,ver4#jg_/bg_/ja99;,,end99 ,this etext was produced by ,john ,mamoun mamounjoumdnj4edu with the ,online ,distributed ,proofreading ,team of ,charles ,franks4 ,an ,introduction to ,chemical ,science by ,r4,p4 ,williams1 ,a4,m41 ,,contents ,,preface1 ,,by ,r4,p4 ,,williams ,,table ,,of ,,contents ,,an ,,introduction ,,to ,,chemical ,,science ,,appendix ,,textbook ,,advertisements ,,that ,,appeared ,,in ,,the ,,original ,,edition ,,info ,,about ,,this ,e-,,text ,,edition ,,preface1 ,,by ,r4,p4 ,,williams ,the object held constantly in view in writing this book has been to prepare a suitable text-book in ,chemistry for the average ,high ,school1--one that shall be simple1 practical1 experimental1 and inductive1 rather than a cyclopaedia of chemical information4 ,for the accomplishment of this purpose the author has endeavored to omit superfluous matter1 and give only the most useful and interesting experiments1 facts and theories4 ,in calling attention1 by questions1 and otherwise1 to the more important phenomena to be observed and facts to be learned1 the best features of the inductive system have been utilized4 ,especially is the writing of equations1 which constitute the multum in parvo of chemical knowledge1 insisted upon4 ,as soon as the pupil has become imbued with the spirit and meaning of chemical equations1 he need have little fear of failing to understand the rest4 ,to this end ,chapters ,,ix41 ,,xi41 and ,,xvi4 should be studied with great care4 ,in the early stages of the work the equations may with advantage be memorized1 but this can soon be discontinued4 ,whenever symbols are employed1 pupils should be required to give the corresponding chemical names1 or1 better1 both names and symbols4 ,the classification of chemical substances into acids1 bases and salts1 and the distinctions and analogies between each of these classes1 have been brought into especial prominence4 ,the general relationship between the three classes1 and the general principles prevailing in the preparation of each1 must be fully understood before aught but the merest smattering of chemical science can be known4 ,chapters ,,xv4-,,xxi4 should be mastered as a key to the subsequent parts of the book4 ,the mathematical and theoretical parts of ,chemistry it has been thought best to intersperse throughout the book1 placing each where it seemed to be especially needed2 in this way1 it is hoped that the tedium which pupils find in studying consecutively many chapters of theories will be avoided1 and that the arrangement will give an occasional change from the discussion of facts and experiments to that of principles4 ,in these chapters additional questions should be given1 and the pupil should be particularly encouraged to make new problems of his own1 and to solve theta4 ,it is needless to say that this treatise is primarily designed to be used in connection with a laboratory4 ,like all other text- books on the subject1 it can be studied without such an accessory2 but the author attaches very little value to the study of ,chemistry without experimental work4 ,the required apparatus and chemicals involve but little expense1 and the directions for experimentation are the result of several years' experience with classes as large as are to be found in the laboratory of any school or college in the country4 ,during the present year the author personally supervises the work of more than #ahj different pupils in chemistry4 ,this enables him not only to assure himself that the experiments of the book are practical1 but that the directions for performing them are ample4 ,it is found advisable to perform most of the experiments1 with full explanation1 in presence of the class1 before requiring the pupils either to do the work or to recite the lesson4 ,in the laboratory each pupil has a locker under his table1 furnished with apparatus1 as specified in the ,appendix4 ,each has also the author's ,laboratory ,manual1 which contains on every left-hand page full directions for an experiment1 with observations to be made1 etc4 ,the right-hand page is blank1 and on that the pupil makes a record of his work4 ,these notes are examined at the time1 or subsequently1 by the teacher1 and the pupil is not allowed to take the book from the laboratory2 nor can he use any other book on ,chemistry while experimenting4 ,by this means he learns to make his own observations and inferences4 ,for the benefit of the science and the added interest in the study1 it is earnestly recommended that teachers encourage pupils to fit up laboratories of their own at home4 ,this need not at first entail a large outlay4 ,a small attic room with running water1 a very few chemicals1 and a little apparatus1 are enough to begin with2 these can be added to from time to time1 as new material is wanted4 ,in this way the student will find his love for science growing apace4 ,while endeavoring1 by securing an able corps of critics1 and in all other ways possible1 to reduce errors to a minimum1 the author disclaims any pretensions to a work entirely free from mistakes1 holding himself alone responsible for any shortcomings1 and trusting to the leniency of teachers and critics4 ,the manuscript has been read by ,prof4 ,henry ,carmichael1 ,ph4,d41 of ,boston1 and to his broad and accurate scholarship1 as well as to his deep personal interest in the work1 the author is indebted for much valuable and original matter4 ,the following persons have generously read the proof1 as a whole or in part1 and made suggestions regarding it1 and to them the author would return his thanks1 as well as acknowledge his obligation3 ,prof4 ,e4 ,j4 ,bartlett1 ,dartmouth ,college1 ,n4,h42 ,prof4 ,f4 ,c4 ,robinson1 ,bowdoin ,college1 ,me42 ,prof4 ,h4 ,s4 ,carhart1 ,michigan ,university2 ,prof4 ,b4 ,d4 ,halsted1 ,iowa ,agricultural ,college2 ,prof4 ,w4 ,t4 ,sedgwick1 ,institute of ,technology1 ,boston2 ,pres4 ,m4 ,e4 ,wadsworth1 ,michigan ,mining ,school2 ,prof4 ,george ,huntington1 ,carleton ,college1 ,minn42 ,prof4 ,joseph ,torrey1 ,iowa ,college2 ,mr4 ,c4 ,j4 ,lincoln1 ,east ,boston ,high4,school2 ,mr4 ,w4 ,h4 ,sylvester1 ,english ,high ,school1 ,boston2 ,mr4 ,f4 ,w4 ,gilley1 ,chelsea1 ,mass41 ,high ,school2 the late ,d4 ,s4 ,lewis1 ,chemist of the ,boston ,gas ,works1 and others4 ,r4 ,p4 ,w4 ,,boston1 ,january #c1 #ahhh4 ,,table ,,of ,,contents ,,chapter ,i4 ,,the ,,metric ,,system4 ,length4--,volume4--,weight ,,chapter ,,ii4 ,,divisibility ,,of ,,matter4 ,mass4-,molecule4--,atom4--,element4--,c ompound4--,mixture4-- ,analysis4--,synthesis4--,metathesis4--, chemism ,,chapter ,,iii4 ,,molecules ,,and ,,atoms4 ,synthesis ,,chapter ,,iv4 ,,elements ,,and ,,binaries4 ,symbols4--,names4--,coefficients4--,exp onents4--,table of elements ,,chapter ,v4 ,,manipulation4 ,to prepare and cut glass1 etc4 ,,chapter ,,vi4 ,,oxygen4 ,preparation4--,properties4--,combustion of carbon2 sulphur2 phosphorus2 iron4 ,chapter ,,vii ,,nitrogen ,separation--,properties ,,chapter ,,viii ,,hydrogen ,preparation--,properties--,combustion-- ,oxy-hydrogen blowpipe ,,chapter ,,ix ,,union ,,by ,,weight ,meaning of equations--,problems ,,chapter ,x ,,carbon ,preparation--,allotropic forms3 diamond1 graphite1 amorphous carbon1 coke1 mineral coal4--,carbon a reducing agent1 a decolorizer1 disinfectant1 absorber of gases ,,chapter ,,xi ,,valence ,poles of attraction--,radicals ,,chapter ,,xii ,,electro-,,chemical ,,relation ,,of ,,elements ,deposition of silver2 copper2 lead--,table of metals and non- metals1 and discussion of their differences ,,chapter ,,xiii4 ,,electrolysis4 ,decomposition of water and of salts--,conclusions ,,chapter ,,xiv4 ,,union ,,by ,,volume4 ,avogadro's law and its applications4 ,,chapter ,,xv4 ,,acids ,,and ,,bases4 ,characteristics of acids and bases4--,anhydrides4--,naming of acids4--,alkalies ,,chapter ,,xvi4 ,,salts4 ,preparation from acids and bases4--,naming of salts4--,occurrence ,,chapter ,,xvii ,,chlorhydric ,,acid4 ,preparation and tests4--,bromhydric1 iodhiydric1 and fluorhydric acids4--,etching glass ,,chapter ,,xviii4 ,,nitric ,,acid4 ,preparation1 properties1 tests1 and uses4--,aqua regia3 preparation and action ,,chapter ,,xix4 ,,sulphuric ,,acid4 ,preparation1 tests1 manufacture1 and importance4-,fuming sulphuric acid ,,chapter ,,xx4 ,,ammonium ,,hydrate4 ,preparation of bases4--,formation1 preparation1 tests1 and uses of ammonia4 ,chapter ,,xxi4 ,,sodium ,,hydrate4 ,preparation and properties4--,potassium hydrate and calcium hydrate ,,chapter ,,xxii ,,oxides ,,of ,,nitrogen4 ,nitrogen monoxide1 dioxide1 trioxide1 tetroaide1 pentoxide4 ,,chapter ,,xxiii4 ,,laws ,,of ,,definite ,,and ,,of ,,multiple ,,proportion1 and their application ,,chapter ,,xxiv4 ,,carbon ,,protoxide and water gas4 ,,chapter ,,xxv4 ,,carbon ,,dioxide4 ,preparation and tests4--,oxidation in the human system4--,oxidation in water4--,deoxidation in plants ,,chapter ,,xxvi4 ,,ozone4 ,description1 preparation1 and test ,,chapter ,,xxvii ,,chemistry ,,of ,,the ,,atmosphere4 ,constituents of the air4--,air a mixture4--,water1 carbon dioxide1 and other ingredients of the atmosphere ,,chapter ,,xxviii4 ,,the ,,chemistry ,,of ,,water4 ,distillation of water4--,three states4--,pure water1 sea-water1 river-water1 spring-water ,,chapter ,,xxix4 ,,the ,,chemistry ,,of ,,flame4 ,candle flame4--,bunsen flame4--,light and heat4--,temperature of combustion4--,oxidizing and reducing flames4--,combustible and supporter4--,explosive mixture of gases4--,generalizations ,,chapter ,,xxx4 ,,chlorine4 ,preparation4--,chlorine water4--,bleaching properties4-- ,disinfecting power4--,a supporter of combustion4--,sources and uses ,,chapter ,,xxxi4 ,,bromine4 ,preparation4--,tests4--,description4--, uses ,,chapter ,,xxxii4 ,,iodine4 ,preparation4--,tests4--,iodo-starch paper4--,occurrence4--,uses4-- ,fluorine ,,chapter ,,xxxiii4 ,,the ,,halogens4 ,comparison4--,acids1 oxides1 and salts ,,chapter ,,xxxiv4 ,,vapor ,,density ,,and ,,molecular ,,weight4 ,gaseous weights and volumes4--,vapor density defined4--,vapor density of oxygen ,,chapter ,,xxxv4 ,,atomic ,,weight4 ,definition4--,atomic weight of oxygen4--,molecular symbols4-- ,molecular and atomic volumes ,,chapter ,,xxxvi4 ,,diffusion ,,and ,,condensation ,,of ,,gases4 ,diffusion of gases4--,law of diffusion4--,cause4--,liquefaction and solidification of gases ,,chapter ,,xxxvil ,,sulphur4 ,separation4--,crystals from fusion4--,allotropy4--,solution4-- ,theory of ,allotropy4--,occurrence and purification4--,uses4--- ,sulphur dioxide ,,chapter ,,xxxviii4 ,,hydrogen ,,sulphide4 ,preparation4--,tests4--,combustion4--,u ses4--,an analyzer of metals4- -,occurrence and properties ,,chapter ,,xxxix4 ,,phosphorus4 ,solution and combustion4--,combustion under water4--,occurrence4-- ,sources4--,preparation of phosphates and phosphorus4--- ,properties4--,uses4--,matches4--,red phosphorus4---,phosphene ,,chapter ,,xl4 ,,arsenic4 ,separation4--,tests4--,expert analysis4--,properties and occurrence4-- ,atomic volume4--,uses of arsenic trioxide ,,chapter ,,xli4 ,,silicon1 ,,silica1 ,,and ,,silicates4 ,comparison of silicon and carbon4--,silica4--,silicates4--,formati on of silica4 ,chapter ,,xlii ,,glass ,,and ,,pottery4 ,glass an artificial silicate4--,manufacture4--,importance4-- ,porcelain and pottery4 ,,chapter ,,xliii4 ,,metals ,,and ,,their ,,alloys4 ,comparison of metals and non-metals4--,alloys4--,low fusibility4 -- ,amalgams ,,chapter ,,xliv4 ,,sodium ,,and ,,its ,,compounds4 ,order of derivation4--,occurrence and preparation of sodium chloride2 uses4--,sodium sulphate3 manufacture and uses4 --,sodium carbonate3 occurrence1 manufacture1 and uses4-- ,sodium3 preparation and uses4--,sodium hydrate3 preparation and use4-- ,hydrogen sodium carbonate4--,sodium nitrate ,,chapter ,,xlv4 ,,potassium ,,and ,,ammonium4 ,occurrence and preparation of potassium4--,potassium chlorate and cyanide4--,gunpowder4--,ammonium compounds ,,chapter ,,xlvi4 ,,calcium ,,compounds4 ,calcium carbonate4--,lime and its uses4--,hard water4--,formation of caves4--,calcium sulphate ,,chapter ,,xlvii4 ,,magnesium1 ,,aluminium1 ,,and ,,zinc4 ,occurrence and preparation of magnesium4--,compounds of aluminium3 reduction2 properties1 and uses4--,compounds1 uses1 and reduction of zinc ,,chapter ,,xlviii4 ,,iron ,,and ,,its ,,compounds4 ,ores of iron4--,pig-iron4--,steel4--,wrought-iro n4--,properties4 -- ,salts of iron4--,change of valence and of color ,,chapter ,,xlix4 ,,lead ,,and ,,tin4 ,distribution of lead4--,poisonous properties4--,some lead compounds4-- ,tin ,,chapter ,l4 ,,copper1 ,,mercury1 ,,and ,,silver4 ,occurrence and uses of copper4--,compounds and uses of mercury4-- ,occurrence1 reduction1 and salts of silver ,,chapter ,,li4 ,,photography4 ,description4 ,,chapter ,,lii4 ,,platinum ,,and ,,gold4 ,methods of obtaining1 and uses ,,chapter ,,liii4 ,,chemistry ,,of ,,rocks4 ,classification4--,composition4--,import ance of siliceous rocks4-- ,soils4--,minerals4--,the earth's interior4--,percentage of elements ,,chapter ,,liv4 ,,organic ,,chemistry4 ,comparison of organic and inorganic compounds4--,molecular differences4--,synthesis of organic compounds4--,marsh-gas4 series4---,alcohols4--,ethers4--,other substitution products4 -- ,olefines and other series4 ,,chapter ,,lv4 ,,illuminating ,,gas4 ,source1 preparation1 purification1 and composition4--,natural gas ,,chapter ,,lvi4 ,,alcohol4 ,fermented and distilled liquors4--,effect on the system4--,affinity for water4--,purity ,,chapter ,,lvii ,,oils1 ,,fats1 ,,and ,,soaps4 ,sources and kinds of oils and fats4--,saponification4--,manufacture and action of soap4--,glycerin1 nitro-glycerin1 and dynamite4 -- ,butter and oleomargarine4 ,,chapter ,,lviii ,,carbo-,,hydrates4 ,sugars4--,glucose4--,starch4--,cellulos e4--,gun-cotton4--,dextrin4 -- ,zylonite ,,chapter ,,lix4 ,,chemistry ,,of ,,fermentation4 ,ferments4--,alcoholic1 acetic1 and lactic fermentation4-- ,putrefaction4--,infectious diseases ,,chapter ,,lx4 ,,chemistry ,,of ,,life4 ,growth of minerals and of organic life4--,food of plants and of man4--,conservation of energy and of matter ,,chapter ,,lxi4 ,,theories4 ,the ,la ,place theory--,theory of evolution--,new theory of chemistry ,,chapter ,,lxii ,,gas ,,volumes ,,and ,,weights4 ,quantitative experiments with oxygen and hydrogen--,problems ,,an ,,introduction ,,to ,,chemical ,,science ,,chapter ,i4 ,,the ,,metric ,,system4 #a4 ,the ,metric ,system is the one here employed4 ,a sufficient knowledge of it for use in the study of this book may be gained by means of the following experiments1 which should be performed at the outset by each pupil4 #b4 ,length4 ,experiment #a4--,note the length of #aj cm4 7centimeters7 on a metric ruler1 as shown in ,figure #a4 ,estimate by the eye alone this distance on the cover of a book1 and then verify the result4 ,do the same on a t4t4 7test-tube74 ,try this several times on different objects till you can carry in mind a tolerably accurate idea of #aj cm4 ,about how many inches is it8 ,in the same way estimate the length of #a cm1 verifying each result4 ,how does this compare with the distance between two blue lines of foolscap8 ,measure the diameter of the old nickel five- cent piece4 ,next1 try in the same way #e cm4 ,carry each result in mind1 taking such notes as may be necessary4 7,fig4 #a7 #c4 ,capacity4 ,experiment #b4--;,into a graduate1 shown in ,figure #b1 holding #be or #ej cc4 7cubic centimeters7 put #aj cc4 of water2 then pour this into a t4t4 ,note1 without marking1 what proportion of the latter is filled2 pour out the water1 and again put into the t4t4 the same quantity as nearly as can be estimated by the eye4 ,verify the result by pouring the water back into the graduate4 ,repeat several times until your estimate is quite accurate with a t4t4 of given size4 ,if you wish1 try it with other sizes4 ,now estimate #a cc4 of a liquid in a similar way4 ,do the same with #e cc4 ,a cubic basin #aj cm on a side holds a liter4 ,a liter contains #a1jjj cc4 ,if filled with water1 it weighs1 under standard conditions1 #a1jjj grams4 ,verify by measurement4 #d4 ,weight4 ,experiment #c4--,put a small piece of paper on each pan of a pair of scales4 ,on one place a #aj g4 7gram7 weight4 ,balance this by placing fine salt on the other pan4 ,note the quantity as nearly as possible with the eye1 then remove4 ,now put on the paper what you think is #aj g4 of salt4 ,verify by weighing4 ,repeat1 as before1 several times4 ,weigh #a g41 and estimate as before4 ,can #a g4 of salt be piled on a one-cent coin8 ,experiment with #e g4 #e4 ,resume--,lengths are measured in centimeters1 liquids in cubic centimeters1 solids in grams4 ,in cases where it is not convenient to measure a liquid or weigh a solid1 the estimates above will be near enough for most experiments herein given4 ,different solids of the same bulk of course differ in weight1 but for one gram what can be piled on a one-cent piece may be called a sufficiently close estimate4 ,the distance between two lines of foolscap is very nearly a centimeter4 ,a cubic centimeter is seen in ,figure #a4 ,temperatures are recorded in the centigrade scale4 ,,chapter ,,ii4 ,,what ,,chemistry ,,is4 #f4 ,divisibility of ,matter4 ,experiment #d4--;,examine a few crystals of sugar1 and crush them with the fingers4 ,grind them as fine as convenient1 and examine with a lens4 ,they are still capable of division4 ,put #c g4 of sugar into a t4t41 pour over it #e cc4 of water1 shake well1 boil for a minute1 holding the t4t4 obliquely in the flame1 using for the purpose a pair of wooden nippers 7,fig4 #c74 ,if the sugar does not disappear1 add more water4 ,when cool1 touch a drop of the liquid to the tongue4 ,evidently the sugar remains1 though in a state too finely divided to be seen4 ,this is called a solution1 the sugar is said to be soluble in water1 and water to be a solvent of sugar4 7,fig #c47 ,now fold a filter paper1 as in ,figure #d1 arrange it in a funnel 7,fig4 #e71 and pour the solution upon it1 catching what passes through1 which is called the filtrate1 in another t4t4 that rests in a receiver 7,fig4 #e74 ,after filtering1 notice whether any residue is left on the filter paper4 ,taste a drop of the filtrate4 ,has sugar gone through the filter8 ,if so1 what do you infer of substances in solution passing through a filter8 ,save half the filtrate for ,experiment #e1 and dilute the other half with two or three times its own volume of water4 ,shake well1 and taste4 7,fig #d47 7,fig #e47 ,we might have diluted the sugar solution many times more1 and still the sweet taste would have remained4 ,thus the small quantity of sugar would be distributed through the whole mass1 and be very finely divided4 ,by other experiments a much finer subdivision can be made4 ,a solution of4#jjjjjjjb g4 of the red coloring matter1 fuchsine1 in #a cc4 of alcohol gives a distinct color4 ,such experiments would seem to indicate that there is no limit to the divisibility of matter4 ,but considerations which we cannot discuss here lead to the belief that such a limit does exist2 that there are particles of sugar1 and of all substances1 which are incapable of further division without entirely changing the nature of the substance4 ,to these smallest particles the name molecules is given4 ,a mass is any portion of a substance larger than a molecule2 it is an aggregation of molecules4 ,a molecule is the smallest particle of a substance that can exist alone4 ,a substance in solution may be in a more finely divided state than otherwise1 but it is not necessarily in its ultimate state of division4 #g4 ,a ,chemical ,change4--,cannot this smallest particle of sugar1 the molecule1 be separated into still smaller particles of something else8 ,may it not be a compound body1 and will not some force separate it into two or more substances8 ,the next experiment will answer the question4 ,experiment #e4--,take the sugar solution saved from ,experiment #d1 and add slowly #d cc4of strong sulphuric acid4 ,note any change of color1 also the heat of the t4t4 ,add more acid if needed4 ,a substance entirely different in color and properties has been formed4 ,now either the sugar1 the acid1 or the water has undergone a chemical change4 ,it is1 in fact1 the sugar4 ,but the molecule is the smallest particle of sugar possible4 ,the acid must have either added something to the sugar molecules1 or subtracted something from them4 ,it was the latter4 ,here1 then1 is a force entirely different from the one which tends to reduce masses to molecules4 ,the molecule has the same properties as the mass4 ,only a physical force was used in dissolving the sugar1 and no heat was liberated4 ,the acid has changed the sugar into a black mass1 in fact into charcoal or carbon1 and water2 and heat has been produced4 ,a chemical change has been brought about4 ,from this we see that molecules are not the ultimate divisions of matter4 ,the smallest sugar particles are made up of still smaller particles of other things which do not resemble sugar1 as a word is composed of letters which alone do not resemble the word4 ,but can the charcoal itself be resolved into other substances1 and these into still others1 and so on8 ,carbon is one of the substances from which nothing else has been obtained4 ,there are about seventy others which have not been resolved4 ,these are called elements2 and out of them are built all the compounds-- mineral1 vegetable1 and animal--which we know4 #h4 ,an element is a chemically indivisible substance1 or one from which nothing else can be extracted4 ,a compound is a substance which is made up of elements united in exact proportions by a force called chemism1 or chemical affinity4 ,a mixture is composed of two or more elements or compounds blended together1 but not held by any chemical attraction4 ,to which of these three classes does sugar belong8 ,carbon8 ,the solution of sugar in water8 ,carbon is an element2 we call its smallest particle an atom4 ,an atom is the smallest particle of an element that can enter into combination4 ,atoms are indivisible and usually do not exist alone4 ,both elements and compounds have molecules4 ,the molecule of an element usually contains two atoms2 that of a compound may have two1 or it may have hundreds4 ,for a given compound the number is always definite4 ,chemism is the force that binds atoms together to form molecules4 ,the sugar molecule contains atoms1 forty-five in all1 of three different elements3 carbon1 hydrogen1 and oxygen4 ,that of salt has two atoms3 one of sodium1 one of chlorine4 ,should we say an atom of sugar8 ,why8 ,of what is a mass of sugar made up8 ,a molecule8 ,a mass of carbon8 ,a molecule8 ,did the chemical affinity of the acid break up masses or molecules8 ,in this respect it is a type of all chemical action4 ,the distinction between physics and chemistry is here well shown4 ,the molecule is the unit of the physicist1 the atom that of the chemist4 ,however large the masses changed by chemical action1 that action is always on the individual molecule1 the atoms of which are separated4 ,if the molecule were an indivisible particle1 no science of chemistry would be possible4 ,the physicist finds the properties of masses of matter and resolves them into molecules1 the chemist breaks up the molecule and from its atoms builds up other compounds4 ,analysis is the separation of compounds into their elements4 ,synthesis is the building up of compounds from their elements4 ,of which is the sugar experiment an example8 ,metathesis is an exchange of atoms in two different compounds2 it gives rise to still other compounds4 ,a chemical change may add something to a substance1 or subtract something from it1 or it may both subtract and add1 making a new substance with entirely different properties4 ,sulphur and carbon are two stable solids4 ,the chemical union of the two forms a volatile liquid4 ,a substance may be at one time a solid1 at another a liquid1 at another a gas1 and yet not undergo any chemical change1 because in each case the chemical composition is identical4 ,state which of these are chemical changes3 rusting of iron1 falling of rain1 radiation of heat1 souring of milk1 evaporation of water1 decay of vegetation1 burning of wood1 breaking of iron1 bleaching of cloth4 ,give any other illustrations that occur to you4 ,chemistry treats of matter in its simplest forms1 and of the various combinations of those simplest forms4 ,,chapter ,,iii4 ,,molecules ,,and ,,atoms4 #i4 ,molecules are ,extremely ,small4--,it has been estimated that a liter of any gas at #j degrees and #gfj mm4 pressure contains #ajbd molecules1 i4e4 one with twenty-four ciphers4 ,thomson estimates that if a drop of water were magnified to the size of the earth1 and its molecules increased in the same proportion1 they would be larger than fine shot1 but not so large as cricket balls4 ,a ,german has recently obtained a deposit of silver two-millionths of a millimeter thick1 and visible to the naked eye4 ,the computed diameter of the molecule is only one and a half millionths of a millimeter4 ,by a law of chemistry there is the same number of molecules in a given volume of every gas1 if the temperature and pressure are the same4 ,hence1 all gaseous molecules are of the same size1 including1 of course1 the surrounding space4 ,they are in rapid motion1 and the lighter the gas the more rapid the motion4 ,this gives rise to diffusion4 ,see page #aad4 #aj4 ,we ,know ,nothing ,definite of the ,form of ,molecules4--,in this book they will always be represented as of the same size1 that of two squares4 ,a molecule is itself composed of atoms1--from two to several hundred4 ,the size of the atom of most elements we represent by one square4#aa4 ,atoms4--,if the gaseous molecules be of the same size1 it is clear that either the atoms themselves must be condensed1 or the spaces between them must be smaller than before4 ,we suppose the latter to be the case1 and that they do not touch one another1 the same thing being true of molecules4 ,atoms composing sugar must be crowded nearer together than those of salt4 ,these atoms are probably in constant motion in the molecule1 as the latter is in the mass4 ,if we regard this square as a mass of matter1 the dots may represent molecules2 if we call it a molecule1 the dots may be called atoms1 though many molecules have no more than two or three atoms4 ,the following experiments illustrate the union of atoms to form molecules1 and of elements to form compounds4 #ab4 ,union of ,atoms4 ,experiment #f4--,mix1 on a paper1 #e g4 of iron turnings1 and the same bulk of powdered sulphur1 and transfer them to an ignition tube1 a tube of hard glass for withstanding high temperatures4 ,hold the tube in the flame of a burner till the contents have become red-hot4 ,after a minute break it by holding it under a jet of water4 ,put the contents into an evaporating-dish1 and look for any uncombined iron or sulphur4 ,both iron and sulphur are elements4 ,is this an example of synthesis or of analysis8 ,why8 ,is the chemical union between masses of iron and sulphur1 or between molecules1 or between atoms8 ,is the product a compound1 an element1 or a mixture8 ,experiment #g4--,try the same experiment1 using copper instead of iron4 ,the full explanation of these experiments is given on page #ac4 ,,chapter ,,iv4 ,,elements ,,and ,,binaries4 #ac4 ,about ,seventy ,different ,elements are now recognized1 half of which have been discovered within little more than a century4 ,these differ from one another in 7#a7 atomic weight1 7#b7 physical and chemical properties1 7#c7 mode of occurrence1 etc4 ,page #ab contains the most important elements4 ,the symbol of an element is usually the initial letter or letters of its ,latin name1 and stands for one atom of the element4 ,c is the symbol for carbon1 and represents one atom of it4 ,o means one atom of oxygen4,the symbols of elements will also be used in this book to stand for an indefinite quantity of them2 e4g4 ,o will be used for oxygen in general as well as for one atom4 ,the text will readily decide when symbols have a definite meaning1 and when they are used in place of words4 ,write1 explain1 and memorize the symbols of the elements in heavy type4 #ad4 ,the ,atomic ,weight of an element is the weight of its atom compared with that of hydrogen4 ,h is taken as the standard because it has the least atomic weight4 ,the atomic weight of ,o is #af1 which means that its atom weighs #af times as much as the ,h atom4 ,every symbol1 then1 stands for a definite weight of the element1 i4e4 its atomic weight1 as well as for its atom4 ,how much bromine by weight does ,br stand for8 ,what do these symbols mean--,as1 ,na1 ,n1 ,p8 ,if ,o represents one atom1 how much does ,o#b or #b ,o stand for8 ,how much by weight8 ,most elements have two atoms in the molecule4 ,how many molecules in #f ,h8 #aj ,n8 ,s#h8 ,i#bj8 ,the symbol of a compound is formed by writing in succession the symbols of the elements of which it is composed4 ,how many atoms in the following molecules1 and how many of each element3 ,c#b;,h#fj8 ,,hno#c8 ,pb,s,o#d8 ,mg,cl#b8 7,hg#b7,,no#c7b87 #ae4 ,the ,simplest ,compounds are ,binaries4--,a binary is a substance composed of two elements2 e4g4 common salt1 which is a compound of sodium and chlorine4 ,its symbol is ,na,cl1 its chemical name sodium chloride4 ,the ending ide is applied to the last name of binaries4 ,how many parts by weight of ,na and of ,cl in ,na,cl8 ,what is the molecular weight1 i4e4 the weight of its molecule8 ,name ,k,cl4 ,how many atoms in its molecule8 ,parts by weight of each element8 ,molecular weight8 ,does the symbol stand for more than one molecule8 ,how many molecules in #d ,na,cl8 ,how many atoms of ,na and of ,cl8 ,name these3 ,h,cl1 ,na,br1 ,na,i1 ,k,br1 ,ag,cl1 ,ag,i1 ,h,br1 ,,hi1 ,,hf1 ,hg,o1 ,zn,o1 ,zn,s1 ,mg,o1 ,ca,o4 ,compute the proportion by weight of each element in the last three4 ,a coefficient before the symbol of a compound includes all the elements of the symbol1 and shows the number of molecules4 ,how many in these3 #f ,k,br8 #c ,sn#j8 #ab ,na,cl8 ,how many atoms of each element in the above8 ,an exponent1 always written below1 applies only to the element after which it is written1 and shows the number of atoms4 ,explain these3 ,au,cl#c1 ,zn,cl#b1 ,hg#b;,cl#b4 ,write symbols for four molecules of sodium bromide1 one of silver iodide 7always omit coefficient one71 eight of potassium bromide1 ten of hydrogen chloride2 also for one molecule of each of these3 hydrogen fluoride1 potassium iodide1 silver chloride4 ,in all the above cases the elements have united atom for atom4 ,some elements will not so unite4 ,in ,ca,cl#b how many atoms of each element8 ,parts by weight of each8 ,give molecular weight4 ,is the size of the molecule thereby changed8 ,name these1 give the number of atoms of each element in the molecule1 and the proportion by weight1 also their molecular weights3 ,au,cl#c1 ,zn,cl#b1 ,mn,cl#b1 ,na#b,o1 ,k#b,s1 ,h#c,p1 ,h#d;,c4 ,principal ,elements4 ,name4 ,sym4 ,at4 ,wt4 ,valence4 ,vap4,d4 ,at4,vol4 ,mol4,vol4 ,state4 ,aluminium ,al #bg4 ,,ii1 ,,iv 444 444 444 ,solid ,antimony ,sb #abj4 ,,iii1 ,v4 444 444 444 ,arsenic ,as #ge4 ,,iii1 ,v #aej4 ,barium ,ba #acg4 ,,ii 444 444 444 ,bismuth ,bi #baj4 ,,iii1 ,v 444 444 444 ,boron ,b #aa4 ,,iii 444 444 444 ,bromine ,br #hj4 ,i1 7,v7 #hj4 ,liquid ,cadmium ,cd #aab4 ,,ii #ef4 ,solid ,calcium ,ca #dj4 ,,ii 444 444 444 ,carbon ,c #ab4 7,,ii71 ,,iv 444 444 444 ,chlorine ,cl #ce4e ,i1 7,v7 #ce4e ,gas ,chromium ,cr #eb4 7,,ii71,,iv1,,vi 444 444 444 ,solid ,cobalt ,co #ei4 ,,ii1 ,,iv 444 444 444 ,gas ,copper ,cu #fc4 ,i1 ,,ii 444 444 444 ,fluorine ,f #ai4 ,i1 7,v7 444 444 444 ,gas ,gold ,au #aif4 7,i71 ,,iii 444 444 444 ,solid ,hydrogen ,h #a4 ,i #a4 ,gas ,iodine ,i #abg4 ,i1 7,v7 #abg4 444 444 ,solid ,iron ,fe #ef4 ,,ii1,,iv17,,vi7 444 444 444 ,lead ,pb #bjf4 ,,ii1 ,,iv 444 444 444 ,lithium ,li #g4 ,i 444 444 444 ,magnesium ,mg #bd4 ,,ii 444 444 444 ,manganese ,mn #ee4 ,,ii1 ,,iv1 ,,vi 444 444 444 ,mercury ,hg #bjj4 ,i1 ,,ii #ajj4 ,liquid ,nickel ,ni #ei4 ,,ii1 ,,iv 444 444 444 ,solid ,nitrogen ,n #ad4 7,i71,,iii1,v #ad4 ,gas ,oxygen ,o #af4 ,,ii #af4 ,phosphorus ,p #ca4 7,i71,,iii1 ,v #fb4 ,solid ,platinum ,pt #aig4 7,,ii71 ,,iv 444 444 444 ,potassium ,k #ci4 ,i 444 444 444 ,silicon ,si #bh4 ,,iv 444 444 444 ,silver ,ag #ajh4 ,i 444 444 444 ,sodium ,na #bc4 ,i 444 444 444 ,strontium ,sr #hg4 ,,ii 444 444 444 ,sulphur ,s #cb4 ,,ii1,,iv17,,vi7 #cb7if7 ,tin ,sn #aah4 ,,ii1 ,,iv 444 444 444 ,zinc ,zn #fe4 ,,ii #cb4e ,if more than one atom of an element enters into the composition of a binary1 a prefix is often used to denote the number4 ,,so#b is called sulphur dioxide1 to distinguish it from ,,so#c1 sulphur trioxide4 ,name these3 ,,co#b1 ,si,o#b1 ,mn,o#b4 ,the prefixes are3 mono or proto1 one2 di or bi1 two2 tri or ter1 three2 tetra1 four2 pente1 five2 hex1 six2 etc4 ,diarsenic pentoxide is written1 ,as#b,o#e4 ,symbolize these3 carbon protoxide1 diphosphorus pentoxide1 diphosphorus trioxide1 iron disulphide1 iron protosulphide4 ,often only the prefix of the last name is used4 #af4 ,an ,oxide is a ,compound of ,oxygen and ,some ,other ,element1 as ,hg,o4 ,what is a chloride8 ,define sulphide1 phosphide1 arsenide1 carbide1 bromide1 iodide1 fluoride4 ,in ,experiment #f1 where ,s and ,fe united1 the symbol of the product was ,fe,s4 ,name it4 ,how many parts by weight of each element8 ,what is its molecular weight8 ,to produce ,fe,s a chemical union took place between each atom of the ,fe and of the ,s4 ,we may express this reaction1 i4e4 chemical action1 by an equation3-- ,iron ,sulphur ,iron ,sulphide ,or1 using symbols ,fe ,s ,fe,s ,using atomic weights1 #ef #cb #hh4 ,these equations are explained by saying that #ef parts by weight of iron unite chemically with #cb parts by weight of sulphur to produce #hh parts by weight of iron sulphide4 ,this1 then1 indicates the proportion of each element which combines1 and which should be taken for the experiment4 ,if #ef g4 of ,fe be used1 #cb g4 of ,s should be taken4 ,if we use more than #ef parts of ,fe with #cb of ,s1 will it all combine8 ,if more than #cb of ,s with #ef of ,fe8 ,there is found to be a definite quantity of each element in every chemical compound4 ,symbols would have no meaning if this were not so4 ,write and explain the equation for the experiment with copper and sulphur1 using names1 symbols1 and weights1 as above4 ,,chapter ,v4 ,,manipulation4 #ag4 ,to ,break ,glass ,tubing4 ,experiment #h4--,lay the tubing on a flat surface1 and draw a sharp three-cornered file two or three times at right angles across it where it is to be broken1 till a scratch is made4 ,take the tube in the hands1 having the two thumbs nearly opposite the scratch1 and the fingers on the other side4 ,press outward quickly with the thumbs1 and at the same time pull the hands strongly apart1 and the tubing should break squarely at the scratch4 ,to break large tubing1 or cut off bottles1 lamp chimneys1 etc41 first make a scratch as before2 then heat the handle of a file1 or a blunt iron--in a blast-lamp flame by preference--till it is red-hot1 and at once press it against the scratch till the glass begins to crack4 ,the fracture can be led in any direction by keeping the iron just in front of it4 ,re-heat the iron as often as necessary4 #ah4 ,to ,make ,ignition-,tubes4 ,experiment #i4--;,hold the glass tubing between the thumb and forefinger of each hand1 resting it against the second finger4 ,heat it in the upper flame1 slowly at first1 then strongly1 but heat only a very small portion in length1 and keep it in constant rotation with the right hand4 ,hold it steadily1 and avoid twisting it as the glass softens4 ,the yielding is detected by the yellow flame above the glass and by an uneven pressure on the hands4 ,pull it a little as it yields1 then heat a part just at one side of the most softened portion4 ,rotate constantly without twisting1 and soon it can be separated into two closed tubes4 ,no thread should be attached2 but if there be one1 it can be broken off and the end welded4 ,the bottom can be made more symmetrical by heating it red-hot1 then blowing1 gradually1 into the open end1 this being inserted in the mouth4 ,the parts should be annealed by holding above the flame for a short time1 to cool slowly4 ,for hard glass--,bohemian--or large tubes1 the blast-lamp or blowpipe is needed4 ,in the blast-lamp air is forced out with illuminating gas4 ,this gives a high degree of heat4 ,bulbs can be made in the same way as ignition-tubes1 and thistle-tubes are made by blowing out the end of a heated bulb1 and rounding it with charcoal4 #ai4 ,to ,bend ,glass ,tubing4 ,experiment #aj4--;,hold the tube in the upper flame4 ,rotate it so as to heat all parts equally1 and let the flame spread over #c or #d cm4 in length4 ,when the glass begins to yield1 without removing from the flame slowly bend it as desired4 ,avoid twisting1 and be sure to have all parts in the same plane2 also avoid bending too quickly1 if you would have a well-rounded joint4 ,anneal each bend as made4 ,heated glass of any kind should never be brought in contact with a cool body4 ,for making ,o1 ,h1 etc41 a glass tube -- delivery-tube--#ej cm4 long should have three bends1 as in ,figure #f4 ,the pupil should first experiment with short pieces of glass1 #aj or #ae cm4 long4 ,an ordinary gas flame is the best for bending glass4 #bj4 ,to ,cut ,glass4 ,experiment #aa4--,lay the glass plate on a flat surface1 and draw a steel glass-cutter--revolving wheel--over it1 holding this against a ruler for a guide1 and pressing down hard enough to scratch the glass4 ,then break it by holding between the thumb and fingers1 having the thumbs on the side opposite to the scratch1 and pressing them outward while bending the ends of the glass inward4 ,the break will follow the scratch4 ,holes can be bored through glass and bottles with a broken end of a round file kept wet with a solution of camphor in oil of turpentine4 #ba4 ,to ,perforate ,corks4 ,experiment #ab4--;,first make a small hole in the cork with the pointed handle of a round--rat-tail--file4 ,have the hole perpendicular to the surface of the cork4 ,this can be done by holding the cork in the left hand and pressing against the larger surface1 or upper part1 of the cork1 with the file in the right hand4 ,only a mere opening is made in this way1 which must be enlarged by the other end of the file4 ,a second or third file of larger size may be employed1 according to the size of the hole to be made1 which must be a little smaller than the tube it is to receive1 and perfectly round4 ,,chapter ,,vi4 ,,oxygen4 #bb4 ,to ,obtain ,oxygen4 ,experiment #ac4--,take #e g4 of crystals of potassium chlorate 7,k,cl,o#c7 and1 without pulverizing1 mix with the same weight of pure powdered manganese dioxide 7,mn,o#b74 ,put the mixture into a t4t41 and insert a d4t4--delivery-tube--having the cork fit tightly4 ,hang it on a r4s4--ring-stand1-- as in ,figure #g1 having the other end of the d4t4 7,fig #g47 under the shelf1 in a pneumatic trough1 filled with water just above the shelf4 ,fill three or more receivers--wide-mouthed bottles--with water1 cover the mouth of each with a glass plate1 invert it with its mouth under water1 and put it on the shelf of the trough1 removing the plate4 ,no air should be in the bottles4 ,have the end of the d4t4 so that the gas will rise through the orifice4 ,hold a lighted lamp in the hand1 and bring the flame against the mixture in the t4t4 ,keep the lamp slightly in motion1 with the hand1 so as not to break the t4t4 by over-heating in one place4 ,heat the mixture strongly1 if necessary4 ,the upper part of the t4t4 is filled with air3 allow this to escape for a few seconds2 then move a receiver over the orifice1 and fill it with gas4 ,as soon as the lamp is taken away1 remove the d4t4 from the water4 ,the gas contracts1 on cooling1 and if not removed1 water will be drawn over1 and the t4t4 will be broken4 ,let the t4t4 hang on the r4s4 till cool4 ,with glass plates take out the receivers1 leaving them covered1 mouth upward 7,fig4 #h71 with little or no water inside4 ,when cool1 the t4t4 may be cleaned with water1 by covering its mouth with the thumb or hand1 and shaking it vigorously4 ,what elements1 and how many1 in ,k,cl,o#c8 ,in ,mn#jb8 ,it is evident that each of these compounds contains ,o4 ,why1 then1 could we not have taken either separately1 instead of mixing the two8 ,this could have been done at a sufficiently high temperature4 ,mu#jb requires a much higher temperature for dissociation1 i4e4 separation into its elements1 than ,k,cl,o#c1 while a mixture of the two causes ,o to come off from ,k,cl,o#c at a lower temperature than if alone4 ,it is not known that ,mn#jb suffers any change4 ,each molecule of potassium chlorate undergoes the following change3-- ,potassium ,chlorate ,potassium ,chloride ,oxygen ,k,cl,o#c ,k,cl #c ,o4 ,is this analysis or synthesis8 ,complete the equation1 by using weights1 and explain it4 ,notice whether the right- hand member of the equation has the same number of atoms as the left4 ,has anything been lost or gained8 ,what element has heat separated8 ,does the experiment show whether ,o is very soluble in water8 ,how many grams of ,o are obtainable from #abb4eh g4 ,,kcio#c8 ,,properties4 #bc4 ,combustion of ,carbon4 ,,oxygen ,experiment #ad4--;,examine the gas in one of the receivers4 ,put a lighted splinter into the receiver1 sliding along the glass cover4 ,remove it1 blow it out1 and put in again while glowing4 ,is it re-kindled8 ,repeat till it will no longer burn4 ,is the gas a supporter of combustion8 ,how did the combustion compare with that in air8 ,is it probable that air is pure ,o8 ,why did the flame at last go out8 ,has the ,o been destroyed1 or chemically united with something else8 ,wood is in part ,c4 ,,co#b is formed by the combustion2 name it4 ,the equation is ,c #b,o ,,co#b4 ,affix the names and weights4 ,is ,,co#b a supporter of combustion8 ,note that when ,c is burned with plenty of ,o1 ,,co#b is always formed1 and that no matter how great the conflagration1 the union is atom by atom4 ,combustion1 as here shown1 is only a rapid union of ,o with some other substance1 as ,c or ,h4 #bd4 ,combustion of ,sulphur4 ,experiment #ae4--;,hollow out one end of a piece of electric-light pencil1 or of crayon1 #c cm4 long1 and attach it to a ,cu wire 7,fig4 #i74 ,put into this a piece of ,s as large as a pea1 ignite it by holding in the flame1 and then hold it in a receiver of ,o4 ,note the color and brightness of the flame1 and compare with the same in the air4 ,also note the color and odor of the product4 ,the new gas is ,,so#b4 ,name it1 and write the equation for its production from ,s and ,o4 ,how do you almost daily perform a similar experiment8 ,is the product a supporter of combustion8 #be4 ,combustion of ,phosphorus4 ,experiment #af4--,with forceps1 which should always be used in handling this element1 put a bit of ,p1 half as large as the ,s above1into the crayon1 called a deflagrating-spoon4 ,heat another wire1 touch it to the ,p1 and at once lower the latter into a receiver of ,o4 ,notice the combustion1 the color of the flame and of the product4 ,after removing1 be sure to burn every bit of ,p by holding it in a flame1 as it is liable to take fire if left4 ,the product of the combustion is a union of what two elements8 ,is it an oxide8 ,its symbol is ,p#b,o#e4 ,write the equation1 using symbols1 names1 and weights4 ,towards the close of the experiment1 when the ,o is nearly all combined1 ,p#b,o#c is formed1 as it is also when ,p oxidizes at a low temperature4 ,name it and write the equation4 #bf4 ,combustion of ,iron4 ,experiment #ag4--,take in the forceps a piece of iron picture-cord wire #f or #h;cm long1 hold one end in the flame for an instant1 then dip it into some ,s4 ,enough ,s will adhere to be set on fire by holding it in the flame again4 ,then at once dip it into a receiver of ,o with a little water in the bottom4 ,the iron will burn with scintillations4 ,is this analysis or synthesis8 ,what elements combine8 ,a watch-spring1 heated to take out the temper1 may be used1 but picture-wire is better4 ,the product is ,fe#c,o#d4 ,write the equation4 ,how much ,fe by weight in the formula8 ,how much ,o8 ,what per cent by weight of ,fe in the compound8 ,multiply the fractional part by #ajj4 ,what per cent of #j8 ,whatper cent of ,c#j 4is ,c8 ,o#b8 ,find the percentage composition of ,,so#b4 ,p#b,o#e4 ,from the last five experiments what do you infer of the tendency of ,o to unite with other elements8 #bg4 ,oxygen is a ,gas without ,color1 ,odor1 or ,taste4 ,it is chemically a very active element2 that is1 it unites with almost everything4 ,fluorine is the only element with which it will not combine4 ,when oxygen combines with a single element1 what is the compound called8 ,we have found that ,o makes up a certain portion of the air2 later1 we shall see how large the proportion is4 ,its tendency to combine with almost everything is a reason for the decay1 rust1 and oxidation of so many substances1 and for conflagrations1 great and small4 ,new compounds are thusformed1 of which ,o constitutes one factor4 ,water1 ,h#b,o1 is only a chemical union of ,o and ,h4 ,iron rust1 ,fe#b,o#c and ,h#b,o1 is composed of ,o1 ,fe1 and water4 ,the burning of wood or of coal gives rise to carbon dioxide1 ,,co#b1 and water4 ,decay of animal and vegetable matter is hastened by this all-pervading element4 ,o forms a portion of all animal and vegetable matter1 of almost all rocks and minerals1 and of water4 ,it is the most abundant of all elements1 and makes up from one-half to two- thirds of the earth's surface4 ,compute the proportion of it1 by weight1 in water1 ,h#b,o4 ,it is the union of ,o in the air with ,c and ,h in our blood that keeps up the heat of the body and supports life4 ,see page #ha4 ,there are many ways of preparing this element besides the one given above4 ,it may be obtained from water 7,experiment #ch7 and from many other compounds1 e4g4 by heating mercury oxide1 ,hg,o4 ,,chapter ,,vii4 ,,nitrogen4 #bh4 ,separation4 ,experiment #ah4--;,fasten a piece of electric-light pencil1 or of crayon1 to a wire1 as in ,experiment #ae1 and bend the wire so it will reach half-way to the bottom of a receiver4 ,using forceps1 put into the crayon a small piece of phosphorus4 ,pass the wire up through the orifice in the shelf of a p4t4 7pneumatic trough71 having water at least l cm4 above the shelf4 ,heat another wire1 touch it to the ,p1 and quickly invert an empty receiver over the ,p1 having the mouth under water1 so as to admit no air 7,fig4 #aj74 ,let the ,p burn as long as it will1 then remove the wire and the crayon1 letting in no air4 ,note the color of the product1 and leave till it is tolerably clear1 then remove the receiver with a glass plate1 leaving the water in the bottom4 ,do the fumes resemble those of ,experiment #af8 ,does it seem likely 7,fig #aj47 that part of the air is ,o8 ,why a part only8 ,find what proportion of the receiver is filled with water by measuring the water with a graduate2 then fill it with water and measure that2 compute the percentage which the former is of the latter4 ,what proportion of the air1 then1 is ,o8 ,what was the only means of escape for the ,p#b,o#f1 and ,p#b,o#b formed8 ,these products are solids4 ,are they soluble in water8 ,compute the percentage composition1 always by weight1 of ,p#b,o#b and ,p#b,o#e4 ,the gas left in the receiver is evidently not ,o4 ,experiment #ai will prove this conclusively1 and show the properties of the new gas4 #bi4 ,properties4 ,experiment #ai4--,when the white cloud has disappeared1 slide the plate along1 and insert a burning stick2 try one that still glows4 ,see whether the ,p and ,s on the end of a match will burn4 ,is the gas a supporter of combustion8 ,since it does not unite with ,c1 ,s1 or ,p1 is it an active or a passive element8 ,compare it with ,o4 ,air is about #ad #a_/b times as heavy as ,h4 ,which is heavier1 air or ,n8 ,see page #ab4 ,air or ,o8 ,write out the chief properties1 physical and chemical1 of ,n1 as found in this experiment4 #cj4 ,inactivity of ,n4--,n will scarcely unite chemically except on being set free from compounds4 ,it has1 however1 an intense affinity for boron1 and will even go through a carbon crucible to unite with it4 ,it is not combined with ,o in the air2 but the two form a mixture 7page #hf71 of which ,n makes up four-fifths1 its use being to dilute the ,o4 ,what would be the effect1 in case of a fire1 if air were pure ,o8 ,what effect on the human system8 ,growing plants need a great deal of ,n1 but they are incapable of making use of that in the air1 on account of the chemical inactivity of the element4 ,their supply comes from compounds in earth1 water1 and air4 ,by reason of its inertness ,n is very easily set free from its compounds4 ,for this reason it is a constituent of most explosives1 as gunpowder1 nitro-glycerine1 dynamite1 etc4 ,these solids1 by heat or concussion1 are suddenly changed to gases1 which thereby occupy much more space1 causing an explosion4 ,nitrogen exists in many compounds1 such as the nitrates2 but the great source of it all is the atmosphere4 ,see page #he4 ,,chapter ,,viii4 ,,hydrogen4 #ca4 ,preparation4 ,experiment #bj4--,prepare apparatus as for making ,o4 ,be sure that the cork perfectly fits both d4t4 and t4t41 or the ,h will escape4 ,cover #e g4 granulated ,zn1 in the t4t41 with #aj cc4 ,h#b,o1 and add #e cc4 chlorhydric acid1 ,h,cl4 ,adjust as for ,o 7,fig4 #g71 except that no heat is to be applied4 ,if the action is not brisk enough1 add more ,h,cl4 ,collect several receivers of the gas over water1 adding small quantities of ,h,cl when necessary4 ,observe the black floating residuum2 it is carbon1 lead1 etc4 ,with a glass plate remove the receivers1 keeping them inverted 7,fig4 #aa71 or the ,h will escape4 #cb4 ,the ,chemical ,change is as follows3-- ,zinc hydrogen chloride zinc chloride hydrogen4 ,zn #b ,h,cl ,zn,cl#b #b;,h4 ,complete by adding the weights1 and explain4 ,notice that the water does not take part in the change2 it is added to dissolve the ,zn,cl#b formed1 and thus keep it from coating the ,zn and preventing further action of the acid4 ,note also that ,zn has simply changed places with ,h1 one atom of the former having driven off two atoms of the latter4 ,the ,h1 having nothing to unite with1 is set free as a gas1 and collected over water4 ,of course ,zn must have a stronger chemical affinity for ,cl than ,h has1 or the change could not have taken place4 ,why one ,zn atom replaces two ,h atoms will be explained later1 asfar as an explanation is possible4 ,this equation1 should be studied carefully1 as a type of all equations4 ,the left-hand member shows what were taken1 i4e4 the factors2 the right-hand shows what were obtained1 i4e4 the products4 ,h#b,,so#d might have been used instead of ,h,cl4 ,in that case the reaction1 or equation1 would have been3 -- ,zinc hydrogen sulphate zinc sulphate hydrogen4 ,zn ,h#b,,so#d ,zn,s,o#d #b;,h4 ,iron might have been used instead of zinc1 in which case the reactions would have been3-- ,iron hydrogen chloride iron chloride hydrogen4 ,fe #b ,h,cl ,fe,cl#b #b ,h4 ,iron hydrogen sulphate iron sulphate hydrogen4 ,fe ,h#b,,so#d ,fe,s,o#d #b ,h4 ,write the weights and explain the equations4 ,the latter should be memorized4 #cc4 ,properties4 ,experiment #ba4--,lift with the left hand a receiver of ,h1 still inverted1 and insert a burning splinter with the right 7,fig4 #ab74 ,does the splinter continue to burn8 ,does the gas burn8 ,if so1 where8 ,is the light brilliant8 ,note the color of the flame4 ,is there any explosion8 ,try this experiment with several receivers4 ,is the gas a supporter of combustion8 i4e4 will carbon burn in it8 ,is it combustible8 i4e4 does it burn8 ,if so1 it unites with some part of the air4 ,with what part8#cd4 ,collecting ,h by ,upward ,displacement4 ,experiment #bb4--,pass a d4t4 from a ,h generator to the top of a receiver or t4t4 7,fig4 #ac74 ,the escaping ,h being so much lighter than air will force the latter down4 ,to obtain the gas unmixed with air1 the d4t4 should tightly fit a cardboard placed under the mouth of the receiver4 ,when filled1 the receiver can be removed1 inverted as usual1 and the gas tested4 ,in this and other experiments for generating ,h1 a thistle-tube1 the end of which dips under the liquid1 can be used for pouring in acid1 as in ,figure #ac4 #ce4 ,philosopher's ,lamp and ,musical ,flame4 ,experiment #bc4--;,fit to a cork a piece of glass tubing #aj or #ae cm4 long1 having the outer end drawn out to a point with a small opening1 and insert it in the ,h generator4 ,before igniting the gas at the end of the tube take the1 precaution to collect a t4t4 of it by upward displacement1 and bring this in contact with a flame4 ,if a sharp explosion ensues1 air is not wholly expelled from the generator1 and it would be dangerous to light the gas4 ,when no sound1 or very little1 follows1 light the escaping gas4 ,the generation of ,h must not be too rapid1 neither should the t4t4 be held under the face1 as the cork is liable to be forced out by the pressure of ,h4 ,a safety-tube1 similar to the thistle- tube above1 will prevent this4 ,this apparatus is called the philosopher's lamp4 ,thrust the flame into a long glass tube #a- #a_/b to #c cm4 in diameter1 as shown in ,figure #ad1 and listen for a musical note4 #cf4 ,product of ,burning ,h in ,air4 ,experiment #bd4--;,fill a tube #b or #c cm4 in diameter with calcium chloride1 ,ca,cl#b1 and connect one end with a generator of ,h 7,fig4 #ae74 ,at the other end have a philosopher's lamp-tube4,observing the usual precautions1 light the gas and hold over it a receiver1 till quite a quantity of moisture collects4 ,all water was taken from the gas by the dryer1 ,ca,cl#b4 ,what is1 therefore1 the product of burning ,h in air8 ,complete this equation and explain it3 #b;,h ,o 8 ,figure #af shows a drying apparatus arranged to hold ,ca,cl#b4 ,fig4 #ae;,fig4 #af #cg4 ,explosiveness of ,h4 ,experiment #be4 -- ,fill a soda-water bottle of thick glass with water1 invert it in a pneumatic trough1 and collect not over #a_/d full of ,h4 ,now remove the bottle1 still inverted1 letting air in to fill the other #c_/d4 ,mix the air and ,h by covering the mouth of the bottle with the hand1 and shaking well2 then hold the mouth of the bottle1 slightly inclined1 in a flame4 ,explain the explosion which follows4 ,if #c_/d was air1 what part was ,o8 ,what use did the ,n serve8 ,note any danger in exploding ,h mixed with pure ,o4 ,what proportions of ,o and ,h by volume would be most dangerously explosive8 ,what proportion by weight8 ,by the rapid union of the two elements1 the high temperature suddenly expanded the gaseous product1 which immediately contracted2 both expansion and contraction produced the noise of explosion4 #ch4 ,pure ,h ,is a ,gas without ,color1 ,odor1 or ,taste4 --,it is the lightest of the elements1 #ad #a_/b times as light asair4 ,it occurs uncombined in coal-mines1 and some other places1 but the readiness with which it unites with other elements1 particularly ,o1 prevents its accumulation in large quantities4 ,it constitutes two-thirds of the volume of the gases resulting from the decomposition of water1 and one-ninth of the weight4 ,compute the latter from its symbol4 ,it is a constituent of plants and animals1 and some rocks4 ,considering the volume of the ocean1 the total amount of ,h is large4 ,it can be separated from ,h#b,o by electrolysis1 or by ,c1 as in the manufacture of water gas4 ,when burned with ,o it forms ,h#b,o4 ,pure ,o and ,h when burning give great heat1 but little light4 ,the oxy-hydrogen blow-pipe 7,fig4 #ag7 is a device for producing the highest temperatures of combustion4 ,it has ,o in the inner tube and ,h in the outer4 ,why would it not be better the other way8 ,these unite at the end1 and are burned1 giving great heat4 ,a piece of lime put into the flame gives the brilliant ,drummond or calcium light4 ,chapter ,,ix4 ,,union ,,by ,,weight4 #ci4 ,in the ,equation -- ,zn #b ,h,cl ,zn,cl#b #b ,h #fe #gc #acf #b #fe parts by weight of ,zn are required to liberate #b parts by weight of ,h2 or1 by using #fe g ,zn with #gc g ,h,cl1 we obtain #b g ,h4 ,if twice as much ,zn 7#acj g7 were used1 #d g ,h could be obtained1 with1 of course1 twice as much ,h,cl4 ,with #bfj g4 ,zn1 how much ,h could be liberated8 ,a proportion may be made as follows3-- ,zn given 3 ,zn required 33 ,h given 3 ,h required4 #fe 3 #bfj 33 #b 3 x4 footnote3 ,given1 as here used1 means the weight called for by the equation2 required means that called for by the question4 ,solving1 we have #h g ,h4 ,how much ,h is obtainable by using #e g ,zn1 as in the experiment8 ,to avoid error in solving similar problems1 the best plan is as follows3-- ,zn #b;,h,cl ,zn,cl#b #b ,h #fe3e33b3x #fe #b #fe x #aj #e x x #aj_/fe #b_/ac ,ans4 #b_/ac g4 ,the equation should first be written2 next1 the atomic or molecular weights which you wish to use1 and only those1 to avoid confusion2 then1 on the third line1 the quantity of the substance to be used1 with underneath the substance wanted4 ,the example above will best how this4 ,this plan will prevent the possibility of error4 ,the proportion will then be3-- a given 3 a required 33 b given 3 b required4 ,how much ,zn is required to produce #cj g4 ,h8 ,zn #b;,h,cl ,zn,cl#b #b;,h #b3cj33fe3x #fe #b #bx #aiej x #cj x #ige ,ans4 #ige g4 ,zn4 ,solve3-- 7#a7 ,how much ,zn is necessary for #ad g4 ,h8 7#b7 ,how many pounds of ,zn are necessary for #c pounds of ,h8 7#c7 ,how many grams of ,h from #ag g4 of ,zn8 7#d7 ,how many tons of ,h from #a_/b ton of ,zn8 ,suppose we wish to find how much chlorhydric acid--pure gas-- will give #ab g4 ,h4 ,the question involves only ,h,cl and ,h4 ,arrange as follows3-- ,zn #b;,h,cl ,zn,cl#b #b ,h ,h giv4 3 ,h req4 33 ,h,cl giv4 3 ,h,cl req4 #gc #b #b 3 #ab 33 #gc x x #ab #bx#hgf x#dch ,ans4 #dch g4 ,h,cl4 ,solve3-- 7#a7 ,how much ,h,cl is needed to produce #ajj g4 ,h8 7#b7 ,how much ,h in #aj g4 ,h,cl8 7#c7 ,how much ,zn,cl#b is formed by using #ej g4 ,h,cl8 ,the question is now between ,h,cl and ,zn,cl#b4 ,zn #b;,,hc#a ,zn,cl#b #b;,h #gc #acf ,arrange the proportion1 and solve4 #ej x ,suppose we have generated ,h by using ,h#b,s#jd3 the equation is ,zn ,h#b,s#jd ,zn,s,o#d #b ,h4 ,there is the same relation as before between the quantities of ,zn and of ,h1 but the ,h#b,s#jd and ,zn,s#jd are different4 ,how much ,h#b,,so#d is needed to generate #ab g4 ,h8 ,zn ,h#b,,so#d ,zn,s#jd #b ,h #ih #b ,make the proportion1 and solve x #ab ,solve3-- 7#a7 ,how much ,h in #bjj g4 ,h#b,s#jd8 7#b7 ,how much ,zn,s#jd is produced from #bjj g4 ,h#b,s#jd8 7#c7 ,how much ,h#b,s#jd is needed for #g #a_/b g ,h8 7#d7 ,how much ,zn will #dj g4 ,h#b,,so#d combine with8 7#e7 ,how much ,fe will #dj g4 ,h#b,,so#d combine with8 7#f7 ,how much ,h can be obtained by using #ge g ,fe8 ,these principles apply to all reactions4 ,suppose1 for example1 we wish to get l#j g4 of ,o3 how much ,k,cl,o#c will it be necessary to use8 ,the reaction is3-- ,k,cl,o#c ,k,cl ,o#c #dh 3 #aj 33 #abb4e 3 x #abb4e #dh x #aj ,ans4 #be4e g4 ,k,cl,o#c4 ,the pupil should be required to make up problems of his own1 using various reactions1 and to solve them4 ,,chapter ,x4 ,,carbon4 ,examine graphite1 anthracite coal1 bituminous coal1 cannel coal1 wood1 gas carbon1 coke4 #dj4 ,preparation of ,c4 ,experiment #bf4--;,hold a porcelain dish or a plate in the flame of a candle1 or of a ,bunsen burner with the openings at the bottom closed4 ,after a minute examine the deposit4 ,it is carbon1 i4e4 lamp- black or soot1 which is a constituent of gas1 or of the candle4 ,open the valve at the base of the ,bunsen burner1 and hold the deposit in the flame4 ,does the ,c gradually disappear8 ,if so1 it has been burned to ,,co#b4 ,c #b ,o ,,co#b4 ,is ,c a combustible element8 ,experiment #bg4--;,ignite a splinter1 and observe the combustion and the smoke1 if any4 ,try to collect some ,c in the same way as before4 ,with plenty of ,o and high enough temperature1 all the ,c is burned to ,,co#b1 whether in gas1 candle1 or wood4 ,,co#b is an invisible gas4 ,the porcelain1 when held in the flame1 cools the ,c below the point at which it burns1 called the kindling-point1 and hence it is deposited4 ,the greater part of smoke is unburned carbon4 ,experiment #bh4--;,hold an inverted dry t4t4 or receiver over the flame of a burning candle1 and look for any moisture 7,h#b,o74 ,what two elements are shown by these experiments to exist in the candle8 ,the same two are found in wood and in gas4 ,experiment #bi4--,put into a small ,hessian crucible 7,fig4 #ah7 some pieces of wood #b or #c cm long1 cover with sand1 and heat the crucible strongly4 ,when smoking stops1 cool the crucible1 remove the contents1 and examine the charcoal4 ,the gases have been driven off from the wood1 and the greater part of what is left is ,c4 ,experiment #cj4--,put #a g4 of sugar into a porcelain crucible1 and heat till the sugar is black4 ,c is left4 ,see ,experiment #e4 ,remove the ,c with a strong solution of sodium hydrate 7page #bjh74 #da4 ,allotropic ,forms4--,carbon is peculiar in that it occurs in at least three allotropic1 i4e4 different1 forms1 all having different properties4 ,these are diamond1 graphite1 and amorphous --not crystalline--carbon4 ,the latter includes charcoal1 lamp- black1 bone-black1 gas carbon1 coke1 and mineral coal4 ,all these forms of ,c have one property in common2 they burn in ,o at a high temperature1 forming ,,co#b4 ,this proves that each is the element ,c1 though it is often mixed with some impurities4 ,allotropy1 or allotropism1 is the quality which an element often has of appearing under various forms1 with different properties4 ,the forms of ,c are a good illustration4 #db4 ,diamond is the purest ,c2 but even this in burning leaves a little ash1 showing that it is not quite pure4 ,it is a rare mineral1 found in ,india1 ,south ,africa1 and ,brazil1 and is the hardest and most highly refractive to light of all minerals4 ,boron is harder4 ,footnote3 ,b1 not occurring free1 is not a mineral4 ,when heated in the electric arc1 at very high temperatures1 diamond swells and turns black4 #dc4 ,graphite1 or ,plumbago1 is ,one of the ,softest ,minerals4--,it is black and infusible1 and oxidizes only at very high temperatures1 higher than the diamond4 ,it contains from #ie to #ih per cent ,c4 ,graphite is found in the oldest rock formations1 in the ,united ,states and ,siberia4 ,it is artificially formed in the iron furnace4 ,graphite is employed for crucibles where great heat is required1 for a lubricant1 for making metal castings1 and1 mixed with clay1 for lead-pencils4 ,it is often called black-lead4 #dd4 ,amorphous ,carbon comprises the following varieties4 ,charcoal is made by heating wood1 for a long time1 out of contact with the air4 ,the volatile gases are thus driven off from the wood2 what is left is ,c1 and a small quantity of mineral matter which remains as ash when the coal is burned4 #de4 ,lamp-black is prepared as in ,experiment #bf1 or by igniting turpentine 7,c#a,,oh#af71 naphtha1 and various oils1 and collecting the ,c of the smoke4 ,it is used for making printers' ink1 ,india ink1 etc4 ,a very pure variety is obtained from natural gas4 ,bone-black1 or animal charcoal1 is obtained by distilling bones1 i4e4 by heating them in retorts into which no air is admitted4 ,the ,c is the charred residue4 ,gas ,carbon is formed in the retorts of the gas-house4 ,see page #ahb4 ,it is used to some extent in electrical work4 #df4 ,coke is the residue left after distilling soft coal4 ,it is tolerably pure carbon1 with some ash and a little volatile matter4 ,it burns without flame4 #dg4 ,mineral ,coal is fossilized wood or other vegetable matter4 ,millions of years ago trees and other vegetation covered the earth as they do to-day4 ,in certain places they slowly sank1 together with the land1 into the interior of the earth1 were covered with sand1 rock1 and water1 and heated from the earth's interior4 ,a slow distillation took place1 which drove off some of the gases1 and converted vegetable matter into coal4 ,all the coal dug from the earth represents vegetable life of a former period4 ,millions of years were required for the transformation2 but the same change is in progress now1 where peat beds are forming from turf4 ,coal is found in all countries1 the largest beds being in the ,united ,states4 ,from the nature of its formation1 coal varies much in purity4 ,anthracite1 or hard coal1 is purest in carbon1 some varieties having from #ij to #ie per cent4 ,this represents most complete distillation in the earth2 i4e4 the gases have mostly been driven off4 ,it is much used in ,new ,england4 #dh4 ,bituminous1 or soft coal1 crocks the hands1 and burns rapidly with much flame and smoke4 ,the greater part of the coal in the earth is bituminous4 ,it represents incomplete distillation4 ,hence1 by artificially distilling it1 illuminating gas is made4 ,see page #ahj4 ,it is far less pure ,c than anthracite4 #di4 ,cannel ,coal is a variety of bituminous coal which can be ignited like a candle4 ,this is because so many of the gases are still left1 and it shows cannel to be less pure ,c than bituminous coal4 #ej4 ,lignite1 ,peat1 ,turf1 etc41 are still less pure varieties of ,c4 ,construct a table of the naturally occurring forms of this element1 in the order of their purity4 ,carbon forms the basis of all vegetable and animal life2 it is found in many rocks1 mineral oils1 asphaltum1 natural gas1 and in the air as ,,co#b4 #ea4 ,c a ,reducing ,agent4 ,experiment #ca4--,put into a small ignition-tube a mixture of #d or #e g4 of powdered copper oxide 7,cu,o71 with half its bulk of powdered charcoal4 ,heat strongly for ten or fifteen minutes4 ,examine the contents for metallic copper4 ,with which element of ,cu,o has ,c united8 ,the reaction may be written3 ,cu#j ,c ,,co ,cu4 ,complete and explain4 ,a ,reducing1 or ,deoxidizing1 ,agent is a substance which takes away oxygen from a compound4 ,c is the most common and important reducing agent1 being used for this purpose in smelting iron and other ores1 making water-gas1 etc4 ,an ,oxidizing ,agent is a substance that gives up its ,o to a reducing agent4 ,what oxidizing agent in the above experiment8 #eb4 ,c a ,decolorizer4 ,experiment #cb4--,put #c or #d g4 of bone-black into a receiver1 and add #aj or #ae cc4of cochineal solution4 ,shake this thoroughly1 covering the bottle with the hand4 ,then pour the whole on a filter paper1 and examine the filtrate4 ,if all the color is not removed1 filter again4 ,what property of ,c is shown by this experiment8 ,any other coloring solution may be tried4 ,the decolorizing power of charcoal is an important characteristic4 ,animal charcoal is used in large quantities for decolorizing sugar4 ,the coloring matter is taken out mechanically by the ,c1 there being no chemical action4 #ec4 ,c a ,disinfectant4 ,experiment #cc4--,repeat the previous experiment1 adding a solution of ,h#b,s#c i4e4 hydrogen sulphide1 in water1 instead of cochineal solution4 ,see page #abj4 ,note whether the bad odor is removed4 ,if not1 repeat4 ,charcoal has the property of absorbing large quantities of many gases4 ,ill-smelling and noxious gases are condensed in the pores of the ,c2 ,o is taken in at the same time from the air1 and these gases are there oxidized and rendered odorless and harmless4 ,for this reason charcoal is much used in hospitals and sick-rooms1 as a disinfectant4 ,this property of condensing ,o1 as well as other gases1 is shown in the experiment below4 #ed4 ,c an ,absorber of ,gases and a ,retainer of ,heat4 ,experiment #cd4--,put a piece of phosphorus of the size of a pea1 and well dried1 on a thick paper4 ,cover it well with bone-black1 and look for combustion after a while4 ,o has been condensed from the air1 absorbed by the ,c1 and thus communicated to the ,p4 ,burn all the ,p at last4 ,,valence4 #ee4 ,the ,symbols ,na,cl and ,mg,cl#b differ in two ways4--,what are they8 ,let us see why the atom of ,mg unites with two ,cl atoms1 while that of ,na takes but one4 ,if the atoms of two elements attract each other1 there must be either a general attraction all over their surfaces1 or else some one or more points of attraction4 ,suppose the latter to be true1 each atom must have one or more poles or bonds of attraction1 like the poles of a magnet4 ,different elements differ in their number of bonds4 ,na has one1 which may be written graphically ,na-2 ,cl has one1 -,cl4 ,when ,na unites with ,cl1 the bonds of each element balance1 as follows3 ,na-,cl4 ,the element ,mg1 however1 has two such bonds1 as ,mg or -,mg-4 ,when ,mg unites with ,cl1 in order to balance1 or saturate1 the bonds1 it is evident that two atoms of ,cl must be used1 as ,cl-,mg-,cl1 or ,mg,cl#b4 ,a compound or an element1 in order to exist1 must have no free bonds4 ,in organic chemistry the exceptions to this rule are very numerous1 and1 in fact1 we do not know that atoms have bonds at all2 but we can best explain the phenomena by supposing them1 and for a general statement we may say that there must be no free bonds4 ,in binaries the bonds of each element must balance4 #ef4 ,the ,valence1 ,quantivalence1 of an ,element is its ,combining ,power ,measured by ,bonds4--,h1 having the least number of bonds1 one1 is taken as the unit4 ,valence has always to be taken into account in writing the symbol of a compound4 ,it is often written above and after the elements i4e4 written like an exponent1 as ,k,i1 ,mg,,ii4 ,an element having a valence of one is a monad2 of two1 a dyad2 three1 a triad2 four1 tetrad2 five1 pentad2 six1 hexad1 etc4 ,it is also said to be monovalent1 di- or bivalent1 etc4 ,this theory of bonds shows why an atom cannot exist alone4 ,it would have free or unused bonds1 and hence must combine with its fellow to form a molecule1 in case of an element as well as in that of a compound4 ,this is illustrated by these graphic symbols in which there are no free bonds3 ,h-,h1 ,o,o1 ,n#c-;bond symbol,n1 ,c#d-;bond symbol,c4 ,a graphic symbol shows apparent molecular structure4 ,after all1 how do we know that there are twice as many ,cl atoms in the chloride of magnesium as in that of sodium8 ,the compounds have been analyzed over and over again1 and have been found to correspond to the symbols ,mg,cl#b and ,na,cl4 ,this will be better understood after studying the chapter on atomic weights4 ,in writing the symbol for the union of ,h with ,o1 if we take an atom of each1 the bonds do not balance1 ,h-,o1 the former having one2 the latter1 two4 ,evidently two atoms of ,h are needed1 as ,h-,o-,h1 or ,h ,o 1 or ,h#b,o4 ,in the union of ,zn and ,o1 each has two bonds2 ,h hence they unite atom with atom1 ,zn ,o1 or ,zn,o4 ,write the grapbic and the common symbols for the union of ,h,i and ,cl,i2 of ,k,i and ,br,i2 ,ag,i and ,o,,ii2 ,na,i and ,s,,ii2 ,h,i and ,p,,iii4 ,study valences4 ,it will be seen that some elements have a variable quantivalence4 ,sn has either #b or #d2 ,p has #c or #e4 ,it usually varies by two for a given element1 as though a pair of bonds sometimes saturated each other24 e4g4 ,sn1 a quantivalence of #d1 and ,sn1 a quantivalence of #b4 ,there are1 therefore1 two oxides of tin1 ,sn,o and ,sn,o#b1 or ,sn,o and ,o,sn,o4 ,write symbols for the two chlorides of tin2 two oxides of ,p2 two oxides of arsenic4 ,the chlorides of iron are ,fe,cl#b and ,fe#b;,cl#f4 ,in the latter1 it might be supposed that the quantivalence of ,fe is #c1 but the graphic symbol shows it to be #d4 ,it is called a pseudo-triad1 or false triad4 ,cr and ,al are also pseudo-triads4 ,cl ,cl ,cl--,fe--,fe--,cl ,cl ,cl ,write formulae for two oxides of iron2 the oxide of ,al4 #eg4 ,a ,radical is a ,group of ,elements which has no separate existence1 but enters into combination like a single atom2 e4g4 7,,no#c7 in the compounds ,,hno#c or ,,kno#c2 7,,so#d7 in ,h#b,,so#d4 ,in ,,hno#c the radical has a valence of #a1 to balance that of ,h1 ,h-,,no#c74 ,in ,h#b,,so#d1 what is the valence of 7,,so#d78 ,give it in each of these radicals1 noting first that of the first element3 ,k7,,no#c71 ,na#b7,,so#d71 ,na#b7;,,co#c71 ,k7,cl,o#c71 ,h#c7,,po#d71 ,ca#c7,,po#d7b1 ,na#d7,si,o#d74 ,suppose we wish to know the symbol for calcium phosphate4 ,ca and ,,po#d are the two parts4 ,in ,h#c7,,po#d7 the radical is a triad1 to balance ,h#c4 ,ca is a dyad1 ,ca7,p#jd74 ,the least common multiple of the bonds 7#b and #c7 is #f1 which1 divided by #b 7no4 ,ca bonds71 gives #c 7no4 ,ca atoms to be taken74 #f _/ #c 7no4 7,,po#d7 bonds7 gives #b 7no4 ,,po#d radicals to be taken74 ,hence the symbol ,ca#c7,p#jd7b4 ,verify this by writing graphically4 ,write symbols for the union of ,mg and 7,,so#d71 ,na and 7,,po#d71 ,zn and 7,,no#c71 ,k and 7,,no#c71 ,k and 7,,so#d71 ,mg and 7,,po#d71 ,fe and 7,,so#d7 7both valences of ,fe71 ,fe and 7,,no#c71 taking the valences of the radicals from ,,hno#c1 ,h#b,,so#d1 ,h#c,,po#d4 ,chapter ,,xii4 ,,electro-,,chemical ,,relation ,,of ,,elements4 #eh4 ,examine untarnished pieces of iron1 silver1 nickel1 lead1 etc42 also quartz1 resin1 silk1 wood1 paper4 ,notice that from the first four light is reflected in a different way from that of the others4 ,this property of reflecting light is known as luster4 ,metals have a metallic luster which is peculiar to themselves2 and this1 for the present1 may be regarded as their chief characteristic4 ,are they at the positive or negative end of the list8 ,see page #dc4 ,how is it with the non-metals8 ,this arrangement has a significance in chemistry which we must now examine4 ,the three appended experiments show how one metal can be withdrawn from solution by a second1 this second by a third1 the third by a fourth1 and so on4 ,for expedition1 three pupils can work together for the three following experiments1 each doing one1 and examining the results of the others4 #ei4 ,deposition of ,silver4 ,experiment #ce4--,put a ten-cent ,ag coin into an evaporating-dish1 and pour over it a mixture of #e cc4 ,,hno#c and #aj cc4 ,h#b,o4 ,warm till all1 or nearly all1 the ,ag dissolves4 ,remove the lamp4 #c ,ag #d ,,hno#c #c ,ag,n,o#c #b ,h#b,o ,,no4 ,then add #aj cc4 ,h#b,o1 and at once put in a short piece of ,cu wire1 or a cent4 ,leave till quite a deposit appears1 then pour off the liquid1 wash the deposit thoroughly1 and remove it from the coin4 ,see whether the metal resembles ,ag4 #b ,ag,n,o#c ,cu 8#fj4 ,deposition of ,copper4 ,experiment #cf4--;,dissolve a cent or some ,cu turnings in dilute ,,hno#c1 as in ,experiment #ce1 and dilute the solution4 #c ,cu #h ,,hn#ji - #c ,cu 7,,noa#d ,h#b,o#b ,,no47 ,then put in a clean strip of ,pb1 and set aside as before1 examining the deposit finally4 ,cu7,,no#c71 ,pb - 8 #fa4 ,deposition of ,lead4 ,experiment #cg4--,perform this experiment in the same manner as the two previous ones1 dissolving a small piece of ,pb1 and using a strip of ,zn to precipitate the ,pb4 #c ,pb #h ,,hno#c - #c ,pb 7,,no#d7b #d ,ha#j #b ,,no4 ,pb 7,,no#c7 #b ,zn 8 h4 #fb4 ,explanation4 -,these experiments show that ,cu will replace ,ag in a solution of ,ag,n,o#c1 that ,pb will replace and deposit ,cu from a similar compound1 and that ,zn will deposit ,pb in the same way4 ,they show that the affinity of ,zn for 7,,no#c7 is stronger than either ,ag1 ,cu1 or ,pb4 ,we4 express this affinity by saying that ,zn is the most positive of the four metals1 while ,ag is the most nega- tive4 ,cu is positive to ,ag1 but negative to ,pb and ,zn4 ,which of the four elements are positive to ,pb1 and which negative8 ,mg would withdraw ,zn from a similar solution1 and be in its turn withdrawn by ,na4 ,the table on page #dc is founded on this relation4 ,a given element is positive to every element above it in the list1 and negative to all below it4 ,metals are usually classed as positive1 non-metals as negative4 ,each in union with ,o and #a;,i gives rise to a very important class of compounds1--the negative to acids1 the positive to bases4 ,in the following1 note whether the positive or the negative element is written first3--,h,cl1 ,na#bj1-;,as#b,s#c1 -,mg,br#b1 ,ag#b,s4 ,na#b,,so#d is made up of two parts1 ,na#b being positive1 the radical ,,so#d negative4 ,like elements1 radicals are either positive or negative4 ,in the following1 separate the positive element from the negative radical by a vertical line3 ,na#b;,,co#c1 ,na,n,o#c1 ,zn,s,o#d1 ,k,cl,o#c4 ,the most common positive radical is ,,nh#d1 ammonium1 as in ,,nh#d;,cl4 ,it always deports itself as a metal4 ,the commonest radical is the negative ,,oh1 called hydroxyl1 from hydrogen- oxygen4 ,take away ,h from the symbol of water1 ,h-,o-,h1 and hydroxyl --7,,oh7 with one free bond is left4 ,if an element takes the place of ,h1 i4e4 unites with ,,oh1 the compound is called a hydrate4 ,,koh is potassium hydrate4 ,name ,na,o,h1 ,ca7,,oh7#b1 ,,nh#d,,oh1 ,zn7,,oh7#b1 ,al#b7,,oh7#f4 ,is the first part of each symbol above positive or negative8 ,h has an intermediate place in the list4 ,it is a constituent of both acids and bases1 and of the neutral substance1 water4 ,,order4 -- ,negative or ,non-,metallic ,elements4 ,acid-forming with ,h7usually ,,oh74 ,oxygen ,sulphur ,nitrogen ,fluorine ,chlorine ,bromine ,iodine ,phosphorus ,arsenic ,carbon ,silicon ,hydrogen ,positive or ,metallic ,elements4 ,base-forming with ,,oh4 ,gold ,platinum ,mercury ,silver ,copper ,tin ,lead ,iron ,zinc ,aluminium ,magnesium ,calcium ,sodium ,potassium ,,chapter ,,xiii4 ,,electrolysis4 ,the following experiment is to be performed only by the teacher1 but pupils should make drawings and explain4 #fc4 ,decomposition of ,water4 ,experiment #ch4--;,arrange in series two or more cells of a ,bunsen battery 7,physics1 page #afd71 ,references are made in this book to ,gage's ,introduction to ,physical ,science4 and attach the terminal wires to an electrolytic apparatus 7,fig4 #ai7 filled with water made slightly acid with ,h#b,,so#d4 ,construct a diagram of the apparatus1 marking the ,zn in the liquid 1 since it is positive1 and the ,c1 or other element1 -4 ,mark the electrode attached to the ,zn -1 and that attached to the ,c 2 positive electricity at one end of a body commonly implies negative at the other4 ,opposites attract1 while like electricities repel each other4 ,these analogies will aid the memory4 ,at the electrode is the - element of ,h#b,o1 and at the - electrode the element4 ,note1 page #dc1 whether ,h or ,o is positive with reference to the other1 and write the symbol for each at the proper electrode4 ,compare the diagram with the apparatus1 to verify your conclusion4 ,why does gas collect twice as fast at one electrode as at the other8 ,what does this prove of the composition of water8 ,when filled1 test the gases in each tube1 for ,o and ,h1 with a burning stick4 ,electrical analysis is called electrolysis4 ,if a solution of ,na,cl be electrolyzed1 which element will go to the pole8 ,which1 if the salt were ,k#b,,so#d8 ,explain these reactions in the electrolysis of that salt4 ,k#b,,so#d ,k#b ,s#jc ,o4 ,,so#d is unstable1 and breaks up into ,,so#c and ,o4 ,both ,k and ,,so#c have great affinity for water4 ,k#b #b ,h#b,o #b ,,koh ,h#b4 ,s#jc ,h#b,o ,h#b,,so#d4 ,the base ,,koh would be found at the - electrode1 and the acid ,h#b,,so#d at the electrode4 ,the positive portion1 ,k1 uniting with ,h#b,o forms a base2 the negative part1 ,s#jc1 with ,h#b,o forms an acid4 ,of what does this show a salt to be composed8 #fd4 ,conclusions4--,these experiments show 7#a7 that at the electrode there always appears the negative element1 or radical1 of the compound1 and at the - electrode the positive element2 7#b7 that these elements unite with those of water1 to make1 in the former case1 acids1 in the latter1 bases2 7#c7 that acids and bases differ as negative and positive elements differ1 each being united with ,o and ,h1 and yet producing compounds of a directly opposite character2 7#d7 that salts are really compounded of acids and bases4 ,this explains why salts are usually inactive and neutral in character1 while acids and bases are active agents4 ,thus we see why the most positive or the most negative elements in general have the strongest affinities1 while those intermediate in the list are inactive1 and have weak affinities2 why alloys of the metals are weak compounds2 why a neutral substance1 like water1 has such a weak affinity for the salts which it holds in solution2 and why an aqueous solution is regarded as a mechanical mixture rather than a chemical compound4 ,in this view1 the division line between chemistry and physics is not a distinct one4 ,these will be better understood after studying the chapters on acids1 bases and salts4 ,chapter ,,xiv4 ,,union ,,by ,,volume4 #ff4 ,avogadro's ,law of ,gases4--,equal volumes of all gases1 the temperature and pressure being the same1 have the same number of molecules4 ,this law is the foundation of modern chemistry4 ,a cubic centimeter of ,o has as many molecules as a cubic centimeter of ,h1 a liter of ,n the same number as a liter of steam1 under similar conditions4 ,compare the number of molecules in #e l4 of ,n#b,o with that in #aj l4 ,cl4 #g cc4 vapor of ,i to #f cc4 vapor of ,s4 ,the half-molecules of two gases have1 of course1 the same relation to each other1 and in elements the half-molecule is usually the atom4 ,the molecular volumes--molecules and the surrounding space--of all gases must therefore be equal1 as must the half-volumes4 ,notice that this law applies only to gases1 not to liquids or solids4 ,let us apply it to the experiment for the electrolysis of water4 ,in this we found twice as much ,h by volume as ,o4 ,evidently1 then1 steam has twice as many molecules of ,h as of ,o1 and twice as many half-molecules1 or atoms4 ,if the molecule has one atom of ,o1 it must have two of ,h1 and the formula will be ,h#b,o4 ,suppose we reverse the process and synthesize steam1 which can be done by passing an electric spark through a mixture of ,h and ,o in a eudiometer over mercury2 we should need to take twice as much ,h as ,o4 ,now when #b cc4 of ,h combine thus with #a cc4 of ,o1 only #b cc4of steam are produced4 ,three volumes are condensed into two volumes1 and of course three molecular volumes into two1 three atomic volumes into two4 ,this may be written as follows3-- ,h ,h ,o ,h#b,o4 ,this is a condensation of one-third4 ,if #b l4 of chlorhydric acid gas be analyzed1 there will result #a l4 of ,h and #a l4 of ,cl4 ,the same relation exists between the molecules and the atoms1 and the reaction is3-- ,h,cl ,h ,cl4 ,reverse the process1 and #a l4 of ,h unites with #a l4 of ,cl to produce #b l4 of the acid gas2 there is no condensation1 and the symbol is ,h,cl4 ,in seven volumes ,h,cl how many of each constituent8 ,the combination of two volumes of ,h with one volume of ,s is found to produce two volumes of hydrogen sulphide4 ,therefore two atoms of ,h combine with one of ,s to form a molecule whose symbol is ,h#b,s4 ,h ,h ,s ,h#b,s4 ,what is the condensation in this case8 ,,problems4 7#a7 ,how many liters of ,s will it take to unite with #d l4 of ,h8 ,how much ,h#b,s will be formed8 7#b7 ,how many liters of ,h will it take to combine with #e l4 of ,s8 ,how much ,h#b,s results8 7#c7 ,in #f l4 ,h#b,s how many liters ,h1 and how much ,s8 ,prove4 7#d7 ,in four volumes ,h#b,s how many volumes of each constituent8 7#e7 ,if three volumes of ,h be mixed with two volumes of ,s1 so as to make ,h#b,s1 how much will be formed8 ,how much of either element will be left8 ,an analysis of #b cc4 of ammonia gives #a cc4 ,n and #c cc4 ,h4 ,the symbol must then be ,,nh#c1 the reaction1-- ,,nh#c ,n ,h ,h ,h4 ,what condensation in the synthesis of ,,nh#c8 ,in #ab cc4 ,,nh#c how many cubic centimeters of each element8 ,in #b #a_/b cc8 ,how much ,h by volume is required to combine with nine volumes of ,n8 ,how many volumes of ,,nh#c are produced8 ,in elements that have not been weighed in the gaseous state1 as ,c1 the evidence of atomic volume is not direct1 but we will assume it4 ,thus two volumes of marsh gas would separate into one of ,c and four of ,h4 ,what is its symbol and supposed condensation8 ,two volumes of alcohol vapor resolve into two of ,c1 six of ,h1 and one of ,o4 ,what is its symbol8 its condensation8 ,the symbol itself of a compound will usually show what its condensation is2 e4g4 ,h,cl1 ,h,br1 ,,hf1 etc41 have two atoms2 hence there will be no shrinkage4 ,in ,h#b,o1 ,,so#b1 ,,co#b1 the molecule has three atoms condensed into the space of two1 or one-third shrinkage4 ,in ,,nh#c four volumes are crowded into the space of two1 a condensation of one-half4 ,p1 ,as1 ,hg1 ,zn1 have exceptional atomic volumes4 ,chapter ,,xv4 ,,acids ,,and ,,bases4 #ff4 ,what ,acids ,are4 ,experiment #ci4--,pour a few drops of chlorhydric acid1 ,h,cl1 into a clean evaporating-dish4 ,add #e cc4 ,h#b,o1 and stir4 ,touch a drop to the tongue1 noting the taste4 ,dip into it the end of a piece of blue litmus paper1 and record the result4 ,thoroughly wash the dish1 then pour in a few drops of nitric acid1 ,,hno#c1 and #e cc4 ,h#b,o1 and stir4 ,taste1 and test with blue litmus4 ,test in the same way sulphuric acid1 ,h#b,,so#d4 ,name two characteristics of an acid4 ,in a vertical line write the formulae of the acids above4 ,what element is common to them all8 ,is the rest of the formula positive or negative8 #fg4 ,an ,acid is a substance composed of ,h and a negative element or radical4 ,it has usually a sour taste1 and turns blue litmus red4 ,litmus is a vegetable extract obtained from lichens in ,southern ,europe4 ,acids have the same action on many other vegetable pigments4 ,are the following acid formulae1 and why8 ,h#b,,so#c1 ,h,br1 ,,hno#b1 ,h#c,,po#c1 ,h#d,si,o#d4 ,most acids have ,o as well as ,h4 ,complete the symbols for acids in the following list1 and name them1 from the type given3-- ,h,cl1 chlorhydric acid4 ,,hn#jc1 nitric acid4 8,br1 8 8,cl8 8 8,i1 8 8,br8 8 8,f1 8 8,i8 8 ,h#c,,po#d1 phosphoric acid4 ,h#c,,po#c1 phosphorous acid4 8,as8 8 8,as8 8 ,complete these equations3-- ,h#b,,so#c - ,h#b,o 8 #b ,,hn#jc - ,h#b,o 8 ,h#b,,so#d - ,h#b,o 8 #b ,,hno#b - ,h#b,o 8 ,h#b;,,co#c - ,h#b,o 8 #b ,h#c;,as,o#d - #c ,h#b,o 8 ,are the products in each case metallic or non-metallic oxides8 ,they are called anhydrides4 ,notice that each is formed by the withdrawal of water from an acid4 ,reverse the equations2 as1 ,,so#c ,h#b,o 8 #fh4 ,an ,anhydride is what remains after water has been removed from an acid2 or1 it is the oxide of a non- metallic element1 which1 united with water1 forms an acid4 ,,so#b is sulphurous anhydride1 ,,so#b sulphuric anhydride1 the ending ic meaning more ,o1 or negative element1 than ous4 ,name the others above4 ,anhydrides were formerly called acids1--anhydrous acids1 in distinction from hydrated ones1 as ,,co#b even now is often called carbonic acid4 ,experiment #dj4--;,hold a piece of wet blue litmus paper in the fumes of ,,so#b1 and note the acid test4 ,try the same with dry litmus paper4 ,experiment #da4--;,burn a little ,s in a receiver of air containing #aj cc4 ,h#b,o1 and loosely covered1 as in the ,o experiment4 ,then shake to dissolve the ,,so#b4 ,h#b,o ,,so#b ,h#b,,so#c4 ,apply test paper4 #fi4 ,naming ,acids4--,compare formulae ,h#b,,so#c and ,h#b,,so#d4 ,of two acids having the same elements1 the name of the one with least ,o1 or negative element1 ends in ous1 the other in ic4 ,h#b,,so#c is sulphurous acid1 ,h#b,,so#d1 sulphuric acid4 ,name ,h#c,,po#d and ,h#c,,po#c2 ,h#c;,as,o#c and ,h#c;,,aso#d2 ,,hno#b and ,,hno#c4 ,if there are more than two acids in a series1 the prefixes hypo1 less1 and per1 more1 are used4 ,the following is such a series3 ,h,cl,o1 ,h,cl,o#b1 ,h,cl,o#c1 ,h,cl,o#d4 ,h,cl,o#c is chloric acid2 ,h,cl,o#b1 chlorous2 ,h,cl,o1 hypochlorous2 ,h,cl,o#d perchloric4 ,hypo means less of the negative element than ous2 per means more of the negative element than ic4 ,name3 ,h#c,,po#d 7ic71 ,h#c,,po#c1 ,h#c,,po#b4 ,also ,h,br,o 7,h,br,o#b does not exist71 ,h,br,o#c 7ic71 ,h,br,o#d4 ,what are the three most negative elements8 ,note their occurrence in the three strongest and most common acids4 ,hereafter note the names and symbols of all the acids you see4 #gj4 ,what ,bases ,are4 ,experiment #db4--,put a few drops of ,,nh#d,,oh into an evaporating- dish4 ,add #e cc4 ,h#b,o1 and stir4 ,taste a drop4 ,dip into it a piece of red litmus paper1 noting the effect4 ,cleanse the dish1 and treat in the same way a few drops ,na,o,h solution1 recording the result4 ,do the same with ,,koh4 ,acid stains on the clothing1 with the exception of those made by ,,hno#c1 maybe removed by ,,nh#d,,oh4 ,h#b,,so#d1 however1 rapidly destroys the fiber of the cloth4 ,name two characteristics of a base4 ,in the formulae of those bases1 what two common elements8 ,name the radical4 ,compare those symbols with the symbol for water1 ,,hoh4 ,is 7,,oh7 positive or negative8 ,is the other part of each formula positive or negative8 ,what are two constituents1 then1 of a base8 ,bases are called hydrates4 ,write in a vertical line five positive elements4 ,note the valence of each1 and complete the formula for its base4 ,affix the names4 ,can you see any reason why the three bases above given are the strongest8 ,taking the valences of ,cr and ,fe1 write symbols for two sets of hydrates1 and name them4 ,try to recognize and name every base hereafter met with4 ,a ,base is a substance which is composed of a metal1 or positive radical1 and ,,oh4 ,it generally turns red litmus blue1 and often has an acrid taste4 ,an ,alkali is a base which is readily soluble in water4 ,the three principal alkalies are ,,nh#d,,oh1 ,,koh1 and ,na,o,h4 ,alkali ,metals are those which form alkalies4 ,name three4 ,an ,alkaline ,reaction is the turning of red litmus blue4 ,an ,acid ,reaction is the turning of blue litmus red4 ,experiment #dc4--,pour #e cc4 of a solution of litmus in water1 into a clean t4t4 or small beaker4 ,pour #b or #c cc4 of ,h,cl into an evaporating-dish1 and the same quantity of ,,nh#d,,oh into another dish4 ,take a drop of the ,h,cl on a stirring-rod and stir the litmus solution with it4 ,note the acid reaction4 ,clean the rod1 and with it take a drop 7or more if necessary7 of ,,nh#d,,oh1 and add this to the red litmus solution1 noting the alkaline reaction4 ,experiment in the same way with the two other principal acids and the two other alkalies4 ,litmus paper is commonly used to test these reactions1 and hereafter whenever the term ,,litmus is employed in that sense1 the test-paper should be understood4 ,this paper can be prepared by dipping unglazed paper into a strong aqueous solution of litmus4 ,,chapter ,,xvi4 ,,salts4 #ga4 ,acids and ,bases are usually ,opposite in ,character4--,when two forces act in opposition they tend to neutralize each other4 ,we may see an analogy to this in the union of the two opposite classes of compounds1 acids and bases1 to form salts4 #gb4 ,neutralization4 ,experiment #dd4--,put into an evaporating-dish #e cc4 of ,na,o,h solution4 ,add ,h,cl to this from a t4t41 a few drops at a time1 stirring the mixture with a glass rod 7,fig4 #bj71 and testing it with litmus paper1 until the liquid is neutral1 i4e4 will not turn the test paper from blue to red1 or red to blue4 ,test with both colors4 ,if it turns blue to red1 too much acid has been added2 if red to blue1 too much base4 ,when it is very nearly neutral1 add the reagent1 ,h,cl or ,na,o,h1 a drop at a time with the stirring-rod4 ,it must be absolutely neutral to both colors4 ,evaporate the water by heating the dish over asbestus paper1 wire gauze1 or sand1 in an iron plate 7,fig4 #ba7 till the residue becomes dry and white4 ,cool the residue1 taste1 and name it4 ,the equation is3 ,h,cl ,na,o,h ,na,cl ,,hoh or ,h#b,o4 ,note which elements1 positive or negative1 change places4 ,why was the liquid boiled8 ,the residue is a type of a large class of compounds1 called salts4 7,fig4 #bj7 7,fig4 #ba7 ,experiment #de4 -- ,experiment in the same way with ,,koh solution and ,h#b,,so#d1 applying the same tests4 ,h#b,,so#d #b ,,koh ,k#b,,so#d #b ,,hoh4 ,what is the solid product8 ,experiment #df4--,neutralize ,,nh#d,,oh with ,,hno#c1 evaporate1 apply the tests1 and write the equation4 ,write equations for the combination of ,na,o,h and ,h#b,,so#d2 ,na,o,h and ,,hno#c2 ,,koh and ,h,cl2 ,,koh and ,,hno#c2 ,,nh#d,,oh and ,h,cl2 ,,nh#d,,oh and ,h#b,,so#d4 ,describe the experiment represented by each equation1 and be sure you can perform it if asked to do so4 ,what is the usual action of a salt on litmus8 ,how is a salt made8 ,what else is formed at the same time8 ,have all salts a saline taste8 ,does every salt contain a positive element or radical8 ,a negative8 #gc4 ,a ,salt is the product of the union of a positive and a negative element or radical2 it may be made by mixing a base and an acid4 ,the salt ,,ki represents what acid8 ,what base1 or hydrate8 ,write the equation for making ,,ki from its acid and base4 ,describe the experiment in full4 ,classify1 as to acids1 bases1 or salts3 ,k,br1 ,fe7,,oh7#b1 ,,hi1 ,na,br1 ,,hno#b1 ,al#b7,,oh7#f1 ,k,cl,o#c1 ,h,cl,o#c1 ,h#b,s1 ,k#b,s1 ,h#b,s#jc1 ,k#b,,so#d1 ,ca7,,oh7#b1 ,ca,c,o#c1 ,na,br#jc1 ,ca,s,o#d1 ,h#b;,,co#c1 ,k#b;,,co#c1 ,cu7,,oh7#b1 ,cu7,,no#c7b1 ,pb,s,o#d1 ,h#c,p#jd1 ,na#b,p#jd4 ,in the ,,salts above1 draw a light vertical line1 separating the positive from the negative part of the symbol4 ,now state what acid each represents4 ,what base4 ,write the reaction in the preparation of each salt above from its acid and base2 then state the experiment for producing it4 #gd4 ,naming ,salts4--7,,no#c7 is the nitrate radical2 ,,kno#c is potassium nitrate4 ,from what acid8 7,,no#b7 is the nitrite radical2 ,,kn#jb is potassium nitrite4 ,from what acid8 ,note that the endings of the acids are ,,ous and ,,ic2 also that the names of their salts end in ,,ite and ,,ate4 ,from which acid--,,ic or ,,ous--is the salt ending in ,,ate derived8 ,that ending in ,,ite8 ,name these salts1 the acids from which they are derived1 and the endings of both acids and salts3 ,na,n,o#c1 ,na,n,o#b1 ,k#b,,so#d1 ,k#b,,so#c1 ,ca,s,o#d1 ,ca,s,o#c1 ,k,cl,o#c1 ,k,cl,o#b1 ,k,cl,o1 ,k,cl,o#d 7use prefixes ,,hypo and ,,per1 as with acids71 ,ca#c7,,po#d7b1 ,ca#c7,p#jc7b1 ,cu,s,o#d1 ,cu,s,o#c1 ,ag,n,o#c1 ,cu7,,no#c7b4 ,fe,s1 ,fe,s#b1 are respectively ,,ferrous ,,sulphide and ,,ferric ,,sulphide4 ,name3 ,hg,cl1 ,hg,cl#b1 ,fe,cl#b1 ,fe#b;,cl#f1 ,fe,s,o#d1 ,fe#b7,,so#d7c4ge4 ,acid ,salts4--,write symbols for nitric1 sulphuric1 phosphoric acids4 ,how many ,h atoms in each8 ,replace all the ,h in the symbol of each with ,na1 and name the products4 ,again1 in sulphuric acid replace one atom of ,h with ,na2 then in phosphoric replace first one1 then two1 and finally three ,h atoms with ,na4 ,h,na,s,o#d is hydrogen sodium sulphate2 ,h,na#b,p#jd is hydrogen di-sodium phosphate4 ,name the other salts symbolized4 ,name ,h,na,n,h#d,p#jd4 ,though these products are all salts1 some contain replaceable ,h1 and are called acid salts4 ,those which have all the ,h replaced by a metal are normal salts4 ,name and classify1 as to normal or acid salts3 ,na#b;,,co#c1 ,h,na,c,o#c1 ,k#b,,so#d1 ,,hkso#d1 7,,nh#d7b,,so#d1 ,,hnh#d,,so#d1 ,na#c,p#jd1 ,h,na#b,p#jd1 ,h#b,na,p#jd4 ,the ,,basicity of an acid is determined by the number of replaceable ,h atoms in its molecule4 ,it is called ,,monobasic if it has one2 ,,dibasic if two2 ,,tri- if three1 etc4 ,note the basicity of each acid named above4 ,how many possible salts of ,h#b,,so#d with ,na8 ,of ,h#c,p#jd with ,na8 ,which are normal and which acid8 ,what is the basicity of ,h#d,si#jd8 ,some normal1 as well as acid1 salts change litmus4 ,na#b;,,co#c1 representing a strong base and a weak acid1 turns it blue4 ,there are other modes of obtaining salts1 but this is the only one which we sball consider4 #gf4 ,salts ,occur ,abundantly in ,nature1 such as ,na,cl1 ,mg,s,o#d1 ,ca,c,o#c4 ,acids and bases are found in small quantities only4 ,why is this8 ,why are there not springs of ,h#b,,so#d and ,,nh#d,,oh8 ,we have seen that acids and bases are extremely active1 have opposite characters1 and combine to form relatively inactive salts4 ,if they existed in the free state1 they would soon combine by reason of their strong affinities4 ,this is what in all ages of the world has taken place1 and this is why salts are common1 acids and bases rare4 ,active agents rarely exist in the free state in large quantities4 ,oxygen seems to be an exception1 but this is because there is a superabundance of it4 ,while vast quantities are locked up in compounds in rocks1 water1 and salts of the earth1 much remains with which there is nothing to combine4 ,,chapter ,,xvii4 ,,chlorhydric ,,acid4 #gg4 ,we have seen that salts are made by the union of acids and bases4 ,can these last be obtained from salts8 #gh4 ,preparation of ,h,cl4 ,experiment #dg4--;,into a flask put #aj g4 coarse ,na,cl1 and add #bj cc4 ,h#b,,so#d4 ,connect with ,woulff bottles ,woulff bottles may be made by fitting to wide-mouthed bottles corks with three holes1 through which pass two delivery tubes1 and a central safety tube dipping into the liquid1 as in ,figures #bb and #bc4 partly filled with water1 as in ,figure #bb4 ,one bottle is enough to collect the ,h,cl2 but in that case it is less pure1 since some ,h#b,,so#d and other impurities are carried over4 ,several may be connected1 as in ,figure #bc4 ,the water in the first bottle must be nearly saturated before much gas will pass into the second4 ,heat the mixture #ae or #bj minutes1 not very strongly1 to prevent too much foaming4 ,notice any current in the first bottle4 ,na,cl ,h#b,,so#d ,h,na,s,o#d ,h,cl4 ,intense heat would have given3 #b,na,cl ,h#b,,so#d ,na#b,,so#d #b;,h,cl4 ,compare these equations with those for ,,hno#c4 ,in which equation above is ,h#b,,so#d used most economically8 ,both reactions take place when ,h,cl is made on the large scale4 7,fig4 #bb7 #gi4 ,tests4 ,experiment #dh4--7a7 ,test with litmus the liquid in each ,woulffbottle4 7#b7 ,put a piece of ,zn into a t4t4 and cover it with liquid from the first bottle4 ,write the reaction1 and test the gas4 7#c7 ,to #b cc4solution ,ag,n,o#c in a t4t4 add #b cc4of the acid4 ,describe1 and write the reaction4 ,is ,ag,cl soluble in water8 7#d7 ,into a t4t4 pour #e cc4,pb7,,no#c7b solution1 and add the same amount of prepared acid4 ,give the description and the reaction4 7#e7 ,in the same way test the acid with ,hg#b7,,no#c7b solution1 giving the reaction4 7#f7 ,drake a little ,h,cl in a t4t41 and bring the gas escaping from the d4t4 in contact with a burning stick4 ,does it support the combustion of ,c8 7#g7 ,hold a piece of dry litmus paper against it4 figure #bc 7#h7 ,hold it over #b cc4of ,,nh#d,,oh in an evaporating-dish4 ,describe1 name the product1 and write the reaction4 7#c71 7#d71 7#e71 7#h71 are characteristic tests for this acid4 #hj4 ,chlorhydric1 ,hydrochloric or ,muriatic1 ,acid is a ,gas4--,as used1 it is dissolved1 in water1 for which it has great affinity4 ,water will hold1 according to temperature1 from #djj to #ejj times its volume of ,h,cl4 ,hundreds of thousands of tons of the acid are annually made1 mostly in ,europe1 as a bye-product in ,na#b;,,co#c manufacture4 ,the gas is passed into towers through which a spray of water falls2 this absorbs it4 ,the yellow color in most commercial ,h,cl indicates impurities1 some of which are ,fe1 ,s1 ,as1 and organic matter4 ,as1 ,s1 etc41 come from the pyrites used in making ,h#b,,so#d4 ,chemically pure 7,c4,p47 acid is freed from these1 and is without color4 ,the gas may be dried by passing it through a glass tube holding ,ca,cl#b 7,fig4 #af7 and collecting it over mercury4 ,the muriatic acid of commerce consists of about two- thirds water by weight4 ,h,cl can also be made by direct union of its constituents4#ha4 ,uses4--,h,cl is used to make ,cl1 and also bleaching- powder4 ,its use as a reagent in the laboratory is illustrated by the following experiment3-- ,experiment #di4--,put into a t4t4 #b cc4 ,ag,n,o#c solution1 add #e cc4 ,h#b,o1 then add slowly ,h,cl so long as a ppt4 7precipitate7 is formed4 ,this ppt4 is ,ag,cl4 ,now in another t4t4 put #b cc4 ,cu7,,no#c7b1 solution1 add #e cc4 ,h#b,o1 then a little ,h,cl4 ,no ppt4 is formed4 ,now if a solution of ,ag,n,o#c and a solution of ,cu7,,no#c7b were mixed1 and ,h,cl added1 it is evident that the silver would be precipitated as chloride of silver1 while the copper would remain in solution4 ,if now this be filtered1 the silver will remain on the filter paper1 while in the filtrate will be the copper4 ,thus we shall have performed an analysis1 or separated one metal from another4 ,perform it4 ,note1 however1 that any soluble chloride1 as ,na,cl1 would produce the same result as ,h,cl4 ,,bromhydric ,,and ,,iodihydric ,,acids4 #hb4 ,na,cl1 being the most abundant compound of ,cl1 is the source of commercial ,h,cl4 ,k,cl treated in the same way would give a like product4 ,theoretically ,h,br and ,,hi might be made in the same way from ,na,br and ,na,i1 but the affinity of ,h for ,br and ,i is weak1 and the acids separate into their elements1 when thus prepared4 #hc4 ,to make ,,hi4 ,experiment #ej4--;,drop into a t4t4 three or four crystals of ,i1 and add #aj cc4 ,h#b,o4 ,hold in the water the end of a d4t4 from which ,h#b,s gas is escaping4 ,observe any deposit1 and write the reaction4 ,,fluorhydric ,,acid4 #hd4 ,preparation and ,action4 ,experiment #ea4--,put #c or #d g4 powdered ,ca,f#b1 i4e4 fluor spar or fluorite1 into a shallow lead tray1 e4g4 #dx#e cm1 and pour over it #d or #e cc4 ,h#b,,so#d4 ,a piece of glass large enough to cover this should previously be warmed and covered on one side with a very thin coat of beeswax4 ,to distribute itevenly1 warm the other side of the glass over a flame4 ,when cool1 scratch a design 7,fig4 #bd7 through the wax with a sharp metallic point4 ,lay the glass1 film side down1 over the lead tray4 ,warm this five minutes or more by placing it high over a small flame 7,fig4 #be7 to avoid melting the wax4 ,do not inhale the fumes4 ,take away the lamp1 and leave the tray and glass where it is not cold1 for half an hour or more4 ,then remove the wax and clean the glass with naphtha or benzine4 ,look for the etching4 ,two things should have occurred3 7#a7 the generation of ,,hf4 ,write the equation for it4 7#b7 ,its etching action on glass4 ,in this last process ,,hf acts on ,si,o#b of the glass1 forming ,h#b,o and ,si,f#d4 ,why cannot ,,hf be kept in glass bottles8 ,a dilute solution of ,,hf1 which is a gas1 may be kept in gutta percha bottles1 the anhydrous acid in platinum only2 but for the most part1 it is used as soon as made1 its chief use being to etch designs on glass-ware4 ,glass is also often etched by a blast of sand 7,si,o#b74 ,notice the absence of ,o in the acids ,,hf1 ,,hci1 ,h,br1 ,,hi1 and that each is a gas4 ,,hf is the only acid that will dissolve or act appreciably on glass4 ,chapter ,,xviii4 ,,nitric ,,acid4 #he4 ,preparation4 ,experiment #eb4--,to #aj g4 ,,kno#c or ,na,n,o#c1 in a flask1 add #ae cc4 ,h#b,,so#d4 ,securely fasten the cork of the d4t41 as ,,hno#c is likely to loosen it1 and pass the other end to the bottom of a t4t4 held deep in a bottle of water 7,fig4 #bf74 ,apply heat1 and collect #d or #e cc4of the liquid4 ,the usual reaction is3 ,,kno#c ,h#b,,so#d ,,hkso#d ,,hno#c4 ,with greater heat1 #b ,,kno#c ,h#b,,so#d ,k#b,,so#d #b;,,hno#c4 ,which is most economical of ,,kno#c8 ,of ,h#b,,so#d8 ,instead of a flask1 a t4t4 may be used if desired 7,fig4 #bg74 #hf4 ,properties and ,tests4 ,experiment #ec4--7a7 ,note the color of the prepared liquid4 7#b7 ,put a drop on the finger2 then wash it off at once4 7#c7 ,dip a quill or piece of white silk into it2 then wash off the acid4 ,what color is imparted to animal substances8 7#d7 ,add a little to a few bits of ,cu turnings1 or to a ,cu coin4 ,write the equation4 7#e7 ,to #b cc4indigo solution1 add #b cc4 ,,hno#c4 ,state the leading properties of ,,hno#c1 from these tests4 #hg4 ,chemically ,pure ,,hno#c is a ,colorless ,liquid4-- ,the yellow color of that prepared in ,experiment #eb is due to liquid ,,no#b dissolved in it4 ,it is then called fuming ,,hno#c1 and is very strong4 ,,no#b is formed at a high temperature4 ,commercial or ordinary ,,hno#c1 is made from ,na,n,o#c1 this being cheaper than ,,kno#c2 it is about half water4 #hh4 ,uses4 ,,hno#c is the basis of many nitrates1 as ,ag,n,o#c1 used for photography1 ,ba7,,no#c7b and ,sr7,,no#c7b for fire-works1 and others for dyeing and printing calico2 it is employed in making aqua regia1 sulphuric acid1 nitro-glycerine1 gun-cotton1 aniline colors1 zylonite1 etc4 ,enough experiments have been performed to answer the question whether some acids can be prepared from their salts4 ,h#b,,so#d is not so made1 because no acid is strong enough to act on its salts4 ,in making ,h,cl1 ,,hno#c1 etc41 sulphuric acid was used1 being the strongest4 ,,aqua ,,regia4 #hi4 ,preparation and ,action4 ,experiment #ed4--;,into a t4t4 put #b cc4 ,,hno#c1 and #ad qcm4 of either ,au leaf or ,pt4 ,warm in a flame4 ,if the metal is pure1 no action takes place4 ,into another tube put #f cc4 ,h,cl and add a similar leaf4 ,heat this also4 ,there should be no action4 ,pour the contents of one t4t4 into the other4 ,note the effect4 ,which is stronger1 one of the acids1 or the combination of the two8 ,note the odor4 ,it is that of ,cl4 #c;,h,cl ,,hno#c ,n,o,cl #b;,h#b,o ,cl#b4 ,this reaction is approximate only4 ,the strength is owing to nascent chlorine1 which unites with ,au4 ,au #c;,cl ,au,cl#c4 ,if ,pt be used1 ,pt,cl#d is produced4 ,no other acid except nitro-hydrochloric will dissolve ,au or ,pt2 hence the ancients called it aqua regia1 or king of liquids4 ,it must be made as wanted1 since it cannot be kept and retain its strength4 ,,chapter ,,xix4 ,,sulphuric ,,acid4 #ij4 ,preparation4 ,experiment #ee4--;,having fitted a cork with four or five perforations to a large t4t41 pass a d4t4 from three of these to three smaller t4t41 leaving the others open to the air1 as in ,figure #bh4 ,into one t4t4 put #e cc4 ,h#b,o1 into another #e g4 ,cu turnings and #aj cc4 ,h#b,,so#d1 into the third #e g4 ,cu turnings and #aj cc4 dilute ,,hno#c1 half water4 ,hang on a ring stand1 and slowly heat the tubes containing ,h#b,o and ,h#b,,so#d4 ,notice the fumes that pass into the large t4t4 ,trace out and apply to ,figure #bh these reactions3-- 7#a7 ,cu #b ,h#b,,so#d ,cu,s,o#d #b ,h#b,o ,,so#b4 7#b7 #c ,cu #h ,,hno#c #c ,cu7,,no#c7b #d ,h#b,o #b ,,no4 7#c7 ,,no ,o ,,no#b4 7#d7 ,,so#b ,h#b,o ,,no#b ,h#b,,so#d ,,no4 7#d7 comes from combining the gaseous products in 7#a71 7#b71 7#c74 ,in 7#c71 ,,no takes an atom of ,o from the air1 becoming ,,no#b1 and at once gives it up1 to the ,h#b,,so#c 7,h#b,o ,,so#b71 making ,h#b,,so#d1 and again goes through the same operation of taking up ,o and passing it along4 ,,no is thus called a carrier of ,o4 ,it is a reducing agent1 while ,,no#b is an oxidizing agent4 ,this is a continuous process1 and very important1 since it changes useless ,h#b,,so#c into valuable ,h#b,,so#d4 ,if exposed to the air1 ,h#b,,so#c would very slowly take up ,o and become ,h#b,,so#d4 ,instead of the last experiment1 this may be employed if preferred3 ,burn a little ,s in a receiver4 ,put into an evaporating-dish1 #e cc4 ,,hno#c1 and dip a paper or piece of cloth into it4 ,hang the paper in the receiver of ,,so#b1 letting no ,,hno#c drop from it4 ,continue this operation till a small quantity of liquid is found in the bottle4 ,the fumes show that ,,hno#c has lost ,o4 #b ,,hno#c ,,so#b ,h#b,,so#d #b ,,no#b4 #ia4 ,tests for ,h#b,,so#d4 ,experiment #ef4--7a7 ,test the liquid with litmus4 7#b7 ,transfer it to a t4t41 and add an equal volume of ,ba,cl#b solution4 ,h#b,,so#d ,ba,cl#b 8 ,is ,ba,s,o#d soluble8 7#c7 ,put one drop ,h#b,,so#d from the reagent bottle in #aj cc4 ,h#b,o in a clean t4t41 and add #a cc4 ,ba,cl#b solution4 ,look for any cloudiness4 ,this is the characteristic test for ,h#b,,so#d and soluble sulphates1 and so delicate that one drop in a liter of ,h#b,o can be detected4 7#d7 ,instead of ,h#b,,so#d1 try a little ,na#b,,so#d solution4 7#e7 ,put two or three drops of strong ,h#b,,so#d on writing-paper1 and evaporate1 high over a flame1 so as not to burn the paper4 ,examine it when dry4 7#f7 ,put a stick into a t4t4 containing #b cc4 ,h#b,,so#d1 and note the effect4 7#g7 ,review ,experiment #e4 7#h7 ,into an e4d4 pour #e cc4 ,h#b,o1 and then #ae cc4 ,h#b,,so#d4 ,stir it meantime with a small t4t4 containing #b or #c cc4 ,,nh#d,,oh1 and notice what takes place in the latter2 also note the heat of the e4d4 ,the effects of 7#e71 7#f71 7#g71 and 7#h7 are due to the intense affinity which ,h#b,,so#d has for ,h#b,o4 ,so thirsty is it that it even abstracts ,h and ,o from oxalic acid in the right proportion to form ,h#b,o1 combines them1 and then absorbs the water4 #ib4 ,affinity for ,water4--,this acid is a desiccator or dryer1 and is used to take moisture from the air and prevent metallic substances from rusting4 ,in this way it dilutes itself1 and may increase its weight threefold4 ,in diluting1 the acid must always be poured into the water slowly and with stirring1 not water into the acid1 since1 as ,h#b,o is lighter than ,h#b,,so#d1 heat enough may be set free at the surface of contact to cause an explosion4 ,contraction also takes place1 as may be shown by accurately measuring each liquid in a graduate1 before mixing1 and again when cold4 ,the mixture occupies less volume than the sum of the two volumes4 ,for the best results the volume of the acid should be about three times that of the water4 #ic4 ,sulphuric ,acid made on a ,large ,scale involves the same principles as shown in ,experiment #ee1 excepting that ,s#jb is obtained by burning ,s or roasting ,fe,s#b 7pyrite71 ,fig4 #bi4 and ,,hno#c is made on the spot from ,na,n,o#c and ,h#b,,so#d4 ,,so#b enters a large leaden chamber1 often #ajj to #cjj feet long1 and jets of steam and small portions of ,,hno#c are also forced in4 ,the chamber acid thus formed is very dilute1 and must be evaporated first in leaden pans1 and finally in glass or platinum retorts1 since strong ,h#b,,so#d1 especially if hot1 dissolves lead4 ,see ,experiment #abd4 ,study ,figure #bi1 and write the reactions4 #b ,,hno#c breaks up into #b ,,no#b1 ,h#b,o1 and ,o4 #id4 ,importance4--,sulphuric acid has been called1 next to human food1 the most indispensable article known4 ,there is hardly a product of modern civilization in the manufacture of which it is not directly or indirectly used4 ,nearly a million tons are made yearly in ,great ,britain alone4 ,it is the basis of all acids1 as ,na#b;,,co#c is of alkalies4 ,it is the life of chemical industry1 and the quantity of it consumed is an index of a people's civilization4 ,only a few of its uses can be stated here4 ,the two leading ones are the reduction of ,ca#c7,,po#d7b for artificial manures and the sodium carbonate manufacture4 ,foods depend on the productiveness of soils and on fertilizers1 and thus indirectly our daily bread is supplied by means of this acid2 and from sodium carbonate glass1 soap1 saleratus1 baking- powders1 and most alkalies are made directly or indirectly4 ,h#b,,so#d is employed in bleaching1 dyeing1 printing1 telegraphy1 electroplating1 galvanizing iron and wire1 cleaning metals1 refining ,au and ,ag1 making alum1 blacking1 vitriols1 glucose1 mineral waters1 ether1 indigo1 madder1 nitroglycerine1 gun- cotton1 parchment1 celluloid1 etc41 etc4 ,,fuming ,,sulphuric ,,acid4 #ie4 ,nordhausen or ,fuming ,sulphuric ,acid1 ,h#b,s#bjg used in dissolving indigo and preparing coal-tar pigments1 is made by distilling ,fe,s,o#d4 #d;,fe,s,o#d ,h#b,o ,h#b,s#bjg #b;,fe#bjc #b,s#jb4 ,this was the original sulphuric acid4 ,it is also formed when ,s#jc is dissolved in ,h#b,,so#d4 ,when exposed to the air1 ,s#jc escapes with fuming4 ,,chapter ,,xx4 ,,ammonium ,,hydrate4 #if4 ,preparation of ,bases4--,we have seen that many acids are made by acting on a salt of the acid required1 with a stronger acid4 ,this is the direct way4 ,the following experiments will show that bases may be prepared in a similar way by acting on salts of the base required with other bases1 which we may regard as stronger than the ones to be obtained4 #ig4 ,preparation of ,,nh#d,,oh and ,,nh#c4 ,experiment #eg4--,powder #aj g4 ammonium chloride1 ,,nh#d;,cl1 in a mortar and mix with #aj g4 calcium hydrate1 ,ca7,,oh7#b2 recently slaked lime is the best4 ,cover with water in a flask1 and connect with ,woulff bottles1 as for making ,h,cl 7,fig4 #bb72 heat the flask for fifteen minutes or more4 ,the experiment may be tried on a smaller scale with a t4t4 if desired4 ,the reaction is3 #b,,nh#d;,cl ,ca7,,oh7#b ,ca,cl#b #b,,nh#d,,oh4 ,,nh#d,,oh is broken up into ,,nh#c1 ammonia gas1 and water4 ,,nh#d,,oh ,,nh#c ,h#b,o4 ,these pass over into the first bottle1 where the water takes up the ,,nh#c1 for which it has great affinity4 ,one volume of water at #j will absorb more than #ajjj volumes of ,,nh#c4 ,thus ,,nh#d,,oh may be called a solution of ,,nh#c1 in ,h#b,o4 ,write the reaction4 ,experiment #eh4--,powder and mix #b or #c g4 each of ammonium nitrate1 ,,nh#d,,no#c1 and ,ca7,,oh7#b2 put them into a t4t41 and heat slowly4 ,note the odor4 #b,,nh#d,,no#c ,ca7,,oh7#b 8 #ih4 ,tests4 ,experiment #ei4--7a7 ,generate a little of the gas in a t4t41 and note the odor4 7#b7 ,test the gas with wet red litmus paper4 7#c7 ,put a little ,h,cl into an e4d41 and pass over it the fumes of ,,nh#c from a d4t4 ,note the result1 and write the equation4 7#d7 ,fill a small t4t4 with the gas by upward displacement2 then1 while still inverted1 put the mouth of the t4t4 into water4 ,explain the rise of the water4 7#e7 ,how might ,,nh#d;,cl be obtained from the ,,nh#d,,oh in the ,woulff bottles8 7#f7 ,test the liquid in each bottle with red litmus paper4 7#g7 ,add some from the first bottle to #e or #aj cc4 of a solution of ,fe,s,o#d or ,fe,cl#b1 and look for a ppt4 ,state the reaction4 #ii4 ,formation4--,ammonia1 hartshorn1 exists in animal and vegetable compounds1 in salts1 and1 in small quantities1 in the atmosphere4 ,rain washes it from the atmosphere into the soil2 plants take it from the soil2 animals extract it from plants4 ,coal1 bones1 horns1 etc41 are the chief sources of it1 and from them it is obtained by distillation4 ,it results also from decomposing animal matter4 ,,nh#c can be produced by the direct union of ,n and ,h1 only by an electric discharge or by ozone4 ,it may be collected over ,hg like other gases that are very soluble in water4 #ajj4 ,uses4 --,ammonium hydrate1 ,,nh#d,,oh1 and ammonia1 ,,nh#c1 are used in chemical operations1 in making artificial ice1 and to some extent in medicine2 from them also may be obtained ammonium salts4 ,state what you would put with ,,nh#d,,oh to obtain 7,,nh#d7b,,so#d4 ,to obtain ,,nh#d,,no#c4 ,the use of ,,nh#d,,oh in the laboratory may be illustrated by the following experiment3-- ,experiment #fj4--;,into a t4t4 put #aj cc4 of a solution of ferrous sulphate1 ,fe,s,o#d4 ,into another put #aj cc4 of sodium sulphate solution1 ,na#b,,so#d4 ,add a little ,,nh#d,,oh to each4 ,notice a ppt4 in the one case but none in the other4 ,if solutions of these two compounds were mixed1 the metals ,fe and ,na could be separated by the addition of ,,nh#d,,oh1 similar to the separation of ,ag and ,cu by ,h,cl4 ,try the experiment4 ,,chapter ,,xxi4 ,,sodium ,,hydrate4 #aja4 ,preparation4 ,experiment #fa4--;,dissolve #c g4 sodium carbonate1 ,na#b;,,co#c1 in #aj or #ae cc4 ,h#b,o in an e4d41 and bring it to the boiling-point4 ,then add to this a mixture of #a or #b g4 calcium hydrate1 ,ca7,,oh7#b1 in #e or #aj;cc4 ,h#b,o4 ,it will not dissolve4 ,boil the whole for five minutes4 ,then pour off the liquid which holds ,na,o,h in solution4 ,evaporate if desired4 ,this is the usual mode of preparing ,na,o,h4 ,the reaction is ,na#b;,,co#c ,ca7,,oh7#b #b,na,o,h ,ca,c,o#c4 ,the residue is ,ca7,,oh7#b and ,ca,c,o#c2 the solution contains ,na,o,h1 which can be solidified by evaporating the water4 ,sodium hydrate is an ingredient in the manufacture of hard soap1 and for this use thousands of tons are made annually1 mostly in ,europe4 ,it is an important laboratory reagent1 its use being similar to that of ammonium hydrate4 ,exposed to the air1 it takes up water and ,,co#b1 forming a mixture of ,na,o,h and ,na#b;,,co#c4 ,it is one of the strongest alkalies1 and corrodes the skin4 ,experiment #fb4--,put #bj cc4 of ,h#b,o in a receiver4 ,with the forceps take a piece of ,na1 not larger than half a pea1 from the naphtha in which it is kept1 drop it into the ,h#b,o1 and at once cover the receiver loosely with paper or cardboard4 ,watch the action1 as the ,na decomposes ,h#b,o4 ,,hoh ,na ,na,o,h ,h4 ,if the water be hot the action is so rapid that enough heat is produced to set the ,h on fire4 ,that the gas is ,h can be shown by putting the ,na under the mouth of a small inverted t4t41 filled with cold water1 in a water-pan4 ,na rises to the top1 and the t4t4 fills with ,h1 which can be tested4 ,na,o,h dissolves in the water4#ajb4 ,properties4 ,experiment #fc4--7a7 ,test with red litmus paper the solutions obtained in the last two experiments4 7#b7 ,to #e;cc4of alum solution1 ,k#b;,a#ab7,,so#d7d1 add #b;cc4of the liquid1 and notice the color and form of the ppt4 ,,potassium ,,hydrate4 #ajc4 ,,koh is made in the ,same ,way as ,na,o,h4 ,describe the process in full 7,experiment #fa71 and give the equation4 ,experiment #fd4--;,drop a small piece of ,k into a receiver of ,h#b,o1 as in ,experiment #fb4 ,the ,k must be very small1 and the experiment should not be watched at too close a range4 ,the receiver should not be covered with glass1 but with paper4 ,the ,h burns1 uniting with ,o of the air4 ,the purple color is imparted by the burning1 or oxidation of small particles of ,k4 ,write the equation for the combustion of each4 ,h#b,o might be considered the symbol of an acid1 since it is the union of ,h and a negative element2 or1 if written ,,hoh1 it might be called a base1 since it has a positive element and the 7,,oh7 radical4 ,it is neutral to litmus1 and on this account might be called a salt4 ,it is better1 however1 to call it simply an oxide4 ,potassium hydrate1 caustic potash1 is employed for the manufacture of soft soap4 ,as a chemical reagent its action is almost precisely like that of caustic soda1 though it is usually considered a stronger base1 as ,k is a more electro-positive element than ,na4 ,,calcium ,,hydrate4 #ajd4 ,calcium ,hydrate1 the ,most ,common of the ,bases1 is nearly as important to them as ,h#b,,so#d is to acids4 ,since it is used to make the other bases1 it might be called the strongest base2 as ,h#b,,so#d is often called the strongest acid4 ,the strength of an acid or base1 however1depends on the substance to which it is applied1 as well as on itself1 and for most purposes this one is classified as a weaker base than the three previously described4 ,sulphuric acid1 the most useful of the acids1 is not made directly from its salts1 but has to be synthesized4 ,calcium hydrate is also made by an indirect process1 as follows3 ,ca,c,o#c1 i4e4 limestone1 marble1 etc41 is burnt in kilns with ,c1 a process which separates the gas1 ,,co#b1 according to the reaction3 ,ca,c,o#c ,ca,o ,,co#b4 ,ca,o is unslaked lime1 or quick-lime4 ,on treating this with water1 slaked lime1 ,ca7,,oh7#b is formed1 with generation of great heat4 ,ca,o ,h#b,o ,ca7,,oh7#b4 ,its affinity for ,h#b,o is so great that it takes the latter from the air1 if exposed4 ,experiment #fe4--,saturate some unslaked lime with water1 in an e4d41 and look for the results stated above1 leaving it as long as may be necessary4 #aje4 ,resume4--,from the experiments in the last few chapters on the three divisions of chemical compounds1 acids1 bases and salts1 we have seen 7#a7 that acids and bases are the chemical opposites of each other2 7#b7 that salts are formed by the union of acids and bases2 7#c7 that some acids can be obtained from their salts by the action of a stronger acid2 7#d7 that some bases can be got from salts by the similar action of other bases2 7#e7 that the strongest acids and bases1 as well as others1 may be obtained in an indirect way by synthesis4 ,,chapter ,,xxii4 ,,oxides ,,of ,,nitrogen4 #ajf4 ,there are five oxides of ,n1 only two of which are important4 ,,nitrogen ,,monoxide 7,n#b,o74 #ajg4 ,preparation4 ,experiment #ff4--,put into a flask1 holding #bjj;cc1 l,og of ammonium nitrate1 ,,nh#d,,no#c2 heat it over wire gauze or asbestus in an iron plate1 having a d4t4 connected with a large t4t41 which is held in a receiver of water1 and from this t4t41 another d4t4 passing into a pneumatic trough1 so as to collect the gas over water 7,fig4 #cj74 ,have all the bearings tight4 ,the reaction is ,,nh#d,,no#c #b;,h#b,o ,n#b,o4 ,the t4t4 is for collecting the ,h#b,o4 ,fig4 #cj4 ,note the color of the liquid in the t4t42 taste a drop1 and test it with litmus4 ,if the flask is heated too fast1 some ,,no is formed1 and this taking ,o from the air makes ,,no#b1 which liquefies and gives an acid reaction and a red color4 ,some ,,nh#d,,no#c is also liable to be carried over4 #ajh4 ,properties4 ,experiment #fg4--,test the gas in the receiver with a burning stick and a glowing one1 and compare the combustion with that in ,o4 ,n#bjmay also be tested with ,s and ,p1 if desired4 ,n is set free in each case4 ,write the reactions4 ,nitrogen monoxide or protoxide1 the nitrous oxide of dentists1 when inhaled1 produces insensibility to pain1-- anaesthesia1-- and1 if continued1 death from suffocation4 ,birds die in half a minute from breathing it4 ,mixed with one-fourth ,o1 and inhaled for a minute or two1 it produces intoxication and laughter1 and hence is called laughing gas4 ,as made in ,experiment #ff1 it contains ,cl and ,,no1 as impurities1 and should not be breathed4 ,,nitrogen ,,dioxide 7,,no1 ,,or ,n#b,o#b74 #aji4 ,preparation4 ,experiment #fh4--;,into a t4t4 or receiver put #e;g ,cu turnings1 add #e cc4 ,h#b,o and #e cc4 ,,hno#c4 ,collect the gas like ,h1 over water4 #c;,cu #h;,,hno#c 8 ,what two products will be left in the generator8 ,notice the color of the liquid4 ,this color is characteristic of ,cu salts4 ,notice also the red fumes of ,,no#b4 #aaj4 ,properties4 ,experiment #fi4--,test the gas with a burning stick1 admitting as little air as possible4 ,test it with burning ,s4 ,,no is not a supporter of ,c and ,s combustion4 ,put a small bit of ,p in a deflagrating-spoon1 and when it is vigorously burning1 lower it into the gas4 ,it should continue to burn4 ,state the reaction4 ,what combustion will ,,no support8 ,note that ,,no is half ,n1 while ,n#b,o is two-thirds ,n1 and account for the difference in supporting combustion4 ,,nitrogen ,,tetroxide 7,,no#b or ,n#b,o#d74 #aaa4 ,preparation4 ,experiment #gj4--,lift from the water-pan a receiver of ,,no1 and note the colored fumes4 ,they are ,,no#b1 or ,n#b,o#d1 nitrogen tetroxide4 ,,no ,o ,,no#b4 ,is ,,no combustible8 ,what is the source of ,o in the experiment8,,oxides ,,of ,,nitrogen4 ,,nitrogen ,,trioxide 7,n#b,o#c74 #aab4 ,preparation4 ,experiment #ga4--,put into a t4t4 #a g4 of starch and #a cc4 of ,,hno#c4 ,heat the mixture for a minute4 ,the red fumes are ,n#b,o#c and ,,no#b4 ,nitrogen pentoxide1 ,n#b,o#e1 is an unimportant solid4 ,united with water it forms ,,hno#c4 ,n#b,o#e ,h#b,o #b;,,hno#c4 ,,chapter ,,xxiii4 ,,laws ,,of ,,definite ,,and ,,of ,,multiple ,,proportion4 #aac4 ,weight and ,volume4--,we have seen that water contains two parts of ,h by volume to one part of ,o2 or1 by weight1 two parts of ,h to sixteen of ,o4 ,these proportions are invariable1 or no symbol for water would be possible4 ,every compound in the same way has an unvarying proportion of elements4 #aad4 ,law of ,definite ,proportion4--,in a given compound the proportion of any element by weight1 or1 if a gas1 by volume is always constant4 ,apply the law1 by weight and by volume1 to these3 ,h,cl1 ,,nh#c1 ,h#b,s1 ,n#b,o4 ,there is another law of equal importance in chemistry1 which the compounds of ,n and ,o well illustrate4 ,weight4 ,volume4 ,n4 ,o4 ,n4 ,o4 ,nitrogen protoxide ,n#b,o #bh #af #b #a ,nitrogen dioxide ,n#b,o#b #bh #cb #b #b ,nitrogen trioxide4 ,n#b,o#c #bh #dh #b #c ,nitrogen tetroxide ,n#b,o#d #bh #fd #b #d ,nitrogen pentoxide ,n#b,o#e #bh #hj #b #e ,note that the proportion of ,o by weight is in each case a multiple of the first1 #af4 ,also that the proportion by volume of ,o is a multiple of that in the first compound4 ,in this example the ,n remains the same4 ,if that had varied in the different compounds1 it would also havevaried by a multiple of the smallest proportion4 ,this is true in all compounds4 #aae4 ,law of ,multiple ,proportion4--,whenever one element combines with another in more than one proportion1 it always combines in some multiple1 one or more1 of its least combining weight1 or1 if a gas1 of its least combining volume4 ,the least combining weight of an element is its atomic weight2 and it is this fact of a least combining weight that leads us to believe the atom to be indivisible4 ,apply the law in the case of ,p#b,o1 ,p#b,o#c1 ,p#b,o#e2 in ,h,cl,o1 ,h,cl,o#b1 ,h,cl,o#c1 ,h,cl,o#d1 arranging the symbols1 weights1 and volumes in a table1 as above4 ,the volumetric proportions of each element in the oxides of nitrogen are exhibited below4 ,n ,n ,o ,n#b,o ,n ,n ,o ,o ,n#b,o#b ,n ,n ,o ,o ,o ,n#b,o#c ,n ,n ,o ,o ,o ,o ,n#b,o#d ,n ,n ,o ,o ,o ,o ,o ,n#b,o#e ,,chapter ,,xxiv4 ,,carbon ,,protoxide4 #aaf4 ,preparation4 ,experiment #gb4--,put into a flask1 of #bjj cc41 #e g4 of oxalic acid crystals1 ,h#b;,c#b,o#d1 and #be cc4 ,h#b,,so#d4 ,have the d4t4 pass into a solution of ,na,o,h in a ,woulff bottle 7,fig4 #ca71 and collect the gas over water4 ,heat the flask slowly1 and avoid inhaling the gas4 #aag4 ,tests4 ,experiment #gc4--,remove a receiver of the gas1 and try to light the latter with a splinter4 ,is it combustible1 or a supporter of 7,c7 combustion8 ,what is the color of the flame8 ,when the combustion ceases1 shake up a little lime water with the gas left in the receiver4 ,what gas has been formed by the combustion1 as shown by the test8 ,see page #hj4 ,give the reaction for the combustion4 ,we have seen that ,h#b,,so#d has great affinity for ,h#b,o4 ,oxalic acid consists of ,h1 ,c1 ,o in the right proportion to form ,h#b,o1 ,,co#b1 and ,,co4 ,h#b,,so#d withdraws ,h and ,o in the right proportion to form water1 unites them1 and then absorbs the water1 leaving the ,c and ,o to combine and form ,,co#b and ,,co4 ,na,o,h solution removes ,,co#b from the mixture1 forming ,na#b;,,co#c1 and leaves ,,co4 ,write both reactions4 #aah4 ,carbon ,protoxide1 called also carbon monoxide1 carbonic oxide1 etc41 is a gas1 having no color or taste1 butpossessing a faint odor4 ,it is very poisonous4 ,being the lesser oxide of ,c1 it is formed when ,c is burned in a limited supply of ,o1 whereas ,,co#b is always produced when ,o is abundant4 ,the formation of each is well shown by tracing the combustion in a coal fire4 ,air enters at the bottom1 and ,,co#b is first formed4 ,c #b,o ,,co#b4 ,as this gas passes up1 the white-hot coal removes one atom of ,o1 leaving ,,co4 ,,co#b ,c - #b;,,co4 ,at the top1 if the draft be open1 a blue flame shows the combustion of ,,co4 ,,co ,o ,,co#b4 ,the same reduction of ,,co#b takes place in the iron furnace1 and whenever there is not enough oxygen to form ,,co#b1 the product is ,,co4 ,great care should be taken that this gas does not escape into the room1 as one per cent has proved fatal4 ,not all of it is burned at the top of the coal2 and when the stove door is open1 the upper drafts should be open also4 ,it is the most poisonous of the gases from coal2 hence the danger from sleeping in a room having a coal fire4 #aai4 ,water ,gas4--,,co is one of the constituents of water gas1 which1 by reason of its cheapness1 is supplanting gas made from coal1 as an illuminator1 in some cities4 ,it is made by passing superheated steam over red-hot charcoal or coke4 ,c unites with the ,o of ,h#b,o1 forming ,,co1 and sets ,h free1 thus producing two inflammable gases4 ,c ,h#b,o --8 ,as neither of these gives much light1 naphtha is distilled and mixed with them in small quantities to furnish illuminating power ,see page #ahc4 ,,chapter ,,xxv4 ,,carbon ,,dioxide4 #abj4 ,preparation4 ,experiment #gd4--,put into a t4t41 or a bottle with a d4t4 and a thistle-tube1 #aj or #bj g4 ,ca,c,o#c1 marble in lumps2 add as many cubic centimeters of ,h#b,o1 and half as much ,h,cl1 and collect the gas by downward displacement 7,fig4 #ci74 ,add more acid as needed4 ,ca,c,o#c #b ,h,cl ,ca,cl#b ,h#b;,,co#c4 ,h#b;,,co#c ,h#b,o ,,co#b4 ,h#b;,,co#c is a very weak compound1 and at once breaks up4 ,by some1 its existence as a compound is doubted4 #aba4 ,tests4 ,experiment #ge4--7a7 ,put a burning and a glowing stick into the t4t4 or bottle4 7#b7 ,hold the end of the d4t4 directly against the flame of a small burning stick4 ,does the gas support combustion8 7#c7 ,pour a receiver of the gas over a candle flame4 ,what does this show of the weight of the gas8 7#d7 ,pass a little ,,co#b into some ,h#b,o 7,fig4 #cb71 and test it with litmus4 ,give the reaction for the solution of ,,co#b in ,h#b,o4 ,experiment #gf4--,put into a t4t4 #ea cc4 of clear ,ca7,,oh7#b solution1 i4e4 lime water2 insert in this the end of a d4t4 from a ,,co#b generator 7,fig4 #cb74 ,notice any ppt4 formed4 ,it is ,ca,c,o#c4 ,let the action continue until the ppt4 disappears and the liquid is clear4 ,then remove the d4t41 boil the clear liquid for a minute1 and notice whether the ppt4 reappears4 #abb4 ,explanation4 ,ca7,,oh7#b ,,co#b ,ca,c,o#c ,h#b,o4 ,the curious phenomena of this experiment are explained by the solubility of ,ca,c,o#c in water containing ,,co#b1 and its insolu-bility in water1 having no ,,co#b4 ,when all the ,ca7,,oh7#c is combined1 or changed to ,ca,c,o#c1 the excess of ,,co#b unites with ,h#b,o1 forming the weak acid ,h#b;,,co#c1 which dissolves the precipitate1 ,ca,c,o#c1 and gives a clear liquid4 ,on heating this1 ,h#b;,,co#c gives up its ,,co#b1 and ,ca,c,o#c is reprecipitated1 not being soluble in pure water4 ,lime water1 ,ca7,,oh7#b solution1 is therefore a test for the presence of ,,co#b4 ,to show that carbon dioxide is formed in breathing1 and in the combustion of ,c1 and that it is present in the air1 perform the following experiment3 ,experiment #gg4--7a7 ,put a little lime water into a t4t41 and blow into it through a piece of glass tubing4 ,any turbidity shows what8 7#b7 ,burn a candle for a few minutes in a receiver of air1 then take out the candle and shake up lime water with the gas4 7#c7 ,expose some lime water in an e4d4 to the air for some time4 #acc4 ,oxidation in the ,human ,system4--,carbon dioxide1 or carbonic anhydride1 carbonic acid1 etc41 ,,co#b1 is a heavy gas1 without color or odor4 ,it has a sharp1 prickly taste1 and is commonly reckoned as poisonous if inhaled in large quantities1 though it does not chemically combine with the blood as ,,co does4 ,ten per cent in the air will sometimes produce death1 and five per cent produces drowsiness4 ,it exists in minute portions in the atmosphere1 and often accumulates at the bottom of old wells and caverns1 owing to its slow diffusive power4 ,before going down into one of these1 the air should always be tested by lowering a lighted candle4 ,if this is extinguished1 there is danger4 ,,co#b is the deadly choke damp after a mine explosion1 ,,ch#d being converted into ,,co#b and ,h#b,o2 a great deal is liberated during volcanic eruptions1 and it is formed in breathing by the union of ,o in the air with ,c in the system4 ,this union of ,c and ,o takes place in the lungs and in all the tissues of the body1 even on the surface4 ,oxygen is taken into the lungs1 passes through the thin membrane into the blood1 forms a weak chemical union with the red corpuscles1 and is conveyed by them to all parts of the system4 ,throughout the body1 wherever necessary1 ,c and ,h are supplied for the ,o1 and unite with it to form ,,co#b and ,h#b,o4 ,these are taken up by the blood though they do not form a chemical union with it1 are carried to the lungs1 and pass out1 together with the unused ,n and surplus ,o4 ,the system is thus purified1 and the waste must be supplied by food4 ,the process also keeps up the heat of the body as really as the combustion of ,c or ,p in ,o produces heat4 ,the temperature of the body does not vary much from #ii degrees ,f41 any excess of heat passing off through perspiration1 and being changed into other forms of energy4 ,if1 as in some fevers1 the temperature rises above about #aje degrees ,f41 the blood corpuscles are killed1 and the person dies4 ,during violent exercise much material is consumed1 circulation is rapid1 and quick breathing ensues4 ,oxygen is necessary for life4 ,a healthy person inhales plentifully2 and this element is one of nature's best remedies for disease4 ,deep and continued inhalations in cold weather are better than furnace fires to heat the system4 ,all animals breathe ,o and exhale ,,co#b4 ,fishes and other aquatic animals obtain it1 not by decomposing ,h#b,o1 but from air dissolved in water4 ,being cold-blooded1 they need relatively little2 but if no fresh water is supplied to those in captivity1 they soon die of ,o starvation4 #abd4 ,oxidation in ,water4--,swift-running streams are clear and comparatively pure1 because their organic impurities are constantly brought to the surface and oxidized1 whereas in stagnant pools these impurities accumulate4 ,reservoirs of water for city supply have sometimes been freed from impurities by aeration1 i4e4 by forcing air into the water4 #abe4 ,deoxidation in ,plants4--,since ,,co#b is so constantly poured into the atmosphere1 why does it not accumulate there in large quantity8 ,why is there not less free ,o in the air to-day than there was a thousand years ago8 ,the answer to these questions is found in the growth of vegetation4 ,in the leaf of every plant are thousands of little chemical laboratories2 ,,co#b diffused in small quantities in the air passes1 together with a very little ,h#b,o1 into the leaf1 usually from its under side1 and is decomposed by the radiant energy of the sun4 ,the ,c is built into the woody fiber of the tree1 and the ,o is ready to be re-breathed or burned again4 ,,co#b contributes to the growth of plants1 ,o to that of animals2 and the constituents of the atmosphere vary little from one age to another4 ,the compensation of nature is here well shown4 ,plants feed upon what animals discard1 transforming it into material for the sustenance of the latter1 while animals prepare food for plants4 ,all the ,c in plants is supposed to come from the ,,co#b in the atmosphere4 ,animals obtain their supply from plants4 ,the utility of the small percentage of ,,co#b in the air is thus seen4 #abf4 ,uses4--,,co#b is used in making soda-water1 and in chemical engines to put out fires in their early stages4 ,in either case it may be prepared by treating ,na#b;,,co#c or ,ca,c,o#c with ,h#b,,so#d4 ,give the reactions4 ,on a small scale ,,co#b is made from ,h,na,c,o#c4 ,,co#b has a very weak affinity for water1 but probably forms with it ,h#b;,,co#c4 ,much carbon dioxide can be forced into water under pressure4 ,this forms soda-water1 which really contains no soda4 ,the justification for the name is the material from which it is sometimes made4 ,salts from ,h#b;,,co#c1 called carbonates1 are numerous1 ,na#b;,,co#c and ,ca,c,o#c being the most important4 ,chapter ,,xxvi4 ,,ozone4 #abg4 ,preparation4 ,experiment #gh4--,scrape off the oxide from the surface of a piece of phosphorus #b cm long1 put it into a wide-mouthed bottle1 half cover the ,p with water1 cover the bottle with a glass1 and leave it for half an hour or more4 #abh4 ,tests4 ,experiment #gi4--,remove the glass cover1 smell the gas1 and hold in it some wet iodo-starch paper4 ,look for any blue color4 ,iodine has been set free1 according to the reaction1 #b ,,ki #jc ,k#bj ,o#b ,i#b1 and has imparted a blue color to the starch1 and ordinary oxygen has been formed4 ,why will not oxygen set iodine free from ,,ki84 ,what besides ozone will liberate it8 #abi4 ,ozone1 oxidized oxygen1 active oxygen1 etc41 is an allotropic form of ,o4 ,its molecule is #jc1 while that of ordinary oxygen is #jb4 ,three atoms of oxygen are condensed into the space of two atoms of ozone1 or three molecules of ,o are condensed into two molecules of ozone1 or three liters of ,o are condensed into two liters of ozone4 ,ozone is thus formed by oxidizing ordinary oxygen4 #jb ,o #jc4 ,this takes place during thunder storms and in artificial electrical discharges4 ,the quantity of ozone produced is small1 five per cent being the maximum1 and the usual quantity is far less than that4 ,ozone is a powerful oxidizing agent1 and will change ,s1 ,p1 and ,as into their ic acids4 ,cotton cloth was formerly bleached1 and linen is now bleached1 by spreading it on the grass and leaving it for weeks to be acted on by ozone1 which is usually present in the air in small quantities1 especially in the country4 ,ozone is a disinfectant1 like other bleaching agents1 and serves to clear the air of noxious gases and germs of infectious diseases4 ,so much ozone is reduced in this way that the air of cities contains less of it than country air4 ,a third is consumed in uniting with the substance which it oxidizes1 while two-thirds are changed into oxygen1 as in ,experiment #gi4 ,it is unhealthful to breathe much ozone1 but a little in the air is desirable for disinfection4 ,ozone will cause the inert ,n of the air to unite with ,h1 to form ammonia4 ,no other agent capable of doing this is known1 so that all the ,,nh#c in the air1 in fact all ammonium compounds taken up by plants from soils and fertilizers1 may have been made originally through the agency of ozone4 ,at a low temperature ozone has been liquefied4 ,it is then distinctly blue4 ,electrolysis of water is the best mode of preparing this substance in quantity4 ,when prepared from ,p it is mixed with ,p#b,o#c4 ,chapter ,,xxvii4 ,,chemistry ,,of ,,the ,,atmosphere4 #acj4 ,constituents4--,the four chief constituents of the atmosphere are ,n1 ,o1 ,h#b,o1 ,,co#b1 in the order of their abundance4 ,what experiments show the presence of ,n1 ,o1 and ,,co#b in the air8 ,set a pitcher of ice water in a warm room1 and the moisture that collects on the outside is deposited from the air4 ,this shows the presence of ,h#b,o4 ,rain1 clouds1 fog1 and dew prove the same4 ,h#b,,so#d and ,ca,cl#b1 on exposure to air1 take up water4 ,experiment #ah shows that there is not far from four times as much ,n as ,o by volume in air4 ,hence if the atmosphere were a compound of ,n and ,o1 and the proportion of four to one were exact1 its symbol would be ,n#d,o4 #aca4 ,air not a ,compound4--,the following facts show that air is not a compound1 but rather a mixture of these gases4 #a4 ,the proportion of ,n and ,o in the air1 though it does not vary much1 is not always exactly the same4 ,this could not be true if it were a compound4 ,why8 #b4 ,if ,n#d,o were dissolved in water1 the ,n would be four times the ,o in volume2 but when air is dissolved1 less than twice as much ,n as ,o is taken up4 #c4 ,no heat or condensation takes place when four measures of ,n are brought in contact with one of ,o4 ,it cannot then be ,n#d,o1 for the vapor density of ,n#d,o would be #cf--;i4e4 7#ad x #d #af7 _/ #b2 but that of air is #ad #a_/b nearly --i4e4 7#ad x #d #af7 _/ #e4 ,analysis shows about #gi parts of ,n to #ba parts of ,o by volume in air4 #acb4 ,water4--,the volume of ,h#b,o1 watery vapor1 in the atmosphere is very variable4 ,warm air will hold more than cold1 and at any temperature air may be near saturation1 i4e4 having all it will hold at that temperature1 or it may have little4 ,but some is always present2 though the hot desert winds of ,north ,africa are not more than #a_/ae saturated4 ,a cubic meter of air at #be degrees1 when saturated1 contains more than #bb g4 of water4 #acc4 ,carbon ,dioxide4--,carbon dioxide does not make up more than three or four parts in ten thousand of the air2 but1 in the whole of the atmosphere1 this gives a very large aggregate4 ,why does not ,,co#b form a layer below the ,o and ,n8 #acd4 ,other ,ingredients4--,other substances are found in the air in minute portions1 e4g4 ,,nh#c constitutes nearly one-millionth4 ,air is also impregnated with living and dead germs1 dust particles1 unburned carbon1 etc41 but these for the most part are confined to the portion near the earth's surface4 ,in pestilential regions the germs of disease are said sometimes to contaminate the air for miles around4 ,chapter ,,xxviii4 ,,the ,,chemistry ,,of ,,water4 #ace4 ,pure ,water4--,review the experiments for electrolysis1 and for burning ,h4 ,pure water is obtained by distillation4 ,experiment #hj4--,provide a glass tube #dj or #ej cm long and #c or #d cm in diameter4 ,fit to each end a cork with two perforations1 through one of which a long tube passes the entire length of the larger tube 7,fig4 #cb;a74 ,connect one end of this with a flask of water arranged for heating2 pass the other end into an open receptacle for collecting the distilled water4 ,into the other perforations lead short tubes1-- the one for water to flow into the large tube from a jet2 the other1 for the same to flow out4 ,this condenses the steam by circulating cold water around it4 ,the apparatus is called a ,liebig's condenser4 ,put water into the flask1 boil it1 and notice the condensed liquid4 ,it is comparatively pure water2 for most of the substances in solution have a higher boiling-point than water1 and are left behind when it is vaporized4 7,fig4 #cb;a47 #acf4 ,test4 ,experiment #ha4--,test the purity of distilled water by slowly evaporating a few drops on ,pt foil in a room free from dust4 ,there should be no spot or residue left on the foil4 ,test in the same way undistilled water4 #acg4 ,water exists in ,three ,states1-- solid1 liquid1 and vaporous4 ,it freezes at #j degrees1 suddenly expanding considerably as it passes into the solid state4 ,it boils1 i4e4 overcomes atmospheric pressure and is vaporized1 at #ajj degrees 7#gfj mm pressure74 ,if the pressure is greater1 the boiling-point is raised1 i4e4 it takes a higher temperature to overcome a greater pressure4 ,if there be less pressure1 as on a mountain1 the boiling-point is lowered below #ajj degrees4 ,salts dissolved in water raise its boiling-point1 and lower its freezing-point to an extent depending on the kind and quantity of the salt4 ,water1 however1 evaporates at all temperatures1 even from ice4 ,pure water has no taste or smell1 and1 in small quantities1 no color4 ,it is rarely if ever found on the earth4 ,what is taken up by the air in evaporation is nearly pure2 but when it falls as rain or snow1 impurities are absorbed from the atmosphere4 ,water falling after a long rain1 especially in the country1 is tolerably free from impurities4 ,some springs have also nearly pure water2 but to separate all foreign matter from it1 water must be distilled4 ,even then it is liable to contain traces of ammonia1 or some other substance which vaporizes at a lower temperature than water4 #ach4 ,sea-,water4--,the ocean is the ultimate source of all water4 ,from it and from lakes1 rivers1 and soils1 water is taken into the atmosphere1 falls as rain or snow1 and sinks into the ground1 reappearing in springs1 or flowing off in brooks and rivers to the ocean or inland seas4 ,ocean water must naturally contain soluble salts2 and many salts which are not soluble in pure water are dissolved in sea-water4 ,in fact1 there is a probability that all elements exist to some extent in sea-water1 but many of them in extremely minute quantities4 ,sodium and magnesium salts are the two most abundant1 and the bitter taste is due to ,mg,s,o#d and ,mg,cl#b4 ,a liter of sea- water1 nearly #ajjj g41 holds over #cg g4 of various salts1 #bi of which are ,na,cl4 ,see ,hard ,water4 #aci4 ,river ,water4--,river water holds fewer salts1 but has a great deal of organic matter1 living and dead1 derived from the regions through which it flows4 ,to render this harmless for drinking1 such water should be boiled1 or filtered through unglazed porcelain4 ,carbon filters are now thought to possess but little virtue for separating harmful germs4 #adj4 ,spring ,water4--,the water of springs varies as widely in composition as do the rocks whence it bubbles forth4 ,sulphur springs contain much ,h#b,s2 many geysers hold ,si,o#b in solution2 chalybeate waters have compounds of ,fe2 others have ,na#b,,so#d1 ,mg,s,o#d ,na,cl1 etc4 ,,chapter ,,xxix4 ,,the ,,chemistry ,,of ,,flame4 #ada4 ,candle ,flame4 ,experiment #hb4--;,examine a candle flame1 holding a dark object behind it4 ,note three distinct portions3 7#a7 a colorless interior about the wick1 7#b7 a yellow light-giving portion beyond that1 7#c7 a thin blue envelope outside of all1 and scarcely discernible4 ,hold a small stick across the flame so that it may lie in all three parts1 and observe that no combustion takes place in the inner portion4 #adb4 ,explanation4--,a candle of paraffine1 or tallow1 is chiefly composed of compounds of ,c and ,h1 in the solid state4 ,the burning wick melts the solid2 the liquid is then drawn up by the wick till the heat vaporizes and decomposes it1 and ,o of the air comes in contact with the outer heated portion of gas1 and burns it completely4 ,air tends to penetrate the whole body of the flame1 but only ,n can pass through uncombined1 for the ,o that is left after combustion in the outer portion seizes upon the compounds of ,c and ,h in the next1 or yellow1 part4 ,there is not enough ,o here for complete combustion2 at this temperature ,h burns before ,c1 and the latter is set free4 ,in that state it is of course a solid4 ,now an incandescent solid1 or one glowing with heat1 gives light1 while the combustion of a gas gives scarcely any light1 though it may produce great heat4 ,while ,c in the middle flame is glowing1 during the moment of its dissociation from ,h1 it gives light4 ,in the outer flame the temperature is high enough to burn entirely the gaseous compounds of ,c and ,h together1 so that no solid ,c is set free1 and hence no light is given except the faint blue4 ,no combustion takes place in the inner blue cone1 because no ,o reaches there4 ,by packing a wick into a cylindrical tin cup #e or #aj cm high and #d cm in diameter1 containing alcohol1 and lighting it1 gunpowder can be held in the middle of the flame in a def4 spoon1 without burning4 ,this shows the low temperature of that portion4 ,burning ,p will also be extinguished1 thus showing the exclusion of ,o4 #adc4 ,bunsen ,flame4 ,experiment #hc4--;,examine a ,bunsen burner4 ,unscrew the top1 and note the orifices for the admission of gas and of air4 ,make a drawing4 ,replace the parts2 then light the gas at the top1 opening the air-holes at the base4 ,notice that the flame burns with very little color4 ,try to distinguish the three parts1 as in the candle flame4 ,these parts can best be seen by allowing direct sunlight to fall on the flame and observing its shadow on a white ground4 ,make a drawing of the flame4 ,hold across it a ,pt wire and note at what part the wire glows most4 ,also press down on the flame for an instant with a cardboard or piece of paper2 remove before it takes fire1 and notice the charred circle4 ,put the end of a match into the blue cone1 and note that it does not burn4 ,put the end of a ,pt wire into this blue cone1 and observe that it glows when near the top of the cone4 ,what do these experiments show8 ,ascertain whether this inner portion contains a combustible material1 by holding in it one end of a small d4t41 and trying to ignite any gas escaping at the other end4 ,it should burn4 ,this shows that no combustion takes place in the interior of the flame1 because sufficient free ,o is not present4 ,next1 close the air-holes1 and note that the flame is yellow and gives much light4 ,from this we infer the presence of solid particles in an incandescent state4 ,but these could not come from the air4 ,they must be ,c particles which have been set free from the ,c and ,h compounds of the gas1 just as in the candle flame4 ,the smoke that rises proves this4 ,hold an e4d4 in the flame and collect some ,c4 ,try the same with the air-holes open4 #add4 ,light and ,heat of ,flame4--,which of the two flames is hotter1 the one with the air-holes open1 or that with them closed8 ,evidently the former2 for air is drawn in and mixes with the gas as it rises in the tube1 and1 on reaching the flame at the top1 the two are well mingled1 and the gaseous compounds of ,c and ,h burn at so high a temperature that solid ,c is not freed2 hence there is little light4 ,on closing the air-holes1 no ,o can reach the flame except from the outside1 and the heat is much less intense4 7,fig #cc47 7,fig #cd47 ,the ,h burns first1 and sets the ,c free1 which1 while glowing1 gives the light4 ,this again illustrates the facts 7#a7 that flame is caused by burning gas2 7#b7 that light is produced by incandescent solids4 ,charcoal1 coke1 and anthracite coal burn without flame1 or with very little1 because of the absence of gases4 #ade4 ,temperature of ,combustion4 ,experiment #hd4--,light a ,bunsen flame1 with the basal orifices open1 and hold over it a fine wire gauze4 ,notice that the flame does not rise above the gauze4 ,extinguish the light1 and try to ignite the gas above the gauze1 holding the latter within #e or #f cm of the burner tube4 ,notice that it does not burn below the gauze 7,fig4 #cc74 ,gas and ,o are both present4 ,evidently1 then1 the only condition wanting for combustion is a sufficiently high temperature4 ,the gauze cools the gas below its kindling- point4 ,this principle is made use of in the miner's lamp of ,davy 7,fig4 #cd74 ,in coal mines a very inflammable gas1 ,,ch#d1 called fire-damp1 issues from the coal4 ,if this collects in large quantities and mixes with ,o of the air1 a kindling-point is all that is needed to make a violent explosion4 ,an ordinary lamp would produce this1 but the gauze lamp prevents it2 for1 though the inside may be filled with burning gas1 ,,ch#d1 the flame cannot communicate with the outside4 7,fig #ce47 7,fig #cf47 a1 reducing flame b1 oxidizing flame #adf4 ,oxidizing and ,reducing ,flames4--,the hottest part of a ,bunsen flame is just above the inner blue cone 7b1 ,fig4 #cf74 ,evidently there is more ,o at that point4 ,if a reducing agent1 i4e4 a substance which takes up ,o1 be put into this part of the flame1 the latter will remove the ,o and appropriate it1 forming an oxide4 ,cu heated there would become copper oxide4 ,this part is called the oxidizing flame4 ,the inner blue part of the ,bunsen flame is devoid of ,o4 ,it ought to remove ,o from an oxidizing agent1 i4e4 a substance which supplies ,o4 ,if copper oxide be heated there 7a1 ,fig4 #cf7 by means of a mouth blow-pipe 7,fig4 #ce71 the flame will appropriate the ,o and leave the copper4 ,this is called the reducing flame4 ,only the upper part of this blue central cone has heat enough to act in this way4 ,by using a prepared piece of metal1 to make the flame thin and to shut off the air1 and then blowing the flame with a blow-pipe1 greater strength can be obtained in both oxidizing and reducing flames 7,fig4 #cf74 #adg4 ,combustible and ,supporter ,interchangeable4-- ,h was found to burn in ,o4 ,h was the combustible1 ,o the supporter4 ,would ,o itself burn in ,h8--i4e4 would the combustible become the supporter1 and the supporter the combustible8 ,as illuminating gas consists largely of ,h1 and as air is part ,o1 we may try the experiment with gas and air4 ,gas will burn in air4 ,will air burn in gas8 ,experiment #he4--;,fit a cork with two holes in it to the large end of a lamp chimney4 ,through each hole pass a short piece of tubing1 and connect one of these with a rubber tube leading to a gas-jet4 ,pass a metallic tube1 long enough to reach the top of the chimney1 through the other1 so that it will move easily up and down4 ,turn on the gas1 and light it at the top of the chimney4 ,hold the end of the tube passing through the cork in the flame for a minute1 then draw it down to the middle of the chimney 7,fig4 #cg1 a7 and finally slowly remove it 7b74 ,note that ,o from the air is burning in the gas4 ,which is the supporter1 and which the combustible in this case8 ,o will burn equally well in an atmosphere of ,h1 as can be shown by experiment4 #adh4 ,explosive ,mixture of ,gases4 ,experiment #hf4--,slowly turn down the burning gas of a ,bunsen lamp1 having the orifices open1 and notice that it suddenly explodes and goes out at the top1 but now burns at the base4 ,as the gas was gradually turned off1 more air became mixed with it1 until there was the right proportion of each gas for an explosion4 ,figure #ch shows the same thing4 ,light the gas at the top a1 when the tube c covers the jet b4 ,then gradually raise the tube c4 ,at a certain place there is the same explosion as with the lamp4 #adi4 ,generalizations4--,these experiments show 7#a7 that three conditions are necessary for combustion1--a combustible1 a supporter1 and a burning temperature which varies for different substances4 ,given these1 a fire always results4 ,the conditions for spontaneous combustion do not differ from those of any combustion4 ,see ,experiments #cd1 #aab1 #aac1 #aad4 7#b7 ,that combustible and supporter are interchangeable4 ,if ,h burns in ,o1 ,o will burn in ,h1 the product1 being the same in each case4 7#c7 ,for any combustion there must be a certain proportion of combustible and of supporter4 ,twenty per cent of ,,co#b in the air dilutes the ,o to such an extent that ,c will not burn4 ,hence the utility of the chemical engine for putting out fires4 7#d7 ,when two gases1 a combustible and a supporter1 are mixed in the requisite proportion1 they form an explosive mixture1 needing only the kindling temperature to unite them4 ,chemical combination is always accompanied by disengagement of heat4 ,chemical dissociation is always accompanied by absorption of heat4 ,the disengagement1 or the absorption1 is not always evident to the senses4 ,combustion is the chemical combination of two or more substances with the self-evident disengagement of great heat1 and usually of light4 ,the temperature of ignition varies greatly with different substances4 ,,ph#c burns spontaneously at the usual temperatures of the air4 ,p takes fire at #fj degrees1 but even at #aj degrees it oxidizes with rapidity enough to produce phosphorescence4 ,the vapor of ,,cs#b may be set on fire by a glass rod heated to #aej degrees1 but a red-hot iron will not ignite illuminating gas4 ,spontaneous combustion often takes place in woolen or cotton rags which have been saturated with oil4 ,the oil rapidly absorbs ,o1 and sets fire to the cloth4 ,this is thought to be the origin of some very destructive fires4 ,,chapter ,,xxx4 ,,chlorine4 #aej4 ,preparation4 ,experiment #hg4--,put into a t4t4 #e g4 of fine granular ,mn,o#b and #aj cc4 ,h,cl4 ,apply heat carefully1 and collect the gas by downward displacement in a receiver loosely covered with paper 7,fig4 #ci74 ,add more ,h,cl if needed4 ,have a good draft of air1 and do not inhale the gas4 ,if you have accidentally breathed it1 inhale alcohol vapor from a handkerchief2 alcohol has great affinity for ,cl4 ,note the color of the gas1 and compare its weight with that of air4 ,mn,o#b #d ,h,cl ,mn,cl#b #b ,h#b,o #b ,cl4 ,how much ,cl can be separated with #e g4 ,mn,o#b8 ,if preferred1 a flask may be used for a generator instead of a t4t4 ,cl can be obtained directly from ,na,cl by adding ,h#b,,so#d 7which produces ,h,cl7 and ,mn,o#b4 #b ,na,cl #b ,h#b,,so#d ,mn,o#b ,mn,s,o#d ,na#b,,so#d #b ,h#b,o #b ,cl4 ,try the experiment1 using a t4t4 and adding water4 #aea4 ,cl from ,bleaching-,powder4 ,experiment #hh4--,put a few grams of bleaching- powder into a small beaker1 and set this into a larger one4 ,cover the latter with pasteboard or paper1 through which passes a thistle-tube reaching into the small beaker 7,fig4 #dj74 ,pour through the tube a little ,h#b,,so#d dilated with its volume of ,h#b,o4 #aeb4 ,chlorine ,water4--,a solution of ,cl in water is often useful1 and may be made as follows3-- ,experiment #hi4--,to #c or #d crystals of ,k,cl,o#c add a few drops of ,h,cl4 ,heat a minute1 and when the gas begins to disengage1 pour in #aj cc4 ,h#b,o1 which dissolves the gas4 #b ,k,cl,o#c #d ,h,cl #b ,k,cl ,cl#b,o#d #b ,h#b,o #b ,cl4 #aec4 ,bleaching ,properties4 ,experiment #ij4--,put into a receiver of ,cl1 preferably before generating it1 two pieces of ,turkey red cloth1 one wet1 the other dry2 a small piece of printed paper and a written one2 also a red rose or a green leaf1 each wet4 ,note from which the color is discharged4 ,if it is not discharged from all1 put a little ,h#b,o into the receiver1 shake it well1 and state what ones are bleached4 ,experiment #ia4--7a7 ,add #e cc4 of ,cl water to #e cc4 of indigo solution4 7#b7 ,treat in the same way #e cc4 ,k#b;,cr#b,o#g 7potassium dichromate7 solution1 and record the results4 ,indigo1 writing-ink1 and ,turkey red or madder1 are vegetable pigments2 printer's ink contains ,c1 and ,k#b;,cr#b,o#g is a mineral pigment4 ,state what coloring matters ,cl will bleach4 #aed4 ,disinfecting ,power4 ,experiment #ib4--,pass a little ,h#b,s gas from a generator into a t4t4 containing ,cl water4 ,look for a deposit of ,s4 ,notice that the odor of ,h#b,s disappears4 ,h#b,s #b ,cl #b ,h,cl ,s4 #aee4 ,a ,supporter of ,combustion4 ,experiment #ic4--,sprinkle into a receiver of ,cl a very little fine powder or filings of ,cu1 ,as1 or ,sb1 and notice the combustion4 ,observe that here is a case of combustion in which ,o does not take part4 ,chlorides of the metals are of course formed4 ,write the reactions4 ,see whether ,cl will support the combustion of paper or of a stick of wood4 ,experiment #id4--,warm #b or #c cc4 of oil of turpentine 7,c#a,,oh#af7 in an evaporating-dish2 dip a piece of tissue paper into it1 and very quickly thrust this into a receiver of ,cl4 ,it should take fire and deposit carbon4 ,c#a,,oh#af #af ,cl 8 ,test the moisture on the sides of the receiver with litmus4 ,clean the receiver with a little petroleum4 ,experiment #ie4--,prepare a ,h generator with a lamp-tube bent as in ,figure #da4 ,light the ,h1 observing the cautions in ,experiment #bc1 and when well burning1 lower the flame into a receiver of ,cl4 ,observe the change of color which the flame undergoes as it comes in contact with ,cl4 ,give the reaction for the burning4 ,test with litmus any moisture on the sides of the receiver4 ,a mixture of ,cl and ,h1 in direct sunlight combines with explosive violence2 whereas in diffused sunlight it combines slowly1 and in darkness it does not combine4 ,from these experiments state the chief properties of ,cl1 and what combustion it will support4 ,figure #da4 #aef4 ,sources and ,uses4--,the great source of ,cl is ,na,cl1 though it is often made from ,h,cl4 ,its chief use is in making bleaching- powder1 one pound of which will bleach #cjj to #ejj pounds of cloth4 ,cl is very easily liberated from this powder by a dilute acid1 or1 slowly1 by taking moisture from the air4 ,hence its use as a disinfectant in destroying noxious gases and the germs of infectious diseases4 ,cl attacks organic matter and germs as it does the membrane of the throat or lungs1 owing to its affinity for ,h4 ,cl is the best bleaching agent for cotton goods4 ,it is not suitable for animal materials1 such as silk and wool1 as it attacks their fiber4 ,it does not discharge either mineral or carbon colors4 ,the chemistry of bleaching is obscure4 ,as dry material will not bleach1 ,cl seems to unite with ,h in ,h#b,o and to set ,o free4 ,the ,o then unites with some portion of the coloring matter1 oxidizing it1 and breaking up its molecule4 ,colors bleached by ,cl cannot be restored4 ,chapter ,,xxxi4 ,,bromine4 ,examine bromine1 potassium bromide1 sodium bromide1 magnesium bromide4 #aeg4 ,preparation4 ,experiment #if4--,pulverize #b or #c g4 ,k,br1 and mix it with about the same bulk of ,mn,o#b4 ,after putting this into a t4t1 add as much ,h#b,,so#d1 mix them together by shaking1 attach a d4t41 and conduct the end of it into a t4t4 that is immersed in a bottle of cold water4 ,slowly heat the contents of the t4t41 and notice the color of the escaping vapor1 and any liquid that condenses in the receiver4 ,avoid inhaling the fumes1 or getting them into the eyes4 ,mn,o#b #b ,k,br #b ,h#b,,so#d 8 ,compare this with the equation for making ,cl from ,na,cl4 #aeh4 ,tests4 ,experiment #ig4--,try the bleaching action of ,br vapor as in the case of ,cl4 ,bleach a piece of litmus paper1 and try to restore the color with ,,nh#d,,oh4 ,explain its bleaching and disinfecting action4 ,try the combustibility of ,as1 ,sb1 and ,cu4 #aei4 ,description4--,bromine at usual temperatures is a liquid element2 it is the only common one except ,hg2 it4 quickly evaporates on exposure to air4 ,the chemistry of its manufacture is like that of ,cl2 its bleaching and disinfecting powers are similar to the latter1 though they are not quite so strong as those of ,cl4 ,its affinity for ,h and for metals is also strongly marked4 ,a drop of ,br on the skin produces a sore slow to heal4 ,bromine salts are mainly ,k,br1 ,na,br1 ,mg,br#b4 ,these in small quantities accompany ,na,cl1 and are most common in brine springs4 ,the world's supply of ,br comes chiefly from ,west ,virginia and ,ohio1 over #cjj1jjj pounds being produced from the salt 7,na,cl7 wells there in #ahhd4 ,the water taken from these wells is nearly evaporated1 after which ,na,cl crystallizes out1 leaving a thick liquid--bittern1 or mother liquor--which contains the salts of ,br4 ,the bittern is treated with ,h#b,,so#d and ,mn#jb1 as above4 ,for transportation in large quantities1 ,br has to be made into the salts ,na,br and ,k,br1 on account of the danger attending leakage or breakage of the receptacles for ,br4 #afj4 ,uses4--,its chief uses are in photography 7page #afg71 medicine1 as ,k,br1 and analytical chemistry4 ,chapter ,,xxxii4 ,,iodine4 ,examine iodine1 potassium iodide4 #afa4 ,preparation of ,i4 ,experiment #ih4--,put into a t4t4 #b or #c g4 of powdered ,,ki mixed with an equal bulk of ,mn,o#b1 add ,h#b,,so#d enough to cover well1 shake together1 complete the apparatus as for making ,br1 and heat4 ,notice the color of the vapor1 and any sublimate4 ,the direct product of the solidification of a vapor is called a sublimate4 ,the process is sublimation4 ,observe any crystals formed4 ,write the reaction1 and compare the process with that for making ,br and ,cl4 ,compare the vapor density of ,i with that of ,br and of ,cl4 ,with that of air4 ,what vapor is heavier than ,i8 ,what acid and what base are represented by ,,ki8 #afb4 ,tests4 ,experiment #ii4--7a7 ,put a crystal of ,i in the palm of the hand and watch it for a minute4 7#b7 ,put #b or #c crystals into a t4t41 and warm it1 meanwhile holding a stirring-rod half-way down the tube4 ,notice the vapor1 also a sublimate on the sides of the t4t4 and rod4 7#c7 ,add to #b or #c crystals in a t4t4 #e cc4 of alcohol1 ,c#b;,h#e,,oh2 warm it1 and see whether a solution is formed4 ,if so1 add #e cc4 ,h#b,o and look for a ppt4 of ,i4 ,does this show that ,i is not at all soluble in ,h#b,o1 or not so soluble as in alcohol8 #afc4 ,starch ,solution and ,iodine ,test4 ,experiment #ajj4--,pulverize a gram or two of starch1 put it into an evaporating-dish1 add #d or #e drops of water1 and mix2 then heat to the boiling-point #aj cc4 ,h#b,o in a t4t41 and pour it over the starch1 stirring it meanwhile4 7#a7 ,dip into this starch paste a piece of paper1 hold it in the vapor of ,i1 and look for a change of color4 7#b7 ,pour a drop of the starch paste into a clean t4t41 and add a drop or two of the solution of ,i in alcohol4 ,add #e cc4 ,h#b,o1 note the color1 then boil1 and finally cool4 7#c7 ,the presence of starch in a potato or apple can be shown by putting a drop of ,i solution in alcohol on a slice of either1 and observing the color4 7#d7 ,try to dissolve a few crystals of ,i in #e cc4 ,h#b,o by boiling4 ,if it does not disappear1 see whether any has dissolved1 by touching a drop of the water to starch paste4 ,this should show that ,i is slightly soluble in water4 #afd4 ,iodo-,starch ,paper4 ,experiment #aja4--;,add to some starch paste that contains no ,i #e cc4 of a solution of ,,ki1 and stir the mixture4 ,why is it not colored blue8 ,dip into this several strips of paper1 dry them1 and save for use4 ,this paper is called iodo-starch paper1 and is used as a test for ozone1 chlorine1 etc4 ,bring a piece of it in contact with the vapor of chlorine1 bromine1 or ozone1 and notice the blue color4 ,experiment #ajb4--;,add a few drops of chlorine water to #b;cc4 of the starch and ,,ki solution in #aj cc4 ,h#b,o4 ,this should show the same effect as the previous experiment4 #afe4 ,explanation4--,only free ,i1 not compounds of it1 will color starch blue4 ,it must first be set free from ,,ki4 ,ozone1 chlorine1 etc41 have a strong affinity for ,k1 and when brought in contact with ,,ki they unite with ,k and set free ,i1 which then acts on the starch present4 ,com- plete the equation3 ,,ki ,cl 8 #aff4 ,occurrence4--,the ultimate source of ,i is sea water1 of which it constitutes far too small a percentage to be separated artificially4 ,sea-weeds1 or algae1 especially those growing in the deep sea1 absorb its salts--,na,i1 ,,ki1 etc4--from the water4 ,it thus forms a part of the plant1 and from this much of the ,i of commerce is obtained4 ,algae are collected in the spring1 on the coasts of ,ireland1 ,scotland1 and ,normandy1 where rough weather throws them up4 ,they are dried1 and finally burned or distilled2 the ashes are leached to dissolve ,i salts2 the water is nearly evaporated1 and the residue is treated with ,h#b,,so#d1 and ,mn,o#b1 as in the case of ,br and ,cl4 ,i also occurs in ,chili1 as ,na,i and ,na,i,o#c1 mixed with ,na,n,o#c4 ,this is an important source of the ,i supply4 #afg4 ,uses4--,i is much used in medicine1 and was formerly employed in taking daguerreotypes and photographs4 ,its solution in alcohol or in ether is known as tincture of iodine4 #afh4 ,fluorine4--,f1 ,cl1 ,br1 ,i1 are called halogens or haloids1 and exist in compounds--salts--in sea water4 ,f is the most active of all elements1 combining with every element except ,o4 ,until recently it has never been isolated1 for as soon as set free from one compound it attacks the nearest substance1 and seems to be as much averse to combining with itself1 or to existing in the elementary state1 as to uniting with ,o4 ,it is supposed to be a gas1 and1 as is claimed1 has lately been isolated by electrolysis from ,,hf in a ,pt ,u-tube4 ,fluorite 7,ca,f#b7 and cryolite 7,al#b;,f#f #f ,na,f7 are its two principal mineral sources4 ,the enamel of the teeth contains ,f in composition4 ,,chapter ,,xxxiii4 ,,the ,,halogens4 #afi4 ,halogens ,compared4--,the elements ,f1 ,cl1 ,br1 ,i1 form a natural group4 ,their properties1 as well as those of their compounds1 vary in a step-by-step way1 as seen below4 ,f is sometimes an exception4 ,they are best remembered by comparing them with one another4 ,notice3 #a4 ,similarity of name-ending4 ,each name ends in ine4 #b4 ,similarity of origin4 ,salt water is the ultimate source of all1 except ,f4 #c4 ,similarity of valence4 ,each is usually a monad4 #d4 ,similarity of preparation4 ,cl1 ,br1 ,i1 are obtained from their salts by means of ,mn,o#b end ,h#b,,so#d4 #e4 ,variation in occurrence4 ,cl occurs in sea-salt1 ,br in sea- water1 ,i in sea-weed4 #f4 ,variation in color2 ,f being colorless1 ,cl green1 ,br red1 ,i violet4 #g4 ,gradation in sp4 gr42 ,f #ai1 ,cl #ce4e1 ,br #hj1 ,i #abg4 #h4 ,gradation in state1 corresponding to sp4 gr42 ,f being a light gas1 ,cl a heavy gas1 ,br a liquid1 ,i a solid4 #i4 ,corresponding gradation in their usual chemical activity2 ,f being most active1 then ,cl1 ,br1 and ,i4 #aj4 ,corresponding gradation in the strength of the ,h acids2 the strongest being ,,hf1 the next1 ,h,cl1 etc4 #aa4 ,corresponding gradation in the explosibility of their ,n compounds2 the strongest ,n,cl#c1 the next1 ,n,br#c1 etc4 #ab4 ,corresponding gradation in the number of ,h and ,o acids2 ,cl #d1 ,br #c1 ,i #b4 #agj4 ,compounds4--,the following are some of the oxides1 acids1 and salts of the halogens4 ,name them4 ,,ci#b,o 7,h#b,o7 #b ,h,cl,o4 ,the salts are hypochlorites1 as ,ca7,cl,o7#b4 ,cl#b,o#c 7,h#bj7 #b ,h,cl,o#b4 ,the salts are chlorites1 as ,k,cl,o#b4 ,cl#b,o#d -- ,h,cl,o#c ,the salts are chlorates1 as ,k,cl,o#c4 -- ,h,cl,o#d ,the salts are perchlorates1 as ,k,cl,o#d1 -- ,h,br,o ,the salts are 8 ,k,br,o1 -- -- ,the salts are wanting4 -- ,h,br,o#c4 ,the salts are 8 ,k,br,o#c1 -- ,h,br,o#d4 ,the salts are 8 ,k,br,o#d1 -- -- ,the salts are wanting4 -- -- ,the salts are wanting4 ,i#b,o#e 7,h#b,o7 #b ,,hio#c4 ,the salts are 8 ,,kio#c4 -- ,,hio#d4 ,the salts are 8 ,,kio#d4 ,f forms no oxides1 and no acids except ,,hf4 ,,hf1 ,h,cl1 ,h,br1 ,,hi1 are striking illustrations of acids with no ,o4 ,h,cl,o#d is a very strong oxidizing agent4 ,a drop of it will set paper on fire1 or with powdered charcoal explode violently4 ,this is owing to the ease with which it gives up #j4 ,notice why its molecule is broken up more readily than ,,hc#ajc4 ,the higher the molecular tower1 or the more atoms it contains1 the greater its liability to fall4 ,some organic compounds contain hundreds of atoms1 and hence are easily broken down1 or1 as we say1 are unstable4 ,inorganic compounds are1 as a rule1 much more stable than organic ones4 ,it is not always true1 however1 that the compound with the least number of atoms is the most stable4 ,,so#b is more stable than ,,so#c1 but ,h#b,,so#c is less so than ,h#b,,so#d4 ,chapter ,,xxxiv4 ,,vapor ,,density ,,and ,,molecular ,,weight4 ,examine a liter measure1 in the form of a cube1--cubic decimeter1 --and a cubic centimeter4 #aga4 ,gaseous ,weights and ,volumes4--,a liter of ,h1 at #j degrees and #gfj mm41 weighs nearly #j4ji g4 ,this weight is called a crith4 ,find the weight of ,h in the following1 in criths and in grams3 #ae #a41 #j4jg #a41 #ej4c #a41 #j4jce #a41 #j4f #a44 ,it has been estimated that there are 7#aj7 #bd4 molecules of ,h in a liter4 ,does the number vary for different gases8 ,the weight of a molecule of ,h in parts of a crith is #a_/7aj7 #bd42 in parts of a gram 4#ji_/7aj7 #bd44 ,if the ,h molecule is composed of #b atoms1 what is the weight of its atom in fractions of a crith8 ,what in fractions of a gram8 ,the weight of the ,h atom is a microcrith4 ,what part of a crith is a microcrith8 #agb4 ,vapor ,density4--,vapor density1 or specific gravity referred to ,h as the standard1 7,physics7 is the ratio of the weight of a given volume of a gas or vapor to the weight of the same volume of ,h4 ,a liter of steam weighs nine times as much as a liter of ,h4 ,its vapor density is therefore nine4 ,for convenience1 a definite volume of ,h is usually taken as the standard1 viz41 the ,h atom4 ,the volume of the ,h atom and that of the half-molecule of ,h#b,o1 or of any gas are identical1 each being represented by one square4 ,if1 then1 the standard of vapor density is the ,h atom1 half the molecular weight of a gas must be its vapor density1 since it is evident that we thus compare the weights of equal volumes4 ,the vapor density of ,h#b,o1 steam1 is found from the symbol as follows3 7#b #af7 _/ #b #i4 ,to obtain the vapor density of any compound from the formula1 we have only to divide its molecular weight by two4 ,find the vapor density of ,h,cl1 ,n#b,o1 ,,no1 ,c#ab;,h#bb,o#aa1 ,cl1 ,,co#b1 ,,hf1 ,,so#b4 ,explain each case4 ,the half-molecule1 instead of the whole1 is taken2 because our standard is the hydrogen atom1 the smallest portion of matter1 by weight1 known to science4 ,how many criths in a liter of ,h,cl8 ,how many grams8 ,compute the number of criths and of grams in one liter of the compounds whose symbols appear above4 ,,problems4 7#a7 ,a certain volume of ,h weighs #j4cf g4 at standard temperature and pressure4 ,how many liters does it contain8 ,if one liter weighs #j4ji g41 to weigh #j4cf g4 it will take #j4cf _/ #j4ji #d liters4 7#b7 ,how many liters1 or criths1 of ,h in #fc g48 #b4g g48 #a g48 #e g48 #bej g48 ,explain each4 7#c7 ,suppose the gas to be twice as heavy as ,h1 how many liters in #j4cf g48 ,a liter of the gas will weigh #j4ah g4 7#j4ji ,x #b74 ,in #j4cf g4 there will be #j4cf _/ #j4ah #b4 ,answer the question for #fc g41 #b4g g41 etc4 7#d7 ,how many liters of ,cl in each of the above numbers of grams8 7#e7 ,how many of ,h,cl8 ,h#b,o 7steam78 ,,co#b8 ,explain fully every case4 ,vapor density is very easily determined from the formula by the method given above4 ,but in practice the formula is obtained from the vapor density1 and hence the method there given has to be reversed4 #agc4 ,vapor ,density of ,oxygen4--,suppose we were to obtain the vapor density of ,o4 ,we should carefully seal and weigh a given volume1 say a liter1 at a noted temperature and barometric pressure1 which are reducedto #j degrees and #gfj mm1 and compare it with the weight of the same volume of ,h4 ,this has been done repeatedly1 and ,o has been found to weigh #af times as much as ,h1 volume for volume1 or1 more exactly1 #ae4if4 ,now a liter of each gas has the same number of molecules1 therefore the ,o molecule weighs #af times the ,h molecule4 ,the half-molecule of each has the same proportion1 and the vapor density of ,o is #af4 ,atomic weight is obtained in a very different way4 ,,problems4 7#a7 ,a liter of ,cl is found to weigh #c4aie g4 ,compute its vapor density1 and explain fully4 7#b7 ,a liter of ,hg vapor1 under standard conditions1 weighs #i g4 ,find its vapor density1 and explain4 ,the vapor density of only a few elements has been satisfactorily determined4 ,see page #ab4 ,some cannot be vaporized2 others can be1 but only under conditions which prevent weighing them4 ,the vapor density of very many compounds also is unknown4 7#c7 ,a liter of ,,co#b weighs #a4ih g4 ,find the vapor density1 and from that the molecular weight1 remembering that the latter is twice the former4 ,see whether it corresponds to that obtained from the formula1 ,,co#b4 ,this is1in fact1 the way a formula is ascertained1 if the atomic weights of its elements are known4 7#d7 ,a liter of a compound gas weighs #b4hh g4 ,analysis shows that its weight is half ,s and half ,o4 ,as the atomic weight of ,s is #cb1 and that of ,o is #af1 what is the symbol for the gas8 ,solution4 ,its molecular weight is #fd1 i4e4 7#b4hhj4ji7 ,x #b1 of which #cb is ,s and #cb ,o4 ,the atomic weight of ,s is #cb1 hence there is one atom of ,s1 while of ,o there are two atoms4 ,the formula is ,,so#b4 7#e7 ,a liter of a compound gas1 which is found to contain #a ,c and #c ,o by weight1 weighs #a4bf g4 ,what is its formula8 ,atomic weights are taken from page #ab4 ,prove your answer4 7#f7 ,a liter of a compound of ,n and ,o weighs #a4ih g4 ,the ,n is #g_/aa2 and the ,o #d_/aa4 ,what is the gas8 7#g7 ,a compound of ,n and ,h gas weighs #j4gfe g4 to the liter4 ,the ,n is #ad_/ag of the whole1 the ,h #c_/ag4 ,what gas is it8 ,,chapter ,,xxxv4 ,,atomic ,,weight4 #agd4 ,definition4--,we have seen that the molecular weight of a compound1 as well as of most elements1 is obtained from the vapor density by doubling the latter4 ,it remains to explain how atomic weights are obtained4 ,the term is rather misleading4 ,the atomic weight of an element is its least combining weight1 the smallest portion that enters into chemical union1 which is1 of course1 the weight of an atom4 #age4 ,atomic ,weight of ,oxygen4--,suppose we wish to find the atomic weight of oxygen4 ,we must find the smallest proportion by weight in which it occurs in any compound4 ,this can only be done by analyzing all the compounds of ,o that can be vaporized4 ,as illustrative of these compounds take the six following3-- ,wt4 of other ,names4 ,v4 d4 ,mol4 ,wt4 ,wt4 of ,o4 ,elem4 ,symbol4 ,carbon monoxide444 #ad #bh #af #ab 8 ,carbon dioxide4444 #bb #dd #cb #ab 8 ,hydrogen monoxide444 #i #ah #af #b 8 ,nitrogen monoxide444 #bb #dd #af #bh 8 ,nitrogen trioxide444 #ch #gf #dh #bh 8 ,nitrogen pentoxide444 #ed #ajh #hj #bh 8 #agf4 ,molecular ,symbols4--,from the vapor density of the gases-- column #b--we obtain their molecular weight-- column #c4 ,to find the proportion of ,o1 it must be separated by chemical means from its compounds and separately weighed4 ,these relative weights are given in column #d4 ,now the smallest weight of ,o which unites in any case is its atomic weight4 ,if any compound of ,o should in future be found in which its combining weight is #h or #d1 that would be called its atomic weight4 ,by dividing the numbers in column #d1 wt4 of ,o1 by #af1 the atomic weight of ,o1 we obtain the number of ,o atoms in the molecule4 ,subtracting the weights of ,o from the molecular weights1 we have the parts of the other elements1 column #e1 and dividing these by the atomic weight of the respective elements1 we have the number of atoms of those elements1 these last1 combined with the number of ,o atoms1 give the symbol4 ,in this way complete the last column4 ,show how to get the atomic weight of ,cl from these compounds1 arranging them in tabular form1 and completing as above3 ,h,cl1 ,k,cl1 ,na,cl1 ,zn,cl#b1 ,mg,cl#b2 the atomic weight of ,n in these3 ,n#b,o1 ,,no1 ,,nh#c4 #agg4 ,molecular and ,atomic ,volumes4--,we thus see that vapor density and atomic weight are obtained in two quite different ways4 ,in the case of elements the two are usually identical1 i4e4 with the few whose vapor density is known2 but this is not always true1 and it leads to interesting conclusions regarding atomic volume4 ,in ,o both vapor density and atomic weight are #af4 ,this gives #b atoms of ,o to the molecule1 i4e4 the molecular weight _/ the atomic weight4 ,the size of an ,o atom is therefore half the gaseous molecule1 and is represented by one square4 ,s has a vapor density and an atomic weight of #cb each4 ,compute the number of atoms in the molecule4 ,compute for ,i1 in which the two are identical1 #abg4 ,p has an atomic weight of #ca1 while its vapor density is #fb4 ,its molecule must consist of #d atoms1 each half the size of the ,h atom1 ,the vapor density of ,as is #aej1 the atomic weight #ge4 ,compute the number of atoms in its molecule1 and represent their relative size4 ,hg has an atomic weight of #bjj1 a vapor density of #ajj4 ,compute as before1 and compare the results with those on page #ab4 ,ozone has an atomic weight of #af1 a vapor density #bd4 ,compute4 ,chapter ,,xxxvi4 ,,diffusion ,,and ,,condensation ,,of ,,gases4 #agh4 ,diffusion of ,gases4--,oxygen is #af times as heavy as ,h4 ,if the two gases were mixed1 without combining1 in a confined space1 it might be supposed that ,o would settle to the bottom and ,h rise to the top4 ,this would1 in fact1 take place at first1 but only for an instant1 for all gases tend to diffuse or become intimately mixed4 ,the lighter the gas the more quickly it diffuses4 #agi4 ,law of ,diffusion of ,gases4--,the diffusibility of gases varies inversely as the square roots of their vapor densities4 ,compare the diffusibility of ,h with that of ,o4 dif4 ,h3dif4 ,o33 sqrt7#af73 sqrt7#a71 or dif3 ,h3 dif4 ,o33 #d3 #a4 ,that is to say1 if ,h and ,o be set free from separate receivers in a room1 the ,h will become intermingled with the atmosphere four times as quickly as the ,o4 ,compare the diffusibility of ,o and ,n2 of ,cl and ,h4 ,take the atomic weights of these1 since they are the same as the vapor densities4 ,in case of a compound gas1 half the molecular weight must be taken for the vapor density2 e4g4 dif4 ,n#bj3 dif4 ,o433 sqrt7#af73 sqrt7#bb74 #ahj4 ,cause4--,diffusion is due to molecular motion2 the lighter the gas the more rapid the vibration of its molecules4 ,compare the diffusibility of ,,co#b and that of ,cl2 of ,h,cl and ,,so#b2 of ,,hf and ,i4 #aha4 ,liquefaction and ,solidification of ,gases4--,water boils at #ajj degrees1 under standard pressure1 though evaporating at all temperatures2 it vaporizes at a lower point if the pressure be less1 as on a mountain1 and at a higher temperature if the pressure be greater1 as at points below the sea level4 ,alcohol boils at #gh degrees1 standard pressure1 and every liquid has a point of temperature and pressure above which it must pass into the gaseous state4 ,likewise every gas has a critical temperature above which it cannot be liquefied at any pressure4 ,this condition was not recognized formerly1 and before #ahgg1 ,o1 ,h1 ,n1 ,c#d1 ,,co1 ,,no1 etc41 had not been liquefied1 though put under a pressure of more than #b1jjj atmospheres4 ,they were called permanent gases4 ,in #ahgg ,cailletet and ,pictet liquefied and solidified these and others4 ,the lowest temperature1 about -#bbe degrees1 was produced by suddenly releasing the pressure from solid ,n to #dmm1 which caused it rapidly to evaporate4 ,evaporation1 especially under diminished pressure1 always lowers the temperature by withdrawing heat4 ,these low degrees are indicated by a ,h thermometer1 or if too low for that1 by a thermo-electric couple of copper and ,german silver4 ,the pupil can easily liquefy ,,so1 by passing it through a ,u-tube which is surrounded by a mixture of ice and salt in a large receiver4 ,at the meeting of the ,american ,association for the ,advancement of ,science in #ahhg1 a solid brick of ,,co#b was seen and handled by the members1 ,liquid ,h is steel blue4 ,a few results obtained under a pressure of one atmosphere are3-- ,boiling ,points3 ,c#b;,h#d--ajb degrees2 ,,ch#d--ahd degrees2 ,o--#aha degrees2 ,n --#aid degrees2 ,,co--#aij degrees2 ,,no--#aed degrees2 ,air-- #aia degrees4 ,solidifying ,points3 ,cl -#ajb degrees2 ,h,cl -#aae degrees2 ,ether -#abi degrees2 ,alcohol -#acj degrees4 ,chapter ,,xxxvii4 ,,sulphur4 ,examine brimstone1 flowers of sulphur1 pyrite1 chalcopyrite1 sphalerite1 galenite1 gypsum1 barite4 #ahb4 ,separation4 ,experiment #ajc4--,to a solution of #b g4 of sodium sulphide11 ,na#b,s#b in #aj cc4 ,h#b,o add #c or #d;cc4 ,h,cl1 and look for a ppt4 ,filter1 and examine the residue4 ,it is lac sulphur1 or milk of sulphur4 #ahc4 ,crystals from ,fusion4 ,experiment #ajd4--;,in a beaker of #be or #ej cc4 capacity put #bj g4 brimstone4 ,place this over a flame with asbestos paper interposed1 and melt it slowly4 ,note the color of the liquid1 then let it cool1 watching for crystals4 ,when partly solidified pour the liquid portion into an evapo- rating-dish of water1 and observe the crystals of ,s forming in the beaker 7,fig4 #db74 ,the hard mass may be separated from the glass by a little ,,hno#c and a thin knife-blade1 or by ,,cs#b4 #ahd4 ,allotropy4 ,experiment #aje4--,place in a t4t4 #ae;g of brimstone1 then heat slowly till it melts4 ,notice the thin amber-colored liquid4 ,the temperature is now a little above #ajj degrees4 ,as the heat increases1 notice that it grows darker till it becomes black and so viscid that it cannot be poured out4 ,it is now above #bjj degrees4 ,still heat1 and observe that it changes to a slightly lighter color1 and is again a thin liquid4 ,at this time it is above #cjj degrees4 ,now pour a little into an evaporating dish containing water4 ,examine this1 noticing that it can be stretched like rubber4 ,leave it in the water till it becomes hard4 ,continue heating thebrimstone in the t4t4 till it boils at about #dej degrees1 and note the color of the escaping vapor4 ,just above this point it takes fire4 ,cool the t4t41 holding it in the light meantime1 and look for a sublimate of ,s on the sides4 #ahe4 ,solution4 ,experiment #ajf4--,place in an evaporating-dish a gram of powdered brimstone1 and add #e;cc1 ,,cs#b1 carbon disulphide4 ,stir1 and see whether ,s is dissolved4 ,put this in a draft of air1 and note the evaporation of the liquid ,,cs#b1 and the deposit of ,s crystals4 ,these crystals are different in form from those resulting from cooling from fusion4 #ahf4 ,theory of ,allotropy4--,the last three experiments well illustrate allotropy4 ,we found ,s to crystallize in two different ways4 ,substances can crystallize in seven different systems1 and usually a given substance is found in one of these systems only2 e4g4 galena is invariably cubical4 ,an element having two such forms is said to be dimorphous4 ,if it crystallizes in three systems1 it is trimorphous4 ,a crystal has a definite arrangement of its molecules4 ,if without crystalline form1 a substance is called amorphous4 ,an illustration of amorphism was ,s after it had been poured into water4 ,thus ,s has at least three allotropic forms1 and the gradations between these probably represent others4 ,allotropy seems to be due to varied molecular structure4 ,we know but little of the molecular condition of solids and liquids1 since we have no law to guide us like ,avogadro's in gases2 but1 from the density of ,s vapor at different temperatures1 we infer that liquids and solids have their molecules very differently made up from those of gases4 ,the least combining weight of ,s is #cb4 ,its vapor density at #a1jjj degrees is #cb2 hence its molecular weight is #fd1 i4e4 vapor density x #b2 and there are #b atoms in its molecule at that temperature1 molecular weight _/ atomic weight4 ,at #ejj degrees1 however1 the vapor density is #if;and the molecular weight #aib4 ,at this degree the molecule must contain #f atoms4 ,how many it has in the allotropic forms1 as a solid1 is beyond our knowledge2 but it seems quite likely that allotropy is due to some change of molecular structure4 ,the above experiments show two modes of obtaining crystals1 by fusion and by solution4 #ahg4 ,occurrence and ,purification4--,sulphur occurs both free and combined1 and is a very common element4 ,it is found free in all volcanic regions1 but ,sicily furnishes most of it4 ,great quantities are thrown up from the interior of the earth during an eruption4 ,the heat of volcanic action probably separates it from its compound1 which may be ,ca,s,o#d4 ,vast quantities of the poisonous ,,so#b gas are also liberated during an eruption1 this being1 in volume of gases evolved1 next to ,h#b,o4 ,s is crudely separated from its earthy impurities in ,sicily by piling it into heaps1 covering to prevent access of air1 and igniting1 when some of the ,s burns1 and the rest melts and is collected4 ,after removal from the island it is further purified by distilling in retorts connected with large chambers where it sublimes on the sides as flowers of sulphur 7,fig4 #dc74 ,this is melted and run into molds1 forming roll brimstone4 ,s also occurs as a constituent of animal and vegetable compounds1 as in mustard1 hair1 eggs1 etc4 ,the tarnishing of silver spoons by eggs is due to the formation of silver sulphide1 ,ag#b,s4 ,the yellow color of eggs1 however1 is due to oils1 not to ,s4 ,the main compounds of ,s are sulphides and sulphates4 ,what acids do they respectively represent8 ,metallic sulphides are as common as oxides2 e4g4 ,fe,s#b1 or pyrite1 ,pb,s1 or galenite1 ,zn,s1 or sphalerite1 ,cu,fe,s#b1 or chalcopyrite1 etc4 ,the most abundant sulphate is ,ca,s,o#d1 or gypsum4 ,ba,s,o#d1 or barite1 and ,na#b,,so#d1 or ,glauber's salt1 are others4 ,the only one of these compounds that is utilized for its ,s is ,fe,s#b4 ,in ,europe this furnishes a great deal of the ,s for ,h#b,,so#d4 ,s is obtained by roasting ,fe,s#b4 #c ,fe,s#b ,fe#c,s#d #b ,s4 #ahh4 ,uses4 -,the greatest use of ,s is in the manufacture of ,h#b,,so#d4 ,a great deal is used in making gunpowder1 matches1 vulcanized rubber1 and the artificial sulphides1 like ,hg,s1 ,h#b,s1 ,,cs#b1 etc4 ,the last is a very volatile1 ill- smelling liquid1 made by the combination of two solids1 ,s being passed over red-hot charcoal4 ,it dissolves ,s1 ,p1 rubber1 gums1 and many other substances insoluble in ,h#b,o4 #ahi4 ,sulphur ,dioxide1 ,,so#b1 has been made in many experiments4 ,it is a bleaching agent1 a disinfectant1 and a very active compound1 having great affinity for water1 but it will not support combustion4 ,like most disinfectants1 it is very injurious to the system4 ,it is used to bleach silk and wool--animal substances-- and straw goods1 which ,cl would injure2 but the color can be restored1 as the coloring molecule seems not to be broken up1 but to combine with ,,so#b1 which is again separated by reagents4 ,goods bleached with ,,so#b often turn yellow after a time4 #aij4 ,,so#b a ,bleacher4 ,experiment #ajg4-,test its bleaching power by burning ,s under a receiver under which a wet rose or a green leaf is also placed4 ,chapter ,,xxxviii4 ,,hydrogen ,,sulphide4 ,examine ferrous sulphide1 natural and artificial4 #aia4 ,preparation4 ,experiment #ajh4--,put a gram of ferrous sulphide 7,fe,s7 into a t4t4 fitted with a d4t41 as in ,figure #cb4 ,add #aj;cc4 ,h#b,o and #e;cc4 ,h#b,,so#d4 ,h#b,s is formed4 ,write the equation1 omitting ,h#b,o4 ,what is left in solution8 #aib4 ,tests4 ,experiment #aji4-7a7 ,take the odor of the escaping gas4 7#b7 ,pour into a t4t4 #e;cc4solution ,ag,n,o#c1 and place the end of the d4t4 from a ,h#b,s generator into the solution and note the color of the ppt4 ,what is the ppt48 ,write the equation4 7#c7 ,experiment in the same way with ,pb7,,no#c7b solution4 ,write the equation4 7#d7 ,let some ,h#b,s bubble into a t4t4 of clean water4 ,to see whether ,h#b,s is soluble in ,h#b,o1 put a few drops of the water on a silver coin4 ,ag#b,s is formed4 ,describe1 and write the equation4 ,do the same with a copper coin4 7#e7 ,put a drop of lead acetate solution1 ,pb7,c#b;,h#c,o#b7b1 on a piece of unglazed paper1 and hold this before the d4t4 from which ,h#b,s is escap- ing4 ,pb,s is formed4 ,write the equation4 ,this is the characteristic test of ,h#b,s4 #aic4 ,combustion of ,h#b,s ,experiment #aaj4--;,attach a philosopher's lamp tube to the ,h#b,s generator1 and1 observing the same precautions as with ,h1 light the gas4 ,what two products must be formed8 ,state the reaction4 ,the color of the flame4 ,compute the molecular weight and the vapor density of ,h#b,s4 #aid4 ,uses4 -,hydrogen sulphide or sulphuretted hydrogen1 ,h#b,s1 is employed chiefly as a reagent in the chemical laboratory4 ,it forms sulphides with many of the metals1 as shown in the last experiment4 ,these are precipitated from solution1 and may be separated from other metals which are not so precipitated1 as was found in the case of ,h,cl and ,,nh#d,,oh4 ,the subjoined experiment will illustrate this4 ,suppose we wished to separate ,pb from ,ba1 having salts of the two mixed together1 as ,pb7,,no#c7b and ,ba7,,no#c7b4 #aie4 ,h#b,s an ,analyzer of ,metals4 ,experiment #aaa4--,pass ,some ,h#b,s gas in to #e;cc4solution ,ba7,,no#c7b4 ,no ppt4 is formed4 ,do the same with ,pb7,,no#c7b solution4 ,a ppt4 appears4 ,now mix #e;cc4of each of these solutions in a t4t4 and pass the gas from a ,h#b,s generator into the liquid4 ,what is precipitated1 and what is unchanged8 ,when fully saturated with the gas1 as indicated by the smell1 filter4 ,which metal is on the filter and which is in the filtrate8 ,other reagents1 as ,na#b;,,co#c solution1 would precipitate the latter4 #aif4 ,occurrence and ,properties4 -- ,h#b,s is an ill-smell- ing1 poisonous gas1 formed in sewers1 rotten eggs1 and other decaying albuminous matter4 ,it is formed in the earth1 probably from the action of water on sulphides1 and issues with water from sulphur springs4 ,a characteristic property is the formation of metallic sulphides1 as above4 ,a skipper one night anchored his newly painted vessel near the ,boston gas-house1 where the refuse was deposited1 with its escaping ,h#b,s4 ,in the morning1 to his consternation1 the craft was found to be black4 ,h#b,s had come in contact with the lead in the white paint1 forming black ,pb,s4 ,this gradually oxidized after reaching the open sea1 and the white color reappeared4 ,chapter ,,xxxix4 ,,phosphorus4 ,,note4--,phosphorus should be kept in water1 and handled with forceps1 never with the fingers1 except under water1 as it is liable to burn the flesh and produce ulcerating sores4 ,pieces not larger than half a pea should be used1 and every bit should finally be burned4 #aig4 ,solution and ,combustion4 ,experiment #aab4 -,put #a or #b pieces of ,p into an evaporating- dish1 and pour over them #e or #aj;cc4,,cs#b carbon disulphide4 ,this will be enough for a class4 ,when dissolved1 dip pieces of unglazed paper into it1 and hold these in the air1 looking for any combustion as they dry4 ,the ,p is finely divided in solution1 which accounts for its more ready combustion then4 ,notice that the paper is not destroyed4 ,this is an example of so-called spontaneous combustion4 ,the burning- point of ,p1 the combustible1 in air1 the supporter1 is about #fj degrees4 #aih4 ,combustion under ,water4 ,experiment #aac4 -,put a piece of ,p in a t4t4 which rests in a receiver1 add a few crystals ,k,cl,o#c and #e;cc4 ,h#b,o4 ,now pour in through a thistle-tube #a;cc4or more of ,h#b,,so#d4 ,look for any flame4 ,h#b,,so#d acts very strongly on ,k,cl,o#c4 ,what is set free8 ,from this fact explain the combustion in water4 #aii4 ,occurrence4--,p is very widely disseminated1 but not abundant1 and is found only in compounds1 the chief of which is calcium phosphate ,ca#c7,,po#d7b4 ,it occurs in granite and other rocks1 as the mineral apatite1 in soils1 in plants1 particularly in seeds and grains1 and in the bones1 brains1 etc41 of vertebrates4 ,from the human system it is excreted by the kidneys as microcosmic salt1 ,h,na,n,h#d,,po#d2 and when the brain is hard- worked1 more than usual is excreted4 ,hence brain-workers have been said to burn phosphorus4 #bjj4 ,sources4--,rocks are the ultimate source of this element4 ,these1 by the action of heat1 rain1 and frost1 are disintegrated and go to make soils4 ,the rootlets of plants are sent through the soil1 and1 among other things1 soluble phosphates in the earth are absorbed1 circulated by the sap1 and selected by the various tissues4 ,animals feed on plants1 and the phosphates are circulated through the blood1 and deposited in the osseous tissue1 or wherever needed4 ,human bones contain nearly #fj per cent of ,ca#c7,,po#d7b2 those of some birds over #hj per cent4 ,the main sources of phosphates and ,p are the phosphate beds of ,south ,carolina1 the apatite beds of ,canada1 and the bones of animals4 #bja4 ,preparation of ,phosphates and ,phosphorus4--,bone ash1 obtained by burning or distilling bones1 and grinding the residue1 is treated with ,h#a,,so#d1 and forms soluble ,h#d;,ca7,,po#d7b1 superphosphate of lime1 and insoluble ,ca,s,o#d4 ,ca#c7,,po#d7b #b ,h#b,,so#d ,h#d;,ca7,,po#jd7b #b ,ca,s,o#d4 ,this completes the process for fertilizers4 ,if ,p is desired1 the above is filtered2 charcoal1 a reducing agent1 is added to the filtrate2 the substance is evaporated1 then very strongly heated and distilled in retorts1 the necks of which dip under water4 ,it is then purified from any uncombined ,c by melting in hot water and passing into molds in cold water4 ,the work is very dangerous and injurious1 on account of the low burning-point of ,p1 and its poisonous properties4 ,while its compounds are necessary to human life1 ,p itself destroys the bones1 particularly the jaw bones1 of the workers in it4 ,between #a1jjj and #b1jjj tons are made yearly1 mostly for matches1 but almost all at two factories1 one in ,england1 and one in ,france4 #bjb4 ,properties4--,p is a colorless1 transparent solid1 when pure2 the impure article is yellowish1 translucent1 and waxy4 ,it is insoluble in water1 slightly soluble in alcohol and ether1 and it readily dissolves in ,,cs#b1 oil of turpentine1 etc4 ,fumes1 having a garlic odor1 rise when it is exposed to the air1 and in the dark it is phosphorescent1 emitting a greenish light4 #bjc4 ,uses4 -,the uses of this element and its compounds are for fertilizers1 matches1 vermin poisons1 and chemical operations4 #bjd4 ,matches4-,the use of ,p for matches depends on its low burning-point4 ,prepared wood is dipped into melted ,s1 and the end is then pressed against a stone slab having on it a paste of ,p1 ,k,cl,o#c1 and glue4 ,,kno#c is often used instead of ,k,cl,o#c4 ,in either case the object is to furnish ,o to burn ,p4 ,matches containing ,k,cl,o#c snap on being scratched1 while those having ,,kno#c burn quietly4 ,the friction from scratching a match generates heat enough to ignite the ,p1 that enough to set the ,s on fire1 and the ,s enough to burn the wood4 ,give the reaction for each4 ,paraffine is much used instead of ,s4 ,safety matches have no ,p1 and must be scratched on a surface of red ,p and ,sb#b,s#c1 or on glass4 #bje4 ,red ,phosphorus4-,two or three allotropic forms of ,p are known1 the principal one being red4 ,if heated between #bcj degrees and #bfj degrees1 away from air1 the yellow variety changes to red1 which can be kept at all temperatures below #bfj degrees4 ,above that it changes back4 ,red ,p is not poisonous1 ignites only at a high temperature1 and is not phosphorescent1 like the yellow4 #bjf4 ,spontaneous ,combustion of ,phosphene1 or ,hydrogen ,phosphide1 ,,ph#c4 ,experiment #aad4--,put into a #bj;cc4flask #a g4 ,p and #ej;cc4saturated solution ,na,o,h or ,,koh4 ,connect with the p4t4 by a long d4t41 as in ,figure #dd1 the end of which must be kept under water4 ,pour #c or #d;cc4of ether into the flask1 to drive out the air4 ,it is necessary to exclude all air1 as a dangerously explosive mixture is formed with it4 ,heat the mixture1 and as the gas passes over and into the air1 it takes fire spontaneously1 and rings of smoke successively rise4 ,it will do no harm if1 on taking away the lamp1 the water is drawn back into the flask2 but in that case the flask should be slightly lifted to prevent breakage by the sudden rush of water4 ,on no account let the air be drawn over4 ,the experiment has no practical value1 but is an interesting illustration of the spontaneous combustion of ,,ph#c and of vortex rings4 ,what are the products of the combustion8 ,an admixture of another compound of ,p and ,h causes the combustion4 ,chapter ,,xl4 ,,arsenic4 ,examine metallic arsenic1 realgar1 orpiment1 arsenopyrite1 arsenic trioxide1 copper arsenite4 ,the compounds of arsenic are very poisonous if taken into the system1 and must be handled with care4 #bjg4 ,separation4 ,experiment #aae4--;,draw out into two parts in the ,bunsen flame a piece of glass tubing #bj;cm long and #a or #b;cm in diameter4 ,into the end of one of the ignition tubes thus formed1 when it is cool1 put one-fourth of a gram of arsenic trioxide1 ,as#b,o#c1 using paper to transfer it4 ,now put into the tube a piece of charcoal1 and press it down to within #b or #c;cm of the ,,as#b,o#c 7,fig4 #de74 ,next heat the coal red-hot1 and then at once heat the ,as#bjc4 ,continue this process till you see a metallic sublimate- metallic mirror-on the tube above the coal4 ,break the tube and examine the sublimate4 ,it is ,as4 ,heat vaporizes the ,as#b,o2#c4 ,explain the chemical action4 ,what is the agency of ,c in the experiment8 ,of ,as#b,o#c8 #b ,as#b,o#c #c ,c 8 #bjh4 ,tests4-,experiments #aae and #aaf are used as tests for the presence of arsenic4 ,experiment #aaf4--,prepare a ,h generator1 - a flask with a thistle- tube and a philosopher's lamp tube 7,fig4 #df71 put in some granulated ,zn1 water1 and ,h,cl4 ,test the purity of the escaping gas 7,experiment #bc71 and when pure1 light the jet of ,h4 ,h is now burning in air4 ,to be sure that there is no ,as in the ingredients used1 hold the inside of a porcelain evaporating-dish directly against the flame for a minute4 ,if no silvery-white mirror is found1 the chemicals are free from ,as4 ,then pour through the thistle-tube1 while the lamp is still burning1 #a;cc4solution of ,,as#b,o#c in ,h,cl or ,h#b,o a bit of ,as#b,o#c not larger than a grain of wheat in #aj cc4 ,h,cl4 ,see whether the color of the flame changes2 then hold the evaporating-dish once more in the flame1 and notice a metallic deposit of ,as4 ,set away the apparatus under the hood and leave the light burning4 ,this experiment must not be performed unless all the cautions are observed1 since the gas in the flask 7,as,h#c7 is the most poisonous known1 and a single bubble of it inhaled is said to have killed the discoverer4 ,by confining the gas inside the flask there is no danger4 ,instead of using ,as#b,o#c solution1 a little ,paris green1 wall paper suspected of containing arsenic1 green silk1 or green paper labels1 etc41 may be soaked in ,h,cl1 and tested4 #bji4 ,explanation4--,the chemical changes are as follows3 ,the compounds of ,as1 in this case ,as#b,o#c1 in presence of nascent ,h1 are immediately converted into the deadly hydrogen arsenide 7arsine1 arseniuretted hydrogen71 ,as,h#c4 ,as#b,o#c #ab ,h #b ,as,h#c #c ,h#b,o4 ,the ,as,h#c mixed with excess of ,h tends to escape and is burned to ,as#b,o#c and ,h#b,o1 and thus is rendered comparatively harmless as it passes into the air4 ,this is why the flame must be burning when the arsenic compound is introduced4 #b ,as,h#c #f ,o ,as#b,o#c #c ,h#b,o4 ,in the combustion of ,as,h#c1 ,h burns at a lower point than ,as4 ,the introduction of a cold body like porcelain cools the flame below the kindling-point of ,as1 and this is deposited1 while ,h burns1 in exactly the same way as lamp- black was collected in ,experiment #bf4 #baj4 ,expert ,analysis4--,a modification of this experiment is employed by experts to test for ,,as#b,o#c poisoning4 ,the organs4-- stomach or liver--are cut into small pieces dissolved by nascent ,cl1 or ,h,cl,o1 made from ,,kc#a,o#c and ,h,cl1 and the solution is introduced into a ,h generator1 as above4 ,,as#b,o#c preserves the tissues it comes in contact with1 for a long time1 and the test can be made years after death4 ,all the chemicals must be pure1 since ,as is found in small quantities in most ores1 and the ,zn1 ,h,cl1 and ,h#b,,so#d of commerce are very likely to contain it4 ,the above is called ,marsh's test1 and is so delicate that a mere trace of arsenic can be detected4 #baa4 ,properties and ,occurrence4--,as is a grayish white solid1 of metallic luster1 while a few of its characters are non-metallic4 ,it is very widely distributed1 being sometimes found native1 and sometimes combined1 as ,as,s1 realgar1 ,as#b,s#h1 orpiment1 and ,fe,as,s1 arsenopyrite4 ,its chief source is the last1 the fine powder of which is strongly heated1 when ,as separates and sublimes4 ,it has the odor of garlic1 as may be observed by heating a little on charcoal with the blow-pipe4 #bab4 ,atomic ,volume4--,as is peculiar in that its atomic volume1 so far as the volume can be determined1 is only half that of the ,h atom4 ,its vapor density is #aej1 which gives #cjj for the molecular weight1 while its least combining or atomic weight is #ge4 #cjj1 the molecular weight #ge1 the atomic weight #d1 the number of atoms in the molecule4 ,all gaseous molecules being of the same size1 represented by two squares1 the atomic volume of ,as must be one-fourth of this size1 represented by half of one square4 ,of what other element is this true8 #bac4 ,uses of ,as#b,o#c4-;,arsenic is used in shot-manufacture1 for hardening the metal4 ,its most important compound is ,as#b,o#c1 arsenic trioxide1 called also arsenious anhydride1 arsenious acid1 white arsenic1 etc4 ,so poisonous is this that enough could be piled on a one-cent piece to kill a dozen persons4 ,taken in too large quantities it acts as an emetic4 ,the antidote is ferric hydrate ,fe#b7,,oh7#f and a mustard emetic1 followed by oil or milk4 ,the vapor density of this compound shows that its symbol should be ,as#d,o#f1 but the improper one1 ,as#b,o#c1 is likely to remain in use4 ,another oxide1 ,as#b,o#e1 arsenic pentoxide1 exists1 but is less important4 ,show how the respective acid formulae are obtained from these anhydrides4 ,see page #ej4 ,,as#b,o#c is used in making ,paris green2 in many green coloring materials1 in which it exists as copper arsenite2 in coloring wall papers1 and in fly and rat poisons4 ,it is employed for preserving skins1 etc4 ,fashionable women sometimes eat it for the purpose of beautifying the complexion1 to which it imparts a ghastly white1 unhealthy hue4 ,mountaineers in some parts of ,europe eat it for the greater power of endurance which it is supposed to give them4 ,by beginning with small doses these arsenic-eaters finally consume a considerable quantity of the poison with apparent impunity2 but as soon as the habit is stopped1 all the pangs of arsenic-poisoning set in4 ,wall paper containing arsenic is said to be injurious to some people1 while apparently harmless to others4 ,chapter ,,xli4 ,,silicon1 ,,silica1 ,,and ,,silicates4 #bad4 ,comparison of ,si and ,c4--,the element ,si resembles carbon in valence and in allotropic forms4 ,it occurs in three forms like ,c1 a diamond form1 a graphite1 and an amorphous4 ,c forms the basis of the vegetable and animal world2 ,si1 of the mineral4 ,most soils and rocks1 except limestone1 are mainly compounds of ,o1 ,si1 and metals4 ,while ,o is estimated to make up nearly one- half of the known crust of the earth1 ,si constitutes fully a third4 ,the two are usually combined1 as silica1 ,si,o#b1 or silicates1 ,si,o#b combined with metallic oxides4 ,this affinity for ,o is so strong that ,si is not found uncombined1 and is separated with great difficulty and only at the highest temperatures4 ,no special use has yet been found for it1 except as an alloy with ,al4 ,its compounds are very important4 #bae ,silica4--,examine some specimens of quartz1 rock crystal1 white and colored sands1 agate1 jasper1 flint1 etc42 test their hardness with a knife blade1 and see whether they will scratch glass4 ,notice that quartz crystals are hexagonal or six-sided prisms1 terminated by hexagonal pyramids4 ,the coloring matters are impurities1 often ,fe and ,mn1 if red or brown4 ,when pure1 quartz is transparent as glass1 infusible except in the oxy- hydrogen blow- pipe1 and harder than glass4 ,rock crystal is massive ,si#jb4 ,sand is generally either silica or silicates4 ,the common variety of ,si#jb is not soluble in water or in acids1 except ,,hf4 ,an amorphous variety is to some extent soluble in water4 ,most geysers deposit the latter in successive layers about their mouths4 ,agate1 chalcedony1 and opal have probably an origin similar to this4 ,a solution of this variety of ,si,o#b forms a jelly-like masscolloid--which will not diffuse through a membrane of parchment -dialyzer--when suspended in water4 ,crystalloids will diffuse through such a membrane1 if they are in solution4 ,this principle forms the basis of dialysis4 ,all substances are supposed to be either crystalloids1 i4e4 susceptible of crystallization1 or colloids-jelly-like masses4 ,h,cl is the most diffusible in liquids of all known substances2 caramel is one of the least so4 ,to separate the two1 they would be put into a dialyzer suspended in water1 when ,h,cl will diffuse through into the water1 and caramel will remain4 ,as#b,o#c1 in cases of suspected poisoning1 was formerly separated from the stomach in this way1 as it is a crystalloid1 whereas most of the other contents of the stomach are colloidal4 #baf4 ,silicates4--,si is a tetrad4 ,si,o#b #b ,h#b,o 8 ,si#jb ,h#b,o 8 ,in either case the product is called silicic acid4 ,replace all the ,h with ,na1 and name the product4 ,replace it with ,k2 ,mg2 ,fe2 ,ph2 ,ca4 ,na#d,si,o#d and ,na#b,si,o#c are typical silicates of ,na1 but others exist4 #bag4 ,formation of ,si,o#b from ,sodium ,silicate4 ,experiment #aag4--,to #e;cc4,na#d,si,o#d in au evaporating-dish add #e;cc4 ,h,cl4 ,describe the effect4 ,pour away any extra ,h,cl4 ,heat the residue gently1 above a flame1 till it becomes white1 then cool it and add water4 ,in a few minutes taste a drop of the water1 then pour it off1 leaving the residue4 ,crush a little in the fingers1 and compare it with white sand1 ,si,o#b4 ,apply to the experiment these equations3 - ,na#d,si,o#d #d ,h,cl #d ,na,cl ,h#d,si,o#d4 ,h#d,si,o#d #b ,h#b,o ,si#jb4 ,why was ,h#d,si#jd heated8 ,why was water finally added8 ,water glass1 sodium or potassium silicate1 used somewhat for making artificial stone1 is made by fusing ,si,o#b with ,na#b;,,co#c or ,k#b;,,co#c1 and dissolving in water4 ,silicic acid forms the basis of a very important series of compounds1 - the silicates4 ,the above two are the only soluble ones1 and may be called liquid glass4 ,chapter ,,xlii4 ,,glass ,,and ,,pottery4 ,examine white sand1 calcium carbonate1 sodium carbonate1 smalt2 bottle1 window1 ,bohemian and flint glass4 #bah4 ,glass is an ,artificial ,silicate4--,si#jb alone is almost infusible1 as is also ,ca#j2 but mixed and heated the two readily fuse1 forming calcium silicate4 ,ca#j ,si,o#b 8 ,notice that ,si#jb is the basis of an acid1 while ,ca,o is essentially a base1 and the union of the two forms a salt4 ,there are four principal kinds of glass3 7#a7 ,bohemian1 a silicate of ,k and ,ca1 not easily fused1 and hence used for chemical apparatus where high temperatures are required2 7#b7 window or plate glass1 a silicate of ,na and ,ca2 7#c7 bottle glass1 a silicate of ,na1 ,ca1 ,al1 ,fe1 etc41 a variety which is impure1 and is tinged green by salts of ,fe2 7#d7 flint glass1 a silicate of ,k and ,pb1 used for lenses in optical instruments1 cut glass ware1 and1 with ,b added1 for paste1 or imitation diamonds1 etc4 ,pb gives to glass high refracting power1 which is a valuable property of diamonds1 as well as of lenses4 #bai4 ,manufacture4--,pure white sand1 ,si#jb1 is mixed with ,ca,c,o#c and ,na#b;,,co#c1 some old glass - cullet - is added1 and the mixture is fused in fire-clay crucibles4 ,for flint glass1 ,pb#cjd1 red lead1 is employed4 ,if color is desired1 mineral coloring matter is also added1 but not always at this stage4 ,co,o1 or smalt1 gives blue2 uranium oxide1 green2 a mixture of ,au and ,sn of uncertain composition1 called the purple of ,cassius1 gives purple4 ,mn,o#b is used to correct the green tint caused by ,fe,o1 which it is supposed to oxidize4 ,opacity1 or enamel1 as in lamp-shades1 is produced by adding ,as#b,o#c1 ,sb#b,o#c1 ,sn,o#b1 cryolite1 etc4 ,the glass- worker dips his blowpipe--a hollow iron rod five or six feet long--into the fused mass of glass1 removes a small portion1 rolls it on a smooth surface1 swings it round in the air1 blowing meanwhile through the rod1 and thus fashions it as desired1 into bottles1 flasks1 etc4 ,for some wares1 e4g4 common goblets1 the glass is run into molds and stamped2 for others it is blown and welded4 ,all glass must be annealed1 i4e4 cooled slowly1 for several days4 ,the molecules thus arrange themselves naturally4 ,if not annealed1 it breaks very easily4 ,it may be greatly toughened by dipping1 when nearly red-hot1 into hot oil4 ,cut glass is prepared at great expense by subsequent grinding4 ,glass may be rendered semi-opaque by etching either with ,,hf1 or with a blast of sand4 #bbj4 ,importance4--,few manufactured articles have more importance than glass4 ,without it the sciences of chemistry1 physics1 astronomy1 microscopic anatomy1 zoology1 and botany1 not to mention its domestic uses1 would be almost impossible4 #bba4 ,porcelain and ,pottery4--,genuine porcelain and china-ware are made of a fine clay1 kaolin1 which results from the disintegration of feldspathic rocks4 ,bricks are baked clay4 ,the ,fe,o in common clay is oxidized to ,fe#b,o#c1 on heating1 a process which gives their red color4 ,some clay1 having no ,fe1 is white2 this is used for fire-bricks and clay pipes4 ,that containing ,fe is too fusible for fire-clay1 which must also have much ,si,o#b4 ,the electric arc1 however1 will melt even this1 and the most refractory vessels are of calcium oxide or of graphite4 ,pottery is clay1 molded1 baked1 and either glazed1 like crockery1 or unglazed1 like flower-pots4 ,jugs and coarse earthenware are glazed by volatilizing ,na,cl in an oven which holds the porous material4 ,this coats the ware with sodium silicate4 ,to glaze china1 it is dipped into a powder of feldspar and ,si,o#b suspended in water and vinegar1 and then fused4 ,if the ware and glaze expand uniformly with heat1 the latter does not crack4 ,chapter ,,xliii4 ,,metals ,,and ,,their ,,alloys4 #bbb4 ,comparison of ,metals and ,non-,metals4--,the majority of elements are metals1 only about a dozen being non-metallic in their properties4 ,the division line between the two classes is not very well defined2 e4g4 ,as has certain properties which ally it to metals2 it has other properties which are non-metallic4 ,h occupies a place between the two classes4 ,the following are the more marked characteristics of each group3 - ,,metals4 #a4 ,metals are solid at ordinary temperatures1 and usually of high specific gravity4 ,exceptions3 ,hg is liquid above -#ci4e degees2 ,li is the lightest solid known2 ,na and ,k will float on water4 #b4 ,metals reflect light in a way peculiar to themselves4 ,they have what is called a metallic luster4 #c4 ,they are white or gray4 ,exceptions3 ,au1 ,ca1 ,sr are yellow2 ,cu is red4 #d4 ,in general they conduct heat and electricity well4 ,,non-,,metals4 #a4 ,non-metals are either gaseous or solid at ordinary temperatures1 and of low specific gravity4 ,exceptions3 ,br is a liquid2 ,i has the heaviest known vapor4 #b4 ,non-metallic solids have different lusters1 as glassy1 resinous- silky1 etc4 ,exceptions3 ,i1 ,b1 and ,c have metallic luster4 #c4 ,non-metals have no characteristic color4 #d4 ,they are non-conductors of heat and electricity4 ,exceptions3 ,c and some others are conductors4 #e4 ,they are usually malleable and ductile4 #f4 ,they form alloys1 or chemical mixtures1 with one another1 similar to other solutions4 ,exceptions3 ,some1 as ,ph and ,zn1 will not alloy with one another4 #g4 ,metals are electro-positive elements1 and unite with ,o and ,h to form bases4 ,exceptions3 ,some of the less electro-positive metals1 with a large quantity of ,o1 form acids1 as ,cr1 ,as1 etc4 ,numbers #b1 #f1 and #g are the most characteristic and important properties4 #e4 ,they are deficient in malleability and ductility4 #f4 ,they often form liquid solutions1 similar to alloys in metals4 #g4 ,non-metals are electronegative1 and with ,h1 or with ,h and ,o1 form acids4 ,examine brass1 bronze1 bell-metal1 pewter1 ,german silver1 solder1 type-metal4 #bbc4 ,alloys4-,an alloy is not usually a definite chemical compound1 but rather a mixture of two or more metals which are melted together4 ,one metal may be said to dissolve in the other1 as sugar dissolves in water4 ,the alloy has1 however1 different properties from those of its elements4 ,for example1 plumber's solder melts at a lower temperature than either ,ph or ,sn1 of which it is composed4 ,some metals can alloy in any proportions4 ,solder may have two parts of ,sn to one of ,pb1 two of ,pb to one of ,sn1 or equal parts of each1 or the two elements may alloy in other proportions4 ,not all metals can be thus fused together indefinitely2 e4g41 ,zn and ,pb4 ,nickel and silver coins are alloyed with ,cu1 gold coins with ,cu and ,ag4 ,gun-metal1 bell-metal1 and speculum-metal are each alloys of ,cu and ,sn4 ,speculum-metal1 used for reflectors in telescopes1 has relatively more ,sn than either of the others2 gun-metal has the least4 ,an alloy of ,sb and ,pb is employed for type-metal as it expands at the instant of solidification4 ,pewter is composed of ,sn and ,pb2 brass1 of ,cu and ,zn2 ,german silver1 of brass and ,ni2 bronze1 of ,cu1 ,sn1 and ,zn2 aluminium bronze1 of ,cu and ,al4 #bbd4 ,low ,fusibility is a feature of many alloys4 ,wood's metal1 composed of ,pb eight parts1 ,bi fifteen1 ,sn four1 ,cd three1 melts at just above #fj degrees1 or far below the boiling-point of water4 ,by varying the proportions1 different fusing-points are obtained4 ,this principle is applied in automatic fire alarms1 and in safety plugs for boilers and fire extinguishers4 ,water pipes extend along the ceiling of a building and are fitted with plugs of some fusible alloy1 at short distances apart4 ,when1 in case of fire1 the heat becomes sufficiently intense1 these plugs melt and the water flows out4 #bbe4 ,amalgams4--,an amalgam is an alloy of ,hg and another metal4 ,mirrors are silvered with an amalgam of ,sn4 ,tin-foil is spread on a smooth surface and covered with ,hg1 and the glass is pressed thereon4 ,various amalgams are employed for filling teeth1 a common one being composed of ,hg1 ,ag1 and ,sn4 ,au or ,ag1 with ,hg1 forms an amalgam used for plating4 ,articles of gold and silver should never be brought in contact with ,hg4 ,if a thin amalgam cover the surface of a gold ring or coin1 ,hg can be removed with ,,hno#c1 as ,au is not attacked by it4 ,would this acid do in case of silver amalgam8 ,heat will also quickly cause ,hg to evaporate from ,au4 ,,chapter ,,xliv4 ,,sodium ,,and ,,its ,,compounds4 ,examine ,na,cl1 ,na#b,,so#d1 ,na#b;,,co#c1 ,na1 ,na,o,h1 ,h,na,c,o#c1 ,na,n,o#c4 #bbf4 ,order of ,derivation4--,though ,k is more metallic1 or electro- positive1 than ,na1 the compounds of ,na are more important1 and will be considered first4 ,the only two compounds of ,na which occur extensively in nature are ,na,cl and ,na,n,o#c4 ,almost all others are obtained from ,na,cl1 as shown by this table1 which should be memorized and frequently recalled4 7 ,na ,na,cl 7 ,na#b,,so#d7 ,na#b;,,co#c7 ,na,o,h ,na,n,o#c7 7 7 ,h,na,c,o#c ,from what is ,na#b,,so#d prepared1 as shown by the table8 ,na#b;,,co#c8 ,na8 #bbg4 ,occurrence and ,preparation of ,na,cl4--,na,cl occurs in sea water1 of which it constitutes about three per cent1 in salt lakes1 whose waters sometimes hold thirty per cent1 or are nearly saturated1 and1 as rock salt1 in large masses underground4 ,poland has a salt area of #aj1jjj square miles1 in some parts of which the pure transparent rock salt is a quarter of a mile thick4 ,in ,spain there is a mountain of salt five hundred feet high and three miles in circumference4 ,france obtains much salt from sea water4 ,at high tide it flows into shallow basins1 from which the sun evaporates the water1 leaving ,na,cl to crystallize4 ,in ,norway it is separated by freezing water1 and in ,poland it is mined like coal4 ,in ,new ,york and ,michigan it is obtained by evaporating the brine of salt wells1 either by air and the sun's heat1 or by fire4 ,slow evaporation gives large crystals2 rapid1 small ones4 #bbh4 ,uses4--,the main uses are for domestic purposes and for making the ,na and ,cl compounds4 ,in the ,united ,states the consumption amounts to more than forty pounds per year for every person4 #bbi4 ,sodium ,sulphate4--,what acid and what base are represented by ,na#b,,so#d8 ,which is the stronger acid1 ,h,cl or ,h#b,,so#d8 ,would the latter be apt to act on ,na,cl8 ,why8 #bcj4 ,manufacture4--,this comprises two stages shown by the following reactions1 in which the first needs moderate heat only2 the last1 much greater4 7#a7 #b ,na,cl ,h#b,,so#d ,h,na,s,o#d ,na,cl ,h,cl3 7#b7 ,na,cl ,h,na,s,o#d ,na#b,s#d ,h,cl4 ,the operation is carried on in large furnaces4 ,the gaseous ,h,cl is passed into towers containing falling water in a fine spray1 for which it has great affinity4 ,the solution is drawn off at the base of the tower4 ,thus all commercial ,h,cl is made as a by- product in manufacturing ,na#b,,so#d4 ,when crystalline1 sodium sulphate has ten molecules of water of crystallization 7,na#b,,so#d1 #aj ,h#b,o72 it is then known as ,glauber's salt4 ,this salt readily effloresces2 i4e4 loses its water of crystallization1 and is reduced to a powder4 ,compute the percentage of water4 #bca4 ,uses4--,the leading use of ,na#b,,so#d is to make ,na#b;,,co#c2 it is also used to some extent in medicine1 and in glass manufacture4 #bcb4 ,sodium ,carbonate4--,note the base and the acid which this salt represents4 ,test a solution of the salt with red and blue litmus1 and notice the alkaline reaction4 ,do you see any reason for this reaction in the strong base and the weak acid represented by the salt8 #bcc4 ,manufacture4--,na#b;,,co#c is not made by the union of an acid and a base1 nor is ,h#b;,,co#c strong enough to act on many salts4 ,the process must be indirect4 ,this consists in reducing ,na#b,,so1 to ,na#b,s1 by taking away the ,o with ,c1 charcoal1 and then changing ,na#b,s to ,na#b,o#c by ,ca,c,o#c1 limestone4 ,the three substances1 ,na#b,,so#d1 ,c1 ,ca,c,o#c1 are mixed together and strongly heated4 ,the reactions should be carefully studied1 as the process is one of much importance4 7#a7 ,na#b,,so#d #d ,c ,na#b,s #d ,,co4 7#b7 ,na#b,s ,ca,c,o#c ,ca,s ,na#b;,,co#c4 ,observe that ,c is the reducing agent4 ,the gas ,,co escapes4 ,the solid products ,na#b;,,co#c and ,ca,s form black ash1 the former being very soluble1 the latter only sparingly soluble in water4 ,na#b;,,co#c is dissolved out by water1 and the water is evaporated4 ,this gives commercial soda4 ,ca,s1 the waste compound in the process1 contains the ,s originally in the ,h#b,,so#d used4 ,this can be partially separated and again made into acid4 ,describe the manufacture of ,na,c,o#c in full1 starting with ,na,cl4 ,this is called the ,le ,blanc process1 but is not the only one now employed to produce this important article4 #bcd4 ,occurrence4-,sodium carbonate is found native in small quantities4 ,it forms the chief surface deposit of the alkali belt in western ,united ,states1 where it often forms incrustations from an inch to a foot in thickness4 ,it was formerly obtained from sea-weeds1 by leaching their ashes1 as1 by a like process1 ,k#b;,,co#c was obtained from land plants4 #bce4 ,uses4--,na#b;,,co#c forms the basis of many alkalies1 as ,h#b,,so#d does of acids4 ,of all chemical compounds it is one of the most important1 and its manufacture constitutes one of the greatest chemical industries4 ,its economical manufacture largely depends on the demand for ,h,cl1 which is always formed as a by-product4 ,as but little ,h,cl is used in this country1 ,na#b;,,co#c is mostly manufactured in ,europe4 ,the chief uses are for glass and alkalies4 #bcf4 ,sodium4--,na must always be kept under naphtha1 or some other liquid compound containing no ,o1 since it oxidizes at once on exposure to the air4 ,for this reason it never occurs in a free state4 #bcg4 ,preparation4-,by depriving ,na#b;,,co#c of ,c and ,o1 metallic sodium is formed4 ,as usual1 heated charcoal is the reducing agent4 ,the end of the retort1 which holds the mixture1 dips under naphtha4 ,na#b;,,co#c #b ,c #b ,na #c ,,co4 ,the process is a difficult one1 and ,na brings five dollars per pound1 though in its compounds it is a third as common as ,fe4 ,k is as abundant as ,na1 but more difficult of separation1 and is worth three dollars per ounce4 ,notice the position of ,k and ,na at the positive end of the elements4 #bch4 ,uses4--,na is used to reduce ,al1 ,ca1 ,mg1 ,si1 which are the most difficult elements to separate from their compounds4 ,it acts in these cases as a reducing agent4 #bci4 ,sodium ,hydrate4 ,review ,experiment #fb4 ,experiment #aah4--,put into a t4t4 #aj;cc4 ,h#b,o and #b or #c g4 ,na,o,h4 ,note its easy solubility4 ,test with litmus4 ,will it neutralize any acids8 #bdj4 ,preparation4 -- ,sodium hydrate1 caustic soda1 or soda by lime1 is made by treating a solution of ,na#b;,,co#c with milk of lime4 ,ca,c,o#c is precipitated and al- lowed to settle1 the solution is poured off1 and ,na,o,h is obtained by evaporating the water and running the residue into molds4 #bda4 ,use4--,na,o,h is a powerful caustic1 but its chief use is in making hard soap4 #bdb4 ,hydrogen ,sodium ,carbonate4--,hydrogen so- dium carbonate1 bicarbonate of sodium1 acid sodium carbonate1 cooking-soda1 etc41 ,h,na,c,o#c1 is prepared by passing ,,co#b into a solution of ,na#b;,,co#c4 ,na#b;,,co#c ,h#b,o ,,co#b #b ,h,na,c,o#c4 ,test a solution of it with litmus4 ,account for the result4 ,its use in bread-making depends on the ease with which ,,co#b is liberated4 ,even a weak acid1 as the lactic acid of sour milk1 sets this free1 and thus causes the dough to rise4 #bdc4 ,sodium ,nitrate4--,sodium nitrate occurs in ,chili and ,peru4 ,it is the main source of ,,hno#c4 ,review ,experiments #df and #eb4 ,from ,na,n,o#c is also made ,,kno#c1 7,na,n,o#c ,k,cl ,na,cl ,,kno#c71 one of the ingredients of gunpowder4 ,by reason of its deliqcescence ,na,n,o#c is not suitable for making gunpowder1 though it is sometimes used for blasting-powder4 ,the action of the latter is slower than that made from ,,kno#c4 ,na,n,o#c is cheaper and more abundant than ,,kno#c2 this is true of most ,na compounds in comparison with those of ,k4 ,chapter ,,xlv4 ,,potassium ,,and ,,ammonium4 ,,potassium ,,and ,,its ,,compounds4 ,examine ,k1 ,k,cl1 ,k#b,,so#d1 ,k#b;,,co#c1 ,,koh1 ,,hkco#c1 ,,kclo#c1 ,,kcn4 #bdd4 ,occurrence and ,preparation4--,potassium occurs only in combination1 chiefly as silicates1 in such minerals as feldspar and mica4 ,by their disintegration it forms a part of soils from which such portions as are soluble are taken up by plants4 ,the ashes of land-plants are leached in pots to dissolve ,k#b;,,co#c2 hence it is called potash4 ,sea-plants likewise give rise to ,na#b;,,co#c4 ,wood ashes originally formed the main source of ,k#b;,,co#c4 ,from plants this substance is taken into the animal system1 and makes a portion of its tissue4 ,sheep excrete it in sweat1 which is then absorbed by their wool4 ,large quantities are now obtained by washing wool and evaporating the water4 ,k#b;,,co#c and other compounds of ,k are mainly derived from ,k,cl1 beds of which exist in ,germany4 ,in the following list each ,k compound is prepared like the same ,na compound1 and the uses of each of the former are similar to those of the latter4 ,k compounds are made in much smaller quantities than those of ,na1 as ,k,cl is far less common than ,na,cl4 ,k ,k,cl ,k#b,,so#d ,k#b;,,co#c ,,koh ,,kno#c ,,hkco#c ,examine specimens of each1 side by side with like ,na compounds4 ,describe in full their preparation1 giving the reactions4 ,also1 perform theexperiments given under ,na1 substituting ,k therefor4 ,from ,,koh are made ,k,cl,o#c and ,,kcn4 ,,koh ,k,cl#jc ,,kcn #bde4 ,potassium ,chlorate4--,k,cl#jc is made by passing ,cl into a hot concentrated solution of ,,koh4 #f ,,koh #f ,cl ,k,cl#jc #e ,k,cl #c ,h#b,o ,its uses are making ,o1 and as an oxidizing agent4 #bdf4 ,potassium ,cyanide1 ,,kcn1 is a salt from ,,hcn--hydrocyanic or prussic acid4 ,each is about equally poisonous1 and more so than any other known substance4 ,a drop of pure ,,hcn on the tongue will produce death quickly by absorption into the system4 ,in examining these compounds take care not to handle them or to inhale the fumes4 ,,kcn is used as a solvent for metals in electro-plating1 and is the source of many cyanides1 i4e4 compounds of ,,cn and a metal4 ,,kcn is employed to kill insects for cabinet specimens4 ,in a wide-mouthed bottle is placed a little ,,kcn1 which is covered with cotton1 and over this a perforated paper4 ,the bottle is inverted over the insect1 and the fumes destroy life without injuring the delicate parts4 ,,hcn is made from ,,kcn and ,h#b,,so#d4 #bdg4 ,gunpowder4--,gunpowder is a mixture of ,,kno#c1 ,c1 and ,s4 ,heat or concussion causes a chemical change1 and transforms the solids into gases4 ,these gases at the moment of explosion occupy #aejj or more times the volume of the solids4 ,hence the great rending power of powder4 ,if not confined1 powder burns quietly but quickly4 ,the appended reaction is a part of what takes place1 but it by no means represents all the chemical changes4 #b,,kno#c ,s #c;,c ,k#b,s #b,n #c;,,co#b4 ,from this equation compute the percentage1 by weight1 of each substance used to make gunpowder economically4 ,thoroughly burned charcoal1 distilled sulphur1 and the purest nitre are powdered and mixed in a revolving drum1made into a paste with water1 put under great pressure between sheets of gun metal1 granulated1 sifted1 to separate the coarse and fine grains1 and glazed by revolving in a barrel which sometimes contains a little powdered graphite4 ,experiment #aai4--,pulverize and mix intimately #d g4 ,,kno#c1 l_/#b g4 ,s1 #a_/b g4 charcoal4 ,pile the mixture on a brick1 and apply a lighted match4 ,the adhering product can be removed by soaking in water4 ,,ammonium ,,compounds4 #bdh4 ,read the chapter on ,,nh#c4 ,also1 review the experiments on bases4 ,examine ,,nh#d;,cl1 ,,nh#d,,no#c1 7,,nh#d7b,,so#d1 7,,nh#d7b;,,co#c4 ,ammonium1 ,,nh#d1 is too unstable to exist alone1 but it forms salts similar to those of ,k and ,na4 ,,nh#c dissolved in water forms ,,nh#d,,oh4 ,the food of plants1 as well as that of animals1 must contain ,n4 ,it has not yet been shown that they can make use of that contained in the air1 but they do absorb its compounds from the soil4 ,all fertilizers and manures contain a soluble compound of ,,nh#d4 ,all ,,nh#d compounds are now obtained either from coal1 in making illuminating-gas1 or from bones1 by distillation4 ,suppose the product obtained from the gas-house to be ,,nh#d,,oh1 how would ,,nh#d;,cl be made8 7,,nh#d7b,,so#d8 ,,nh#d,,no#c8 ,write the reactions4 7,,nh#d7b;,,co#c is made by heating ,,nh#d;,cl with ,ca,c,o#c4 ,give the reaction4 ,chapter ,,xlvi4 ,,calcium ,,compounds4 ,examine ,ca,c,o#c--marble1 limestone1 chalk1 not crayon1--,ca,s,o#d -- gypsum or selenite--,ca,cl#b1 ,ca,o4 #bdi4 ,occurrence4--,the above are the chief compounds of ,ca4 ,the element itself is not found uncombined1 is very difficult to reduce 7page #ada71 is a yellow metal1 and has no use4 ,its most abundant compound is ,ca,c,o#c4 ,shells of oysters1 clams1 snails1 etc41 are mainly ,ca,c,o#c1 and coral reefs1 sometimes extending thousands of miles in the ocean1 are the same4 ,ca,c,o#c dissolves in water holding ,,co#b1 and thence these marine animals obtain it and therefrom secrete their bony framework4 ,all mountains were first laid down on the sea bottom layer by layer1 and afterwards lifted up by pressure4 ,rocks and mountains of ,ca,c,o#c were formed by marine animals1 and all large masses of ,ca,c,o#c are thought to have been at one time the framework of animals4 ,marble is crystallized1 transformed limestone4 ,the process1 called metamorphism1 took place in the depths of the earth1 where the heat is greater than at the surface4 #bej4 ,lime4--,if ,ca,c,o#c be roasted with ,c1 ,,co#b escapes and ,ca,o is left4 ,ca,c,o#c - ,,co#b 8 ,this is called burning lime1 and is a large industry in limestone countries4 ,ca,o is unslaked lime1 quicklime or calcium oxide4 ,it may be slaked either by exposure to the air1 air-slaking1 when it gradually takes up ,h#b,o and ,,co#b2 or by mixing with ,h#b,o1 water-slaking4 ,ca#j ,h#b,o ,ca7,,oh7#b4 ,great heat is generated in the latter case1 though not so much as in the formation of ,,koh and ,na,o,h4 ,like them1 ,ca7,,oh7#b dissolves in water1 forming lime-water4 ,milk of lime1 cream of lime1 etc41 consist of particles of ,ca7,,oh7#b suspended in ,h#b,o4 #bea4 ,uses of ,lime--,ca,o is infusible at the highest temperatures4 ,if it be introduced into the oxy-hydrogen blow-pipe 7page #bh71 a brilliant light1 second only to the electric1 is produced4 ,mortar is made by mixing ,ca,o1 ,h#b,o1 and ,si#jb4 ,it hardens by evaporating the extra ,h#b,o1 absorbing ,,co#b from the air1 and uniting with ,si#jb to form calcium silicate4 ,it often continues to absorb ,,co#b for hundreds or thousands of years before being saturated1 as is found in the ,egyptian pyramids4 ,hence the tenacity of old mortar4 ,hydraulic mortar contains silicates of ,al and ,ca1 and is not affected by water4 ,what are the uses of mortar8 ,being the important constituent of mortar and plaster1 lime is the most useful of the bases4 #beb4 ,hard ,water4--,review ,experiment #gf4 ,the solubility of ,ca,c,o#c in water that contains ,,co#b leads to important results4 ,much dissolves in the waters of all limestone countries2 and the water1 though perfectly transparent1 is hard2 i4e4 soap has little action on it4 ,see page #ahg4 ,such water may be softened by boiling1 a deposit of ,ca,c,o#c being formed as a crust on the kettle4 ,such water is called water of temporary hardness4 ,mg,c,o#c produces a similar effect1 and water containing it is softened in the same way4 ,permanently hard waters contain the sulphates of ,ca and ,mg1 which cannot be removed by boiling1 but may be by adding 7,,nh#d7b;,,co#c4 #bec4 ,the ,formation of ,caves in limestone rocks is due also to the solubility of ,ca,c,o#c4 ,water collects on the mountains and trickles down through crevices1 dissolving1 if it contains ,,co#b1 some of the ,ca,c,o#c1 and thus making a wider opening1 and forcing its way along fissures and lines of least resistance into the interior of the earth1 or out at the base of the mountain4 ,its channel widens as it dissolves the rock1 and the stream enlarges until in the course of ages an immense cavern may be formed1 with labyrinths extending for miles1 from the entrance of which a river often issues4 ,in the long ages which elapsed during the slow formation of ,mammoth ,cave its denizens lost many of the characters of their ancestors1 and eyeless fish and also eyeless insects now abound there4 #bed4 ,reverse ,action4--,drops of water on the roofs of these caverns lose their ,,co#b1 and deposit ,ca,c,o#c4 ,thus long1 pendant masses of limestone1 called stalactites1 are slowly formed on the roofs like icicles4 ,from these1 water charged with ,ca,c,o#c drops to the bottom1 loses ,,co#b and deposits ,ca,c,o#c1 which forms an upward- growing mass1 called stalagmite4 ,in time it may meet the stalactite and form a pillar4 ,notice that the same action which formed the cave is filling it up2 i4e4 the solubility of ,ca,c,o#c in water charged with ,,co#b4 #bee4 ,famous ,marbles4--,the marble from ,carrara1 ,italy1 is most esteemed on account of a pinkish tint given by a trace of oxide of iron4 ,the best of ,grecian marble was from ,paros1 one of the ,cyclades4 ,the isles of the ,mediterranean are of limestone1 or of volcanic1 origin1 often of both4 #bef4 ,calcium ,sulphate occurs in two forms1 7#a7 with water of crystallization--gypsum1 ,ca,s,o#d #b ,h#b,o1 --7#b7 without it--anhydrite1 ,ca,s,o#d4 ,the former1 on being strongly heated1 gives up its water1 and is reduced to a powder-- plaster of ,paris4 ,this1 on being mixed with water1 again takes up #b ,h#b,o1 and hardens1 or sets1 without crystallizing4 ,if once more heated to expel water1 it will not again absorb it4 ,when plaster of ,paris sets1 it expands slightly1 and on this account is admirable for taking casts4 #beg4 ,uses4--,gypsum finds use as a fertilizer and as an adulterant in coloring-materials1 etc4 ,ca,s,o#d is employed in making casts1 molds1 statuettes1 wall-plaster1 crayons1 etc4 ,how can ,ca,cl#b be made8 ,what is its use8 ,see page #bg4 ,what else is used for a similar purpose8 ,symbolize and name the acid represented by ,ca7,cl,o7#b1 and name this salt 7page #ajg74 ,it is one of the constituents of bleaching- powder1 the symbol of which1 though still under discussion1 may be considered ,ca7,cl,o7#b ,ca,cl#b4 ,this is made by passing ,cl over ,ca7,,oh7#b #b ,ca7,,oh7#b #d ,cl ,ca7,cl,o7#b ,ca,cl#b #b ,h#b,o4 ,,chapter ,,xlvii4 ,,magnesium1 ,,aluminium1 ,,and ,,zinc4 ,,magnesium ,,and ,,its ,,compounds4 ,examine magnesite1 dolomite1 talc1 serpentine1 hornblende1 meerschaum1 magnesium ribbon1 magnesia alba1 ,epsom salt4 #beh4 ,occurrence and ,preparation4--,mg is very widely distributed1 but does not occur uncombined4 ,its salts are found in rocks and soils1 in sea water and in the water of some springs1 to which they impart a brackish taste4 ,the most common minerals containing ,mg are magnesite1 ,mg,c,o#c1 dolomite1 ,mg,c,o#c ,ca,c,o#c1 and talc1 serpentine1 hornblende1 and meerschaum4 ,the last four are silicates1 and often are unctious to the touch4 ,what proportion of the earth's crust is composed of ,mg8 ,see page #agc4 #bei4 ,metallic ,mg is prepared by fusing ,mg,cl#b with ,na4 ,why is the process expensive8 ,write the reaction4 ,experiment #abj4--,with forceps hold a short strip of ,mg ribbon in a flame4 ,note the brilliancy of the light1 and give the reaction4 ,examine and name the product4 ,photographs of the interior of caverns1 where sunlight does not penetrate1 are taken by ,mg light4 ,gun-cotton sprinkled with powdered ,mg has recently been employed for that purpose4 ,mg tarnishes slightly in moist air4 ,compounds of ,mg4--,mg,o1 magnesia1 like ,ca,o1 is very infusible1 and is used for crucibles4 ,magnesia alba1 a variable mixture of ,mg,c,o#b and ,mg7,,oh7#b1 is employed in medicine1 as is also ,epsom salt1 ,mg,s,o#d #g ,h#b,o4 ,,aluminium ,,and ,,its ,,compounds4 ,examine aluminium1 aluminium bronze1 corundum1 emery1 feldspar1 argillite1 clay4 ,note especially the color1 luster1 specific gravity and flexibility of ,al4 ,what elements are more common in the earth than ,al8 ,what metals8 ,compare the abundance of ,al with that of ,fe4 #bfj4 ,compounds of ,al4--,al occurs only in combination with other elements4 ,feldspar1 mica1 slate1 and clay are silicates of it4 ,it occurs in all rocks except ,ca,c,o#c and ,si,o#b1 and in nearly #bjj minerals4 ,though found in all soils1 its compounds are not taken up by plants1 except by a few cryptogams4 ,corundum1 ,al#b,o#c1 is the richest of its ores4 ,compute its percent of ,al4 ,compounds of ,al are very infusible and difficult of reduction4 #bfa4 ,reduction4--,like most other metals not easily reducible by ,c or ,h1 it was originally obtained by electrolysis1 but more recently from its chloride1 by the reducing action of strongly heated ,k or ,na4 ,al#b;,cl#f #f ,na #f ,na,cl #b ,al4 ,what is the chief use of ,na8 ,as it takes three pounds of ,na to make one pound of ,al1 the cost of the latter has been fifteen dollars or more per pound4 ,its use has thus been restricted to light apparatus and aluminium bronze1 an alloy of ,cu #ij1 ,al #aj1 which is not unlike gold in appearance4 ,al#b,o#c has lately been reduced by ,c4 ,higher temperatures than have heretofore been known are obtained by means of the electric arc and large dynamo machines4 ,afurnace made of graphite1 because fire-clay melts like wax at such a high temperature1 is filled with ,al#b,o#c--;corundum1 --,c1 and ,cu4 ,in the midst of this are embedded large carbon terminals1 connected with dynamos4 ,the reduction takes several hours4 ,the following reaction takes place3 ,al#b,o#c #c ,c #b ,al #c ,,co4 ,cu is also added1 and an alloy of ,al and ,cu is thus formed4 ,this alloy is not easily separable into its elements4 ,explain the action of the ,c4 ,,co escapes through perforations in the top of the furnace1 burning there to ,,co#b4 ,only alloys of ,al have yet been obtained by this process4 ,this method has not been employed before1 simply because the highest temperatures of combustion1 #bjjj degrees or #bejj degrees1 would not effect a reduction4 ,in the same way ,si1 ,b1 ,k1 ,na1 ,ca1 ,mg1 ,cr1 have recently been reduced from their oxides2 but a process has yet to be found for separating them easily from their alloys4 #bfb4 ,properties and ,uses4--,al is a silvery white metal1 lighter than glass1 and only one-third the weight of iron4 ,it does not readily rust or oxidize1 it fuses at #ajjj degrees 7compare with ,fe71 is unaffected by acids1 except by ,h,cl and1 slightly1 by ,h#b,,so#d1 is a good conductor of electricity1 can be cast and hammered1 and alloys with most metals1 forming thus many valuable compounds4 ,every clay-bank is a mine of this metal1 which has so many of the useful properties of metals and has so few defects that1 if it could be obtained in sufficient quantities1 it might1 for many purposes1 take the place of iron1 steel1 tin1 and other metals4 ,from its properties state any advantages which it would have over iron in ocean vessels1 railroads1 and bridges4 ,why is it better than ,sn or ,cu for culinary utensils8 ,an alloy of ,al1 ,cu1 and ,si is used for telephone wires in ,europe1 and the ,bennett-,mackay cable is of the same material4 ,washington monument1 the tallest shaft in the world1 is capped with a pyramid of ,al1ten inches high4 ,for the uses of alumina1 ,al#b,o#c1 and its silicates1 see page #acc4 ,,zinc ,,and ,,its ,,compounds4 ,examine zincite1 sphalerite1 ,smithsonite1 sheet zinc1 galvanized iron1 granulated zinc1 zinc dust4 #bfc4 ,compounds4--,the compounds of zinc are abundant4 ,its chief ores are zincite1 ,zn,o1 sphalerite or blende1 ,zn,s1 ,smithsonite1 ,zn,c,o#c4 ,for their reduction these ores are first roasted1 i4e4 heated in presence of air4 ,with ,zn,s this reaction takes place3 ,zn,s #c ,o ,zn#j ,s#jb4 ,the oxide is reduced with ,c1 and then ,zn is distilled4 ,state the reaction4 ,zinc is sublimed-in the form of zinc dust-like flowers of ,s4 ,granulated ,zn is made by pouring a stream of the molten metal into water4 ,experiment #aba4--;,burn a strip of ,zn foil1 and note the color of the flame and of the product4 ,state the reaction4 ,the red color of zincite is supposed to be imparted by ,mn present in the compound4 #bfd4 ,uses4--,name any use of ,zn in the chemical laboratory4 ,it is employed for coating wire and sheet iron --galvanized iron4 ,this is done by plunging the wire or the sheets of iron into melted ,zn4 ,describe the use of ,zn as an alloy4 ,see page #acf4 ,zn,o forms the basis of a white paint called zinc white4 ,white vitriol1 ,zn,s,o#d #g ,h#b,o1 is employed in medicine4 ,name two other vitriols4 ,,chapter ,,xlviii4 ,,iron ,,and ,,its ,,compounds4 ,examine magnetite1 hematite1 limonite1 siderite1 pig-iron1 wrought-iron1 steel4 #bfe4 ,ores and ,irons4--,as ,fe occurs native only in meteorites and in small quantities of terrestrial origin1 it is obtained from its ores4 ,there are four of these ores--magnetite 7,fe#c,o#d71 hematite 7,fe#b,o#c71 limonite 7#b ,fe#b,o#c #c ,h#b,o71 and siderite 7,fe,c,o#c74 ,which is richest in ,fe8 ,compute the proportion4 ,fe,c,o#c occurs mostly in ,europe4 ,the reduction of these ores1 as well as of other metallic oxides1 consists in removing ,o by ,c at a high tempera- ture4 ,as ordinarily classified there are three kinds of iron1--pig- or cast-iron1 steel1 and wrought-iron4 ,study this table1 noting the purity1 the fusing-point1 and the per cent of ,c in each case4 ,per ,cent ,fe ,fusibility4 ,per ,cent 7general74 ,c4 ,pig444444444 #ij #abjj degrees #b-f ,steel44444444 #ii #adjj degrees #j4e-b ,wrought4444444 #ii4g #aejj degrees ,fraction4 ,pure iron melts at about #ahjj degrees4 ,pig-iron is obtained from the ore by smelting1 and from this are made steel and wrought- iron4 #bff4 ,pig-,iron4--,the ore is reduced in a blast furnace 7,fig4 #dg71 in some cases eighty or one hundred feet high1 and having a capacity of about #ab1jjj cubic feet4 ,the reducing agent is either charcoal1 anthracite coal1 or coke1bituminous coal being too impure4 ,charcoal is the best agent1 and is used in preparing ,swedish iron2 but it is too expensive for general use4 ,fig4 #dg4 ,blast furnace4 ,f1 entrance of tuyeres1 or blast-pipes4 ,e1 ,f1 hottest part4 ,c1 conductor for gases1 which are subsequently used to heat the air going into the tuyeres4 ,g1 upper portion1 slag1 lower portion1 melted iron4 ,were ores absolutely pure1 only ,c would be needed to reduce them4 ,complete3 ,fe#c,o#d #d ,c 8 ,fe#c,o#d #b;,c8 ,much earthy material--gangue--containing silica and silicates is always found with iron ores4 ,these are infusible1 and something must be added to render them fusible4 ,ca,o forms with ,si,o#b just the flux needed4 ,see page #acb4 ,ca#j ,si#jb 8 ,which of these is the basic1 and which the acidic compound8 ,ca,o results from heating ,ca,c,o#c2 hence the latter is employed instead of the former4 ,in what case would ,si#jb be used as the flux8 ,into the blast furnace are put1 in alternate layers1 the fuel1 the flux1 and the ore4 ,the fire1 once kindled1 is kept burning for months or years4 ,hot air is driven in through the tuyeres 7tweers74 ,o unites with ,c of the fuel1 forming ,,co#b and ,,co4 ,the ,c also reduces the ore4 ,fe#b,o#c #c ,c 8 ,,co accomplishes the same thing4 #c ,,co ,fe#b,o#c 8 ,the intense heat fuses ,ca,o and ,si,o#b to a silicate which1 with other impurities1 forms a slag2 this1 rising to the surface of the molten mass1 is drawn off4 ,the iron is melted1 falls in drops to the bottom1 and is drawn off into sand molds4 ,see ,figure #dg4 ,this is pig-iron4 ,it contains as impurities1 ,c1 ,si1 ,s1 ,p1 ,mn1 etc4 ,if too much ,s or ,p is present in an ore1 it is worthless4 ,this is why the abundant mineral ,fe,s#b cannot be used as a source of iron4 ,from the top of the furnace ,n1 ,,co1 ,,co#b1 ,h#b,o1 etc41 escape4 ,these gases are used to heat the air which is forced through the tuyeres1 and to make steam in boilers4 #bfg4 ,steel4--,the manufacture of steel and wrought-iron consists in removing most of the impurities from pig-iron4 ,it will be seen that the most common compounds of ,c1 ,s1 ,si1 and ,p1 are their oxides1 and these are for the most part gases4 ,hence these elements are removed by oxidation4 ,bessemer steel is prepared by melting pig-iron and blowing hot air through it4 ,a converter 7,fig4 #dh7 lined with siliceous sand1 and holding several tons1 is partially filled with the molten metal2 blasts of hot air are driven into it1 and the ,c and other impurities1 together with a little of the ,fe1 are oxidized4 ,the exact moment when the process has gone far enough1 and most of the impurities have been removed1 is indicated by the appearance of the escaping flame4 ,it usually takes from five to ten minutes4 ,the blast is then stopped1 and the metal has about the composition of wrought-iron2 it contains some uncombined ,o4 ,a white pig-iron 7spiegeleisen71 which contains a known quantity of ,c and of ,mn1 is at once added4 ,mn removes part of the extra ,o1 and1 though it remains1 does not injure the metal4 ,the ,c is dissolved by the ,fe1 which is then run into molds 7ingots74 ,this process1 the ,bessemer1 invented in #ahef1 has revolutionized steel manufacture4 ,no less than ten tons of iron have been converted into steel1 in five minutes1 in a single converter4 #bfh4 ,wrought-,iron4--,the chemical principle involved in making wrought-iron is the same as that in making steel1 but the process is different4 ,impurities are burned out from pig-iron in an open reverberatory furnace1 by constantly stirring the metal in contact with air4 ,this is called puddling4 ,a reverberatory furnace is one in which the fuel is in one compartment1 and the heat is reflected downward into another1 that holds the substance to be acted upon 7,fig4 #di74 ,steel may also be made by carburizing wrought-iron4 ,iron and charcoal are packed together and heated for days1 without melting1 when it is found that1 in some unknown way1 solid ,c has penetrated solid ,fe4 ,the finer kinds of steel are made in this way1 but they are very expensive4 ,wrought-iron may also be made directly from the ore in an open hearth furnace1 with charcoal4 ,this was the original mode4 #bfi4 ,properties4--,the varying properties of pig-iron1 steel1 and wrought-iron are due in part to the proportion of ,c and of other elements present1 either as mixtures or as compounds1 and in part to other causes not well understood4 ,wrought-iron is fibrous1 as though composed of fine wires1 and hence is ductile1 malleable1 tough1 and soft1 and cannot be hardened or tempered1 but it is easily welded4 ,pig-iron is crystalline1 and so is not ductile or malleable2 it is hard and brittle1 and cannot be welded4 ,on account of its low melting-point it is generally employed for castings4 ,steel is crystalline in structure1 and when suddenly cooled from red heat by plunging into cold water1 becomes hard and brittle4 ,the tempering can be varied by afterwards heating to any required degree1 indicated by the color of the oxide formed on the exterior4 ,the higher temperatures give the softer steel4 #bgj4 ,salts of ,iron4--,examine ,fe,s,o#d1 ,fe,s1 ,fe,s#b4 ,fe has a valence of #b or #d4 ,this gives rise to two kinds of salts1 ferrous and ferric1 as in ,fe,cl#b and ,fe#b;,cl#f ,the valence of ,fe in ferric salts is #d4 ,ferrous sulphate is ,fe,s,o#d2 ferric sulphate1 ,fe#b7,,so#d7c4 ,write the symbols for ferrous and ferric hydrate2 for the oxides2 for the nitrates4 ,write the graphic symbols for each4 #bga4 ,colors4--,the characteristic color of ferrous salts is green1 as in ,fe,s,o#d4 ,these salts give the green color to the chlorophyll in leaves and grass1 and bottle glass owes its green color to ferrous silicate4 ,ferric salts are a brownish red1 as shown in hematite and limonite1 and in some bottles4 ,red sandstone1 and most soils and earths1 are illustrations of this coloring action4 ,the blood of vertebrates owes its color to ferric salts4 ,bricks are made from a greenish blue clay in which iron exists in the ferrous state4 ,on being heated1 ferrous salts are oxidized to ferric1 and their color is changed to red4 ,iron rust is hydrated ferric oxide1 ,fe#b,o#c and ,fe#b7,,oh7#f4 #bgb4 ,change of ,valence4 ,experiment #abb4--;,dissolve #b g4 of iron filings in diluted ,h,cl4 ,filter or pour off the clear liquid1 divide it into two parts1 and add ,,nh#d,,oh to one part till a ppt4 occurs4 ,notice the greenish color of ,fe7,,oh7#b4 ,oxidize the other part by adding a few drops of ,,hno#c and boiling a minute4 ,now add ,,nh#d,,oh1 and observe the reddish color of the ppt41 ,fe#b7,,oh7#f4 ,solutions of ferrous salts will gradually change to ferric1 if allowed to stand1 thus showing the greater stability of the latter4 ,in changing from ,fe,cl#b to ,fe#b;,cl#f oxidation does not consist in adding ,o1 but in increasing the negative element or radical4 ,this is possible only by changing the valence of ,fe from #b to #d4 ,hence oxidation1 in its larger sense1 means increasing the valence of the positive element4 ,to oxidize ,fe,s,o#d is to make it ,fe#b7,,so#d7c1 changing the valence of ,fe as before4 ,reduction or deoxidation diminishes the valence of the positive element4 ,illustrate this by the same iron salts4 ,illustrate it by ,pb,o and ,pb#jb2 ,au,cl and ,au,cl#c2 ,sb#b,s#c and ,sb#b,s#e4 ,in this sense define an oxidizing agent4 ,a reducing agent4 #bgc4 ,ferrous ,sulphate4 ,experiment #abc4--;,dissolve a few iron filings in dilute ,h#b,,so#d1 and slowly evaporate for a few minutes4 ,write the equation4 ,ferrous sulphate1 green vitriol1 or copperas1 ,fe,s,o#d #g ,h#b,o1 is the source of what acid8 ,see page #ff4 ,it is also one of the ingredients in many writing inks4 ,on being heated1 or exposed to the air1 it loses its water of crystallization and becomes a white powder4 ,it is prepared as above1 or by oxidizing moistened ,fe,s#b by exposure to the air4 ,ferrous sulphide1 protosulphide of iron1 ,fe,s1 is how prepared8 ,see ,experiment #f4 ,state its use4 ,see ,experiment #ajh4 ,it also occurs native4 ,ferric sulphide1 pyrite1 ,fe,s#b1 occurs native in large quantities4 ,what is its use8 ,see page #fe4 ,,chapter ,,xlix4 ,,lead ,,and ,,tin4 ,,lead4 ,examine galena1 lead protoxide and dioxide1 red-lead1 lead carbonate1 acetate1 and nitrate4 ,note especially the colors of the oxides1 the cubical crystallization and cleavage of galena1 the specific gravity of the compounds1 the softness of ,pb1 and the tarnish1 ,pb#b,o1 which covers it1if long exposed4 #bgd4 ,distribution of ,pb4--,pb is widely distributed1 occurring as ,pb,s and ,pb,c,o#c4 ,pb,s1 galenite or galena1 is its main source4 ,by heating it in air1 ,,so#b is formed1 and ,pb liberated and drawn off4 ,pb is but little acted on by cold ,h#b,,so#d1 unless concentrated4 ,describe its use in making that acid4 ,see page #fe4 ,to show that a little ,pb has been dissolved1 as ,pb,s,o#d1 in the manufacture of that acid1 perform this experiment4 ,experiment #abd4--,to #e;cc4 of water in a clean t4t4 add the same volume of ,h#b,,so#d1 not ,c4,p42 shake1 and notice any fine powder suspended4 ,pb,s,o#d1 being insoluble in water1 is precipitated4 ,what is the test for ,pb8 ,see ,experiment #aji4 #bge4 ,poisonous ,properties4--,ph is very flexible and soft1 and is much used for water pipes4 ,in moist air it is soon coated with suboxide1 ,pb#bj1 as may be seen by exposing a fresh surface4 ,some portion of this is liable to dissolve in water1 and1 as all soluble salts of ,pb are poisonous1 water that has stood in pipes should not be used fordrinking4 ,lead is employed as an alloy of tin for covering sheet-iron in terne plate4 ,t his plate is rarely used except for roofing4 ,the bright plate1 used for tin cans and other purposes1 scarcely ever contains any lead except the small portion in solder4 ,in soldering1 ,zn,cl#b is employed for a flux4 ,sn1 ,pb1 and ,zn are somewhat soluble in vegetable acids4 ,if citric acid be present1 as it usually is1 citrates of these metals are formed1 and all of them are poisonous4 ,the action is far more rapid after opening the can1 since oxidation is hastened4 ,hence the contents should be taken out directly after opening4 ,lead poisons seem to have an affinity for the tissues of the body1 and accumulate little by little4 ,painter's colic results from lead poisoning4 ,epsom salt1 or other soluble sulphate1 is an antidote1 since with ,pb it makes insoluble ,pb,s,o#d4 #bgf4 ,some ,lead ,compounds4--,lead salts form the basis of many paints4 ,white paint is a mixture of ,pb,c,o#c and ,pb7,,oh7#b suspended in linseed oil4 ,it is often adulterated with ,ba,s,o#d1 ,zn,o1 ,ca,c,o#c4 ,other lead compounds are used for colored paints4 ,the two chief soluble salts are ,pb7,,no#c7b and lead acetate1 ,pb7,c#b;,h#cjb7b4 ,red-lead1 ,pb#c,o#d1 and1 to some extent1 litharge1 ,pb,o1 are employed in glass manufacture4 ,name the kind of glass in which it is used1 describe its manufacture1 and write a symbol for lead silicate4 ,what is the characteristic of lead glass8 ,see page #acb4 ,experiment #abe4--,put a small fragment of ,pb on a piece of charcoal1 and blow the oxidizing flame against it for some time with a mouth blow-pipe4 ,note the color of the coating on the coal4 ,pb,o has formed4 ,experiment #abf4--;,dissolve a small piece of lead in dilute ,,hno#c4 ,pour off the solution into a t4t4 and add ,h,cl or other soluble chloride4 ,pb7,,no#c7b #b ,h,cl 8 ,what is the insoluble product8 ,experiment #abg4--;,add to a solution of ,pb7,c#b;,h#c,o#b7b some ,h#b,,so#d4 ,give the reaction and the explanation4 ,,tin4 ,examine cassiterite1 tin foil1 terne plate1 bright plate4 #bgg4 ,sn occurs as the mineral cassiterite1 tin stone1 ,sn#jb1 and is found in only a few localities1 as ,banca1 ,malacca1 and ,england4 ,it does not readily tarnish1 and is used to cover thin plates of copper and iron4 ,tin foil is generally an alloy of ,pb and ,sn4 ,sn is sometimes a dyad1 at others a tetrad4 ,write symbols for its two chlorides1 stannous and stannic1 also for its sulphides and oxides4 ,,chapter ,l4 ,,copper1 ,,mercury1 ,,and ,,silver4 ,,copper4 ,examine native copper1 chalcopyrite1 malachite1 azurite1 copper acetate1 copper nitrate1 copper sulphate4 #bgh4 ,occurrence4--,copper occurs both native and in many compounds1 being diffused in rocks and1 in minute quantities1 in soils1 waters1 plants1 and animals4 ,spain1 ,chili1 and the ,united ,states are the chief ,cu producing countries4 ,the extensive mines of ,michigan yield the native ore4 ,the ,calumet and ,heela mine alone produces #d1jjj1jjj pounds per month4 ,the most abundant compound of ,cu is chalcopyrite1 or copper pyrites1 ,cu,fe,s#b4 ,malachite1 which is green1 and azurite1 which is blue1 are carbonates1 the former being used for ornamental purposes4 ,cu is1 next to ,ag1 the best conductor of electricity and heat among the elements2 it is very ductile1 malleable1 and tenacious4 ,cu has two valences1 #a and #b4 ,symbolize and name its chlorides1 iodides1 sulphides1 and oxides4 ,cupric compounds1 as a rule1 are more stable than cuprous4 #bgi4 ,uses4--,thousands of tons of ,cu find use in domestic utensils1 ocean vessels1 electric wires1 batteries1 and plating4 ,name the chief alloys of ,cu and their uses4 ,see page #acf4 ,how may ,cu,s be obtained8 ,see ,experiment #g4 ,cu#b,o1 cuprous oxide1 is used to color glass red4 ,,cuso#d is employed in calico-printing1 electric batteries1 etc4 ,it is called blue vitriol4 ,paris green1 used for killing potato-beetles1 is composed chiefly of copper arsenite4 ,write the symbol for this compound4 ,all soluble salts of ,cu are poisonous2 hence care should be taken not to bring any acid in contact with copper vessels of domestic use4 ,with acetic acid1 what would be formed8 ,,mercury ,,and ,,its ,,compounds4 ,examine cinnabar1 vermilion1 mercury1 red oxide1 mercurous and mercuric chloride4 #bhj4 ,cinnabar1 ,hg,s1 is practically the only source of mercury-- quicksilver4 ,austria1 ,spain1 and ,california contain nearly all the mines4 ,in these mines the metal also occurs native to a small extent4 ,it is the only commonly occurring metal that is liquid at ordinary temperatures2 it solidifies at about -#dj degrees4 ,what other common liquid element8 ,see page #ab4 ,hg is reduced from the ore by ,fe1 ,hg being distilled over and collected in water4 ,heat regularly expands the metal4 #bha4 ,uses4--,for uses see ,reduction of ,ag and ,au1 pages #afe and #agj2 amalgams1 page #acg2 laboratory work1 page #fh4 ,it is also employed for thermometers and barometers1 and as the source of the red pigment vermilion1 which is artificial ,hg,s4 ,compare the vapor density and the atomic weight of ,hg1 and explain4 ,see page #ab4 ,hg is either a monad or a dyad4 ,symbolize its ous and ic oxides and chlorides4 ,which of the following are is salts1 and which are ous1 and why8 ,hg,n,o#c1 ,hg7,,no#c7b1 ,hg,cl1 ,hg,cl#b8 ,calomel1 ,hg,cl or ,hg#b;,cl#b1 used in medicine1 and corrosive sublimate1 ,hg,cl#b1 are illustrations of the ous and ic salts4 ,the former is insoluble1 the latter soluble4 ,all soluble compounds of ,hg are virulent poisons1 for which the antidote is the white of egg1 albumen4 ,with it they coagulate or form an insoluble mass4 ,,silver ,,and ,,its ,,compounds4 #bhb4 ,occurrence and ,reduction4--,silver is found uncombined1 and combined1 as ,ag#b,s1 argenite1 and ,ag,cl1 horn silver4 ,it occurs usually with galena1 ,pb,s4 ,it is abundant in the ,western ,states1 ,mexico1 and ,peru4 ,silver is separated from galena by melting the two metals4 ,as they slowly cool1 ,pb crystallizes1 and is removed by asieve1 while ,ag is left in the liquid mass4 ,the principle is much like crystallizing ,na,cl from solution and leaving behind the salts of ,mg1 etc41 in the mother liquor4 ,when1 by repeating the process1 most of the ,pb is eliminated1 the rest is oxidized by heating in the air4 ,pb ,o ,pb,o4 ,ag does not oxidize1 and is left in the metallic state4 ,another mode of reduction is to change the silver salt to its chloride1 and then remove the ,cl with ,fe4 ,roasting with ,na,cl makes the first change1 #b ,na,cl ,ag#b,s ,na#b,s #b ,ag,cl1 and with ,fe the second1 #b ,ag,cl ,fe ,fe,cl#b #b ,ag4 ,ag is separated from the other products by adding ,hg1 with which it forms an amalgam4 ,by distilling this1 ,hg passes over and ,ag remains4 ,this is the amalgamating process4 #bhc4 ,salts of ,silver are much employed in organic chemistry1 and ,ag,cl1 ,ag,br1 and ,ag,n,o#c are used in photography4 ,ag,n,o#c is a soluble1 colorless crystal1 and is the basis of the silver salts4 ,it blackens when in contact with organic matter4 ,stains on a photographer's hands are due to this substance1 and the use of ,ag,n,o#c in indelible inks depends on the same property4 ,this may be due to a reduction of ,ag,n,o#c to ,ag#d,o4 ,stains can be removed from the skin or from linen by a solution of ,kl1 or of ,cu,cl#b followed by sodium hyposulphite4 ,lunar caustic is made by fusing ,ag,n,o#c crystals1 and is used for cauterizing 7burning7 the flesh4 ,much ,ag,c,n finds use in electroplating4 ,experiment #abh4--,put #e cc4 ,ag,n,o#c solution in each of three t4t4 ,to the first add #c cc4 ,h,cl1 to the second #c;cc4,na,cl solution1 and to the third #c cc4 ,k,br solution4 ,write the reaction for each case1 and notice that the first two give the same ppt41 as in fact any soluble chloride would4 ,filter the second and third1 on separate filter papers1 and expose half the residue to direct sunlight1 observing the change of color by occasionally stirring4 ,solar rays reduce ,ag,cl and ,ag,br1 it is thought1 to ,ag#b;,cl and ,ag#b;,br4 ,try to dissolve the other half in ,na#b,s#b,o#c1 sodium thiosulphate solution4 ,this experiment illustrates the main facts of photography4 ,,chapter ,,li4 ,,photography4 #bhd4 ,descriptive4--,the silver halogens1 ,ag,c,i1 ,ag,br1 ,ag,i1 are very sensitive to certain light rays4 ,red rays do not affect them2 hence ruby glass is used in the dark room4 ,photography involves two processes4 ,the negative of the picture is first taken upon a prepared glass plate1 and the positive is then printed on prepared paper4 ,the negative shows the lights and shades reversed1 while the positive gives objects their true appearance4 ,few photographers now make their own plates1 these being prepared at large manufactories4 ,the glass is there covered on one side with a white emulsion of gelatine and ,ag,br1 making what are called gelatine-bromide plates4 ,this is done in a room dimly lighted with ruby light4 ,the plates are dried1 packed in sealed boxes1 and thus sent to photographers4 ,the artist opens them in his dark room1 similarly lighted1 inserts the plates in holders1 film side out1 covers with a slide1 adjusts to the camera1 previously focused1 and makes the exposure to light4 ,the time of exposure varies with the kind of plate1 the lens1 and the light1 from several seconds1 minutes1 or hours1 to #a_/bej part of a second in some instantaneous work4 ,in the dark room the plates are removed and can be at once developed1 or kept for any time away from the light4 ,no change appears in the plate until development1 though the light has done its work4 ,to develop the plate1 it is put into a solution of pyrogallic acid1 the developer1 and carbonate of sodium1 the motive power in the process4 ,other developers are often used4 ,the chemical action here is somewhat obscure1 but those parts of the plates which were affected by the light are made visible1 a part of the ,agz,br being reduced to ,ag by the affinity which sodium pyrogallate has for ,br4 ,ag#b;,br #b ,ag ,br4 ,br is dissolved and ,ag is deposited4 ,when the rather indistinct image begins to fade out1 the plate is dipped for a minute into a solution of alum to harden the gelatine and prevent it from peeling off 7frilling74 ,it is finally soaked in a solution of sodium thiosulphate 7hyposulphite or hypo71 ,na#b,s#bjh4 ,this removes the ,ag,br that the light has failed to reduce4 ,the processis called fixing1 as the plate may thereafter be exposed to the light with impunity4 ,it must be left in this bath till all the white part1 best seen on the back of the plate1 disappears4 #b;,ag,br #c,na#b,s#b,o#c ,ag#b,na#d7,s#b,o#c7 #b ,na,br4 ,both products are dissolved4 ,it is then thoroughly washed4 ,any dark objects become light in the negative1 and vice versa4 ,why8 ,for the positive1 the best linen paper is covered on one side with albumen1 soaked in ,na,cl solution1 dried1 and the same side laid on a solution of ,ag,n,o#c4 ,what reaction takes place8 ,what is deposited on the paper1 and what is dissolved8 ,this sensitized paper1 when dry1 is placed over a negative1 film to film1 and exposed in a printing frame to direct sunlight till much darker than desired in the finished picture4 ,what is dark in the negative will be light in the positive4 ,why8 ,the reducing action of sunlight is similar to that in the negative4 ,explain it4 ,after printing1 the picture is toned and fixed4 ,toning consists in giving it a rich color by replacing part of the ,ag#b;,cl with gold from a neutral solution of ,au,cl#c4 #c ,ag#b;,cl ,a,u,cl#c #f;,ag,c,i ,au4 ,fixing removes the unaffected ,ag,cl1 as in the negative1 the same substance being used4 ,describe the action4 #b ,ag,c,i #c ,na#b,s#bjc ,ag#b,na#d7,s#bjc7 #b ,na,cl4 ,both the positive and the negative must be well washed after each process1 particularly after the last4 ,the picture is then ready for mounting4 ,in fine portrait work both the negative and the positive are retouched4 ,this consists in removing blemishes with colored pencils or ,india ink4 ,the negative--,no4 #a4 ,dissolve3 sulphite soda crystals1 #b oz4 7#eg g7 in #h oz4 7#bcf cc47 water 7distilled72 citric acid1 #fj grains 7#d g7 in #a_/b oz4 7#ae cc47 water2 bromide ammonium1 #be grains 7#a #a_/b g7 in #a_/b oz4 water2 pyrogallic acid1 #a oz4 7#bh g7 in #c oz4 7#ij cc47 water4 ,after dissolving1 mix in the order named1 and filter4 ,no4 #b4 ,dissolve3 sulphite soda1 #b oz4 7#eg g7 in #d oz4 7#aah cc47 water2 carbonate potash1 #d oz4 7#aac g7 in #h oz4 7#bcf cc47 water4 ,dissolve separately1 mix1 and filter4 ,to develop plates1 mix #a dram 7#c #b_/c cc47 of ,no4 #a and #a dram of ,no4 #b with #b oz4 7#fj cc47 water4 ,cover the plate with the mixture1 and leave as long as the picture increases in distinctness4 ,remove1 wash1 and put it into a saturated solution of alum for a minute or two1 then wash and put it into a half-saturated solution of hypo4 ,leave till no white ,ag,cl is seen through the back of the plate4 ,wash it well4 ,the positive4--#a4 ,dissolve #cj grains 7#b g47 pure gold chloride in #ae oz4 7#dej cc47 water4 ,this forms a stock solution4 #b4 ,make a saturated solution of borax4 #c4 ,prepare a toning bath by adding #a_/b oz4 7#ae cc47 of the gold chloride solution and #a oz4 7#cj cc47 of the borax solution to #g oz4 7#baj cc47 water4 ,after printing the picture1 wash it in #c or #d waters1 put it into the toning bath1 and leave it till considerably darker than desired2 wash1 and put it for #ae minutes into a hypo solution that has been1 after saturation1 diluted with #c or #d volumes of water4 ,then wash repeatedly4 ,,chapter ,,lii4 ,,platinum ,,and ,,gold4 ,,platinum4 ,examine platinum foil and wire4 #bhe4 ,platinum is much rarer than gold1 and is about two-thirds as costly as the latter4 ,it is found alloyed with other metals1 as ,an1 and is obtained from sand1 in which it occurs1 by washing4 ,aqua regia is the only acid which dissolves it1 and the action is much slower than with ,au4 ,pt is one of the heaviest metals1 having a specific gravity three times that of ,fe1 or twenty-one and a half times that of water4 ,its fusing-point is about #afjj degrees1 or just below the temperature of the oxy-hydrogen flame4 ,like ,au it has little affinity for other elements1 but alloys with many metals4 ,pt is so tenacious that it can be drawn into wire invisible to the naked eye1 being drawn out in the center of a silver wire1 which is afterwards dissolved away from the ,pt by ,,hno#c4 ,noting its valences1 #b and #d1 write the symbols for the ous and ic chlorides and oxides4 #bhf4 ,uses4--,pt is much used in chemistry in the form of foil1 wire1 and crucibles4 ,on what properties does this use depend8 ,describe its use in making ,h#b,,so#d4 ,pt,cl#d is made by dissolving ,pt in aqua regia1 and evaporating the liquid4 ,on heating ,pt,cl#d1 half of its ,cl is given up1 leaving ,pt,cl#b4 ,if it be still more strongly heated1 the ,cl all passes off1 leaving spongy ,pt4 ,by fusing this in the oxy-hydrogen flame1 ordinary ,pt is obtained4 ,spongy ,pt has a remarkable power of absorbing1 or occluding1 ,o without uniting with it4 ,this ,o it gives up to some other substances1 and thus becomes indirectly an oxidizing agent4 ,what other element has this property of occluding gases8 ,,gold4 ,examine auriferous quartz1 gold chloride1 yellow and ruby glass colored with gold4 #bhg4 ,gold is rarely found combined1 and has small affinity for other elements1 though forming alloys with ,cu1 ,ag1 and ,hg4 ,its source is usually either quartz rock1 called auriferous quartz1 or sand in placer mines4 ,the element is widely distributed1 occurring in minute quantities in most soils1 sea water1 etc4 ,california and ,australia are the two greatest gold- producing countries4 ,that from ,california has a light color1 due to a slight admixture of ,ag4 ,australian gold is of a reddish hue1 due to an alloy of ,cu4 ,gold-bearing quartz is pulverized1 and treated with ,hg to dissolve the precious metal1 which is then separated from the alloy by distillation4 ,compare this with the preparation of ,ag4 ,such is the malleability of ,au that it has been hammered into sheets not over one-millionth of an inch thick2 it is then as transparent as glass4 ,gold does not tarnish or change below the melting-point4 ,on account of its softness it is usually alloyed with ,cu1 sometimes with ,ag4 ,pure gold is twenty-four carats fine4 ,eighteen carat gold has eighteen parts ,au and six ,cu4 ,gold coin has nine parts ,au to one part ,cu4 ,the most important compound is ,au,cl#c4 ,describe a use of it4 ,this metal is much employed in electroplating1 and somewhat in coloring glass4 ,,chapter ,,liii4 ,,chemistry ,,of ,,rocks4 #bhh4 ,classification4--,rocks may be divided1 according to their origin1 into three classes3 7#a7 ,aqueous rocks4 ,these have been formed by deposition of sedimentary material1 layer by layer1 on the bottoms of ancient oceans1 lakes1 and rivers1 from which they have gradually been raised1 to form dry land4 7#b7 ,eruptive or volcanic rocks4 ,these have been forced1 as hot fluids1 through rents and fissures from the interior of the earth4 7#c7 ,metamorphic rocks4 ,these1 by the combined action of heat1 pressure1 water1 and chemical agents1 have been crystallized and chemically altered4 ,the rocks of the first class1 such as chalk1 limestone1 shale1 and sandstone1 are distinguished by the existence of fossils in them1 or by the successive layers of the material which goes to make up their structure and to give them a stratified appearance4 ,the rocks of the second class are recognized by their resemblance to the products of modern volcanoes and their non-stratified appearance4 ,rocks of the third class are composed of crystals1 which1 though often very minute1 are minerals having a definite chemical composition4 ,examples of the third class are gneiss1 slate1 schist1 and marble4 ,the last two classes abound on the ,eastern sea-board1 while the interior of our continent is composed almost exclusively of stratified sedimentary rocks4 #bhi4 ,composition4--,rocks are not definite compounds1 but variable mixtures of minerals4 ,some1 however1 are tolerably pure1 as limestone 7,ca,c,o#c7 and sand-stone4 ,granite is mainly made up of three minerals1--quartz1 feldspar1 and mica4 ,quartz1 when pure1 is ,si,o#b4 ,feldspar is a mixed silicate of ,k and ,al1 and often several other metals1 ,k#b;,al#b,si#f,o#af 7,k#b,o1 ,al#b,o#c1 #f ,si,o#b7 symbolizing one variety1 while a variety of mica is ,h#h,mg#e;,fe#g;,al#b,si#c,o#ah4 ,the pupil should learn to distinguish the different minerals in granite4 ,quartz is glassy1 mica is in scales1 usually white or black1 and feldspar is the opaque white or red mineral4 #bij4 ,importance of ,siliceous ,rocks4--,slate and schist are also mixed silicates4 ,pure sandstone is ,si,o#b1 the red variety being colored by iron4 ,igneous rocks are always siliceous4 ,obsidian is a glassy silicate4 ,a mountain of very pure glass1 obsidian1 two hundred feet high1 has lately been found in the ,yellow-stone region4 ,we see how important ,si is1 in the compounds ,si#jb and the silicates1 as a constituent of the terrestrial crust4 ,limestone is the only extensive rock from which it is absent4 ,always combined with ,o1 it is1 next to the latter1 the most abundant of elements4 ,silicates of ,al1 ,fe1 ,ca1 ,k1 ,na1 and ,mg are most common1 and these metals1 in the order given1 rank next in abundance4 #bia4 ,soils4--,beds of sand1 clay1 etc41 are disintegrated rock4 ,sand is chiefly ,si,o#b2 clay is decomposed feldspar1 slatestone1 etc4 ,soils are composed of these with an added portion of carbonaceous matter from decaying vegetation1 which imparts a dark color4 ,the reddish brown hue so often observed in soils and rocks results from ferric salts4 #bib4 ,minerals1 of which nearly #ajjj varieties are now known1 may be simple substances1 as graphite and sulphur1 or compounds1 as galena and gypsum4 ,only seven systems of crystallizations are known1 but these are so modified as to give hundreds of forms of crystals4 ,see ,physics4 ,a given chemical substance usually occurs in one system only1 but we saw in the case of ,s that this was not always true4 ,crystals of some substances deliquesce1 or take water from the air1 and thus dissolve themselves4 ,some compounds cannot exist in the crystalline form without a certain percentage of water4 ,this is called water of crystallization2 if it passes into the air by evaporation1 the crystal crumbles to a powder- and is then said to effloresce4 #bic4 ,the ,earth's ,interior4--,we are ignorant of the chemistry of the earth's interior4 ,the deepest boring is but little more than a mile1 and volcanic ejections probably come from but a very few miles below the surface4 ,the specific gravity of the interior is known to be more than twice that of the surface rock4 ,from this it has been imagined that towards the center heavy metals like ,fe and ,au predominate2 but this is by no means certain1 since the greater pressure at the interior would cause the specific gravity of any substance to increase4 #bid4 ,percentage of ,elements4--,compute the percentage of ,o in the following rocks1 which compose a large proportion of the earth's crust3 ,si,o#b1 ,al#b,si,o#d1 ,ca,c,o#c4 ,find the percentage of ,o in pure water4 ,in air4 ,taking cellulose1 ,c#af;,h#cj,o#ae1 as the basis1 find the percentage of ,o in vegetation4 ,an estimate1 based on ,bunsen's analysis of rocks1 of the chief elements in the earth's crust1 is as follows3-- ,o1 #df per cent ,ca1 #c per cent ,si1 #cj per cent ,na1 #b per cent ,al1 #h per cent ,k1 #b per cent ,fe1 #f per cent ,mg1 #a per cent ,more than half the elements are known to exist in sea-water1 and the rest are thought to be there1 though dissolved in such small quantity as to elude detection4 ,what four are found in the atmosphere8,,chapter ,,liv4 ,,organic ,,chemistry4 #bie4 ,general ,considerations4--,inorganic chemistry is the chemistry of minerals1 or unorganized bodies4 ,organic chemistry was formerly defined as the chemistry of the compounds found in plants and animals2 but of late it has taken a much wider range1 and is now defined as the chemistry of the ,c compounds1 since ,c is the nucleus around which other elements centre1 and with which they combine to form the organic substances4 ,new organic compounds are constantly being discovered and synthesized1 so that nearly #ajj1jjj are now known4 ,the molecule of organic matter is often very complex1 sometimes containing hundreds of atoms4 ,in organic as in inorganic chemistry1 atoms are bound together by chemical affinity1 though it was formerly supposed that an additional or vital force was instrumental in forming organic compounds4 ,for this reason none of these substances1 it was thought1 could be built up in the laboratory1 although many had been analyzed4 ,in #ahbh the first organic compound1 urea1 was artificially prepared1 and since then thousands have been synthesized4 ,they are not necessarily manufactured from organic products1 but can be made from mineral matter4 #bif4 ,molecular ,differences4--,molecules may differ in three ways3 7#a7 ,in the kind of atoms they contain4 ,compare ,,co#b and ,,cs#b4 7#b7 ,in the number of atoms4 ,compare ,,co and ,,co#b4 7#c7 ,in the arrangement of atoms1 i4e4 the molecular structure4 ,ethyl alcohol and methyl ether have the same number of the same elements1 ,c#b;,h#f,o1 but their molecular structure is not the same1 and hence their properties differ4 ,qualitative analysis shows what elements enter into a compound2 quantitative analysis shows the proportion of these elements2 structural analysis exhibits molecular structure1 and is the branch to which organic chemists are now giving particular attention4 ,a specialist often works for years to synthesize a series of compounds in the laboratory4 #big4 ,sources4--,some organic products are now made in a purer and cheaper form than ,nature herself prepares them4 ,alizarine1 the coloring principle of madder1 was until lately obtained only from the root of the madder plant2 now it is almost wholly manufactured from coal-tar1 and the manufactured article serves its purpose much better than the native product4 ,ten million dollars' worth is annually made1 and ,holland1 the home of the plant1 is giving up madder culture4 ,artificial naphthol-scarlet is abolishing the culture of the cochineal insect4 ,indigo has also been synthesized4 ,certain compounds have been predicted from a theoretical molecular structure1 then made1 and afterwards found to exist in plants4 ,others are made that have no known natural existence4 ,the source of a large number of artificial organic products is coal-tar1 from bituminous coal4 ,saccharine1 a compound with two hundred and eighty times the sweetening power of sugar1 is one of its latest products4 ,wood1 bones1 and various fermentable liquids are other sources of organic compounds4 #bih4 ,marsh-,gas ,series4--,the chemistry of the hydro-carbons depends on the valence of ,c1 which1 in most cases1 is a tetrad4 ,take successively #a1 #b1 and #c ,c atoms1 saturate with ,h1 and note the graphic symbols3-- ,h ,h ,h ,h ,h ,h ,h-,c-,h1 or ,,ch#d4 ,h-,c-,c-,h1 or8 ,h-,c-,c-,c-,h1 or 8 ,h ,h ,h ,h ,h ,h ,write the graphic and common symbols for #d1 #e1 and #f ,c atoms1 saturated with ,h4 ,notice that the ,h atoms are found by doubling the ,c atoms and adding #b4 ,hence the general formula for this series would be ,cn,h#bn#b4 ,write the common symbol for ,c and ,h with ten atoms of ,c2 twelve atoms2 thirteen4 ,this series is called the marsh-gas series4 ,the first member1 ,,ch#d methane1 or marsh gas1 may be written ,,ch#c;,h1 methyl hydride1 ,,ch#c being the methyl radical4 ,c#b;,h#f1 ethane1 the second one1 is ethyl hydride1 ,c#b;,h#e;,h4 ,theoretically this series extends without limit2 practically it ends with ,c#ce;,h#gb4 ,in each successive compound of the following list1 the ,c atoms increase by unity4 ,give the symbols and names of the compounds1 and commit the latter to memory3-- ,boiling-point4 #a4 ,,ch#d methane1 or ,,ch#c;,h1 methyl hydride1 gas4 #b4 ,c#b;,h#f ethane1 ,c#b;,h#e;,h1 ethyl hydride1 gas #c4 ,c#c;,h#h propane1 ,c#c;,h#g;,h1 propyl hydride1 gas #d4 8 butane1 8 8 #a degree #e4 8 pentane 8 8 #ch degrees #f4 8 hexane1 8 8 #gj degrees #g4 8 heptane1 8 8 #ih degrees #h4 8 octane1 8 8 #abe degrees #i4 8 nonane1 8 8 #adh degrees #aj48 dekane1 8 8 #aga degrees ,note a successive increase of the boiling-point of the compounds4 ,crude petroleum contains these hydro-carbons up to #aj4 ,petroleumissues from the earth1 and is separated into the different oils by fractional distillation and subsequent treatment with ,h#b,,so#d1 etc4 ,rhigoline is mostly #e and #f2 gasoline1 #f and #g2 benzine1 #g2 naphtha1 #g and #h2 kerosene1 #i and #aj4 ,below #aj the compounds are solids4 ,none of those named1 however1 are pure compounds4 ,explosions of kerosene are caused by the presence of the lighter hydro-carbons1 as naphtha1 etc4 ,notice that1 in going down the list1 the proportion of ,c to ,h becomes much greater1 and the lower compounds are the heavy hydro-carbons4 ,to them belong vaseline1 paraffine1 asphaltum1 etc4 #bii4 ,alcohols4--,the following replacements will show how the symbols for alcohols1 ethers1 etc41 are derived from those of the marsh-gas series4 ,notice that these symbols also exhibit the molecular structure of the compound4 ,in ,,ch#c;,h by replacing the last ,h with the radical ,,oh1 we have ,,ch#c,,oh1 methyl hydrate4 ,by a like replacement ,c#b;,h#e;,h becomes ,c#b;,h#e,,oh1 ethyl hydrate4 ,these hydrates are alcohols1 and are known as methyl alcohol1 ethyl alcohol1 etc4 ,the common variety is ,c#b;,h#e,,oh4 ,how does this symbol differ from that for water1 ,,hoh8 ,notice in the former the union of a positive1 and also of a negative1 radical4 ,complete the table below1 making a series of alcohols1 by substitutions as above from the previous table4 #a4 ,,ch#c,,oh1 methyl hydrate1 or methyl alcohol4 #b4 ,c#b;,h#e,,oh1 ethyl hydrate1 or ethyl alcohol4 #c4 8 8 8 #d4 8 8 8 #e4 8 8 8 ,continue in like manner to #aj4 ,the graphic symbol for ,,ch#c,,oh is--- ,h ,h-,c-,,oh2 ,h for ,c#b;,h#e,,oh it is-- ,h ,h ,h-,c-,c-,,oh4 ,h ,h ,write it for the next two4 #cjj4 ,ethers4--,another interesting class of compounds are the oxides of the marsh-gas series4 ,in this series1 ,o replaces ,h4 ,,ch#c;,h becomes 7,,ch#c7b,o1 and ,c#b;,h#e;,h becomes 7,c#b;,h#e7b,o4 ,why is a double radical taken8 ,these oxides are ethers1 common or sulphuric ether being 7,c#b;,h#e7b,o4 ,complete this table1 by substituting ,o in place of ,h1 in the table on page #agf4 #a4 7,,ch#c7b,o1 methyl oxide1 or methyl ether4 #b4 7,c#b;,h#e7b,o1 ethyl oxide1 or ethyl ether4 #c4 8 8 8 #d4 8 8 8 #e1 etc4 8 8 8 ,graphically represented the first two are3-- ,h ,h ,h ,h ,h ,h 7#a7 ,h-,c-,o-,c-,h4 7#b7 ,h-,c-,c-,o-,c-,c-,h4 ,h ,h ,h ,h ,h ,h #cja4 ,substitutions4--,a large number of other substitutions can be made in each symbol1 thus giving rise to as many different compounds4 ,in ,,ch#d1 by substituting #c ,cl for #c ,h1-- ,h ,cl ,h-,c-,h becomes ,h-,c-,,ci1 or ,c,h,cl#c1the symbol for chloroform4 ,h ,cl ,replace successively one1 two1 and four atoms with ,cl1 and write the common symbols4 ,make the same changes with ,br4 ,for each atom of ,h in ,,ch#d substitute the radical ,,ch#c1 giving the graphic and common formulae4 ,also substitute ,c#b;,h#e4 ,are these radicals positive or negative8 ,from the above series of formulae1 of which ,,ch#d is the basis1 are derived1 in addition to the alcohols and ethers1 the natural oils1 fatty acids1 etc4 #cjb4 ,olefines4--,a second series of hydro-carbons is represented by the general formula ,cn,h#bn4 ,the first member of this series is ,c#b;,h#d or1 graphically1-- ,h ,h ,c ,c4 ,h ,h ,compare it with that for ,c#b;,h#f1 in the first series1 noting the apparent molecular structure of each4 ,h ,h ,c ,c - ,c - ,h1 or ,c#c;,h#f is the second member4 ,h ,h ,h ,write formulae for the third and fourth members4 ,write the common formulae for the first ten of this series4 ,this is the olefiant-gas series1 and to it belong oxalic and tartaric acids1 glycerin1 and a vast number of other compounds1 many of which are derived by replacements4 #cjc4 ,other ,series4--,in addition to the two series of hydro- carbons above given1 ,cn,h#bn#b and ,cn,h#bn1 other series are known with the general formulm ,cn,h#bn-#b1 ,cn,h#bn-#d1 ,cn,h#bn-#f1 ,cn,h#bn-#h1 etc41 as far as ,cn,h#bn-#cb1 or ,c#bf;,h#b,o4 ,each of these has a large number of representatives1 as was found in the marsh-gas series4 ,not far from two hundred direct compounds of ,c and ,h are known1 not to mention substitutions4 ,the formula ,cn,h#bn-#f represents a large and interesting group of compounds1 called the benzine series4 ,this is the basis of the aniline dyes1 and of many perfumes and flavors4 ,chapter ,,lv4 ,,illuminating ,,gas4 #cjd4 ,source4--,the three main elements in combustion are ,o1 ,h1 ,c4 ,air supplies ,o1 the supporter2 ,c and ,h are usually united1 as hydro-carbons1 in luminants and combustibles4 ,h gives little light in burning2 ,c gives much4 ,the fibers of plants contain hydro-carbons1 and by destructive distillation these are separated1 as gases1 from wood and coal1 and used for illuminating purposes4 ,mineral coal is fossilized vegetable matter2 anthracite has had most of the volatile hydro-carbons removed by distillation in the earth2 bituminous and cannel coals retain them4 ,these latter coals are distilled1 and furnish us illuminating gas4 ,experiment #abi4--,put into a t4t4 #bj g4 of cannel coal in fine pieces4 ,heat1 and collect the gas over ,h#b,o4 ,test its combustibility4 ,notice any impurities1 such as tar1 adhering to the sides of the t4t41 or of the receiver after combustion4 ,try to ignite a piece of cannel coal by holding it in a ,bunsen flame4 ,is it the ,c which burns1 or the hydrocarbons8 ,distil some wood shavings in a small ignition-tube1 and light the escaping gas4 #cje4 ,preparation and ,purification4--,to make illuminating gas1 fire-clay retorts filled with coal are heated to #aajj degrees or more1 over a fire of coke or coal4 ,tubes lead the distilled gas into a horizontal pipe1 called the hydraulic main1 partly filled with water1 into which the ends of the gas-pipe dip4 ,the gas then passes through condensers consisting of several hundred feet of vertical pipe1 through high towers1 called washers1 in which a fine spray ,fig4 #fj4 ,gas ,works4 ,a1 furnace2 ,c1 retorts containing coal2 ,t1 gas-tubes leading to ,b1 the hydraulic main2 ,d1 condensers2 ,o1 washers1 with a spray of water1 and sometimes coke2 ,m1 purifiers-ferric oxide or lime2 ,g1 gas-holder4 ,in ,c remain the coke and gas carbon4 ,at ,b1 ,d1 ,e1 and ,o1 coal tar1 ,h#b,o1 ,,nh#c1 ,,co#b1 and ,,so#b are removed4 ,at ,m are taken out ,h#b,s and ,,co#b4of water falls1 into chambers with shelves containing the purifiers ,ca,o or hydrated ,fe#b,o#c1 and finally into a gas-holder1 whence it is distributed4 ,at the hydraulic main1 condensers1 washers1 and purifiers1 certain impurities are removed froth the gas4 ,coke is the solid ,c residue after distillation4 ,gas-carbon1 also a solid1 is formed by the separation of the heavier hydro-carbons at high temperature1 and is deposited on the sides of the retort4 ,coal gas1 as it leaves the retort1 has many impurities4 ,it is accompanied with about #c its weight of coal tar1 #a_/b its weight of ,h#b,o vapor1 #a_/ej ,,nh#c1 #a_/bj ,,co#b1 #a_/bj to #a_/ej ,h#b,s1 #a_/cjj to #a_/fjj ,s in other forms4 ,the tar is mostly taken out at the hydraulic main1 which also withdraws some ,h#b,o with other impurities in solution4 ,the condensers remove the rest of the tar1 and the ,h#b,o1 except what is necessary to saturate the gas4 ,at the main1 the condensers1 and the washers1 ,,nh#c is abstracted1 ,,co#b and ,h#b,s are much reduced1 and the other ,s compounds are diminished4 ,lime purification removes ,,co#b and ,h#b,s1 and1 to some extent1 other ,s compounds4 ,iron purification removes ,h#b,s4 ,fe#b,o#c #c ,h#b,s #b ,fe,s ,s #c ,h#b,o4 ,the ,fe,s is revivified by exposure to the air4 #b ,fe,s ,o#c ,fe#b,o#c #b,s4 ,it can then be used again4 ,h#b,s1 if not separated1 burns with the gas1 forming ,h#b,s#jc1 which oxidizes in the air to ,h#b,,so#d2 hence the need of removing it4 ,,co#b diminishes the illuminating power4 #cjf4 ,composition4--,even when freed from its impurities coal-gas is a very complex mixture1 the chief components being nearly as follows3-- ,percent ,diluents1 having little ,c1 give ,h #de7 very little light4 ,notice the small ,,ch1 #da7 diluents4 percentage of luminants1 or light- ,,co #e 7 giving compounds1 also the proportion ,c1,,hb #a4c7 of ,c to ,h in them4 ,c1,h#f #a4b7luminants4 ,,czh#d #b4e7 ,cannel coal contains more of ,c#jb #b7 impurities4 the heavy bydro-carbons1 ,cn,h#bn1 ,n1 etc4 #b7 etc41 than the ordinary bituminous #ajj coal4 ,ten per cent of the coal should be cannel2 naphtha is1 however1 often employed to subserve the same purpose1 one ton of ordinary bituminous coal requiring four gallons of oil4 ,in ,boston1 #g1jjj1jjj cubic feet of gas have been burned in one day1 consuming #ejj tons of coal2 the average is not more than half that quantity4 ,of the other products1 coke is employed for heating purposes1 gas carbon is used to some extent in electrical work1 and coal-tar is the source of very many artificial products that were formerly only of natural origin4 ,,nh#c1 is the main source of ammonium salts1 and ,s is made into ,h#b,,so#d4 #cjg4 ,natural ,gas occurs near ,pittsburg1 ,pa41 and in many other places1 in immense quantities4 ,it is not only employed to light the streets and houses1 but is used for fires and in iron and glass manufactories4 ,it is estimated that #fjj1jjj1jjj cubic feet are burned1 saving #aj1jjj tons of coal daily in ,pittsburg1 ,only half a dozen factories now use coal4 ,more than half the gas is wasted through safety valves1 on account of the great pressure on the pipes as it issues from the earth4 ,these reservoirs of natural gas very frequently occur in sandstone1 usually in the vicinity of coal-beds1 but sometimes remote from them4 ,in all cases the origin of the gas is thought to be in the destructive distillation1 extending through long geological periods1 of coal or of other vegetable or animal matter in the earth's interior4 ,natural gas varies in composition1 and even in the same well1 from day to day2 it consists chiefly of ,,ch#d1 with some other hydro-carbons4 ,,chapter ,,lvi4 ,,alcohol4 #cjh4 ,fermented ,liquor4 ,experiment #acj4--;,introduce #bj cc4of molasses into a flask of #bjj cc1 fill it with water to the neck1 and put in half a cake of yeast4 ,fit to this a d4t41 and pass the end of it into a t4t4 holding a clear solution of lime water4 ,leave in a warm place for two or three days4 ,then look for a turbidity in the lime water1 and account for it4 ,see whether the liquid in the flask is sweet4 ,the sugar should be changed to alcohol and ,,co#b4 ,this is fermented liquor2 it contains a small percentage of alcohol4 #cji4 ,distilled ,liquor4 ,experiment #aca4--;,attach the flask used in the last experiment to the apparatus for distilling water 7,fig4 #cb71 and distil not more than one-fifth of the liquid1 leaving the rest in the flask4 ,the greater part of the alcohol will pass over4 ,to obtain it all1 at least half of the liquid must be distilled2 what passes over towards the last is mostly water4 ,taste and smell the distillate4 ,put some into an e4d4 and touch a lighted match to it4 ,if it does not burn1 redistil half of the distillate and try to ignite the product4 ,try the combustibility of commercial alcohol2 of ,jamaica ginger1 or of any other liquid known to contain alcohol4 #caj4 ,effect on the ,system4 ,experiment #acb4--,put a little of the white of egg into an e4d4 or a beaker2 cover it with strong alcohol and note the effect4 ,strong alcohol has the same coagulating action on the brain and on the tissues generally1 when taken into the system1 absorbing water from them1 hardening them1 and contracting them in bulk4 #caa4 ,affinity for ,water4 ,experiment #acc4--,to show the contraction in mixing alcohol and water1 measure exactly #e;cc4of alcohol and #e;cc4of water4 ,pour them together1 and presently measure the mixture4 ,the volume is diminished4 ,a strip of parchment soaked in water till it is limp1 then dipped into strong alcohol1 becomes again stiff1 owing to the attraction of alcohol for water4 #cab4 ,purity4--,the most important alcohols are methyl alcohol and ethyl alcohol4 ,the former1 wood spirit1 is obtained in an impure state by distilling wood2 it is used to dissolve resins1 fats1 oils1 etc41 and to make aniline4 ,it is poisonous1 as are the others4 ,ethyl alcohol1 spirit of wine1 is the commercial article4 ,it is prepared by fermenting glucose1 and distilling the product4 ,it boils at #gh degrees1 vaporizing #bb degrees lower than water1 from which it can be separated by fractional distillation4 ,by successive distillations of alcohol ninety-four per cent can be obtained1 which is the best commercial article1 though most grades fall far below this4 ,five per cent more can be removed by distilling with ,ca,o1 which has a strong affinity for water4 ,the last one per cent is removed by ,ba,o4 ,one hundred per cent constitutes absolute alcohol1 which is a deadly poison4 ,diluted1 it increases the circulation1 stimulates the system1 hardens the tissues by withdrawing water1 and is the intoxicating principle in all liquors4--,it is very inflammable1 giving little light1 and much heat1 and readily evaporates4 ,beer has usually three to six per cent of alcohol2 wines1 eight to twenty per cent4 ,the courts now regard all liquors having three per cent1 or less1 of alcohol1 as not intoxicating4 ,in ,massachusetts it is one per cent4 ,,chapter ,,lvii4 ,,oils1 ,,fats1 ,,and ,,soaps4 #cac4 ,sources and ,kinds of ,oils and ,fats4--,oils and fats are insoluble in water2 the former are liquid1 the latter solid4 ,most fats are obtained from animals1 oils from both plants and animals4 ,oils are classified as fixed and essential4 ,castor oil is an example of the former and oil of cloves of the latter4 ,fixed oils include drying and non-drying oils4 ,they leave a stain on paper1 while essential1 or volatile oils1 leave no trace1 but evaporate readily4 ,essential oils dissolved in alcohol furnish essences4 ,they are obtained by distilling with water the leaves1 petals1 etc41 of plants4 ,drying oils1 as linseed1 absorb ,o from the air1 and thus solidify4 ,non-drying ones1 as olive1 do not solidify1 but develop acids and become rancid after some time4 ,oils and fats are salts of fatty acids and the base glycerin4 ,the three most common of these salts are olein1 found in olive oil1 palmitin1 in palm oil and human fat1 and stearin1 in lard4 ,the first is liquid1 the second semi-solid1 the last solid4 ,most fats are mixtures of these and other salts4 ,olefin ,glyceryl7 7 oleic7 oleate 7 7 7 ,pahnitin ,glyceryl7salts from 7palmitic7acid and glyceryl hydrate4 palmitate7 7 7 ,stearin ,glyceryl7 7stearic 7 stearate7 #cad4 ,saponification consists in separating these salts into their acids and the base glycerin2 soap-making is the best illustration4 ,to effect this separation1 a strong soluble base is used1 ,,koh for soft1 and ,na,o,h for hard soap4 ,study this reaction3 ,glyceryl oleate 7 7sodium 7 7oleate 7 ,glyceryl palmitate7 7hydrate7 sodium 7palmitate7 7glyceryl ,glyceryl stearate 7 7stearate 7 7hydrate ,soaps are thus salts of fatty acids and of ,k or ,na4 #cae4 ,soap is soluble in soft water1 but the sodium stearate probably unites with water to form hydrogen sodium stearate and ,na,o,h4 ,the grease which exudes from the skin1 or appears in fabrics to be washed1 is attacked by this ,na,o,h and removed1 together with the suspended dirt1 and a new soap is formed and dissolved in the water4 ,hard water contains salts of ,ca and ,mg1 and when soap is used with it the ,na is at once replaced by these metals1 and insoluble ,ca or ,mg soaps are formed4 ,hence in hard water soap will not cleanse till all the ,ca and ,mg compounds have combined4 #caf4 ,glycerin1 ,c#c;,h#e7,,oh7#c1 is a sweet1 thick1 colorless1 unctuous liquid1 used in cosmetics1 unguents1 pomades1 etc4 ,it is prepared in quantity by passing superheated steam over fats when under pressure4 #cag4 ,dynamite4--,treated with ,,hno#c and ,h#b,,so#d glycerin forms the very explosive and poisonous liquid nitro-glycerin4 ,in this process the ,c#c;,h#e7,,oh7#c becomes ,c#c;,h#e7,,no#c7c4 ,c#c;,h#e7,,oh7#c #c;,,hno#c ,c#c;,h#e7,,no#c7cc ,h#b,o4 ,h#b,,so#d is used to absorb the ,h#b,o which is formed4 ,nitro-glycerin1 absorbed by gunpowder1 diatomaceous earth1 sawdust1 etc41 forms dynamite4 ,for obvious reasons the pupil should not experiment with these substances4 #cah4 ,butter and ,oleomargarine4--,milk contains minute particles of fat1 about #a_/ejj of an inch in diameter1 which give it the whitecolor4 ,these particles are lighter than the containing liquid1 and rise to the top as cream4 ,churning unites the particles more closely1 and separates them from the buttermilk4 ,the flavor of butter is due to the presence of five or ten per cent of butyric and other acids of the same series4 ,it was found that cows gave milk after they ceased to have food2 hence it was inferred that the milk was produced at the expense of the cows' fat4 ,why could not butter be artificially made from the same fat8 ,it was but a step from fat to milk1 as it was from milk to butter4 ,oleomargarine1 or butterine1 was the result4 ,beef fat1 suet1 is washed in water1 ground to a pulp1 and partially melted and strained1 the stearin is separated from the filtered liquid and made into soap1 and an oily liquid is left4 ,this is salted1 colored with annotto1 mixed with a certain portion of milk1 and churned4 ,the product is scarcely distinguishable from butter1 and is chemically nearly identical with it1 though less likely to become rancid from the absence of certain fatty acids2 its cost is perhaps one-third as much as that of butter4 ,chapter ,,lviii ,,carbo-,,hydrates4 #cai4 ,carbon and ,water4--,some very important organic compounds have ,h and ,o1 in the proper proportion to form water1 united with ,c4 ,the three leading ones are sugar1 ,c#ab;,h#bb,o#aa or ,c#ab7;,h#b,o7#aa1 starch1 ,c#f;,h#aj,o#f1 or 81 and cellulose1 ,c#ah;,h#cj,o#ae or 84 ,note the significance of the name carbo-hydrates as applied to them4 #cbj4 ,sugars may be divided into two classes1--the sucroses1 ,c#ab;,h#bb,o#aa1 and the glucoses1 ,c#f;,h#ab,o#f4 ,sucrose1 the principal member of the first class1 is obtained from the juice of the maple1 the palm1 the beet and the sugarcane2 in ,europe largely from the beet1 in ,america from cane4 ,granulated sugar is that which has been refined2 brown sugar is the unrefined4 ,from the sap evaporated by boiling1 brown sugar crystallizes1 leaving molasses1 which contains glucose and other substances4 ,good molasses has but a small percentage of glucose4 ,to refine brown sugar it is dissolved in water1 a small quantity of blood is added to remove certain vegetable substances1 after which it is filtered through animal charcoal1 i4e4 bone-black1 a process which takes out the coloring-matter4 ,the water is then evaporated in vacuum-pans1 so as to boil at about #gd degrees and to prevent conversion into grape sugar4 ,by this process much glucose or syrup is formed1 which is separated from the crystalline sucrose by rapidly revolving centrifugal machines4 ,great quantities of sucrose are used for food by all civilized nations4 ,a single refinery in ,new ,york purifies #b1jjj1jjj pounds per day4 #cba4 ,glucose1 or invert sugar1 the principal member of the second class1 consists of two distinct kinds of sugar1 --dextrose and levulose4 ,these differ in certain properties1 but have the same symbol4 ,both are found in equal parts in ripe fruits1 while sucrose occurs in the unripe4 ,honey contains these three kinds of sugar4 ,sucrose1 by the action of heat1 weak acids1 or ferments1 may be resolved into the other two varieties4 ,c#ab;,h#bb,o#aa ,h#b,o ,c#f;,h#ab,o#f ,c#f;,h#ab,o#f4 ,no mode of reversing this process1 or of transforming glucose into sucrose is known4 ,glucose is easily made from starch or from the cellulose in cotton rags1 sawdust1 etc4 ,if boiled with dilute ,h#b,,so#d starch takes up water and becomes glucose4 ,c#f;,h#aj,o#e ,h#b,o ,c#f;,h#ab,o#f4 ,ca,c,o#c is added to precipitate the ,h#b,,so#d1 which remains unchanged4 ,state the reaction4 ,the product is filtered and the filtrate is evaporated4 ,much glucose is made from the starch of corn and potatoes4 #cbb4 ,starch is found in all plants1 especially in grains1 seeds1 and tubers4 ,green plants--those containing chlorophyll-- manufacture their own starch from ,,co#b and ,h#b,o4 ,these chlorophyll grains are the plant's chemical laboratories1 and hundreds of thousands of them exist in every leaf4 ,,co#b and a very little ,h#b,o enter the leaf from the air1 ,h#b,o being also drawn up through the root and stem from the earth4 ,in some unknown way in the leaf1 light has the power of synthesizing these into starch and setting free ,o1 which is returned to the atmosphere4#f ,,co#b #e ,h#b,o ,c#f;,h#aj,o#e #ab ,o4 ,as no such change takes place in darkness1 all green plants must have light4 ,parasitic plants1 which are usually colorless1 obtain starch ready-made from those on which they feed4 #cbc4 ,uses4--,glucose is used in the manufacture of alcohol and cheap confectionery1 and in adulterating sucrose4 ,it is only two- thirds as sweet as the latter4 ,the seeds of all plants contain starch for the germinating sprout to feed upon2 but starch is insoluble1 and hence useless until it is converted into glucose4 ,this is effected by the action of warmth1 moisture1 and a ferment in the seed4 ,glucose is soluble and is at first the plant's main food4 ,commercial starch is made in the ,united ,states chiefly from corn2 in ,europe1 from potatoes4 ,differences in the size of starch granules enable microscopists to determine the plant to which they belong4 #cbd4 ,cellulose1 or woody fiber1 is the basis of all vegetable cell walls4 ,cotton fiber represents almost pure cellulose4 ,from it are made paper and woven tissues4 ,in paper manufacture1 woody fiber is made into a pulp1 washed1 bleached1 filtered1 hot- pressed1 and sometimes glazed4 ,parchment paper1 vegetable parchment1 is made by dipping unglazed paper for half a minute into cold dilute ,h#b,,so#d1 #a part ,h#b,o1 #b #a_/b parts ,h#b,,so#d1 and then washing4 ,the fiber1 by chemical change1 is thus toughened4 ,the cell walls of wood are impure cellulose2 hence the inferior quality of paper made from wood-pulp4 ,paper is now employed for a large number of purposes for which wood has heretofore been used1 such as for barrels1 pails1 and other hollow ware1 wheels1 etc4 #cbe4 ,gun-cotton is made by treating cotton fiber with ,h#b,,so#d and ,,hno#c1 washing and drying4 ,to all appearances no change has taken place1 but the substance has become an explosive compound4 #cbf4 ,dextrin1 a gummy substance used for the backs of postage stamps1 is a carbo-hydrate1 as in fact are gums in general4 ,dextrin is made by heating starch with ,h#b,,so#d at a lower temperature than for dextrose4 #cbg4 ,zylonite and ,celluloid4 -,these two similar substances embody the latest use of cellulose in manufactured articles4 ,for zylonite1 linen paper is cut into strips two feet by one inch1 soaked ten minutes in a mixture of ,h#b,,so#d and ,,hno#c1 a process called nitration1 washed for several hours1 then ground to a fine pulp1 and thoroughly dried4 ,it is then similar to pyroxiline4 ,aniline coloring-matter of any desired shade is added1 after which it is dissolved by soaking some hours in alcohol and camphor1 the liquid is evaporated1 and the substance is kneaded between steam-heated iron rollers1 dried with hot air1 and finally subjected to great pressure1 to harden it1 and cut into sheets4 ,zylonite is combustible at a low temperature1 and when in the pyroxiline stage1 explosively so4 ,ivory1 coral1 amber1 bone1 tortoise shell1 malachite1 etc41 are so closely imitated that the imitation can only be detected by analysis4 ,collars1 combs1 canes1 piano-keys1 and jewelry1 are manufactured from it1 and it can be made transparent enough for windows4 ,,chapter ,,lix ,,chemistry ,,of ,,fermentation4 #cbh4 ,ferments4--,a large number of chemical changes are brought about through the direct agency of bodies called ferments2 their action is called fermentation4 ,ferments are sometimes lifeless chemical products found in living bodies2 but in other cases they are humble plants4 #cbi4 ,yeast is one of the most common of living ferments1 wild yeast being a microscopic plant found on the ground near apple- trees and grape-vines1 and often in the air4 ,the cultivated variety is sold by grocers4 ,the temperature best suited to the rapid multiplication of the germs forming the ferment plant is #be degrees to #ce degrees4 #ccj4 ,alcoholic and ,acetic ,fermentation4--,the changes which the juice of the apple undergoes in forming cider and vinegar are a good illustration of fermentation by a living plant4 ,apple-juice contains sucrose4 ,yeast germs from the air1 getting into this unfermented liquor1 cause it to work4 ,this process changes sucrose to glucose1 and glucose to alcohol and ,,co#b1 and is known as alcoholic fermentation4 ,the latter reaction1 ,c#f;,h#ab,o#f #b ,c#b;,h#f,o #b ,,co1 is only partially correct1 as other products are formed4 ,the juice has now become cider2 the sugar alcohol4 ,after a time1 if left exposed1 another organism finds its way to the alcohol1 and transforms it into acetic acid1 ,,hc#b;,h#h,o#b1 and ,h#b,o4 ,this process is called acetic fermentation4 ,c#b;,h#f,o ,o#b ,,hc#b;,h#c,o#b ,h#b,o4 ,for this fermentation1 a liquor should not have over ten per cent of alcohol4 ,mother of vinegar consists of the germs that caused the fermentation4 ,still a third species of ferment may cause another action1 changing acetic acid to ,h#b,o and ,,co#b4 ,the vinegar then tastes flat4 ,,hc#b;,h#c,o#b #d ,o #b;,h#b,o #b ,,co#b4 ,some mineral acids1 as ,h#b,,so#d and ,h,cl1 and some organic acids1 are regarded as lifeless ferments4 ,to this class are thought to belong the diastase of malt and the pepsin of the stomach4 ,this variety of ferments exists in the seeds of all plants1 and changes starch to glucose4 #cca4 ,bread which is raised by yeast is fermented1 the object being to produce ,,co#b1 bubbles of which1 with the alcohol1 cause the dough to rise and make the bread light4 ,grapes and other fruits ferment and produce wines1 etc41 from which distilled liquors are obtained4 #ccb4 ,lactic ,fermentation changes the sugar of milk1 lactose1 to lactic acid1 i4e4 sour milk4 ,in canning fruit1 any germs present are killed by heating1 and those from the air are excluded by sealing the can4 ,milk has been kept sweet for years by boiling1 and tightly covering the receptacle with two or three folds of cotton cloth4 #ccc4 ,putrefaction is fermentation in which the products of decay are ill-smelling4 ,saprophytes attack the dead matter1 feed on it1 and cause it to putrefy4 ,this action1 as well as that of ordinary fermentation1 used to be attributed solely to oxygen4 ,germs bring back organic matter to a more elementary state1 and so have a very important function4 ,by some scientists1 digestion is regarded as a species of fermentation1 probably due to the action of lifeless ferments2 e4g4 sucrose cannot be taken into the system1 but is first fermented to glucose4 #ccd4 ,most ,infectious ,diseases are now thought to be due to parasites of various kinds1 such as bacteria1 microbes1 etc41 with which the victim often swarms1 and which feed on his tissues1 multiplying with enormous rapidity4 ,such diseases are small-pox1 intermittent and yellow fevers1 etc4 ,consumption1 or tuberculosis1 is believed to be caused by a microbe which destroys the lungs4 ,in some diseases not less than fifteen billions of the organisms are estimated to exist in a cubic inch4 ,these multiply so rapidly that from a single germ in forty-eight hours may be produced nearly three hundred billions4 ,these germs do not spring into life spontaneously from inorganic matter1 but come from pre-existent similar forms4 ,parasites are not so rare in the system even of a healthy person as is generally supposed4 ,they are found on our teeth and in many of the tissues of the body4 ,several infectious diseases are now warded off or rendered less virulent by vaccination1 the philosophy of which is that the organisms are rendered less dangerous by domestication2 several crops1 or generations1 are grown in a prepared liquid1 each less injurious than its parent4 ,some of the more domesticated ones are introduced into the system1 and the person has only a modified form of the disease1 often scarcely any at all1 and is for a more or less limited time insured against further danger4 ,dust particles and motes floating in the air are in part germs1 living or dead1 often requiring only moisture and mild temperature for resuscitation4 ,most of these are harmless4 ,chapter ,,lx4 ,,chemistry ,,of ,,life4 #cce4 ,growth4--,the chemistry of organic life is very complex1 and not well understood4 ,a few of the principal points of distinction between the two great classes of living organisms1 plants and animals1 are all that can be noted here4 ,minerals grow by accretion1 i4e4 by the external addition of molecules of the same material as their interior4 ,a crystal of quartz grows by the addition of successive molecules of ,si,o#b1 arranged in a symmetrical manner around its axis4 ,the growth of crystals can be seen by suspending a string in a saturated solution of ,cu,s,o#d1 or of sugar4 ,in plants and animals the growth is very much more complex1 but is from the interior1 and is produced by the multiplication of cells4 ,to produce this cell-growth and multiplication1 food-materials must be furnished and assimilated4 ,in plants1 sap serves to carry the food-materials to the parts where they are needed4 ,in the higher animals1 vari- ous fluids1 the most important of which is the blood1 serve the same purpose4 #ccf4 ,chemistry of ,plants4--,in ultimate analysis1 plants consist mainly of ,c1 ,h1 ,o1 ,n1 ,p1 ,k4 ,in proximate analysis1 as it is called1 they are found to contain these elements combined to form substances like starch1 sugar1 etc4 ,water is the leading compound in both animals and plants4 ,one of the most important differences between animals and plants is1 that all plants1 except parasitic ones1 are capable of building up such compounds as starch from mineral food-stuffs1 while animals have not that power1 but must have the products of proximate analysis ready prepared1 as it were1 by the plant4 ,hence plants thrive on minerals1 whereas animals feed on plants or on other animals4 ,the power which plants have of transforming mineral matter is largely due to sunlight1 the action of which in separating ,,co1 was described4 ,the reaction in the synthesis of starch from ,,co#b and ,h#b,o in the leaf1 is thought to be as follows3 #f ,,co#b #e ,h#b,o ,c#f;,h#aj,o#e #ab ,o4 ,c#f;,h#aj,o#e is taken into the tree as starch2 #ab ,o is given back to the air4 ,all the constituents1 except ,,co#b and a very small quantity of ,h#b,o1 are absorbed by the roots1 from the soil1 from which they are soon withdrawn by vegetation4 ,to renew the supply1 fertilizers or manures are applied to the soil4 ,these must contain compounds of ,n1 ,p1 and ,k4 ,n is usually applied in the form of ammonium compounds1 e4g4 7,,nh#d7b,,so#d1 7,,nh#d7b;,,co#c1 and ,,nh#d,,no#c4 ,the reduction and application of ,cas7,,po#d7b for this purpose was described4 ,k is usually applied in the form of ,k,cl and ,k#b,,so#d4 #ccg4 ,food of ,man4--,in the higher animals the object is not so much to increase the size as to supply the waste of the system4 ,the principal elements in man's body are ,c1 ,h1 ,o1 ,n1 ,s1 ,p4 ,an illustration of the transformation of mineral foods by plants before they can be used by animals is found in the ,ca#c7,,po#d7b of bones4 ,this is rendered soluble2 plants absorb and transform it2 animals eat the plants and obtain the phosphates4 ,thus man is said to eat his own bones4 ,the food of mankind may be divided into four classes 7#a7 proteids1 which contain ,c1 ,h1 ,o1 ,n1 and often ,s and ,p2 7#b7 fats1 and 7#c7 amyloids1 both of which contain ,c1 ,h1 ,o2 7#d7 minerals4 ,examples of the first class are the gluten of flour1 the albumen of the white of egg1 and the casein of cheese4 ,to the second class belong fats and oils2 to the third1 starch1 sugar1 and gums2 to the fourth1 ,h#b,o1 ,na,cl and other salts4 ,since only proteids contain all the requisite elements1 they are essential to human food1 and are the only absolutely essential ones1 except minerals2 but since they do not contain all the elements in the proportion needed by the system1 a mixed diet is indispensable4 ,milk1 better than any other single food1 supplies the needs of the system4 ,the digestion and assimilation of these food-stuffs and the composition of the various tissues is too complicated to be taken up here2 for their discussion the reader is referred to works on physiological chemistry4 #cch4 ,conservation4--,plants1 in growing1 decompose ,,co#b1 and thereby store up energy1 the energy derived from the light and heat of the sun4 ,when they decay1 or are burned1 or are eaten by animals1 exactly the same amount of energy is liberated1 or changed from potential to kinetic1 and the same amount of ,,co#b is restored to the air4 ,the tree that took a hundred years to complete its growth may be burned in an hour1 or be many years in decaying2 but in either case it gives back to its mother ,nature1 all the matter and energy that it originally borrowed4 ,the ash from burning plants represents the earthy matter1 or salts1 which the plant assimilated during its growth2 the rest is volatile4 ,in the growth and destruction of plants or of animals1 both energy and matter have undergone transformation4 ,animals1 in feeding on plants1 transform the energy of sunlight into the energy of vitality4 ,thus we are children of the sun4 ,,chapter ,,lxi4 ,,theories4 #cci4 ,the ,la ,place ,theory4--,this theory supposes that at one time the earth and the other planets1 together with the sun1 constituted a single mass of vapor1 extending billions of miles in space2 that it rotated around its center2 that it gradually shrank in volume by the transformation of potential into kinetic energy2 that portions of its outer rim were thrown off1 and finally condensed into planets2 that our sun is only the remainder of that central mass which still rotates and carries the planets around with it2 that the earth is a cooling globe2 that the other planets are going through the same phases as the earth2 and finally that the sun itself is destined like them to become a cold body4 #cdj4 ,a ,cooling ,earth4--,the sun's temperature is variously estimated at many thousands1 or even millions o degrees4 ,many metals which exist on the earth as solids -e4g4 iron- are gases in the dense atmosphere of the sun4 ,thus the earth1 in its early existence1 must have been composed of gases only1 which in after ages condensed into liquids and solids4 ,so intense was the heat at that time1 that substances probably existed as elements instead of compounds1 i4e4 the temperature was above the point of dissociation4 ,we have seen that ,al#b,o#c1 ,ca,o1 ,si,o#b1 etc41 are dissociated at the highest temperatures only4 ,if the temperature were above that of combination1 compounds could not exist as such1 but matter would exist in its elemental state4 ,on slowly cooling1 these elements would combine4 ,it is1 then1 a fair inference that such compounds as need the highest temperatures to separate them1 as silica1 silicates1 and some oxides1 were formed from their elements at a much earlier stage of the earth's history than were those compounds that are more easily separable1 such as water1 lead sulphide1 etc41 and that the most infusible substances were solidified first4 #cda4 ,evolution4--,as the earth slowly cooled1 elements united to form compounds1 gases condensed to liquids1 and these to solids4 ,at one time the entire surface of our planet may have been liquid4 ,when the cooling surface reached a point somewhat below that of boiling water1 the lowest forms of life appeared in the ocean4 ,this was many millions of years ago4 ,most scientists believe that all vegetable and animal life has developed from the lowest forms of life4 ,there is also a theory that all chemical elements are derivatives of hydrogen1 or of some other element1 and that all the so-called elements are really compounds1 which a sufficiently high temperature would dissociate4 ,as evidence of this1 it is said that less than half as many elements have been discovered in the sun as in the earth1 and that comets and nebula1 which are less developed forms of matter than the sun1 have a few simple substances only4 ,it is easy to fancy that all living bodies1 both animal and vegetable1 are only natural growths from the lowest forms of life2 that these lowest forms are a development1 with new manifestations of energy1 from inorganic matter2 that compounds are derived from elements2 and that the last are derivatives of some one element2 but it must be borne in mind that this is only a theory4 #cdb4 ,new ,theory of ,chemistry4 ,we have seen that heat lies at the basis of chemical as well as of physical changes4 ,by the loss of heat1 or perhaps by the change of potential into kinetic energy1 in a nebulous parent mass1 planets were formed1 capable of supporting living organisms4 ,heat changes solids to liquids1 and liquids to gases2 it resolves compounds1 or it aids chemical union4 ,in every chemical combination heat is developed2 in every case of dissociation heat is absorbed4 ,properly written1 every equation should be3 a b c heat2 e4g4 #b ,h #j ,h#b,o heat2 or1 c - a b - heat2 e4g4 ,h#b,o - #b ,h #j - heat4 ,another illustration is the combination of ,c and ,o1 and the dissociation of ,,co#b1 as given on page #hb4 ,c ,o#b ,,co#b energy4 ,,co#b - ,o#b ,c - energy4 ,in fact1 there are indications that the present theory of atoms and molecules of matter1 as the foundation of chemistry1 will at no distant day give place to a theory of chemistry based on the forms of energy1 of which heat is a manifestation4 ,chapter1 ,,lxii4 ,,gas ,,volumes ,,and ,,weights4 #cdc4 ,oxygen4 ,experiment #acd4--,weigh accurately1 using delicate balances1 #e g4 ,k,cl,o#c1 and mix with the crystals #a or #b g4 of pure powdered ,mn,o#b4 ,put the mixture into a t4t4 with a tight-fitting cork and delivery-tube1 and invert over the water-pan1 to collect the gas1 a flask of at least one and a half liters' capacity1 filled with water4 ,apply heat1 and1 without rejecting any of the gas1 collect it as long as any will separate4 ,then press the flask down into the water till the level in the flask is the same as that outside1 and remove the flask1 leaving in the bottom all the water that is not displaced4 ,weigh the flask with the water it contains2 then completely fill it with water and weigh again4 ,subtract the first weight from the second1 and the result will evidently be the weight of water that occupies the same volume as the ,o collected4 ,this weight1 if expressed in grams1 represents approximately the number of cubic centimeters of water1--since #a cc4 of water weighs lg1--or the number of cubic centimeters of ,o4 ,at the time the experiment is performed the temperature should be noted with a centigrade thermometer1 and the atmospheric pressure with a barometer graduated to millimeters4 ,suppose that we have obtained #adej cc4 of ,o1 that the temperature is #bg degrees1 and the pressure #geh mm42 we wish to find the volume and the weight of the gas at #j degrees and #gfj mm4 ,according to the law of ,charles--the volume of a given quantity of gas at constant pressure varies directly as the absolute temperature4 ,to reduce from the centigrade to the absolute scale1 we have only to add #bgc degrees4 ,adding the observed temperature1 we have #bgc degrees #bg degrees #cjj degrees4 ,applying the above law to ,o obtained at #cjj degrees ,a1 we have the proportion below4 ,since the volume of ,o at #bgc degrees will be less than it will at #cjj degrees1 the fourth term1 or answer will be less than the third1 and the second term must be less than the first4 #cjj 3 #bgc 33 #adej 3 x4 ,this would give the result dependent upon temperature alone4 ,by the law of ,mariotte - ,physics1 - the volume of a given quantity of gas at a constant temperature varies inversely as the pressure4 ,applying this law to the ,o obtained at #gehmm1 we have the following proportion4 ,the volume at #gfjmm will be less than at #gehmm2 or the fourth term will be less than the third2 hence the second must be less than the first4 #gfj3 #geh33 #adej3 x4 ,this would give the result dependent on pressure alone4 ,combining the two proportions in one3-- #cjj3 #bgc 733 #adej3 x #acaf;cc4 #gfj3 #geh 7 #acaf;cc#a4caf liters4 ,it remains to find the weight of this gas4 ,a liter of ,h weighs #j4jhif;g4 ,the vapor density of ,o is #af4 ,hence #a4caf liters of ,o will weigh #a4caf ,x #af ,x #j4jhif #a4hi;g4 7,k,cl,o#c ,k,cl ,o#c7 ,from the equation 7#abb4e #dh7 we make a proportion1 7 #e x7 #abb4e3 #e33 #dh3 x #a4ie1 and obtain1 as the weight of ,o contained in #e;g of ,k,cl,o#c1 #a4ie;g4 ,the weight we actually1obtained was #a4hi;g4 ,this leaves an error of #j4jf;g1 or a little over #d per cent of error 7#j4jf _/ #a4ie #j4jc 74 ,the percentage of error1 in performing this experiment1 should fall within #aj4 ,some of the liabilities to error are as follows3-- #a4 ,impure ,mn,o#b1 which sometimes contains ,c4 ,,co#b is soluble m ,h#b,o4 #b4 ,solubility of ,o in water4 #c4 ,escape of gas by leakage4 #d4 ,moisture taken up by the gas4 #e4 ,difference between the temperature of the gas and that of the air in the room4 #f4 ,errors in weighing4 #g4 ,want of accuracy in the weights and scales4 #cdd4 ,hydrogen4 ,experiment #ace4--,weigh #e;g1 or less of sheet or granulated ,zn1 and put it into a small flask provided with a thistle-tube and a delivery-tube4 ,cover the ,zn with water1 and introduce through the thistle-tube measured quantities of ,h,cl1 a few cubic centimeters at a time4 ,collect the ,h over water in large flasks1 observing the same directions as in removing ,o4 ,weigh the water1 compute the volume of the gas1 reduce it to the standard1 and obtain the weight1 as before4 ,should any ,zn or other solid substance be left1 pour off the water or filter it1 weigh the dry residue1 and deduct its weight from that of the ,zn originally taken4 ,suppose the residue to weigh #j4e;g4 ,make and solve the proportion from the equation3- ,zn #b;,h,cl ,zn,cl#b #b;,h4 #fe #b4 #d4e x4 ,compute the percentage of errcr1 as in the case of ,o4 ,if the purity of the ,h,cl be known1 i4e4 the weight of ,h,cl gas in one cubic centimeter of the liquid1 a proportion can be made between ,h,cl and ,h1 provided no free ,h,cl is left in the flask4 ,state any liabilities to error in this experiment4 ,,problems4 7#a7 ,a gas occupies #bjjj;cc4when the barometer stands #gejmm4 ,what volume will it fill at #gfjmm8 7#b7 ,at #gejmm my volume of ,o is #d #a_/b liters4 ,what will it be at #gcjmm8 7#c7 ,at #hbemm8 7#d7 ,at #bjjmm8 7#e7 ,compute the volume of a gas at #gj degrees1 which at #cj degrees is #aej;cc4 7#f7 ,at #j degrees ,i have #cjjj;cc4of ,o4 ,what volume will it occupy at #ajj degrees8 7#g7 ,i fill a flask holding #b litres with ,h4 ,the thermometer indicates #bf degrees1 the barometer #gfbmm4 ,what is the volume of the gas at #j degrees and #gfjmm8 ,if the volumes of gases vary as above1 it is evident that their vapor densities must vary inversely4 ,a liter of ,h at #j degrees weighs #j4jhif4 ,what will a liter of ,h weigh at #bgc degrees8 ,at #bgc degrees the one liter has be- come two liters1 one of which weighs #j4jddh 7 #j4jhif _/ #b74 ,the vapor density of a gas is inversely proportional to the temperature4 ,also1 the vapor density is directly proportional to the pressure1 since a liter of any gas under a pressure of one atmosphere is reduced to half a liter under two atmospheres4 ,,problems4 7#a7 ,find the weight of a liter of ,o at #j degrees2 then compute the weight of a liter at #bg degrees4 7#b7 ,find the weight of #ejj;cc4of ,n#b,o at #fj degrees4 7#c7 ,of #bjj cc4 of ,,co at -#e degrees4 7#d7 ,a given volume of ,o weighs #j4be;g at a pressure of #gejmm2 find the weight of a like volume of ,o at #gehmm4 ,,appendix4 ,,individual ,,apparatus4 ,each pupil should be provided with the apparatus given below1 but in cases where great economy must be exercised different pupils may1 by working at different times1 use the same set4 ,the author has selected apparatus specially adapted1 as to exact dimensions1 quality1 and cheap- ness1 for performing in the best way the experiments herein described1 and sets or separate pieces of this1 together with other apparatus and chemicals1 can be had of the ,l4,e4 ,knott ,apparatus ,co41 #ad ,ashburton ,place1 ,boston1 to which firm teachers are referred for catalogs4 #d wide-mouthed bottles 7horse-radish size71 with corks4 #a soda-bottle4 #d pieces window-glass 7#c in4 sq474 #b pieces thick glass tubing 7#bj in4 long1 #d in4 outside diam474 #a glass stirring-rod4 #a glass funnel 7#b #a_/b in4 wide1 #fj degrees74 #b pieces glass tubing 7#ab in4 long2 #e_/h in4 diam474 #a porcelain evaporating-dish 7#c in4 wide74 #a asbestus paper and #a fine wire gauze 7#c in4 sq474 #a iron 7or tin7 plate4 #a pair forceps4 #a triangular file and #a round file4 #a copper wire 7#ae in4 long74 #f test-tubes1 and corks to fit4 #a wooden test-tube holder4 #a flask with cork 7#bjj;cc74 #a ,bunsen burner 7or alcohol lamp74 #a iron ring-stand4 #a piece rubber tubing 7#ah in4 long1 #c_/h in4 inside diam474 #d reagent bottles 7#bej;cc71 ,h,cl1 ,,hno#c1 ,h#b,,so#d1 ,,nh#d,,oh4 #a pneumatic trough4 ,wherever in this work ,bunsen burner or lamp is mentioned1 if gas is not to be had1 an alcohol lamp may be substituted4 ,,general ,,apparatus4 ,the following list includes apparatus needed for occasional use3-- ,metric rules 7#bj or #cj;cm long74 ,scales with metric weights 7#a-bjj g74 ,metric graduates 7#be or #ej;cc74 ,filter papers4 ,metric graduates 7#ejj;cc74 ,reagent bottles 7#bej and #ejj;cc74 ,mouth blowpipes4 ,platinum wire and foil4 ,mortars and pestles4 ,test-tube racks4 ,thistle-tubes4 ,filter-stands4 ,beakers4 ,glass tubing 7#c_/af in41 #a_/d in41 and #a in4 outside74 ,rubber tubing 7#a_/h in41 and #c_/h in4 inside74 ,hessian crucibles4 ,porcelain crucibles4 ,electrolytic apparatus1 including #b or more ,bunsen cells4 ,ignition-tubes4 ,steel glass-cutters4 ,wire-cutters4 ,calcium chloride tubes4 ,water baths4 ,thermometers4 ,barometers1 etc4 ,,appendix4 ,,chemicals4 ,the following estimate is for twenty pupils3 - ,alcohol #a pt ,alum #a oz ,ammonium chloride #a_/b lb ,ammonium hydrate #a lb ,ammonium nitrate4 #a_/b lb ,antimony 7powdered metallic7 #a_/b oz4 ,arsenic 7powdered metallic7 #a_/b oz4 ,arsenic trioxide44444 #a oz4 ,barium chloride44444 #a oz4 ,barium nitrate44444 #a oz4 ,beeswax4444444 #a oz4 ,bleaching-powder4444 #a_/d lb4 ,bone-black444444 #a_/b lb4 ,bromine4444444 #a_/d lb4 ,calcium chloride4444 #a lb4 ,calcium fluoride 7powdered7 #a lb4 ,cannel coal #a lb ,carbon disulphide #a_/d lb ,chlorhydric acid #f lb ,cochineal #a oz ,copper 7filings7 #b lb4 ,copper nitrate #a oz ,copper oxide #a_/d lb4 ,ether 7sulphuric7 #a_/d lb ,ferrous sulphide #a lb4 ,ferrous sulphate #a_/d lb ,indigo #a_/d lb ,iodine #a oz ,iron 7filings or turnings7 #a lb4 ,lead 7sheet7 #d lb ,lead acetate #a oz ,lead nitrate #a_/d lb ,litmus #a_/b oz ,litmus paper #c sheets ,magnesium ribbon4444 #c ft4 ,manganese dioxide4444 #b lb4 ,mercurous nitrate4444 #a_/b oz4 ,nitric acid #c lb4 ,oxalic acid #a_/d lb ,phosphorus #a_/d lb ,potassium 7metallic7 #a_/h oz ,potassium bromide #a_/d lb4 ,potassium dichromate #a_/d lb4 ,potassium chlorate #b lb4 ,potassium hydrate #a_/d lb4 ,potassium iodide #b oz ,potassium nitrate #a_/d llb ,silver nitrate #a oz4 ,sodium #a_/h oz4 ,sodium carbonate #a_/d lb ,sodium hydrate #a lb4 ,sodium nitrate #a_/b lb ,sodium silicate44444 #a_/blb ,turkey red cloth4444 #a_/byd ,sodium sulphate44444 #a_/dlb ,turpentine7spirits74 #a_/dlb ,sodium sulphide44444 #a_/dlb ,zinc7granulated74444 #blb ,sodium thiosulphate4 #a_/dlb ,zinc foil44444444444 #c;ft ,sulphur4444444444444 #blb ,sulphuric acid444444 #ablb ,additional ,material ,these substances are best obtained of local dealers4 ,calcium carbonate7marble744444 #alb ,molasses4444444444444444444444 #apt ,calcium oxide7unslaked lime744 #alb ,sodium chloride7fine7444444444 #alb ,charcoal4444444444444444444444 #alb ,sodium chloride7coarse74444444 #alb ,sheet lead44444444444444444444 #dlb ,sugar4444444444444444444444444 #a_/blb ,,for ,,examination ,those in capitals are most important ,rocks and ,minerals4 ,,argillite1 ,,aresenic1 ,,arsenopyrite1 ,barite1 ,,calcite1 ,,cassiterite1 ,,chalcopyrite1 ,,chalk1 ,,cinnabar1 ,,copper 7native71 ,corundum1 ,dolomite1 ,,emery1 ,,feldspar1 ,flint1 ,,galenite1 ,,granite1 ,,graphite1 ,,gypsum1 ,,hematite1 ,hornblende1 ,jasper1 ,,limonite1 ,,magnesite1 ,,magnetite1 ,,malachite1 ,meerschaum1 ,,mica1 ,,obsidian1 ,orpiment1 ,,pyrite1 ,,quartz1 ,realgar1 ,,sand1 ,,serpentine1 ,,siderite1 ,,sphalerite1 ,talc1 ,,zincite ,metals and ,alloys4 ,aluminium1 ,iron 7cast71 ,aluminium bronze4 ,pewter1 ,bell metal1 ,solder1 ,brass1 ,steel1 ,bronze1 ,type metal1 ,copper1 ,tin foil1 ,galvanized iron1 ,tin 7bright plate and terne plate71 ,german silver1 ,zinc 7sheet74 ,iron 7wrought7 ,additional ,compounds1 for ,examination3 ,copper acetate1 ,lead carbonate1 ,copper arsenite1 ,red lead1 ,copper nitrate1 ,magnesia alba1 ,copper sulphate1 ,smalt1 ,lead dioxide1 ,vermilion4 ,lead protoxide1 ,,table ,,of ,,solutions4 ,number of grams of solids to be dissolved in #ejj;cc of water4 ,ag,n,o#c444444444 #be ,k#b;,al#b7,,so#d7d444444 #ej ,ba,cl#b444444444 #ej ,k,br4444 #be ,ba7,n#j #c7b44444444 #cj ,k#b;,cr#bjg44444444 #ej ,ca,clz444444444 #fj ,,ki4444444444 #be ,ca7,,oh7#b444444 saturated ,,koh4444444 #fj ,ca,s#jd4444444 saturated ,na,i,c,o,s44444444 #ej ,,cuc#ab #ej ,na,o,h #fj ,cu7,n#jc7444444444 #ej ,nal,sl#jc4444444 saturated ,fe,s#jd444444444 #ej ,,nh1,n#jc44444444 #ej ,hg,c#ab444444444 #cj ,pb7,c#b;,h#cjb7b444444 #ej ,hg,n#jc44444 #be #be ,,hn#jc ,pb7,n,os7#b4444444 4 #ej ,other solutions4444saturated4 ,indigo solution 7sulphindigotic acid7 is prepared by heating for several hours over a water bath1 a mixture of ten parts of ,h #b,,so#d with one of indigo1 and1 after letting it stand twenty-four hours1 adding twenty parts of water and filtering4 ,,textbook ,,advertisements ,,that ,,appeared ,,in ,,the ,,original ,,edition ,,introduction ,,to ,,chemical ,,science ,by ,r4,p4 ,,williams1 ,instructor in ,chemistry in the ,english ,high ,school1 ,boston4 l#bmo4 ,cloth4 #baf pages4 ,by mail1 #ij cents2 for introduction1 #hj cents4 ,this work is strictly1 but easily1 inductive4 ,the pupil is stimulated by query and suggestion to observe important phenomena1 and to draw correct conclusions4 ,the experiments are illustrative1 the apparatus is simple and easily made4 ,the nomenclature1 symbols1 and writing of equations are made prominent features4 ,in descriptive and theoretical chemistry1 the arrangement of subjects is believed to be especially superior in that it presents1 not a mere aggregation of facts1 but the science of chemistry4 ,brevity aud concentration1 induction1 clearness1 accuracy1 and a legitimate regard for interest1 are leading characteristics4 ,the treatment is full enough for any high school or academy4 ,though the method is an advanced one1 it has been so simplified that pupils experience no difficulty1 but rather an added interest1 in following it4 ,the author himself has successfully employed this method in classes so large that the simplest and most practical plan has been a necessity4 ,thomas ,c4 ,van ,nuys1 ,professor of ,chemistry1 ,indiana ,university1 ,bloomington1 ,ind43 ,i consider it an excellent work for students entering upon the study of chemistry4 ,c4,f4 ,adams1 ,teacher of ,science1 ,high ,school1 ,detroit1 ,mich43 ,i have carried two classes through ,williams's ,chemistry4 ,the book has surpassed my highest expectations4 ,it gives greater satisfaction with each succeeding class4 ,j4,w4 ,simmons1 ,county ,superintendent of ,schools1 ,owosso1 ,mich43 ,the proof of the merits of a textbook1 is found in the crucible of the class-room work4 ,there are many chemistries1 and good ones2 but1 for our use1 this leads them all4 ,it is stated in language plain1 interesting and not misleading4 ,a logical order is followed1 and the mind of the student is at work because of the many suggestions offered4 ,we use ,williams's work1 and the results are all we could wish4 ,there is plenty of chemistry in the work for any of our high schools4 ,w4,j4 ,martin1 ,professor of ,chemistry1 ,davidson ,college1 ,n4,c43 ,one of the most admirable little text-books ,i have ever seen4 ,t4,h4 ,norton1 ,projessor of ,chemistry1 ,cincinnati ,university1 ,o43 ,its clearness1 accuracy1 and compact form render it exceptionally well adapted for use in high and preparatory schools4 ,i shall warmly recommend it for use1 whenever the effort is made to provide satisfactory training in accordance with the requirements for admission to the scientific courses of the ,university4 ,,chemical ,,experiments ,general and ,analytical4 ,by ,r4,p4 ,,williams1 ,instructor in ,chemistry1 ,english ,high ,school1 ,boston4 #hvo4 ,boards4 xv #bab pages4 ,fully illustrated4 ,mailing price1 #fj cents2 for introduction1 #ej cents4 ,this book is for the use of students in the chemical laboratory4 ,it contains more than one hundred sets of the choicest illustrative experiments1 about half of which belong to ,general ,chemistry1 the rest to ,metal and ,acid ,analysis4 ,great care has been taken to describe accurately and minutely the methods of performing experiments1 and in directing pupils to observe phenomena and to explain what is seen4 ,the work is amply illustrated and is replete with questions and suggestions4 ,blank pages are inserted for pupils to make a record of their work1 for which careful directions are given1 with a model1 laboratory rules1 tables of solubilities1 etc4 ,a new feature is the supplementary and original work1 vhich is given at the end of each set of experiments for such pupils as complete the prescribed work ahead of others in the class1 and a list of terms to be looked up in some text-book4 ,this gives an elasticity to the book and fits it for use in schools where much time is devoted to chemistry1 as well as in the most elementary classes in labortttory work4 ,another original feature which it is believed will be heartily welcomed by teachers is the method of treating ,metal ,analysis successfully used by the author for several years4 ,briefly1 the aim of this book is to aid the pupil to do1 to observe1 to explain1 to record1 aud thus to learn the essentials of chemistry4 ,,laboratory ,,manual ,,of ,,general ,,chemistry ,by ,r4,p4 ,,williams1 ,instructor in ,chemistry1 ,english ,high ,school1 ,boston4 #abmo4 ,boards4 xvi #bjj pages4 by mail1 #cj cents2 for introduction1 #be cents4 ,the book contains one hundred experiments in general chemistry a,nd qualitative analysis1 blanks opposite each for pupils to to take notes1 laboratory rules1 complete tables of symbols1 with chemical and common names1 reagents1 solutions1 chemicals1 and apparatus1 and the plan of a model laboratory4 ,,an ,,elementary ,,chemistry ,by ,,george ,r4 ,,white1 ,instructor in ,chemistry at ,phillips ,academy1 ,exeter4 #abmo4 ,cloth4 xxix #bgb pages4 ,mailing price1 #a4aj2 for introduction1 #a4jj4 ,this is an excellent text-book for ,high ,schools and ,academies1 and for elementary classes in ,colleges4 ,the strictly inductive method here followed1 together with the insertion of numerous questions that must cause the student to do his own reasoning from the observations1 renders this book particularly useful4 ,t4,h4 ,norton1 ,professor of ,chemistry1 ,university of ,cincinnati1 ,cincinnati1 ,ohio43 ,i am greatly pleased with the plan and its execution4 ,it is an admirable arrangement for our inductive course in chemistry and should not fail to yield good results4 ,a ,,students' ,,manual ,,of ,a ,,laboratory ,,course ,,in ,,physical ,,measurements ,by ,wallace ,c4 ,sabine1 ,assistant ,professor of ,physics1 ,harvard ,university4 #hvo4 ,cloth4 ix #abf pages4 ,mailing price1 #a4ce2 for introduction1 #a4be4 ,this manual1 which is intended for use in supplementing college courses in physics1 contains an outline of seventy experiments1 arranged with special regard to a systematic and progressive development of the subject4 ,le ,roy ,c4 ,cooley1 ,professor of ,physics1 ,vassar ,college3 ,i have examined it and am ready to commend it4 ,j4,f4 ,woodhull1 ,professor of ,sciences1 ,teachers' ,college1 ,new ,york3 ,i find ,sabine's ,laboratory ,manual a thoroughly good thing4 ,,high ,,school ,,laboratory ,,manual ,,of ,,physics ,by ,dudley ,g4 ,hays1 ,charles ,d4 ,lowry1 and ,austin ,c4 ,rishel1 ,teachers of ,physics in the ,chicago ,high ,schools4 #hvo4 ,cloth4 iv #aed pages4 ,mailing price1 #fj cents2 for introduction1 #ej cents4 ,this manual has been written3 ,first1 to present a logically arranged course of experimental work covering the ground of ,elementary ,physics4 ,second1 to provide sufficient laboratory work to meet college entrance requirements4 ,the experiments are largely quantitative1 but qualitative work is introduced4 ,w4,s4 ,jackman1 ,teacher of ,science1 ,cook ,co4 ,normal ,school1 ,englewood1 ,ill43 ,it is a most excellent manual1 and ,i believe it meets the needs of high schools on this subject better than any other book ,i have seen4 ,,young',s ,,lessons ,,in ,,astronomy ,including ,uranography4 ,revised ,edition4 ,by ,,charles ,a4 ,,young1 ,professor of ,astronomy in the ,college of ,new ,jersey4 #abmo4 ,cloth4 ,illustrated4 ix #ceg pages1 exclusive of four double-page star maps4 ,by mail1 #a4cj2 for introduction1 #a4bj4 ,the revised edition of this book has been prepared for schools that desire a brief course free from mathematics4 ,it is based upon the author's ,elements of ,astronomy1 but many changes of arrangement have been made4 ,in fact1 everything has been carefully worked over and re-written to adapt it to the special requirements4 ,great pains has been taken not to sacrifice accuracy and truth to brevity1 and no less to bring everything thoroughly down to date4 ,the latest results of astronomical investigation will be found here4 ,the author has endeavored1 too1 while discarding mathematics1 to give the student a clear understanding and a good grasp of the subject4 ,as a body of information and as a means of discipline1 this book will be found1 it is believed1 of notable value4 ,the most important change in the arrangement of the book has been in bringing the ,uranography1 or constellation tracing1 into the body of the text and placing it near the beginning1 a change in harmony with the accepted principle that those whose minds are not mature succeed best in the study of a new subject by beginning with what is concrete and appeals to the senses1 rather than with the abstract principles4 ,brief notes on the legendary mythology of the constellations have been added for the benefit of such pupils as are not likely to become familiar with it in the study of classical literature4 ,n4,w4 ,rarrington1 ,president of ,university of ,washington1 ,seattle1 ,wash41 formerly chief of the ,u4,s4 ,weather ,bureau1 ,washington1 ,d4,c43 ,i shall take pleasure in commending it to schools requiring an astronomy of this grade4 ,the whole series of ,astronomies reflects credit on their distinguished author and shows that he appreciates the needs of the schools4 ,clarence ,e4 ,kelly1 ,prin4 of ,high ,school1 ,haverhill1 ,mass43 ,it seems to me the book is admirably adapted to its purpose1 and that it accomplishes the difficult task of presenting to the student or reader not conversant with ,algebra and ,geometry1 an excellent selection of what may with profit be given him as an introduction to the science of astronomy4 ,,young',s ,,elements ,,of ,,astronomy ,with a ,uranography4 ,by ,,charles ,a4 ,,young1 ,professor of ,astronomy in the ,college of ,new ,jersey4 #abmo4 ,half leather4 x #dgb pages1 and four star maps4 ,mailing price1 #a4ee3 for introduction1 #a4dj4 ,uranography4 ,from ,youpg's ,elements of ,astronomy4 #abmo4 ,flexible covers4 #db pages4 besides four star maps4 ,by mail1 #ce cents2 for introduction1 #cj cents4 ,this volume is an independent work1 and not an abridgment of the author's ,general ,astronomy4 ,it is a text-book for advanced ,high ,schools1 ,seminaries1 and ,brief ,courses in colleges generally4 ,it was prepared by one of the most distinguished astronomers of the world1 a most popular lecturer1 and most successful teacher4 ,it had every presumption in its favor1 and the event has more than justified expectations4 ,special attention has been paid to making all statements correct and accurate so far as they go4 ,in the text no mathematics higher than elementary algebra and geometry is introduced2 in the foot-notes and in the ,appendix an occasional trigonometric formula appears1 for the benefit of the very considerable number of ,high school students who understand such expressions4 ,g4,b4 ,merriman1 formerly ,prof4 of ,mathemutics and ,astronomy1 ,rutgers ,college1 ,new ,brunswick1 ,n4,j43 ,for a short course in elementary astronomy1 it is by far the best book ,i have ever examined4 ,warren ,mann1 ,state ,normal ,school1 ,potsdam1 ,n4 ,y43 ,accuracy in use of terms is a marked feature4 ,i consider it the best text-book on this subject4 ,h4,n4 ,chute1 ,high ,school1 ,ann ,arbor1 ,mich43 ,it is just the book the scholars have been waiting for4 ,g4,h4 ,howe1 ,state ,normal ,school1 ,warrensburg1 ,,mo43 ,it is indeed an admirable book1 up to the times1 clear1 and complete4 ,jeremiah ,slocum1 ,south ,division ,high ,school1 ,cugo1 ,ill43 ,it is well adapted both as to scope and manner of treatment to high-school work4 ,ray ,g4 ,huling1 ,prin4 of ,english ,high ,school1 ,cambridge1 ,mass43 ,it is delightfully fresh1 full1 and clear4 ,a4,s4 ,roe1 recently of ,high ,school1 ,worcester1 ,muss43 ,the book is extended enough to please the exacting teacher4 ,i4,p4 ,bishop1 ,state ,normal ,school1 ,buffalo1 ,n4,y43 ,the book seems to have all the essentials of a first-class text for high school work2 viz41 conciseness1 clearness1 and the results of recent research4 ,,young',s ,,general ,,astronomy ,a ,text-book for ,colleges and ,technical ,schools4 ,by ,,charles ,a 4 ,,young1 ,professor of ,astronomy in the ,college of ,new ,jersey4 #hvo4 viii #eea pages4 ,half morocco4 ,illustrated with over #bej cuts and and diagrams1 and supplemented with the necessary tables4 ,mailing price1 #b4ej2 for introduction1 #b4be4 ,in amount1 the work has been adjusted as closely as possible to the prevailing courses of study in our colleges4 ,by omitting the fine print1 a briefer course may be arranged4 ,the eminence of ,professor ,young as an original investigator in astronomy1 a lecturer and writer on the subject1 and an instructor of college classes1 and his scrupulous care in preparing this volume1 led the publishers to present the work with the highest confidence2 and this confidence has been fully justified by the event4 ,more than one hundred colleges adopted the work within a year from its publication1 and it is conceded to be the best astronomical text-book of its grade to be found anywhere4 ,edw4 ,c4 ,pickering1 ,prof4 of ,astronomy1 ,harvard ,university3 ,i think this work the best of its kind1 and admirably adapted to its purpose4 ,s4,p4 ,langley1 ,sec4 ,smithsonian ,inst41 ,washington1 ,d4,c43 ,i know no better book 7not to say as good a one7 for its purpose1 on the subject4 ,,an ,,introduction ,,to ,,spherical ,,and ,,practical ,,astronomy ,by ,,dascom ,,greene1 ,professor of ,mathematics and ,astronomy in the ,rensselaer ,polytechnic ,institute1 ,troy1 ,n4,y4 ,,nw4 ,cloth4 ,illustrated4 viii #aeh pages4 ,mailing price1 #a4fj2 for introduction1 #a4ej4 ,the book is intended for class-room use and affords such a preparation as the student needs before entering upon the study of the larger and more elaborate works on this subject4 ,the appendix contains an elementary exposition of the method of least squares4 ,daniel ,carhart1 ,act4 ,prof4 ,mathematics1 ,western ,univ4 of ,pa41 ,allegheny1 ,pa43 ,professor ,greene has supplied that which is needed to make the usual course in ,astronomy in our colleges more practical4 ,rodney ,g4 ,kimball1 ,polytechnic ,institute1 ,brooklyn1 ,n4,y43 ,the hasty examination which ,i have given it has left a very favorable impression as to its merits as a judicious compound of the practical work which it professes to cover4 ,,scheiner',s ,,astronomical ,,spectroscopy ,department of ,special ,publication4--,revised ,edition4 ,translated1 revised and enlarged by ,e4,b4 ,,frost1 ,professor of ,astronomy in ,dartmouth ,college4 #hvo4 ,half leather4 ,illustrated4 xiii #dhb pages4 ,price by mail1 #e4jj2 for introdoctiort1 #d4ge4 ,this work aims to explain the most practical and modern methods of research1 and to state our present knowledge of the constitution1 physical condition alld motions of the heavenly bodies1 as revealed by the spectroscope4 ,edward ,s4 ,holden1 ,director of the ,lick ,observatory1 ,mt4 ,hamilton1 ,california3 ,i congratulate you on the appearance of this very important book2 it is indispensable to all astronomers and students of spectroscopy4 ,,elements ,,of ,,plant ,,anatomy ,by ,,emily ,l4 ,,gregory1 ,professor of ,botany in ,barnard ,college4 #hvo4 ,cloth4 viii #adh pages4 ,illustrated4 ,mailing price1 #a4ce2 for introduction1 #a4be4 ,this book is designed as a text-book for students who have already some knowledge of general botany4 ,it consists of an outline of the principal facts of plant anatomy1 in a form available not only for those who wish to specialize in botany but for all who wish to know the leading facts about the inner structure of plants4 ,it affords a preparation for the study of the more intricate and difficult questions of plant anatomy and physiology1 while it is especially adapted to the wants of students1 who need a practical knowledge of plant structure4 ,,elements ,,of ,,structural ,,and ,,systematic ,,botany ,for ,high ,schools and ,elementary ,college ,courses4 ,by ,,douglas ,h4 ,,campbell1 ,professor of ,botany in the ,leland ,stanford ,junior ,university4 #abmo4 ,cloth4 ix #bec pages4 ,price by mail1 #a4be2 for introduction1 #a4ab4 ,the special merit of this book is that it begins with the simple forms1 and follows the order of nature to the complex ones4 ,,plant ,,organization ,by ,r4 ,,halstead ,,ward1 formerly ,professor of ,botany in the ,rensselaer ,polytechnic ,institute1 ,troy1 ,n4,y4 ,quarto4 #agf pages4 ,illustrated4 ,flexible boards4 ,mailing price1 #he cents2 for introduction1 #ge cents4 ,,elementary ,,meteorology ,by ,,william ,,morris ,,davis1 ,professor of ,physical ,geography in ,harvard ,college4 ,with maps and charts4 #hvo4 ,cloth4 xi #cee pages4 ,mailing price1 #b4gj2 for introduction1 #b4ej4 ,this work is believed to be very opportune1 since no elementary work on the subject has been issued for over a quarter of a century4 ,it represents the modern aspects of the science4 ,it is adapted to the use of advanced students1 and will meet the needs of members of the ,national and ,state ,weather ,services who wish to acquaint themselves with something more than methods of observation4 ,the essential theories of modern ,meteorology are presented in such form that the student shall perceive their logical connection1 and shall derive from their mastery something of the intellectual training that comes with the grasp of well-tested conclusions4 ,the charts of temperature1 pressure1 winds1 etc41 are reduced from the latest available sources1 while the diagrams freely introduced through the text are for the most part new4 ,a4,w4 ,greeley1 retired ,brigadier ,general ,u4,s4,a41 and formerly ,chief of ,signal ,office1 ,washington3 ,a valuable and timely contribution to scientific text-books4 ,winslow ,upton1 ,professor of ,astronomy1 ,brown ,university3 ,the best general book on the subject in our language4 ,wm4 ,b4 ,clark1 ,professor of ,geology1 ,johns ,hopkins ,university3 ,an excellent book and of great value to the teacher of meteorology4 ,david ,todd1 ,professor of ,astronomy1 ,amherst ,college3 ,clear1 concise1 and direct4 ,to teach meteorology with it must be a delight4 ,,molecules ,,and ,,the ,,molecular ,,theory ,,of ,,matter ,department of ,special ,publioation4 ,by ,a4 ,d4 ,,risteen4 #hvo4 ,cloth4 ,illustrated4 viii #bbc pages4 ,retail price1 #b4jj ,this work is a complete popular exposition of the molecular theory of matter1 as it is held by the leading physicists of today4 ,considerable space is devoted to the kinetic theory of gases4 ,liquids also are discussed1 and solids receive much attention4 ,there is also a division discussing the methods that have been proposed for finding the sizes of molecules1 and here1 as elsewhere throughout the book1 the methods described are illustrated by numerical examples4 ,the last division of the book touches upon the constitution of molecules4 ,the subject is everywhere treated from a physical standpoint4 ,,end ,,of ,,an ,,introduction ,,to ,,chemical ,,science ,,information ,,about ,,this ,,electronic ,,edition ,the original edition of this text was published by ,ginn and ,company1 ,publishers1 ,boston1 ,u4,s4,a4 in #ahif4 ,the typography was by ,j4,s4 ,cushing and ,co41 ,boston and the ,presswork was by ,ginn and ,co41 ,boston4 ,the book was ,entered according to ,act of ,congress1 in the year #ahhg1 by ,r4,p4 ,williams1 in the ,office of the ,librarian of ,congress1 at ,washington4 ,this electronic text was prepared by ,john ,mamoun with help from numerous other proofreaders1 including those associated with ,charles ,franks' ,distributed ,proofreaders website4 ,thanks to ,r4 ,zimmerman1 ,d4 ,starner1 ,b4 ,schak1 ,k4 ,rieff1 ,d4 ,kokales1 ,n4 ,harris1 ,k4 ,peterson1 ,e4 ,beach1 ,w4,m4 ,maull1 ,m4 ,beauchamp ,j4 ,roberts and others for proofing this e-text4 ,this e-text is public domain1 freely copyable and distributable for any non-commercial purpose1 and may be included without royalty or permission on a mass media storage product1 such as a cd-rom1 that contains at least #ej public domain electronic texts1 whether offered for non-commercial or commercial purposes4 ,any other commercial usage requires permission4 ,use of the ,project ,gutenberg ,trademark requires separate permission4