation of gases in soils1 #bhb-bii ,f ,ferric oxid1 estimation1 #cec1 #cef1 #ceg1 #cfb1 #cii1 #dja ,fine soil1 capacity for holding water1 #ace ,fish as fertilizer1 #ad ,flocculation1 #aga effect of chemical action1 #agg theory1 #agg ,floccules1 destruction1 #age ,florida phosphates1 origin1 #g-ab ,fluorin1 #ag-bd ,forchhammer1 agricultural value of fucoids1 #ac ,frear1 method of determining soil temperatures1 #aaa ,freezing and thawing1 #dd ,fuchs and ,de ,launy1 origin of potash deposits1 #ba ,fuelling1 determination of water absorption1 #aci ,g ,gases1 collection1 #bia methods of study1 #bhc passage through the soil1 #adi1 #aej determination1 #aej relation to soil composition1 #bhb ,gasparin1 method of silt analysis1 #aie ,gautier1 occurrence of oldest phosphates1 #g ,gelatin1 culture1 #dga-dgc mineral1 #dgc1 #dgd ,gembloux station1 method of soil solution1 #cej ,german experiment stations1 method of soil solution1 #cdi ,glaciers1 action1 #de ,glucinic acid1 #fb ,goessmann1 analysis of sea-weeds1 #ac ,gooch and ,gruener1 method for nitric acid1 #edf estimation of boric acid1 #ehj ,goss1 method for phosphoric acid1 #daf-dah ,grandeau1 method of estimating humus1 #cbd ,h ,hands1 sterilization1 #dhi ,hannn1 diffusion of carbon dioxid in soils1 #big ,harada's apparatus1 #bge ,heinrich1 determination of passage of gases through soils1 #aej water absorption1 #adc method of determining cohesion1 #aaf1 #aag ,henrici1 determination of water capacity of soils1 #adc ,hilgard1 alkaline soils1 #ee digestion vessels1 #cdg humus estimation1 #cbd hygroscopic coefficient1 #bhd influence of surface tension1 #agd method for soil solution1 #cdh of silt analysis1 #bbe methods of analysis of soil extract1 #cef-cfa preliminary examination of soils1 #hg ,hilgard's elutriator1 #bbf method1 comparison with ,osborne's1 #bci ,hooker's method for nitric acid1 #edh ,humic acid1 #fa1 #fb estimation1 #cca ,humus1 #fj combustion1 #ehi estimation1 #cbd ,german method1 #ccc method of ,pasturel1 #ccf ,raulin1 #ccd ,van ,bemmeln1 #ccb summary of results1 #ccj mineral contents1 #ehi ,huston and ,mc,bride1 humus estimation1 #cbf method of determining soil absorption1 #abh ,hydrochloric acid1 solvent for soils1 #cdd strength1 #cde time of digestion1 #cde treatment of soil with cold1 #cej ,hydrofluoric acid1 solvent for soils1 #ceb ,hydrogen1 #e estimation of organic1 #cbc ,hygroscopic coefficient1 determination1 #bhd ,i ,ignition1 loss1 #cjg ,ilosvay1 nessler reagent1 #egc ,indiana1 lysimeter of agricultural experiment station1 #afe ,indigo method for nitric acid1 #ebd-eca ,insoluble residue1 analysis1 #cfc ,belgian method1 #cfd ,wolff's method1 #cfc ,interstitial space1 determination1 #acd ,inverse capillarity1 #adf ,iron1 #bb and alumina1 separation from phosphoric acid1 #dad ,french method1 #cii1 #djj method of ,sachsse and ,becker1 #dja-djc microchemical examination1 #bff ,j ,jenkins1 analysis of sea-weeds1 #ac ,johnson1 method for nitric acid1 #eef ,k ,kaolin1 estimation1 #dbf-dbh ,kedzie1 digestion vessels1 #cdg influence of drainage1 #acb ,king1 apparatus for soil sampling1 #hb capillary movement of water1 #aec methods of water movement1 #aea ,knop1 method of determining soil absorption1 #abh ,knop's silt cylinder1 #ahi ,knorr1 apparatus for carbon dioxid1 #ccg ,kostytchoff1 origin of humus1 #fj ,khn's silt cylinder1 #ahi ,l ,lateral capillary flow1 #aec ,latitude1 effect on decay of rocks1 #df ,lead1 estimation1 #eib ,lime1 assimilable1 #cib estimation1 #ced1 #ceg1 #cfb1 #cfe1 #chd1 #chf1 #chh-cid of active1 #chi available1 #cij ,french method1 #chf1 #chh method of ,halle station1 #cic1 #cid ,russian method1 #cia ,lithium1 microchemical examination1 #bfd ,logarithmic constants1 #bed ,loges1 humus estimation1 #ccc ,loose soils1 #hi ,loughridge1 time of digestion1 #cde1 #cdf ,lunge and ,lwoff1 method for nitrous acid1 #efc ,lunge's nitrometer1 #eai improved1 #ebj-ebd ,lysimetry1 #aeh1 #afe ,mc ,mc,gowan's method for nitric acid1 #edc ,m ,magnesia1 estimation1 #ced1 #cfj1 #cfb1 #cfe1 #chd1 #cid1 #cif method of ,halle station1 #cif ,magnesium1 #ah microchemical examination1 #bfd ,magnet1 separation of silt particles1 #bgh ,manganese1 #bc estimation1 #ced1 #cfj1 #cif1 #cig ,french method1 #cig-cii ,marx1 method for nitric acid1 #ebf-ebh ,masure's silt apparatus1 #baj ,matire noire1 #cbd ,mayer1 determination of water absorption1 #ach ,mayer's modification of ,schne's method1 #bbj ,mechanical analysis of soils1 #aga-agi ,mercury and sulfuric acid method1 ,noyes' modification1 #eai ,warington's modification1 #eah ,metamorphic rocks1 #ci ,metaphenylenediamin1 reagent for nitrous acid1 #eeg1 #eei ,microchemical examination of silt1 #bfb1 #bff ,microscopic apparatus1 #die examination of silt separates1 #bef ,microscopical structure of rocks1 #bh1 #bi ,mineralogical examination of silt separates1 #bed-bgh ,minerals1 classification1 #bf in rocks1 #bd-bf machine for making sections1 #bfg ,mckern1 reduction method1 for nitric acid1 #ecc ,moissan1 estimation of boric acid1 #eha ,moisture1 effect on soil temperature1 #ajb estimation1 #ded ,moore1 modification of silt analysis1 #aib ,muck soils1 alcohol extract1 #eij estimation of humus1 #ehi phosphoric acid1 #ehh sulfur1 #ehg ether extract1 #eij organic carbon and hydrogen1 #ehf petroleum ether extract1 #eij phosphoric acid1 #dae sampling1 #ehd special treatment1 #ehc total volatile and organic matter1 #ehf water content1 #ehe ,mulder1 humic acid1 #fb ,mller1 method of determining soil absorption1 #abf ,mntz and ,marcano1 origin of nitrate deposits1 #ad ,n ,naphthylamin1 reagent for nitrous acid1 #efj ,nessler's process1 #egj reagent1 #egj ,nitrate deposits1 #ad-af ,nitrates1 estimation1 #dce ,nitric acid1 classification of reduction methods1 #eca1 #ecb development in soils1 #dfa estimation by colorimetric comparison1 #edh-eei oxidation of a colored solution1 #ebd-eca reduction to ammonia1 #eca-edc classification of methods1 #dif-dih in presence of nitrous acid1 #eeg extraction from soil1 #dih-ejj ferrous salt process1 #ejj-eah iodometric estimation1 #edc-edh mercury and sulfuric acid method1 #eah methods1 relative merit1 #dih nitric oxid process1 #ejj-ebd reduction by electric current1 #edj-edc solvent for soils1 #cea ferment1 isolation1 #dga1 #dgg1 #dha ,nitrification1 apparatus and manipulation1 #dfh effect of potassium salts1 #dfc general conclusions1 #dif necessary conditions1 #dfa-dfc preparation of seed1 #dfh progress1 #dfi statement of results1 #dgh test of commencement1 #dfi ,nitrifying organisms1 classification1 #dhg distribution1 #dgj1 #dga microscopic examination1 #dhj1 #dhd occurrence1 #dfg ,nitrites1 destruction1 #dgh1 #eeh ,nitrogen1 #ab active soil1 #dcd ,arnold and ,wedemeyer's method1 #ddj ,dumas' volumetric method1 #ddf-ddh economic value1 #cie estimation in soils1 #dbh-def of amid1 #dea volatile compounds1 #deb-ded ,hilgard's method1 #dcf ,methods of ,official ,agricultural ,chemists1 #dcd ,mller's method #dch-ddj soda-lime method1 #dde nature in soils1 #dcj-dcd order of oxidation1 #dfe organic1 in soils1 #dei-dfa oxidized1 estimation in soils1 #dei-egj soda-lime method1 #dda-ddd in presence of nitrates1 #ddd ,nitrous acid1 development in soils1 #dfa estimation1 by coloration of a ferrous salt1 #efg colorimetric comparison1 #eei potassium ferrocyanid1 #efg classification of methods1 #dif-dih iodometric method1 #efd-efg ferment1 isolation1 #dga1 #dgg ,nbel's apparatus1 #bjg ,nllner1 nitrate deposits1 #af ,norwacki and ,borchardt1 auger for soil sampling1 #hc ,o ,odoriferous matters1 determination1 #ih in soils1 #ig ,official ,agricultural ,chemists1 latest methods1 #ded-def method for reduction of nitric acid1 #ecb1 #ecc of analysis of soil extract1 #cec-cef soil solution1 #cdi ,organic matter1 estimation1 #cad influence on absorption1 #abd total1 #cae ,origin of soils1 #dc ,orth1 classification1 #ahe ,osborne1 ,berlin-,schne method1 #bbd method1 comparison with ,schloesing's1 #bda of silt analysis1 #aif -,schne method1 #bai comparisons1 #bbc ,oxygen1 #c absorption1 #bhf estimation of organic1 #cbd ,p ,packard1 separation of silt particles1 #bgc ,pasturel1 estimation of humus1 #ccf ,peligot1 preliminary treatment of samples1 #ia ,percolation1 measurement1 #afa soils in situ1 #afd ,petermann1 determination of water absorption1 #ach method for phosphoric acid1 #dji preliminary treatment of samples1 #ib ,petrographic examination of silt particles1 #bff microscope1 #bef ,pfaundler1 specific heat method1 #ajd-aaj ,phenylsulfuric acid1 reagent for nitric acid1 #eed ,phosphoric acid1 ,carnot's method1 #djc estimation1 #ced1 #cfb1 #djc-djf1 #dji-daf ,french method1 #djf-dji ,halle method1 #djd1 #dje in muck soils1 #dae method of ,goss1 #daf-dah ,hilgard1 #dac ,petermann's method1 #dji ,russian method1 #dab separation from iron and alumina1 #dad ,phosphorus1 #f microchemical examination1 #bff state of existence in soils1 #daa ,piccini method for nitric acid1 #eeh nitrous acid1 #efg ,pillitz and ,zalomanoff1 method of determining soil absorption1 #abe ,pissis1 nitrate deposits1 #af ,polarized light1 examination1 #bfa ,porosity1 #aca determination1 #acc ,potash1 condition in soils1 #cfg estimation1 #cee1 #ceh1 #cfa1 #cfe1 #cfh1 #cgj-cgb1 #cge-cgh1 #cha1 #chb international method1 #cha ,italian method1 #cgg method of ,german experiment stations1 #cge ,tatlock and ,dyer1 #chb ,russian method1 #cgf salts1 deposits1 #bj ,smith's method1 #cgh-cha soluble in cold dilute acid1 #cgj concentrated acids1 #cfh ,potassium1 #ah microchemical examination1 #bfc ,pratt1 bowlder phosphates1 #i ,q ,qualities of soils1 #eb1 #ec ,r ,rain water1 method of collecting1 #efi preparation for analysis1 #efi ,raulin1 method of estimating humus1 #ccd potash1 #cge ,reaction of a soil1 #cjc ,refractive index1 determination1 #bei ,rideal1 method for nitric acid1 #eec ,rocks1 aeolian1 #ch aqueous1 #cb chemical composition1 #cj color1 #ca composition1 #dc decay1 #dc-eb eruptive1 #da-db kinds1 #cb metamorphic1 #ci microscopical structure1 #bh minerals1 #bd-bf sedimentary1 #ce types1 #bh ,rohrbach's solution1 #bga ,rowland1 fall of particles in liquid1 #ahj ,s ,sachsse and ,becker1 method for iron1 #dja-djc ,salts1 preparation for absorption1 #acj ,samples for moisture1 #gd permeability1 #gd staple crops1 #ge preparation1 #ded for elutriation1 #bbi ,sampling1 general directions1 #ff method of ,caldwell1 #ga ,german experiment stations1 #fi ,grandeau1 #gg ,hilgard1 #fg ,lawes1 #hj ,official ,agricultural ,chemists1 #gi ,french ,commission1 #fi1 #hj ,peligot1 #gb ,richards1 #fi ,royal ,agricultural ,society1 #gf ,wahnschaffe1 #gb1 #ha ,whitney1 #fh1 #gc ,wolff1 #ha ,sandstone1 #ce ,schaeffer and ,deventer1 method for nitrous acid1 #efg ,schloesing method1 comparison with ,beaker1 #bda ,de,konick's modification1 #ead-eaf for nitric acid1 #ejj ,french modification1 #ejj-eje of collecting soil gases1 #bia silt analysis1 #bjj ,schmidt's process1 #eaf ,schulze-,tiemann modification1 #eaj-ead ,spiegel's modification1 #eji ,warington's modification1 #eje-ejh ,schmidt's method for nitric acid1 #eci ,schne's elutriator1 #bab ,schulze-,tiemann method1 #eaj-ead ,sea-weeds1 analysis1 #ac ,sedimentary rocks1 classification1 #ce ,sediments1 separation of fine1 #bcc weighing1 #bce ,seeding1 method employed1 #dge ,selective absorption of soils1 #abb ,separation of silt particles1 #bgb ,shaler1 phosphatic limestones1 #ab ,sieve analysis1 classification1 #ahe ,german experiment stations1 #ahc separation1 #ahb ,sievert's method for nitric acid1 #ecf ,sifting with water1 #ahc ,silica1 #d direct estimation1 #dbd estimation1 #cef1 #cfa1 #cfe ,silt analyses1 value1 #bgi analysis1 ,belgian method1 #bjd classification of results1 #bce1 #bcf interpretation1 #bea ,italian method1 #aie1 #bjf method of ,hilgard1 #bbe ,osborne1 #aif ,schne1 #bab-bbj methods1 #ahe ,moore's modification1 #aib ,schloesing's method1 #bjj statement of results1 #aid subsidence of soil particles1 #ahf-ahh ,wolff's method1 #aib classes1 illustrations1 #beh particles1 color and transparency1 #bgh examination1 with polarized light1 #bfa forms and dimensions1 #beg microchemical examination1 #bfb-bff petrographic examination1 #bff separation by specific gravity1 #bfh-bgg staining1 #bfa percentage in soils1 #bdi separates1 microscopic examination1 #bef ,mineralogical examination1 #bed-bgh ,siphon silt cylinder1 #aij ,soda1 estimation1 #cee1 #ceh1 #cfa1 #cfe1 #cgd1 #chd ,sodium1 #bb amalgam process1 #ecg-eci microchemical examination1 #bfc ,soil absorption1 importance1 #abd method of determining1 #abe analyses1 special methods1 #cfg-dbh definition1 #a extracts1 method of preparing1 #aeh gases1 #adi1 #aej heat1 sources1 #ajb ingredients1 distribution1 #bdg moisture1 #acb particles1 number1 #bea-bec standard sizes1 #aha surface area1 #bec samples1 air drying1 #hh preliminary examination1 #hg-ic treatment in laboratory1 #hg sampling1 general principles1 #fe solutions1 analyses1 #ceb-cfg temperatures1 method of determining1 #aaa thermometry1 #aaa-aaf ,soils1 absorptive power1 #aag-aca and subsoils1 #fb1 #fc as a mass1 #ie carbon dioxid1 #bic chemical elements1 #b classification2 according to deposition1 #eb cohesion and adhesion1 #aaf1 #aag color1 #ie compact1 #ij composition1 relation to gases1 #bhb conductivity for heat1 #aae deficient in carbonates1 #cdj digestion with solvents1 #cdc-ceb estimation of carbonates1 #ccg loose1 #hi mechanical analysis1 #aga-agi method of estimating absorption of heat1 #aae nitrifying power1 #dfg origin1 #a1 #dc preliminary treatment1 #hg-ic qualities1 #eb-ec reaction1 #cjc selective absorption1 #abb specific gravity1 #ih determination1 #ii unusual constituents1 #eia-eic volume1 #ajj weight of one hectare1 #ajb ,solar heat1 absorption1 #ajc ,specific gravity1 #cj of soils1 #ih-aaj apparent1 #aja determination of apparent1 #aja heat of soils1 #ajb determination1 #ajd-aaj variations1 #aaj ,spencer1 photomicrographs1 #bei ,squanto1 manurial value of fish1 #ad ,staining organisms1 method1 #dhg silt particles1 #bfa ,stassfurt potash salts1 #bj ,sterilization1 #dhi by heat1 #dij high pressure steam1 #dib ,sterilized soil1 nitrification1 #dhg1 #dhh ,sterilizing apparatus1 #dij1 #dic oven1 #dia ,stockbridge1 composition of humus1 #fa soil moisture1 #acb ,strontium1 microchemical examination1 #bfe ,stutzer's method for nitric acid1 #ecg ,subcultures1 method1 #dgi ,subsidence1 physical explanation1 #ahj ,sulfanilic acid1 preparation1 #efb reagent for nitrous acid1 #efj ,sulfur1 #ea state of existence in soils1 #dai ,sulfuric acid1 estimation1 #cee1 #ceh1 #cfa ,french method1 #dai ,italian method1 #dbb method of ,berthelot and ,andr1 #dai ,von ,bemmeln1 #dbj-dbb ,wolff1 #dbb ,surface area1 influence on absorption1 #abc particles1 effect of potential1 #agb tension1 influence1 #agd method of estimating1 #aeg of fertilizers1 #aef ,t ,thenard1 humic acid1 #fb ,thermometry1 general principles of soil1 #aaa ,thermostats1 #did ,thoulet's solution1 #bfh ,u ,ulmic acid1 #fa ,ulsch's method for nitric acid1 #eci ,v ,von ,bemmeln1 determination of water1 #caj method of humus estimation1 #ccb ,vegetable life1 action1 #dh soils1 #eh-fj ,volatile matter1 estimation1 #dee ,w ,wahnschaffe1 preliminary treatment of samples1 #ia ,warington1 absorption of potash and ammonia1 #abj and ,peake1 oxidation of carbon1 #caf experiments in nitrification1 #dfh-dgj1 #dhe-dhh indigo method1 #ebh-eca ,schloesing method1 #eje-ejh ,water absorption by soils1 determination1 #acf-adc capacity of soils1 effect of pressure1 #adc determination at #aaj1 #cjf general conclusions1 #cac estimation after air drying1 #cje in water-free atmosphere1 #adi in fresh samples1 #cjd soils1 determination1 #cjc-cad movement1 causes1 #aee in soils1 #aea-afi methods1 #aea relative flow1 #aei residual amount1 dried at #aaj1 #cjh solvent1 action1 #dg for soils1 #cdc special examination1 #egf-ehc total solid matter1 #egf ,way1 absorptive power of soils1 #aah1 #abj ,weight of soil1 #ajb ,welitschowsky1 measurement of percolation1 #afa-afc ,wheeler and ,hartwell1 analysis of sea-weeds1 #ac ,whitney and ,marvin1 method of determining soil temperatures1 #aab-aae causes of water movement1 #aee determination of interstitial space1 #acd effect of potential1 #agb influence of surface area on absorption1 #abc measurement of percolation1 #afc relative flow of water1 #aei surface tension of fertilizers1 #aef theory of subsidence1 #ahj ,williams1 machine for mineral sections1 #bfg -,warington method for nitric acid1 #edj1 #eda ,winogradsky1 experiments in nitrification1 #dga-dhc ,wolff and ,wahnschaffe1 method of determination of water absorption1 #acf determination of coefficient of evaporation1 #adh method for silt analysis1 #aib preliminary treatment of soil samples1 #hh ,wollny1 determination of water absorption1 #adb occurrence of carbon dioxid1 #bhb ,wlfing's apparatus1 #bgg ,wyatt1 phosphate deposits1 #h ,x ,xylic acid1 #fb ,z ,zinc1 estimation1 #eib ---------------------------------------- -------------------------------- ,,transcriber',s ,,notes #a4 ,silently corrected palpable typographical errors2 retained non-standard spellings and dialect4 #b4 ,corrected the items listed on p4 viii4 #c4 ,reindexed chapter footnotes using numbers and table footnotes using letters4 #d4 ,enclosed italics font in underscores4 #e4 ,enclosed bold or blackletter font in equals4 #f4 ,denoted superscripts by a caret before a single superscript character or a series of superscripted characters enclosed in curly braces1 e4g4 ,mr4 or ,mister4 #g4 ,denoted subscripts by an underscore before a series of subscripted characters enclosed in curly braces1 e4g4 ,h,o4