,transcriber's ,notes3 ,italics are surrounded with and ,greek words have been transliterated and surrounded with 4 ,isolated ,greek letters have been replaced by the name of the letter 7e4g4 alpha74 ,the oe ligature has been replaced by the letters oe4 ,subscripted characters have been preceded by and surrounded with ,fractions have been represented as #a-a_/b 7for one and one-half7 and where a range of fractions has been specified1 the numbers have been surrounded by to prevent confusion 7i4e4 #c-a_/b-d-a_/b represents the range three and one-half to four and one-half47 ,dittos and dashes used to represent text have been replaced with the indicated text4 ,some presumed printer's errors have been corrected4 ,in particular1 the use of c4c4 has been normalized when periods were missing1 the degree symbol 77 has been added when it appears to have been missing1 and words and numbers in the ,index were changed to match the spelling and placement in the body of the text4 ,some additional presumed errors which have been corrected are listed below with the original text 7top7 and the replacement text 7bottom73 ,table of ,contents ,literature xiv ,literature xiii p4 #ei vesse vessel p4 #fb ,gay ,lussac ,gay-,lussac p4 #fe #af ,feb #aijd #af ,feb #ahid p4 #ajb ,konigsberg ,knigsberg p4 #aed ,royal ,musums ,royal ,museums ,footnote #a ,lexikon d4 gesamsen ,technik1 ,lexikon d4 gesamten ,technik1 ,,the ,,preservation ,,of ,,antiquities ,time1 which antiquates antiquities1 and hath an art to make dust of all things1 hath yet spared these minor monuments4 7,,sir ,,thomas ,,browne1 ,hydriotaphia1 cap4 v47 ,,the ,,preservation ,,of ,,antiquities ,a ,,handbook ,,for ,,curators ,,translated1 ,,by ,,permission ,,of ,,the ,,authorities ,,of ,,the ,,royal ,,museums1 ,,from ,,the ,,german ,,of ,,dr ,,friedrich ,,rathgen ,director of the ,laboratory of the ,royal ,museums1 ,berlin ,,by ,,george ,a4 ,,auden1 ,m4,a41 ,m4,d4 7,cantab47 ,,and ,,harold ,a4 ,,auden1 ,m4,sc4 7,vict471 ,d4,sc4 7,tbingen7 ,,cambridge3 at the ,university ,press #aije ,,cambridge ,,university ,,press ,,warehouse1 ,c4 ,f4 ,,clay1 ,,manager4 ,london3 ,,ave ,,maria ,,lane1 ,e4,c4 ,glasgow3 #ej1 ,,wellington ,,street4 ,illustration ,leipzig3 ,f4 ,a4 ,,brockhaus4 ,new ,york3 ,,the ,,macmillan ,,company4 ,bombay and ,calcutta3 ,,macmillan ,,and ,,co41 ,,ltd4 ,all ,rights reserved4 ,,author',s ,,preface4 ,the increasing recognition of the importance of the preservation of antiquities justifies the publication of a handbook dealing with this subject4 ,as far as ,i can ascertain1 with the exception of a short article#a for which ,i am myself responsible1 only one work has appeared which covers the whole field--the ,merkbuch#b prepared by ,dr ,voss at the request of the ,government4 ,but as this book only gives a selection of the known methods of preservation1 the need of a more comprehensive publication will scarcely be denied4 ,in spite of my ten years' experience in the special ,laboratory of the ,royal ,museums and the frequent opportunities of learning the methods in use elsewhere1 which the journeys and correspondence arising out of my duties have given me during this period1 ,i do not feel competent to produce a review of these various methods which will be at once exhaustive and sufficiently critical4 ,there are several reasons for this4 ,in the first place the individual methods have been but rarely published1 and even then through the most varied literary media2 often they are only casually mentioned in articles dealing with anthropological or historical subjects4 ,on the other hand1 the value of an object to be dealt with may prohibit an attempt at treatment1 the success of which is not assured4 ,my own experience has been gained by trials with objects chiefly from the ,egyptian section1 but also to some extent from the ,antiquarian and ,numismatic departments of the ,royal ,museums4 ,this deficiency can only be remedied by a work such as that now offered to the public1 and it is to be hoped that this handbook will stimulate the ,curators of ,state1 ,municipal and ,societies' ,collections1 as well as private collectors and others interested in the subject1 to make public their further experiences in this field of archaeology4 ,i take this opportunity1 therefore1 of expressing the hope that ,i may receive other communications bearing upon the subject and may thus perhaps at some future date be able to produce a more complete work4 ,in using the book it will be noticed that for the proper understanding of the first portion1 which deals with the causes of destruction1 a certain amount of chemical knowledge is assumed4 ,in the second portion1 however1 the methods of preservation are treated from a more elementary standpoint1 and the simple apparatus and manipulations required are so described that the treatment may be readily carried out by those who are unfamiliar with chemical methods4 ,in conclusion1 ,i take this opportunity of expressing my thanks to all those who have given their help1 and especially to ,dr ,otto ,olshausen for his continued interest in the work of the ,museum ,laboratory and in the production of this handbook4 ,especially am ,i indebted to his extensive knowledge of anthropological literature for many references which would otherwise have escaped my notice4 ,,translators' ,,preface4 ,dr ,rathgen has1 in his preface1 stated the aim of this handbook1 and it is with a desire to further this aim that we have prepared an ,english translation4 ,claiming but limited experience in this field of research we have only added such explanatory notes as seem in some way to bear upon the subject or likely to be useful in a handbook of this kind 7viz4 the method of taking squeezes1 ,appendix ,a1 and a few footnotes which are signed and enclosed in square brackets74 ,we take this opportunity of thanking ,dr ,rathgen for his interest in our undertaking1 for his kindness in supplying much additional matter which did not appear in the ,german edition1 and also for the loan of the blocks for ,figs4 #bb and #bc4 ,figs4 #g1 #i-ab1 #cj-cc1 and #cg1 are from photographs of objects treated by ourselves4 ,our thanks are especially due to ,dr ,w4 ,a4 ,caspari1 of the ,national ,physical ,laboratory1 for his invaluable help in the revision of the translation1 and for his advice and suggestions in reference to the more technical aspect of the work4 ,,york1 ,december #aijd4 ,,contents4 ,,page ,literature xiii ,part ,i4 ,the changes undergone by antiquities in earth and in air #a ,limestone and clay #b ,iron #g ,bronze and copper #ae ,silver #di ,lead #ec ,tin #ec ,gold #ec ,glass #ed ,organic substances #ed ,part ,,ii4 ,the preservation of antiquities #ef i4 ,preservation of objects composed of inorganic substances a4 ,limestone #ef b4 ,marble and alabaster #gd c4 ,earthenware #gd d4 ,slightly baked or unbaked clay #ha e4 ,fayence #hf f4 ,stucco and ,nile-mud #hg g4 ,sandstone and granite #hg ,appendix3 ,cement for earthenware4 ,restorations #hg h4 ,iron #hi #a4 ,methods of preserving objects of iron without removal of the rust #hi #b4 ,preservation by steeping and subsequent impregnation #ib #c4 ,preservation by removal of the rust #ajb #d4 ,preservation of medieval iron objects #aai i4 ,bronze and copper #abj ,a4 ,methods of impregnation #abb ,b4 ,preservation by reduction #abe ,reduction of oxidized copper coins #adj ,cleaning copper coins with melted lead #adc ,c4 ,preservation by exclusion of air #add ,appendix3 ,method of bringing out worn lettering #adf upon coins j4 ,silver #adh k4 ,lead and tin #adi l4 ,gold #aej m4 ,glass and enamel #aea ii4 ,preservation of organic substances4 n4 ,bones1 horns1 ivory #aea o4 ,leather #aeb p4 ,textile fabrics1 hair #aec q4 ,feathers #aed r4 ,papyrus #aed s4 ,wood #aef #a4 ,dry preservation #aef #b4 ,preservation in liquids #aei ,protection against wood-worms1 etc4 #afj ,preservation and cleaning of coloured objects of wood #afa t4 ,amber #afb ,care of antiquities after preservative treatment #afb ,concluding remarks #afd ,appendix ,a4 ,method of taking squeezes of inscriptions #aff ,appendix ,b4 ,zapon #afh ,index #aga ,,illustrations4 ,,fig4 ,,page #a4 ,limestone block with well-preserved surface #c #b4 ,limestone block with pitted surface #c #c4 ,limestone block showing destruction of surface #d #d4 ,potsherd showing saline efflorescence #e #e4 ,pottery showing sodium nitrate efflorescence #f #f4 ,portion of horse-trappings showing blue and green patina #ce #g4 ,head of ,osiris showing advanced condition of warty patina #ch #h4 ,etruscan mirror showing warty patina #dj #i4 #db ,bronze figure showing destructive patina #aj4 #dc #aa4 #dd ,the same after treatment 7,finkener's method7 #ab4 #de #ac4 ,gay-,lussac's burette #fb #ad4 ,air-pump fixed to water-tap #fh #ae4 ,apparatus for impregnation by extraction of air #fi #af4 ,assyrian clay tablet showing incrustation #gi #ag4 ,the same after treatment #gi #ah4 #ai4 ,assyrian clay tablet before and after treatment #hj #bj4 #ba4 #bb4 #hb ,babylonian clay cone before and after treatment #bc4 #hc #bd4 ,water-bath for iron objects #id #be4 ,iron sword treated by ,blell's method #ajh #bf4 ,iron spear-head treated by ,blell's method #aji #bg4 ,iron fibula treated by ,blell's method #aji #bh4 ,application of ,krefting's method #aaa #bi4 ,iron spear-head treated by ,krefting's method #aab #cj4 ,iron pin before and after treatment by ,krefting's method #aac #ca4 #cb4 ,iron object before and after treatment by ,krefting's method #aad #cc4 #cd4 ,piece of iron sword-blade with inscription revealed by ,krefting's method #aaf #ce4 ,iron sheath after treatment by combination of ,blell's and ,krefting's method #aag #cf4 ,hammer-heads for removal of bronze incrustations #abj #cg4 ,osiris showing cracking and destructive patina #abc #ch4 ,boeotian bridle showing cracked patina #abd #ci4 ,bronze bull showing warty patina #acb #dj4 ,the same after reduction by ,finkener's method #acc #da4 ,bronze axe-blade before treatment by ,finkener's method #acd #db4 ,the same after treatment by ,finkener's method #ace #dc4 ,reverse side of same after treatment #acf #dd4 ,dagger-sheath before treatment by ,finkener's method #acg #de4 ,dagger-sheath after treatment1 showing design #acg #df4 ,roman coins before treatment by ,krefting's method #adb #dg4 ,roman coins after treatment by ,krefting's method #adc #dh4 ,method of mounting objects in air-tight damp-proof cases #ade ,,literature4 ,aarbger for nordisk ,oldkyndighed og ,historie1 udgivne af det kongelige nordiske ,oldskrift-,selskab4 ,copenhagen4 ,aarsberetning fra ,foreningen till norske ,fortidsmindesmaerkers ,bevaring4 ,christiania4 ,annalen der ,chemie und ,pharmacie4 ,edited by ,whler1 ,liebig and ,kopp4 ,since #ahgc3 ,liebig's ,annalen der ,chemie4 ,antiquarisk ,tidsskrift1 udgivet af det kongelige nordiske ,oldskrift-,selskab4 ,copenhagen #ahdc-fc4 ,archaeological ,journal4 ,london4 ,atti della ,reale ,accademia dei ,lincei4 ,rome4 ,berg- und httenmnnische ,zeitung4 ,leipzig4 ,bibra1 ,e4 v4 ,die ,bronzen und ,kupferlegirungen der alten und ltesten ,vlker4 ,erlangen #ahfi4 ,bibra1 ,e4 v4 ,ueber alte ,eisen- und ,silberfunde4 ,nrnberg and ,leipzig #ahgc4 ,bischoff1 ,c4 ,das ,kupfer und seine ,legirungen4 ,berlin #ahfe4 ,bltter fr ,mnzkunde4 ,hannoversche numismatische ,zeitschrift4 ,edited by ,h4 ,grote4 ,leipzig4 ,chemiker-,zeitung 7,dr ,g4 ,krause74 ,cthen4 ,chemisches ,centralblatt 7,arendt7 ,hamburg and ,leipzig4 ,christiania ,videnskabs-,selskabs ,forhandlinger4 ,christiania4 ,comptes rendus hebdomadaires des sances de l',acadmie des sciences1 publ4 p4 les secrtaires perptuels4 ,paris4 ,dingler's ,polytechnisches ,journal4 ,stuttgart4 ,finska ,fornminnesfreningens ,tidskrift4 ,helsingfors4 ,finskt ,museum4 ,finska ,fornminnesfreningens ,mnadsblad4 ,helsingfors4 ,friedel1 ,e4 ,eintheilungsplan des ,mrkischen ,provinzialmuseums der ,stadt ,berlin4 #fth issue4 ,berlin #ahhb4 ,graham-,otto's ,ausfhrliches ,lehrbuch der ,chemie4 #eth ,edition4 ,anorgan4 ,chemie von ,h4 ,michaelis4 ,brunswick #ahgh-hi4 ,hauenstein1 ,h4 ,die ,kessler'schen ,fluate4 #bnd ,edition4 ,berlin #ahie4 ,journal fr praktische ,chemie4 ,edited by ,erdmann4 ,leipzig1 ,journal of the ,chemical ,society4 ,london4 ,keim1 ,a4 ,technische ,mittheilungen fr ,malerei4 ,munich4 ,kongl4 ,vitterhets ,historie och ,antiqvitets ,akademiens ,mnadsblad4 ,stockholm4 ,krhnke1 ,chemische ,untersuchungen an vorgeschichtlichen ,bronzen ,schleswig-,holsteins4 ,dissertation4 ,kiel #ahig4 ,layard4 ,discoveries in the ruins of ,nineveh and ,babylon4 ,london #ahec4 ,lepsius1 ,c4 ,r4 ,denkmler aus ,aegypten und ,aethiopien4 ,berlin #ahdi-ei4 ,lueger1 ,o4 ,lexikon der gesamten ,technik4 ,stuttgart #ahid4 ,merkbuch1 ,alterthmer aufzugraben und aufzubewahren4 ,herausgeg4 auf ,veranlassung des ,herrn ,ministers der geistlichen1 ,unterrichts- u4 ,medizinal-,angelegenheiten4 #bnd ,edition4 ,berlin #ahid4 ,mittheilungen der naturforschenden ,gesellschaft in ,bern4 ,bern4 ,mittheilungen aus der ,sammlung der ,papyrus ,erzherzog ,bainer4 ,vienna #ahhg-ahhi4 ,morgan1 ,j4 de1 ,fouilles ,dahchour ,mars-,juin #ahid4 ,vienna #ahie4 ,muspratt's theoretische1 praktische u4 analytische ,chemie4 #dth ,edition4 ,brunswick #ahhc4 ,neues ,jahrbuch fr ,mineralogie1 ,geognosie1 ,geologie und ,petrefakten-,kunde1 edited by ,k4 ,c4 von ,leonhard and ,h4 ,g4 ,bronn4 ,stuttgart4 ,polytechnisches ,centralblatt4 ,leipzig #ahce-ge4 ,polytechnisches ,centralblatt4 7,geitel47 ,organ der polytechn4 ,gesellschaft zu ,berlin4 ,berlin #ahhh4 ,prometheus1 edited by ,dr ,o4 ,n4 ,witt4 ,berlin4 ,publications de la socit pour la recherche et la conservation des monuments historiques dans le grandduch de ,luxembourg4 ,luxemburg4 ,j4 ,j4 ,rein1 ,japan4 ,nach ,reisen und ,studien im ,auftrage der ,knigl4 ,preuss4 ,regierung4 #b ,vols4 ,leipzig #ahha-ahhf4 ,revue archologique1 publie sous la direction de ,,mm4 ,a4 ,bertrand et ,g4 ,perrot4 ,paris4 ,schliemann1 ,h41 ,ilios4 ,leipzig #ahha4 ,simon1 ,e41 ,ueber ,rostbildung und ,eisenanstriche4 ,berlin #ahif4 ,sitzungsberichte der ,alterthumsgesellschaft ,prussia in ,knigsberg4 ,verhandlungen der ,berliner ,anthropologischen ,gesellschaft4 ,berlin4 ,verhandlungen des ,vereins zur ,befrderung des ,gewerbefleisses in ,preussen4 ,berlin4 ,zeitschrift fr ,numismatik4 ,edited by ,a4 v4 ,sallet4 ,berlin4 ,zeitschrift fr anorganische ,chemie4 ,zeitschrift fr ,ethnologie4 ,berlin4 ,,part ,i4 ,,the ,,changes ,,undergone ,,by ,,antiquities ,,in ,,earth ,,and ,,in ,,air4 ,the greater number of those objects of antiquity which are composed of inorganic materials1 such as limestone1 earthenware1 and metals1 owe the commencement of any alteration in their character to the situation in which they are discovered1 since they are buried in ground which has been at some period damp or wet1 and has contained1 moreover1 salts soluble in water4 ,amongst these salts the most usual is sodium chloride 7common salt71 but this is mostly accompanied by potassium chloride1 potassium sulphate1 magnesium chloride1 and calcium sulphate2 in short1 by those soluble salts which are found in sea-water4 ,in the fine pores of ,egyptian antiquities1 especially1 such salts occur1 and their presence is readily explained by the fact that the land of ,egypt was originally a sea-bottom4 ,the presence of salt in the soil of ,egypt has been known for a considerable period4 ,thus ,karabacek#c1 quoting from ,volney's ,travels in ,syria and ,egypt 7,jena1 #aghh1 ,i4 p4 #ac73 ,wherever one digs one finds brackish water containing soda1 sea-salt1 and a small quantity of saltpetre4 ,indeed1 when a garden has been flooded for irrigation purposes1 crystals of salt make their appearance on the surface after the water has evaporated or has been soaked up by the soil4 ,in the dry climate of ,egypt1 objects saturated with salt keep better after their removal from the ground than in our climate1 where the variations in the temperature and in the hygroscopic condition of the air produce a partial deliquescence in wet weather1 and in dry weather a re-formation of crystals4 ,the continued alternation of these processes gradually loosens the surface of limestone or earthenware1 or induces certain chemical changes in objects of metal and in both cases leads to their destruction4 ,limestone and ,clay4 ,the series of changes are particularly well illustrated by the ,egyptian grave of ,meten#d1 the stones from which are now in the ,royal ,museum in ,berlin4 ,the three illustrations here given show3 7#a7 an undecayed block of limestone1 7#b7 a block with pitted surface1 and 7#c7 a block the surface of which was formerly covered with hieroglyphics1 but which is now totally destroyed by flaking4 ,the blocks of the latter kind were found in the lowest layer1 or lowest but one1 while those blocks which were above were the best preserved4 ,as the amount of salt present scarcely varied1 these specimens offer a striking illustration of the greater influence of moisture in the deeper soil than at the higher levels4 ,illustration3 ,fig4 #a4 ,limestone block1 surface well preserved4 ,illustration3 ,fig4 #b4 ,limestone block with pitted surface4 ,illustration3 ,fig4 #c4 ,limestone block showing destruction of surface4 ,baked clay1 particularly that of ,egyptian ostraca 7i4e4 fragments of pottery showing inscriptions71 exhibits similar changes1 as is shown in the accompanying illustrations4 ,the surface of some fragments is found to be almost completely covered with a layer of salt1 which1 apart from impurities of clay and dust and remains of the black lettering1 consists of almost pure sodium chloride2 only a trace of magnesium sulphate being found on analysis4 ,in contrast with this very loose superficial incrustation1 the inner portions of the ostracon contained considerable quantities of sulphates4 ,figure #d represents a fragment with granular efflorescences of sodium chloride1 and also fine needles of magnesium sulphate#e4 ,as a general rule the amount of salt is small compared with the bulk of clay or limestone3 thus it was found by titration that three separate fragments contained #jac1 #jbj1 and #jdh calculated as sodium chloride1 and in one series the average of #af fragments was #jac4 ,but the percentage of sodium chloride has often been found higher1 more especially in larger objects of baked clay1 being in one instance as high as #bc4 ,the disintegration of the surface is due to the mechanical action of moisture which results in the scaling off of portions of the surface4 ,this does not however exclude a chemical action of the salts upon the clay1 especially when this has been only slightly baked4 ,thus by merely washing such fragments in cold distilled water1 not only sodium and magnesium compounds but also those of aluminium and calcium may be removed4 ,the soft powdery patches1 which some limestones show instead of scales1 are also evidences of chemical action2 thus in one case a cuneiform tablet#f of dolomitic stone showed decomposition at those spots where the salt was firmly deposited as an incrustation1 and here the stone1 elsewhere smooth and hard1 was found1 on washing away the salt1 to be soft and porous4 ,illustration3 ,fig4 #d4 ,potsherd showing saline efflorescence of sodium chloride and magnesium sulphate4 ,although1 as has been already remarked1 sodium chloride generally constitutes the bulk of the salts present1 and only in rare cases1 as ,i have for instance shown in an ,egyptian ,fayence and in several ,greek clay vases1 is the amount of sulphates greater1 yet there are in collections clay objects 7,fig4 #e7 covered with needles of sodium nitrate#g 7,chili saltpetre7 where the nitric acid has been contributed by the decomposition of organic substances2 and here the presence of nitrates proves inimical to antiquities just in the same way as a coating of limewash may be seen to be destroyed by the so-called wall-saltpetre#h4 ,illustration3 ,fig4 #e4 ,pottery showing efflorescence of sodium nitrate4 ,iron4 ,if in some cases it may be uncertain whether the destruction of antiquities of limestone or earthenware has been due to mechanical or to chemical influences1 this uncertainty is excluded in the case of metallic objects1 of which those of bronze and iron chiefly come under the notice of the antiquary4 ,from the first piece of metallic iron which he possessed man must have soon become acquainted with its untoward property of rusting1 but even at the present day opinions differ as to the origin of rust1 and the cause of its rapid spreading4 ,it has long been known with certainty that iron containing but little carbon 7wrought iron7 rusts with greater ease than iron which is rich in carbon 7cast iron or steel71 and that the rust is a compound of iron with hydrogen and oxygen 7hydroxide74 ,that rust is of variable composition may be inferred from the variations of shade from yellow to dark brown which are met with4 ,widely different views are held on the question of the production of rust4 ,some#i maintain that iron rusts only in the presence of water containing free oxygen and carbonic acid 7,,co#b7 in solution1 a ferrous bicarbonate being first formed2 the bicarbonate is then converted into ferrous carbonate1 which finally yields the hydrate with evolution of carbonic acid4 ,this carbonic acid continues to attack further areas of metallic iron4 ,others#aj maintain that1 while the formation of rust may proceed as described1 carbonic acid is not necessary1 and that free oxygen alone causes rusting when atmospheric moisture is condensed upon the surface of iron4 ,that iron remains free from rust when in a solution of caustic potash or soda is said to be due to the absence of free oxygen and not to the removal of carbonic acid4 ,spennrath holds1 in opposition to the opinion of ,axel ,krefting#aa1 that rust once formed cannot act as an oxidising agent1 except by virtue of its power of condensing water and retaining it in its pores4 ,similarly ,e4 ,simon finds the chief cause of the corroding action of rust in the property of absorption1 that is surface-condensation of gases4 ,this condition is comparable to that of liquefaction1 and produces rapid chemical action4 ,under certain circumstances ferrous hydrate is formed instead of ferric hydrate1 particularly when iron is subjected to vibrations1 as ,tolomei#ab has observed in iron rails etc4 ,stapff#ac believes that mixtures of ferric hydrate with ferroso-ferric oxide1 which possess a similar composition to forge scale1 are formed under the influence of thermal waters4 ,according to ,irvine#ad rusting proceeds rapidly when two kinds of iron1 such as cast and wrought1 are in contact1 since their electro-chemical relations may result in a voltaic couple4 ,the electric current brings about the decomposition of the water1 and the evolved hydrogen1 being in the nascent state1 combines with the nitrogen dissolved in the water to form ammonia1 as had been previously observed by ,akermann#ae4 ,similarly1 electric currents are said to be caused by the contact of ferroso-ferric oxide with metallic iron1 thus causing a further oxidation of the iron#af4 ,the presence of certain neutral salts1 especially sodium chloride 7common salt71 has a very marked influence on the destruction of iron#ag4 ,when iron filings are exposed to air and moisture1 oxidation takes place2 the action is1 however1 according to ,krefting1 far more intense in the presence of an alkaline chloride4 ,a mixture of iron filings and sodium chloride exposed to moisture is converted in a few days into a black powder which has the following composition3--#aad ,fe,o1 #hjj ,fe#b,o#c1 #hf ,h#b,o1 thus resembling the iron-black of ,lemery2 on extraction with water the filtrate is found to be alkaline and to possess a tallow-like smell#ah4 ,without entering further into ,krefting's researches1 we will quote the hypothesis with which he concludes3 ,the iron probably combines with small quantities of chlorine from the sodium chloride1 causing alternate reduction and oxidation1 and this1 owing to the ease with which iron salts pass from one stage of oxidation to another1 very soon gives a visible result in the formation of rust3 ,fe #b,na,cl ,fe,cl#b #b,na #b,na #b;,h#b,o #b,na,o,h ,h#b4 ,if these results be compared with observations made upon the condition of iron objects which have been excavated1 it is evident that these are in many cases exposed to the action of the air to a lesser extent while buried1 and that their decomposition will advance more rapidly when they have been withdrawn from their protective covering of earth4 ,the condition of the objects differs according to the kind of iron1 the length of time during which they have been buried1 and the character of the soil in which they are found4 ,in one place objects are found covered with a slight layer of rust only1 in another with a thicker layer1 in another there remains but a small core of metal1 or even none at all1 or the layer of rust may be intermingled with particles of earth or clay4 ,the rust may be uniform in colour and hardness in one case1 and in another soft areas1 generally light in colour1 may alternate with darker1 harder patches1 while frequently the harder layer is found below the lighter and softer1 etc4--conditions which depend on the occurrence of the various iron compounds4 ,the behaviour of all1 however1 when placed in collections1 even in the driest of rooms1 is the same2 all sooner or later undergo change1 and portions of rust become detached1 until in the course of time every trace of the original metallic core is oxidised4 ,a closer inspection generally shows in these cases small brownish1 glistening bubbles#ai which prove1 when touched1 to be drops consisting of chlorine compounds of iron surrounded and permeated with oxides4 ,krefting#bj gives as the average of a series of analyses of the rust on northern antiquities the following composition3 ,ferric oxide #gje ,ferrous oxide #abg ,carbonic acid #ci ,calcium oxide #jeh ,magnesium oxide #jji ,ferrous chloride #jbfj ,calcium chloride #jbhj #jfa ,soluble ,magnesium chloride #jjbc salts4 ,potassium chloride #jjah ,sodium chloride #jjbg ,water chemically combined #hj ,moisture #aej ,organic matter #jig ,thus the chief part in this rapid decomposition is played by the chlorine compounds1 as indeed was previously determined#ba by the experimental proofs already given4 ,if ferrous chloride is present the further decompositions can be explained by such equations as those given by ,olshausen#bb4 #f;,fe,cl#b #c,o ,fe#b,o#c #b;,fe#b;,cl#f2 #b;,fe#b;,cl#f #b;,fe #f;,fe,cl#b4 ,the equations do not claim to give a complete statement of the reactions1 for other reactions take place at the same time2 thus ferric hydrates and carbonates and perhaps also intermediate compounds of oxygen and chlorine occur2 they show however that in the oxidation of ferrous chloride1 oxides and ferric chloride are produced1 so that new and hitherto intact particles of the metal continually react with the ferric chloride4 ,in many cases the action of the chlorine is not only seen in objects placed in a collection1 but also in freshly excavated objects4 ,not infrequently iron objects are found which are covered with large hard blisters1 and are thus more or less deformed4 ,the interior of these blisters consists of a mixture of ferrous chloride with oxides1 but the shell has become so hard by complete oxidation that it can only be removed with hammer and chisel4 ,iron objects found in peat differ from these chlorine-containing specimens which are found in soil1 and although sometimes much corroded1 many are well preserved4 ,blell#bc is of the opinion that if peat is free from tannic acid1 the finds will be well preserved1 while the theory advanced in the ,merkbuch#bd is that tannic acid acts as a preservative4 ,the latter view is probably the more correct1 for although ordinary tannic acid seldom occurs in peat1 yet peat contains a series of compounds which are tanning agents1 such as ulmic1 humic1 and crenic acids4 ,these form iron compounds which1 being insoluble in water1 protect the metallic iron beneath from further action4 ,if1 however1 the peat contains sulphates1 and especially if it contains free sulphuric acid1 only much corroded iron is likely to be found4 ,moreover the physical condition of the peat may vary2 thus it may be dry or damp or even submerged under water1 and this variation will exercise some influence upon the condition of the iron4 ,iron objects which are covered with the black1 so-called noble rust 7,edel-rost7 usually prove very stable4 ,this1 like forge-scale1 is a ferroso-ferric compound in which there is a preponderance of ferrous oxide where it is in contact with the metallic iron1 and of ferric oxide in the outer layer4 ,noble rust is probably in nearly all instances the result of the action of fire1 which may have been used in funeral rites1 or may have been accidental2 very rarely can it have been produced by the reactions mentioned above1 as has been suggested by ,stapff4 ,iron which has been in contact with the bone ash of burnt corpses has certain characteristics4 ,when entirely surrounded with bone ash objects are well preserved#be1 and only covered with a thin layer of oxide4 ,how far the ash has acted as a preservative1 ,i will not hazard an opinion1 having seen but few specimens1 and these had been already varnished to preserve them4 ,under certain conditions the phosphoric acid of the bones forms a thin bluish layer of iron phosphate1 corresponding in composition to vivianite 7,fe#c,p#b,o#h4h;,h#b,o71 as was pointed out by ,jacobi in a series of objects in the ,saalburg ,museum at ,homburg4 ,these objects also are quite durable4 ,in earth so full of sodium chloride as is that of ,egypt1 objects of iron will be readily corroded1 and the explanation given above will account for the paucity of iron remains of ,egyptian origin4 ,it is difficult1 however1 to find a satisfactory explanation for the fact that objects found in sea-water are specially well preserved4 ,it may be that1 in spite of the presence of free oxygen in solution in the water their complete insulation from the atmospheric air has resulted in the preservation of the objects1 as is the case with those which have lain in a stream of fresh water4 ,bronze and ,copper4 ,copper and its alloys are subject to the same far-reaching changes as iron1 but the action is less rapid4 ,bronzes of widely different composition have to be dealt with to ensure their preservation1 and to a less extent1 copper also#bf4 ,according to von ,fellenberg#bg bronze objects may be classified according to the material in which they have been found1 i4e4 peat mud1 water1 or earth4 7#a7 ,bronzes from peat mud are covered with a black earthy mass1 which can be easily removed by water and brushes1 the alloy then assumes its metallic lustre and the characteristic colour of bronze4 ,the complete preservation of the pure metallic surface of the bronzes1 in the same condition as they were when they were submerged1 is easily accounted for by the enclosure of the metal in mud of organic origin under several feet of water which effectually excludes the oxygen of the air4 7#b7 ,the bronzes found in water1 as for example in the beds of lakes and rivers1 are less perfectly preserved4 ,they have usually a thin coating of a calcareous deposit1 which however often allows the lustre and colour of the metal to appear in places4 ,when such bronzes have dark or green coloured patches or spots1 the layer is very thin and may be removed by treatment with acids1 which allows the metallic colour to become visible4 ,bronzes preserved in water still retain the same definite edges and points which they possessed when they entered the water4 ,if bronzes which are markedly incrusted with verdigris are found in water in all probability they had lain in the ground a considerable time before being covered with water1 and oxidation had penetrated deeply into the metal before immersion4 7#c7 ,bronzes found in the earth or in graves appear covered with a fine green crust of verdigris which may be either light or dark in colour and which often has a vitreous lustre4 ,this is generally known as ,patina4 ,this crust varies in thickness from that of writing-paper to several millimetres4 ,if the green crust be filed away1 or better1 removed by dilute nitric or sulphuric acid1 the bronze is found to possess a reddish colour2 below the crust of cupric carbonate is found a layer of cuprous oxide1 which may be removed by ammonia1 thus revealing the metal with its characteristic colour and lustre4 ,this condition is characteristic of the slow oxidation of bronze in moist earth4 ,the layer of cuprous oxide between the pure metal and the external crust of copper carbonate has been shown by the examination made by ,dr ,wibel to be a product of the reduction of copper carbonate by the metallic copper of the bronze4 ,bronzes belonging to this category have often lost their former metallic properties1 and if of small diameter have often been completely converted into cuprous oxide1 surrounded by a lustrous green or blue crust of carbonates4 ,if a metallic core remains1 it is found to be crystalline1 brittle1 and non-coherent1 that is1 it flies to pieces under the blow of a hammer4 ,fine ornamentation and sharpness1 whether of edge or of point1 have often disappeared4 ,this does not occur with bronzes preserved in water4 ,in another volume of the series#bh von ,fellenberg states that basic copper chloride occurs as a constituent of patina4 ,a few lengthier quotations may be conveniently given here1 in part verbatim1 in part abstracted from literature which is not readily accessible4 ,reuss#bi states that it has been hitherto generally assumed that copper is first converted into cuprous oxide which is then converted into a green hydrated oxy-carbonate which is separated from the metal by a thin layer of cuprous oxide4 ,the specimens examined by him1 however1 showed no such dividing layer1 the metal being either directly in contact with the malachite#cj1 or else separated from it by a black or bluish layer of cupric oxide4 ,he further draws attention to the occurrence of irregular knobs two to three lines in height which consist1 in part1 of azurite#ca4 ,neither oxides of tin nor chlorine were found4 ,the alteration of the bronze he explains by the prolonged oxidising action of water containing carbonic acid4 ,in an exhaustive memoir ,wibel#cb describes the various kinds of patina as malachite1 copper-oxychloride1 and azurite1 with admixtures of tin oxide1 silver1 iron oxide1 lead chloride and copper chloride4 ,he discusses also the occurrence of the cuprous oxide layer which is said to have been described by ,sage as early as #aggi4 ,after detailing the observations of ,davy1 ,hnefeld1 and ,picht1 that the metallic copper exists partly in alloy and partly free as crystals in the layer of cuprous oxide1 he continues as follows#cc3 ,the process of decomposition in bronzes has been regarded as a slow oxidation1 in which cuprous oxide marks the first and incomplete stage1 while the carbonates represent the later completed phase4 ,the formation of both these substances was assumed to be due to moist oxidation1 on bronzes as well as in those superpositions of copper1 cuprite1 and malachite1 so frequently found in minerals4 ,indeed1 no other process of formation of the carbonates is conceivable2 moreover cupric oxide1 if really present1 would be naturally regarded as a product of oxidation4 ,the other substances1 such as tin oxide1 which are occasionally found1 would be produced in part by similar simple processes1 in part by the simultaneous action of particular salts1 the chlorine compounds1 for instance1 by the presence of water containing sodium chloride4 ,similarly the production of cuprous oxide was usually attributed to an incomplete oxidation of the copper1 although it might very well be the result of an inverse process1 viz4 the reduction of pre-existing cupric oxide4 ,from the following considerations ,wibel thinks that he is justified in his assumption that the layer of cuprous oxide is the result of reduction4 ,firstly1 by no means all bronzes which have been dug up1 even though from the same excavation1 show the layer of cuprous oxide4 ,secondly1 the cuprous oxide layer is in the crystallized state4 ,thirdly1 'all the facts of chemistry show that the formation of cuprous oxide can only take place by reduction1 given the ordinary conditions of temperature and pressure4' ,finally1 in addition to oxygen and carbonic acid1 many salts1 those of ammonia for example1 occur in the spots where bronzes are found and favour the formation of copper salts4 ,wibel also quotes in support of his views the experiment of ,bucholz#cd1 that a strip of copper1 the upper half of which is immersed in a layer of distilled water1 and the lower half in a concentrated neutral solution of copper nitrate carefully poured beneath it1 becomes coated with copper and cuprous oxide4 ,he continues3 ,bronze objects are attacked by waters which contain oxygen1 carbonic acid and a greater or less percentage of salts4 ,such soluble salts as are formed are removed by solution1 while the bronzes become covered1 according to circumstances1 with an insoluble layer either of carbonate or of oxide1 whereby the form of the objects is preserved4 ,the water then penetrates by capillary action through the porous coating into the interior1 and attacks further portions of the metal1 forming a layer of soluble cupric salt2 a portion of which is able to pass by diffusion through the external layer4 ,for the same reasons the liquid1 bounded as it is on one side by the metal and on the other by the almost insoluble crust1 shows varying degrees of concentration3 thus all the conditions necessary for the ,bucholz process are fulfilled4 ,if the water is rich in salts1 a concentrated copper solution is formed and even metallic copper may be deposited from it 7i4e4 the 'copper crystals' of bronzes72 but if1 as is usually the case1 the water contains only small quantities of salt1 cuprous oxide crystals only are formed4 ,the fact that the process takes place chiefly in the pores made by the water itself is readily understood1 because of the comparative quiescence of the liquid2 and that it causes a marked progressive change in the object arises from the continual exchange of a portion of the copper solution already formed with fresh solvent from outside4 ,where the absence of carbonic acid or other circumstances hinder the formation of an almost insoluble crust1 the reactions detailed above may1 under favourable conditions1 take place directly upon the surface of the bronze2 if1 on the other hand1 there is a too rapid change of liquid 7as for example in very wet localities71 the process may altogether fail to set in1 since the necessary conditions of rest1 etc4 are wanting4 ,since the absence of the necessary conditions may arise from a number of purely accidental causes1 it will be easily understood1 that bronzes from one and the same grave may show the same percentage of carbonates1 but very dissimilar percentages of cuprous oxide4 ,in short all actually observed conditions in which bronzes are found are accounted for by the explanations given above4 ,the following extract is taken from the section dealing with patina in ,bibra's ,bronzes and ,copper ,alloys#ce3 ,the conditions under which ,patina is formed1 or rather the conditions under which copper alloys are gradually decomposed1 are variable in the extreme4 ,the four main factors which may be instrumental in determining the chemical changes may be thus stated3 7a7 ,the composition 7qualitative and quantitative7 of the particular alloys4 7b7 ,the mode of smelting and the original manipulation of the components1 such as a good or poor mixing1 fine or coarse grain1 etc4 7c7 ,the locality in which the alloy has lain4 7d7 ,the length of time during which the alloy has been exposed to the particular conditions4444 ,marked differences may appear in the extent and nature of the chemical changes shown by the same alloy2 thus one fragment while underground may have been enclosed in an urn containing bone ash and dry sand1 while another fragment may have been in contact with decaying animal matter4 ,from what has been said above1 the variations in the composition of patina may be readily explained4 ,the composition has been found to be3 7alpha7 ,basic carbonate of copper4 7beta7 ,basic carbonate and sulphide of copper4 7gamma7 ,malachite 7normal carbonate of copper71 with occasional admixture of cuprous oxide and azurite 7acid carbonate of copper7 ,stolba4 7delta7 ,crystalline cuprous oxide1 according to ,wibel#cf a reduction product of the carbonate of copper1 by the action of the copper of the bronze4 ,lastly1 copper chloride has been occasionally found in patina ,haidinger#cg4 ,this is only to be expected from the varying character of the localities in which the statues or bronzes are found4 ,the author has himself noticed on board ship1 how objects of copper and brass1 which are exposed to the salt spray1 develop a durable coating of copper oxychloride#ch 7atacamite74 ,in conclusion1 reference may be made to a statement of ,chevreul#ci1 who1 after examination of both hollow and solid specimens of ,egyptian statuettes1 states that the bronze is of an excellent quality and that it occurs in four different conditions4 ,he describes these four conditions1 three of which are undoubtedly patina or altered copper1 as follows3 7alpha7 ,a green deposit with patches of blue4 7beta7 ,a blood-red mass4 7gamma7 ,a reddish coloured bronze4 7delta7 ,ordinary bronze unaltered in appearance4 ,the first in this category represents the ultimate stage of decomposition of bronze and forms the outer incrustation of the statuettes4 ,it is a compound of copper chloride and copper oxide and water in the same proportions as in ,peruvian copper oxychloride 7atacamite72 the blue parts contain water1 carbonic acid and cupric oxide4 ,it is in fact the blue hydrated copper carbonate4 7beta7 ,the blood-red substance consists chiefly of cuprous oxide with an admixture of tin oxide4 ,it contains chlorine1 apparently as cuprous chloride1 sometimes in considerable quantity4 7gamma7 ,the reddish colour seems to be due to the tin undergoing more alteration in the course of time than the copper4 7delta7 ,the well-preserved bronzes are remarkable for the excellent quality of the alloy4 ,chevreul continues3 ,copper and tin have thus undergone gradual changes from without inwards into chlorides1 oxides and carbonates2 the tin has been converted into oxide1 the outermost layer of copper into oxide and chloride1 while the layer in contact with the unaltered bronze beneath can only be oxidised into the suboxide4 ,in a fissure in a statuette he found crystals of blue basic carbonate of copper1 chloride of lead and hydrated oxychloride of copper4 ,bibra himself examined the patina of several bronzes and found it to consist mainly of sulphate and carbonate of copper4 ,to complete the quotation from ,chevreul's work we may observe that he finds the cause of the formation of the patina to be the action of air1 of water containing salt1 and of carbonic acid4 ,it is interesting that ,chevreul succeeded in restoring a small bronze containing chlorine by reduction in a stream of hydrogen4 ,in the year #ahfe ,m4 ,a4 ,terreil#dj published the analysis of a bronze patina containing chlorine4 ,the result is as follows3 ,bronze4 ,patina4 ,copper #heih #egbg ,tin #abfd #hdj ,lead #aji #ajb ,zinc #jej #jdf ,iron trace #afa ,lime 7,ca,o7 #jac ,chlorine #ece ,carbonic acid 7,,co#b7 #dbe ,alumina #ihf ,water #ddj ,oxygen #gbe ------ ------ #ajjba #ajjjj ,so too at a meeting of the ,association for the ,promotion of ,industries in ,prussia1 ,elster#da referred to the existence of chlorine in patina1 and regarded this as a proof that the patina upon antique bronzes was actually intentional on the part of the manufacturers4 ,e4 ,priwoznik#db has described a rare kind of patina which formed a coating #e to #g mm4 in thickness composed of three layers consisting of a reniform or botryoidal incrustation of an indigo blue colour4 ,the uppermost layer which was also the thickest consisted of #ccbb of sulphur and #ffgg of copper1 and was therefore cupric sulphide1 ,cu,s 7which is known in the mineral world as ,indigo ,copper or ,covelline74 ,the second layer1 which existed only in patches1 was #je mm4 in thickness and of a blackish colour2 it consisted of cuprous sulphide1 ,cu#b,s with #ae of tin4 ,the third layer which1 like the second1 was incomplete1 formed a fine black powder1 and consisted of #eih ,cu#b,s1 #bcb ,sn and #cd of water4 ,the patina had been produced by the action of soluble sulphides or of sulphuretted hydrogen upon the copper1 while the sulphur compounds themselves had resulted from the decay of organic matter in the soil in which the bronze was found4 ,mitzopulos#dc described the green patina of the copper alloys found in ,mycene as malachite and atacamite upon a reddish layer of cuprous oxide4 ,another analysis of patina was made by ,j4 ,schuler#dd4 ,the bronze in question had a grey outer layer1 which passed gradually into a light green friable layer #b mm4 in thickness4 ,a detached portion of this layer of patina1 dried in a desiccator over concentrated sulphuric acid with a loss in weight of #idd1 gave the following analysis3 ,tin oxide #diac ,copper oxide #bbdf ,lead oxide #cec ,iron oxide and aluminium oxide #age ,silica and insoluble matter #faf ,carbonic acid determined directly #fce ,carbonic acid determined by ignition #iae ,water determined by ignition #addc ,schuler calculates from these figures that the patina contains3 #fjib ,h#b,sn,o#c #cdee ,cu,c,o#c1 ,cu,h#b,o#b #dea 7,pb,c,o#c7b ,pb,h#b,o#b4 ,the analysis of the bronze itself was as follows3 ,copper #high ,tin #fhc ,lead #ahe ,cobalt and ,nickel #jij ,iron #jbh ,schuler makes the following observations3 ,whilst the percentage of copper in the alloy is high 7#high7 and the percentage of tin is low 7#fhc71 the percentage of copper in the patina 7metallic copper #aihd7 is smaller1 that of tin 7metallic tin #dbfg7 considerably greater4 ,the percentage of lead in the patina has also slightly increased4 ,one of the causes of this alteration in the proportion of the metals may lie in the fact that basic carbonate of copper is soluble in water containing free carbonic acid1 whilst tin hydrate is insoluble4 ,another cause may be found in the action of water which contains in solution ammonia and ammonium carbonate produced by the decomposition of organic matter4 ,confirmative evidence of this supposition is the presence of small quantities of ammonia in the patina#de4 ,schliemann#df asserts that bronze objects are destroyed by copper chloride1 and another reference to the presence of chlorine is made by ,krause4#dg ,arche and ,hassack#dh give the following details as the result of their analyses of three specimens of bronze3 ,i4 ,,ii4 ,,iii4 ,copper #ffig #gcdj #gaih ,lead #agbg #adgg #ahcg ,tin #aaih #eji #gbj ,antimony #abh #ccc ,arsenic ,trace #jhb ,iron #ajj #jca #jhi ,sulphur #aej #bbh #aef ,they obtain the following formulae and composition for the patina of the three bronzes#di3 ,i4 ,,ii4 ,,iii4 ,cu,c,o#c1 #b;,cu,o#b;,h#b #hehc ,cu,c,o#c1 #c;,cu,o#b;,h#b #ieaa #efjh #b,pb,c,o#c1 ,pb,o#b;,h#b #acja #ddi #bdfb ,sn,o#c;,h#b #aaf #jdj #aicj ,reference may be here made to an article by ,mond and ,cuboni#ej published in the ,report of the ,academy of ,florence1 from which the following extract is taken3 ,by the terms 'rogna' or 'caries' of bronze1 archaeologists designate a peculiar change1 to which ancient bronzes1 as statues1 coins1 vases1 etc4 are sometimes liable when preserved in museums4 ,this consists in a species of efflorescence of light green colour at one or more points upon the surface1 which spreads by degrees1 like oil over a sheet of paper1 destroying the surface and converting the interior of the bronze into an amorphous whitish-green powder4 ,the rapidity with which this destruction proceeds varies much according to circumstances which are not yet sufficiently known4 ,sometimes the destructive spot grows so slowly that it is hardly perceptible even after some months2 sometimes it grows very rapidly1 numerous spots form1 spread1 and unite1 until in a few months an ancient coin may be entirely destroyed4 ,in this way antiquities which are valuable for their history1 or for their workmanship1 are sometimes more or less injured by this development of patina1 which archaeologists regard as a plague in their collections4 ,mond and ,cuboni believe that the growths above described are caused by ,bacteria4 ,although they have not succeeded in producing the appearances of spreading patina by transference of cultures of bacteria to intact bronzes they think that their observations sufficiently support this supposition1 which they believe is further strengthened by the fact that bronzes exposed for a quarter of an hour to a temperature of #cjj;,f4 7#aej;,c471 whereby any bacteria would be killed1 showed no further change after a period of six months4 ,the following is an extract from an article by ,berthelot#ea3 ,copper objects1 which have been buried in the earth for several centuries1 are found to be covered with a green patina and with an earthy layer of varying thickness which has the same colour4 ,the metal itself is to a greater or less depth converted into cuprous oxide4 ,after removal the patina returns2 in other words1 the metal shows further growths1 and when in contact with the atmosphere of our climate is in all cases by degrees converted into dust4 ,these facts are well known to every collector and archaeologist1 who designate the specimens thus affected 'mtaux malades'4444 ,analysis shows that the superficial green layer consists in great measure of atacamite 7cuprous oxychloride7 agreeing with the formula #c;,cu,o1 ,cu,cl#b1 #d;,h#b,o4 ,there are also found traces of sodium salts4 ,the changes which have been observed are produced by salts from the soil1 especially sodium chloride1 held in solution by water4 ,in fact a few drops of salt water placed upon a copper plate are sufficient for the formation of oxychloride4444 ,this reaction is the result of the simultaneous action of the oxygen and of the carbonic acid of the air upon the copper and upon the sodium chloride in the presence of moisture1 as is represented by the following equations3 #d;,cu #d,o #d;,cu,o #d;,cu,o #b,na,cl ,,co#b #d;,h#b,o #c;,cu,o1 ,cu,cl#b1 #d;,h#b,o ,na#b;,,co#c4 ,thus the continuous transposition which1 under the influence of a salt-containing water1 often acting in large volume1 converts the metal into oxychloride1 is readily explicable3 while the process whereby the small quantity of sodium chloride originally present in an excavated bronze may cause its destruction after it has been placed in a museum is the following3 ,when the reactions given above have resulted in the formation of a certain amount of copper oxychloride1 it is to be supposed that a small quantity of sodium chloride comes into simultaneous contact with the oxychloride and with the metallic copper4 ,a slow reaction takes place and a double compound of cuprous chloride and sodium chloride is formed4 ,the remaining portion of copper is converted into cuprous oxide3 #c;,cu,o1 ,cu,cl#b1 #d;,h#b,o #d;,cu #b,na,cl ,cu#b;,cl#b1 #b,na,cl #c;,cu#b,o #d;,h#b,o4 ,the solution of the double salt is also in turn oxidized by the air which penetrates the whole mass4 ,the result of the reaction is therefore sodium chloride1 atacamite1 and copper chloride3 #c;,cu#b;,cl#b #c,o #d;,h#b,o #c;,cu,o1 ,cu,cl#b1 #d;,h#b,o #b;,cu,cl#b4 ,the copper chloride which remains1 if in contact with air and copper or even cuprous oxide1 is similarly converted into oxychloride3 ,cu,cl#b #c;,cu #c,o #d;,h#b,o #c;,cu,o1 ,cu,cl#b1 #d;,h#b,o4 ,the cycle is thus complete1 and its constant recurrence under the influence of oxygen and moisture is the cause of the destruction of those objects containing copper which are imbedded in earth1 and even of those which are preserved in our museums4 ,finally a memoir by ,villenoisy#eb should be noticed1 the first portion of which is devoted to a proof that the patina of ancient bronzes is due to natural causes and is not the result of the art and methods of the metal-workers of the ancient world4 ,the second portion deals with the various kinds of patina and their formation1 as the following excerpts will show3 ,the following substances may be mentioned as capable of attacking alloys3--,ordinary oxygen1 which has but a slight action on copper in the dry state but a more vigorous action in the presence of moisture1 or as ozone2 sulphur also1 ammonia1 carbonic acid1 and organic substances4 ,water has no direct influence1 but acts as a solvent4 ,the metals or metalloids of the alloys can unite independently with oxygen1 sulphur1 or carbonic acid1 etc4 to form oxides1 sulphides1 or carbonates2 or again they can react among themselves and produce copper stannate or lead stannate4 ,ammonia will form ternary compounds or play a catalytic part4 ,whatever processes may result in the formation of patina1 the changes which occur are too slow to allow their imitation and examination in the laboratory4 ,the four metals which are found in ancient bronzes1 viz4 copper1 tin1 zinc1 and lead1 are particularly liable to certain changes4 ,copper forms chiefly cupric and cuprous oxides4 ,the first of these is soluble in ammonia2 the latter combines with ammonia to form a substance which is colourless1 but which becomes blue on exposure to air4 ,tin forms stannic acid which probably produces stannates with copper and lead4 ,zinc becomes zinc oxide1 lead is converted into oxides4 ,sulphur1 as sulphuretted hydrogen1 causes the formation of metallic sulphides4 ,ammonia has a threefold action1 viz4 it causes and furthers hydration1 it is an energetic solvent1 and it forms double salts4 ,this last-mentioned action is particularly important in the formation of patina4 ,carbonic acid in the presence of moisture attacks copper1 lead and iron1 and1 as a carbonate1 exists in every metallic oxide which is exposed to the air4 ,several combinations of copper with carbonic acid are known1 while lead is readily converted into lead carbonate by oxidation4 ,the part played by the carbon compounds resulting from the decomposition of animal and vegetable substances has hitherto received little attention1 but this decomposition of organic material is probably the chief cause of the beautiful blue patina4 ,the action of oxygen will depend upon the composition of the metal1 upon the locality1 and upon numerous other circumstances1 while the colour of the patina will vary accordingly4 ,villenoisy proposes to classify patina into three groups3 7#a7 ,blue patina1 with grey to blue-green and apple-green tints4 7#b7 ,dark green patina4 7#c7 ,black patina4 #a4 ,the blue patina produced by the action of ammonia upon the products of previous oxidation does not destroy the outer form of the bronzes1 but is nevertheless unfavourable to the preservation of the metal1 since the substratum of the patina is a porous mass1 consisting of lead stannate and lead carbonate mixed with ammoniacal copper carbonate4 ,the specimen has frequently an intact appearance1 as if covered with a thin layer of oxide only1 whilst in reality all traces of metal have already disappeared1 and slight pressure often suffices to break the bronze into pieces4 ,the nearer the colour of the patina approaches to grey1 the less solid is the bronze likely to be1 a result which is no doubt caused by the presence of lead carbonate4 ,this type of patina has often a yellowish colour1 especially on prominent parts1 where1 being porous1 it has retained in its superficial layers substances which were in suspension in the subsoil water4 ,the occurrence of a pale fine-grained patina of a uniform colour is in almost all cases due to the scaling off of patina belonging to this type4 #b4 ,whilst blue patina is generally formed on bronzes which have been buried in earth1 the dark green patina is formed both in the earth and also in the open air4 ,the presence of lead seems to be an obstacle to its formation4 ,this dark green patina consists of variable proportions of basic copper hydrate and copper carbonate4 ,the green layer frequently rests upon one of a red colour1 a circumstance which proves that the dark green patina is almost always the result of two successive reactions3 cuprous oxide is first formed and subsequently takes up water and carbonic acid4 ,tin is present as copper stannate4 ,the cuprous oxide1 which is generally regarded as unaffected by air1 is perhaps drawn into further reaction through the agency of ammonia4 ,in those situations where there is a flow of rain water a certain translucency of the green patina is often produced1 and this is also possibly caused by ammonia4 ,unlike the blue patina1 the dark green variety assists the preservation of bronze4 #c4 ,black patina is probably due to a variety of circumstances4 ,the substances which enter into its composition are cupric oxide1 lead oxide1 lead peroxide1 copper sulphide and lead sulphide4 ,if bronze does not contain lead it is blackened only by the action of sulphur4 ,the rarity of black patina is no doubt due to the rapid oxidation of the copper on the originally rough1 unpolished surface1 which leads to the formation of a green patina4 ,these extracts show how little value can be attached to a classification of bronzes from the character of the patina present3 the views upon the subject are so divergent1 while the actual composition of the incrustations which form the patina and their external appearance are so widely different4 ,in fact only two groups of bronzes may be distinguished1 i4e4 those which show patina and those from which patina is absent4 ,the first group comprises almost all the bronzes which are found in peat1 which show1 with rare exceptions1 a metallic1 often somewhat darkened1 surface4 ,their state of preservation depends upon the nature of the peat in which they are found1 but the metal surface has1 in the majority of cases1 become somewhat rough and etched1 although all the details are clearly distinguishable4 ,more rarely one side retains the original polished surface while the other side is much corroded4 ,if a much corroded bronze is found1 the peat in which it has lain has probably contained free sulphuric acid 7see also p4 #ac74 ,all bronzes found in water must be included also in this group4 ,the second group will then comprise all bronzes with an oxidized patina4 ,the classification given by ,villenoisy seems entirely unsuitable1 for it does not by any means exhaust all the kinds of patina which may occur4 ,thus no mention is made by him of the frequent occurrence of a patina which contains chlorine4 ,if we separate the dark brown and the blackish patina1 in so far as these two colours are pure1 from those of a green colour1 the first two varieties cannot be regarded as groups1 because the tones of colour differ too much1 and because1 as ,villenoisy himself observes1 widely different patinas often occur on one and the same bronze4 ,the durability of a patina upon a bronze cannot be judged either by the outer appearance or by the chemical composition alone4 ,the fact that there has been no alteration in the outward appearance for many years offers no guarantee against further changes taking place4 ,thus a ,minotaur#ec in the ,berlin ,museum1 which for many years had shown no sign of change1 was eventually found to be completely covered with numerous bright green spots over its entire surface4 ,my own opinion is that the only patina which is really stable is that which consists of combinations of oxygen1 hydrogen and carbonic acid with the metal1 somewhat similar to those analysed by ,schuler 7see page #bd71 and by ,arche and ,hassack 7see page #bg74 ,the presence of sulphides1 and even of sulphates1 does not seem to be injurious4 ,if a patina is to deserve the name of a good1 sound1 or1 as it is termed1 a noble patina 7,edel-patina71 the original contours of the bronze with all its markings must be distinctly visible4 ,for this the patina must not be too thick1 must be of moderate hardness1 and above all must have an enamel-like surface4 ,apart from chemical influences1 such a patina can only have been formed in those cases in which the alloy has been homogeneous1 fine-grained1 dense and not porous1 and when its surface has been so smooth that oxidation has taken place very slowly4 ,under these conditions the colour of the patina may vary greatly1 for it may be bright green1 blue1 or of darker shades from yellowish to brown1 or even black4 ,these latter tints often denote patina layers of very slight thickness4 ,my own observations confirm ,villenoisy's view that the brown and the black patina are for the most part due to the presence of lead in the bronze4 ,rein#ed holds the same opinion in regard to ,japanese bronzes4 ,certain forms of patina are not necessarily prejudicial to the preservation of bronzes1 i4e4 the green and blue varieties which have the composition of malachite 7,cu,c,o#c1 ,cu7,,oh7#b7 and azurite 7#b;,cu,c,o#c1 ,cu7,,oh7#b71 both of which are very often found on the same bronze4 ,this variety of patina shows a crystalline structure4 ,the simultaneous formation of both varieties1 which is due to the greater exposure of one part of the bronze than another to the action of moisture1 is well shown by a specimen in the ,berlin ,museum#ee 7,fig4 #f74 ,this consists of the frontal portion of a ,boeotian bridle1 over parts of which leather straps had probably been tightly fixed4 ,those parts which had been thus somewhat protected from moisture were covered with blue azurite1 which contains a smaller quantity of water4 ,but the crystalline structure of these kinds of patina has often the disadvantage that the surface of the bronze is no longer clear1 and consequently engraved markings and even stamped impressions are not visible4 ,on page #adb may be seen illustrations of ,roman coins1 some parts of which are totally illegible4 ,more frequently met with than these varieties or than the so-called noble patina1 is that in which the bronze presents a more or less rough and pitted surface1 light or dark green1 or even grey in colour if there is a large proportion of lead present4 ,more rarely the tint is blue or brown4 ,the behaviour of such kinds of patina varies greatly1 but durability is for the most part assured if1 under the layer of green oxide1 a reddish layer of cuprous oxide is found4 ,this rule is perhaps not invariable1 for ,i have often found cuprous oxide present under the so-called spreading patina1 but absent beneath one which is undoubtedly durable4 ,illustration3 ,fig4 #f4 ,portion of bronze horse-trappings showing blue and green patina4 ,two instances may be here quoted as confirming ,wibel's view in reference to the reduction of cupric oxides to cuprous oxides and even to metallic copper 7see page #ag7ef4 ,in removing a sandy crust saturated with copper salts from a large ,egyptian bronze#eg1 small crystalline masses of copper were seen here and there1 separated from the metal beneath by a layer of cuprous oxide to which the admixture of tin gave a whitish tint4 ,the copper was mostly deposited in slight depressions upon the surface of the metal and could be easily removed4 ,similarly1 upon an ,etruscan mirror exhibited in the ,berlin ,museum#eh1 reduced copper can still be seen forming red spots upon the lighter coloured surface of the bronze1 which has already been freed from cupric oxide4 ,the copper also can be removed with comparative ease1 and is observed to be separated from the bronze by a thin whitish layer of tin oxide4 ,a quantitative analysis of a small piece showed #ajj of copper4 ,as has been remarked above1 the layers of oxide frequently enclose grains of sand and even fragments of clay1 earth1 and ferruginous particles1 so that the original contours of the bronzes are often indistinct or entirely obliterated 7see ,figures #da-dc74 ,these incrustations may occasionally be removed by a careful use of the hammer1 but they are often so firmly united with the bronze1 which is itself so oxidized1 that removal by mechanical means is no longer possible4 ,illustration3 ,fig4 #g4 ,head of ,osiris1 showing advanced condition of warty patina#ei4 ,these incrustations are however not so injurious as the tuberous and warty patina4 ,figure #h shows an ,etruscan mirror covered with a patina which generally results in the progressive destruction of the bronze#fj4 ,illustration3 ,fig4 #h4 ,etruscan mirror showing warty patina4 ,the following series of quantitative determinations of chlorine obtained from the examination of bronzes in the ,berlin ,museums1 shows conclusively the destructive influence of chlorine in the production of patina3 ,percentage of chlorine ,dark green noble patina 7wine pitcher1 ,ant4 ,misc4 ,inv4 #gafa7 #j ,green patina on a layer of cuprous oxide 7,etruscan vase1 ,ant4 ,fr4 #aega7 #j ,dark blue noble patina 7,etruscan wine pitcher1 ,ant4 ,fr4 #fjh7 #j ,bright blue noble patina 7,etruscan mirror1 ,ant4 ,misc4 ,inv4 #gbge7 #j ,bright blue noble patina 7lid of vessel1 ,ant4 ,misc4 ,inv4 #fcbb1 #bib a7 #j ,hard greenish-yellow exfoliating patina upon a bright green1 softer patina 7,roman saucer1 ,ant4 ,fr4 #afja a7 #j ,bright green fairly firm patina1 the colour rubbing off somewhat in parts 7handle of vessel1 ,ant4 ,fr4 #addj7 #j ,a firm smooth green layer upon a brighter soft patina 7mirror1 ,ant4 ,fr4 #acf7 #j ,blue crystalline patina 7harness from ,boeotia1 ,ant4 ,misc4 ,inv4 #hegi7 #j ,rough dark green patina 7situla1 ,ant4 ,misc4 ,inv4 #heji7 #j ,greenish noble patina 7sword1 ,ant4 ,fr4 #aadd7 trace ,rough green softer patina1 with admixture of earth 7funnel1 ,ant4 ,misc4 ,inv4 #hehb7 trace ,dark green1 compact warty patina 7mirror1 ,ant4 ,fr4 #cb7 trace ,green warty patina1 with translucent cuprous oxide 7mirror1 ,ant4 ,misc4 ,inv4 #ccab7 trace ,green and blue crystalline patina 7,buto1 ,aeg4 #acace7 #ag ,bright green cracked and warty patina 7muzzle of the harness from ,boeotia1 ,ant4 ,misc4 ,inv4 #hegi7 7see ,fig4 #ch7 #ag ,green firm warty patina 7,etruscan mirror1 ,ant4 ,fr4 #ec7 #ba ,completely oxidized ,cyprian bronze fragment 7,ant47 #bb ,green cracked patina upon a thick layer of cuprous oxide 7bronze fragment from ,troy7 #dj ,completely oxidized ,cyprian bronze fragment 7,ant47 #db ,bright green efflorescent patches upon dark tuberous patina 7bronze fragment1 ,ant47 #ei ,bright green powdery patina in the hollows of a darker smoother patina 7,horus1 ,aeg4 #aajaj7 #fg ,bright blue powdery moist patina 7,aeg4 #abffc7 #gd ,green and blue patina mixed with grains of sand 7,buto1 ,aeg4 #acacb7 #hc ,bright green cracked patina 7bronze fragment from ,troy7 #ic ,bright green powdery patches1 dark green rough patina 7cup1 ,ant4 ,fr4 #afed7 #ajb ,thick greenish black tuberous patina 7,besa1 ,aeg4 #igaf7 #ajh ,green firm patina1 with brighter patches 7,buto1 ,aeg4 #acghg7 #aac ,bright green powdery patina 7,isis with ,horus1 ,aeg4 #adjgh7 7copper7 #abe ,green tuberous and cracked patina 7,horus in the lotus flower1 ,aeg4 #bdji7 #aca ,bright green powdery excrescences 7,buto1 ,aeg4 #acghg7 #aci ,bright green soft patina1 with a dark and somewhat firmer surface 7door hinge from ,babylon1 ,aeg4 ,v4,a4 #bahe7 #aea ,a due consideration of these figures must lead to the conclusion that as a rule a malignant patina is one which contains chlorine4 ,that traces of chlorine are found in many cases of benign patina need cause no surprise1 for frequent handling alone may suffice to bring about such a condition4 ,nor is this rule invalidated by the fact that a patina which is proved to contain chlorine 7e4g4 that of the mirror#fa depicted on page #dj71 has remained unchanged for years under certain conditions1 for the formation of patina depends upon various causes1 and it often happens that a bronze carries a patina which outwardly seems to have stood the test of years1 yet internally oxidation has continued and becomes outwardly visible only when some mechanical injury to the patina allows variations of temperature to exert a greater influence4 ,a specimen is often regarded as bronze1 whereas in reality it does not even contain a metallic core1 but consists merely of cuprous oxide1 copper oxychloride1 tin oxide1 etc4#fb1 and is therefore incapable of further change4 ,on the other hand it is not surprising to find a patina1 which1 although containing no chlorine1 affords but a poor protection to the bronze1 for in this case the cause may lie in the non-homogeneous and porous nature of the alloy4 ,this list shows in addition that this high chlorine-content is a distinguishing feature of the patina of ,egyptian bronzes1 as is only to be expected from the character of the ,egyptian soil 7vide pp4 #a1 #b et seq472 in fact1 although in most cases qualitatively only1 ,i have proved the existence of chlorine in each ,egyptian bronze without an exception4 ,the destructive nature of chlorine is not often apparent in bronzes recently excavated1 which usually show an apparently sound1 dark green patina with a smooth surface1 sometimes like malachite or azurite2 personally ,i have not met with any bronze object from ,egypt which could be said to have a patina deserving the name of noble patina4 ,not till some time1 or it may be not till years after the objects have been placed in museums does the change become apparent1 as has been so strikingly described by ,mond and ,cuboni 7see page #bg74 ,the varying amount of moisture in our atmosphere undoubtedly influences the spread of the patina1 which1 if the application of a preservative is delayed1 gradually eats into the bronze4 ,the adjoining figures 7,fig4 #i to #ab7 of the same bronze before and after the process of preservation show distinctly such ravages1 whereby the surface has been in some places eroded to a depth of #b to #c mm4 ,in other cases1 especially hollow bronzes1 the thin walls have been completely perforated4 ,the explanation of these processes is found in the experimental work of ,krefting#fc1 and also in the treatise by ,berthelot1 from which extracts have already been given4 ,the theory enunciated by ,mond and ,cuboni1 that the wild or spreading patina is due to the action of bacteria1 cannot now be maintained1 for not only do chemical reactions give an adequate explanation of the process1 but these observers have failed to transplant the bacteria2 nor were the experiments of ,dr ,stavenhagen1 undertaken at our request1 more successful4 ,that certain bacteria are capable of attacking metal1 as for example the metal lettering on books1 is an established fact1 while the universal distribution of bacteria will naturally lead to their presence upon bronzes and their patina4 ,the application of heat checks chemical change by driving off the moisture1 and therefore arrests the spread of a patina for some time1 until by penetrating the oxidized layer the moisture and carbonic acid can again act upon the patina and the underlying metal4 ,as has been already stated in the passage from ,dingler's ,polytechnic ,journal quoted above1 ,i have observed the renewed formation of efflorescence upon a bronze statuette which had been thus sterilised4 ,this1 it may be urged1 was a case of re-infection3 it is1 however1 strange that ,mond and ,cuboni do not refer to chlorine as a component of the patina4 ,the presence of chlorine may have been overlooked2 it cannot well have been absent1 for in every case of rodent patina ,i have found without exception chlorine in the bright green efflorescences1 whatever may have been the original source of the bronze4 ,illustration3 ,fig4 #i4 ,bronze ,pasht showing destructive patina4 ,illustration3 ,fig4 #aj4 ,the same after treatment 7,finkener's method74 ,illustration3 ,fig4 #aa4 ,bronze ,pasht showing destructive patina4 ,illustration3 ,fig4 #ab4 ,the same after treatment 7,finkener's method#fd74 ,nor am ,i able to endorse the statement of ,friedel#fe that a spreading patina is characterised by a peculiar and disagreeable smell1 although some oxidized bronzes have a distinct smell which it is not easy to describe4 ,the presence of chlorine is particularly dangerous to those bronzes which consist of a casing of metal of variable thickness around a core of sandy clay1 the object of which has been to economize metal4 ,these constitute an important class amongst ,egyptian bronzes4 ,the chlorine often exists in the core as sodium chloride1 and can thus attack the metal from both sides4 ,moreover1 the structure of many ,egyptian statuettes of a later period is very porous and spongy1 and thus presents a large surface to destructive agencies4 ,on sawing through the support of an ,osiris#ff numerous small bright spots were found1 upon examination with a lens1 to be small pores filled with a salt solution4 ,a few days later the action of the carbonic acid had begun1 and the bright spots of moisture were represented by small green patches4 ,the following figures show the absorption of moisture and of carbonic acid by this specimen and by another ,osiris from the ,egyptian collection4 ,i4 ,base of ,osiris4 ,weight1 air-dried #adfeed gr4 ,after one day in the desiccator #adfead gr4 ,air-dried1 after one day #adfedj gr4 ,air-dried1 after ten days #adfegf gr4 ,air-dried1 after one month #adfeii gr4 ,air-dried1 after two months #adffbc gr4 ,air-dried1 after four months #adgbfa gr4 ,after a prolonged period in the desiccator #adgjcc gr4 ,air-dried1 after one day #adgbed gr4 ,air-dried1 after one month #adgcba gr4 ,air-dried1 after two months #adgcfb gr4 ,air-dried1 after four months #adgcha gr4 ,,ii4 ,osiris4 ,weight1 air-dried #gggebb gr4 ,after some time in the desiccator #gggcig gr4 ,air-dried1 after one day #gggdfb gr4 ,air-dried1 after ten days #gggedh gr4 ,air-dried1 after one month #gggehb gr4 ,air-dried1 after two months #gggfag gr4 ,air-dried1 after four months #ggggjd gr4 ,after being heated to #bjj;,c4 in the drying stove and lying one day in the desiccator #ggeifg gr4 ,air-dried1 after one day #ggfgeb gr4 ,air-dried1 after one month #gghjdd gr4 ,air-dried1 after two months #gghaia gr4 ,air-dried1 after four months #gghcbj gr4 ,air-dried1 after seven months #gghddd gr4 ,after four days in the desiccator #gghbbe gr4 ,these figures show that in the first case the absorption of carbonic acid1 oxygen1 and water proceeded at first slowly1 but more rapidly after three months1 as was evidenced also by the appearance of marked efflorescence on the oxidized surfaces4 ,the ,osiris1 which was more highly oxidized1 showed a more rapid increase in weight from the first4 ,the increased action after the heating was also manifest externally1 for at the end of a fortnight the bright green efflorescences had made their appearance4 ,in this case therefore the heating recommended by ,mond and ,cuboni1 so far from proving beneficial1 actually induced a more rapid decay4 ,the patina layer1 as ,schuler has also observed1 often contains a greater proportion of tin than does the alloy2 a result which is manifestly due to the solution and removal of the copper salts by the subsoil water4 ,the bright efflorescences of an ,egyptian statue of ,buto#fg contained #ajdi of tin1 while the percentage in the metal itself was only #gff4 ,in certain circumstances it may even result that an object which was originally composed of bronze is represented only by tin oxide#fh4 ,the small proportion1 and occasionally the complete absence1 of copper is the result of the action of ammonia which may arise from the decomposition of dead bodies and of carbonic acid1 both of which agents1 with the help of oxygen1 attack the buried bronzes1 and1 dissolving the copper compounds by the subsoil water1 leave only the insoluble tin oxide4 ,upon the whole the foregoing remarks upon bronzes are equally applicable to objects of copper1 which however appear to possess a greater power of resistance to the destructive action of carbonic acid and moisture1 even where salt is present4 ,this is probably due to the fact that the absence of tin and lead precludes any interaction between the compounds of these metals and those of copper4 ,copper objects with a sound so-called noble patina apparently do not occur4 ,silver4 ,unless alloyed with a large amount of copper1 in which case they show green efflorescences similar to those of bronzes1 silver objects are almost always covered with a layer of soft silver chloride 7horn-silver7 of varying thickness1 ,ag,cl1 or of the harder silver subchloride1 ,ag#b;,cl2 and when these compounds form a thick layer1 they often show a warty or more rarely a cracked surface4 ,if the layer of chloride is thin1 incised designs upon the silver will be visible both before and after removal of the chloride4 ,the two chlorine compounds frequently appear together in distinct sharply defined layers of different colours1 that nearer the silver being the layer of subchloride4 ,this is especially well shown on fragments of silver from the ,hildesheim silver-find#fi4 ,upon one fragment#gj the layer of silver chloride was about twice as thick as that of the silver subchloride4 ,being unable to separate them ,i determined the silver and the chlorine of both layers together with the following result3 ,silver #gdeb4 ,chlorine #baij4 ,now for #b;,ag,cl1 ,ag#b;,cl #gdeb silver would correspond to #ahaa chlorine only1 while for ,ag,cl the proportions would be #gdeb silver to #bdae chlorine4 ,since the specific weight of silver subchloride is greater than that of silver chloride1 these figures prove that the subchloride is also present4 ,between the metal and the silver chloride there is often a thin powdery layer consisting of finely divided cupric oxide1 or silver sulphide1 and occasionally of gold1 if1 as is frequently the case1 the silver is auriferous4 ,the presence of gold may1 however1 also point to the existence of gilding4 ,the silver chloride often shows a reddish or brown colour on the surface1 due probably1 in some cases1 to the adherence of minute quantities of the earth in which it was found1 but partly also to the action of light upon the silver chloride4 ,thin black layers upon silver1 as also the so-called silver tarnish1 result from the formation of silver sulphide1 from contact with decaying organic substances which have contained sulphur4 ,when placed in museums silver objects remain unaltered1 and no further chemical changes take place4 ,any other changes which have been observed will be gathered from the following extracts4 ,church#ga analysed a specimen of silver upon which two layers were distinguishable4 ,the outer semi-metallic layer consisted of metallic silver1 with traces of chloride1 sulphide1 and iodide of silver1 together with copper carbonate and a small quantity of gold2 the inner layer1 which was soft1 grey and powdery1 had the following composition3 ,silver #idfi ,gold #jda ,copper #cdh ,lead #jbh ,antimony with traces of arsenic and bismuth #aba ,as the composition of the sound metallic core was identical1 it is evident that physical and molecular changes only had taken place similar to those observed by ,warrington#gb as early as #ahdc4 ,silver objects found in ,mycene are said by ,mitzopulos#gc to show three layers1 the outermost of which has a red colour and is not markedly friable1 consisting of silver oxide2 the second is tough and consists of silver chloride 7horn-silver72 while the third1 that next to the metal1 is similar to the outermost layer4 ,mitzopulos thinks that the chlorine must have been brought by rain water1 since there are neither sea nor springs of water in the neighbourhood4 ,schertel#gd distinguished two layers in fragments of silver from the ,hildesheim silver find1 the outermost of which proved to be silver chloride3 ,silver #gedc found1 #geca calculated for ,ag,cl ,chlorine #bdea found1 #bdfi calculated for ,ag,cl ,beneath this layer was a very thin1 almost black1 brittle layer of silver subchloride3 ,silver #hgj found1 #hehi calculated ,chlorine #abh found1 #adaa calculated ,between the metal and the latter layer was a small quantity of dark powder1 which ,schertel recognized as gold4 ,he thinks that the layer of silver subchloride seems to indicate that the water1 which permeated the surrounding clay1 contained chlorides1 and first converted the copper into copper chloride2 that the copper chloride together with the silver then formed silver subchloride and cuprous chloride4 ,should the subchloride again become chloride1 it would be able to attack the silver afresh4 ,the slowness of the process1 when the silver and copper in association with it had been converted into chlorine compounds1 allowed the gold to be deposited as a fine powder upon the intact metal4 ,a silver coin rolled out into a thin plate1 after remaining in a solution of common salt for six months1 was found to have lost #bgg of its copper1 so that the plate became brittle1 especially in those parts where it was thinnest4 ,bibra#ge gives a similar explanation of the conversion into silver chloride4 ,he believes that the reddish colour which is occasionally seen on silver at a fresh fracture must be due to the presence of cuprous oxide4 ,the following extract is taken from the section which deals with silver in the work of ,berthelot#gf previously quoted3 ,silver chloride is for the most part produced by the sodium chloride dissolved in the subsoil water1 which acts in conjunction with the oxygen and the carbonic acid of the air3 #b;,ag ,o 7n #b7 ,na,cl ,,co#b #b;,ag,cl1 n,na,cl ,na#b;,,co#c4 ,but this reaction differs from that which takes place in the case of copper in that it does not proceed continuously except in the presence of a considerable quantity of salt water only1 as for instance in the sea4 ,in museums the alteration goes no further than corresponds to the minute quantity of sodium chloride contained in the object4 ,on the other hand in an earth which contains salts1 the continued presence of water can bring about a more or less marked change1 and in some cases even a stable silver subchloride may be formed4 ,lead4 ,objects of lead have always a white appearance due to the formation of lead carbonate1 as has been already mentioned above in connection with bronze4 ,the carbonate is also often mixed with oxide4 ,tin4 ,objects made of tin#gg are frequently found in pile-dwellings in a good state of preservation4 ,they are1 however1 occasionally covered with white or brown layers of hydrated tin oxide1 while in some cases oxidation has advanced so far that no trace of metallic tin is left in the hard grey masses of oxide which result4 ,gold4 ,gold is found to be unaltered1 or there is at most a thin layer of silver chloride1 which is the result of the action of sodium chloride upon the silver which the gold usually contains4 ,gold objects often have a red coating1 which has been found to consist of ferric oxide1 and is due to extraneous deposits which have been fixed by the silver chloride4 ,i have not been able to prove the presence of gold chloride#gh1 and it does not appear possible that water containing sodium chloride can have the power of acting upon gold4 ,if the ferric oxide is removed mechanically1 some of the gold will naturally be removed with it1 and this can be readily ascertained on analysis4 ,the degree of brittleness in objects of gold depends upon the changes which have taken place in other metals1 especially silver1 which are mixed with it4 ,glass4 ,ancient glass1 which is for the most part lime-soda silicate1 exhibits a dull1 rough surface with the well-known iridescence4 ,the alkali is removed from the glass by the action of moisture1 oxygen and carbonic acid1 while the silicic acid remains in the form of minute scales1 which cause the iridescence by interference4 ,according to ,bunsen the chemical action of the gases of the atmosphere on glass is facilitated by the condensation of water upon its surface2 for the water thus condensed absorbs large quantities of carbonic acid4 ,in certain circumstances almost the whole of the alkali is withdrawn from the glass4 ,an analysis of glass of this kind1 together with a discussion of the chemical reactions involved1 is given in ,muspratt's ,chemistry#gi4 ,glass objects which are markedly iridescent undergo gradual decay even under museum conditions2 this is probably due to the continued action of carbonic acid4 ,organic ,substances4 ,the changes which organic substances undergo are various2 thus1 while leather becomes hard1 papyrus becomes brittle4 ,like all other organic material they may undergo those destructive processes which are due to the growth of moulds or to the agency of various bacteria4 ,they are also liable to be attacked by maggots1 moths1 and other insects4 ,it is unnecessary here to describe in detail these numerous and varied changes2 a few special cases only need be mentioned4 ,acid peat1 in which iron objects perish1 is found to have a good preservative action upon wool and horn1 whilst vegetable fibres are destroyed4 ,on the other hand1 in pile-dwellings wool and horn substances have disappeared4 ,olshausen#hj thinks that animal fibre is destroyed by simple decay brought about by the oxygen in solution in ordinary water1 whilst in peat the immense quantity of vegetable matter takes up the oxygen which can therefore no longer serve for the oxidation of wool and similar material4 ,under certain circumstances woollen textures are found to be remarkably well preserved in oak coffins1 as may be seen in the ,museum at ,copenhagen4 ,bones1 horn1 and ivory show great variety in their behaviour1 which depends of course on the nature of their surroundings4 ,thus for instance in acid peat sometimes the animal matter only is preserved#ha1 while in graves1 beyond a few remains of tooth enamel1 there is often nothing to show that they have enclosed bodies4 ,burned bones are generally found to resist decay1 for the destruction of the animal matter leaves them no longer liable to further decomposition#hb4 ,amber objects are well preserved in water or in peat1 but if they have lain in earth1 they are darkened and often friable4 ,if organic substances1 such as wood1 etc41 have lain in the immediate neighbourhood of oxidized bronze1 and are thereby saturated with copper compounds1 they show a very good state of preservation1 which continues after they have been placed in a collection4 ,similarly the remains of fabrics upon iron objects1 which are permeated with rust1 are sometimes found in good condition4 ,objects imbedded in salt 7sodium chloride7 are in certain circumstances found in a good state of preservation and continue so1 as is shown by the skins1 leather and wooden articles which are exhibited in the ,salzburg ,museum4 ,as a general rule absence of moisture in the earth is essential for the preservation of organic substances1 and is the cause of the splendid condition in which objects of organic material are found in ,egypt4 ,,part ,,ii4 ,,the ,,preservation ,,of ,,antiquities4 ,the object with which it is proposed to deal should first be photographed1 and from different sides if necessary2 for the external appearance is often changed during the process of preservation1 and it is advisable that a representation of the specimen in its original condition should be kept in case any injury should befall the object1 which however rarely happens if proper caution be observed4 ,for this reason in the ,laboratory of the ,royal ,museums at ,berlin all bronzes are photographed before treatment1 as also are all limestone blocks4 ,thus the #abe blocks from the ,grave-chamber of ,meten were each separately photographed4 ,it is only in certain cases that this rule is not observed1 as for instance in the case of the numerous ,egyptian ostraca1 i4e4 fragments of earthenware showing inscriptions which had been previously copied4 ,i4 ,preservation of ,objects composed of ,inorganic ,substances4 7a7 ,limestone4 ,the method formerly employed for the preservation of decaying and crumbling limestones was that of simple impregnation1 and this is still followed in some cases which will be subsequently described4 ,but as the active agents of destruction are not removed by this method the result is not always satisfactory1 and an attempt is now made where possible to remove those salts which are soluble in water1 especially the sodium chloride1 by the simple process of steeping in water4 ,if the presence of salt in a limestone is evidenced by a crumbling surface1 or by the taste when touched with the tip of the tongue1 the question will arise whether it will bear steeping1 or whether the destruction is so far advanced that1 on being placed in water1 the limestone will fall to pieces4 ,if fractures or cracks can be actually seen in the stone1 steeping is contra-indicated1 but if the condition is less manifest1 a preliminary test should be applied4 ,a large drop of water1 e4g4 about #be cubic centimetre in volume1 should be placed on the surface of the stone1 and any changes which take place should be carefully noted4 ,if the drop is not absorbed by the stone1 it may be due to a layer of dust or to previous saturation with solutions of resin or varnish4 ,dust may be removed with a moderately hard brush or by rubbing with the finger1 but if a limestone has been previously saturated with a varnish solution it will not absorb the water1 and is therefore hardly suitable for this treatment4 ,if the drop is absorbed1 an iron or a steel point1 such as the thick end of a medium-sized needle1 should be used to ascertain whether the limestone at the moistened spot shows the same degree of hardness as elsewhere4 ,if this is found to be the case1 especially if the pieces are of a large size1 the test should be repeated at other spots1 including the back of the stone1 for a hardened layer on the front aspect may be the result of former treatment4 ,if the result of this examination is satisfactory and no soluble colouring is observed on the limestone1 the process of steeping may be applied4 ,if on the other hand the moistened area has become softer1 or has become to any extent swollen1 or if any colours which may be present show signs of disappearance or fading1 treatment with water must be abandoned4 ,the difference of behaviour is easily explained1 for limestones do not always consist of lime only1 or1 more correctly1 carbonate of lime 7,ca,c,o#c71 but often contain sand or clay1 and the greater the amount of clay the more readily the stone softens or swells4 ,even when a limestone has borne this preliminary test satisfactorily it should be carefully watched for an hour or two after immersion and should be at once removed from the water should any further changes appear4 ,steeping4 ,the procedure to be observed is as follows4 ,the rapidity with which the salts may be removed varies directly with the quantity of water used in steeping4 ,the treatment of objects of small size presents no difficulties2 any vessel of glass1 porcelain1 or earthenware will serve the purpose4 ,towards the end of the treatment distilled water should be used1 or in default of this1 clean rain water should be used in preference to that from a well4 ,for larger objects 7as1 for example1 the large limestone blocks of the ,meten ,chamber mentioned above1 some of which were #a metre in length and #a_/b metre or more in breadth and thickness71 it is convenient to use wooden tubs fitted with a tap in front to draw off the water1 and so tilted by means of stones placed underneath that the tap may be at the lowest point4 ,the objects should not touch the bottom of the vessel4 ,smaller pieces may be suspended or may be made to rest on glass rings or supports of glass rods2 while large objects should be laid on blocks of wood so placed as to allow the tub to be cleaned when necessary without removal of the blocks1 the weight of which would otherwise entail much labour4 ,the blocks should be as near to the surface of the water as possible1 leaving a considerable depth of water beneath1 for the heavier salt-laden water sinks to the bottom1 thus bringing into contact with the limestone water with a smaller salt-content4 ,the length of the steeping must depend upon the size and porosity of the limestone4 ,under certain circumstances phenomena make their appearance which must not be neglected4 ,thus if the treatment extends over a considerable length of time1 the wooden tubs should be provided with lids to prevent the access of light4 ,this was found indispensable in the treatment of the blocks from the ,meten ,chamber when ,berlin tap-water#hc was used1 for when the tubs were open a large quantity of brown hydrated ferric oxide appeared on the limestone1 the roughness of which rendered its removal an impossibility even with brushes4 ,this oxide is produced by various forms of algae and bacteria which developed in such numbers that the sides of the tubs were frequently covered with a layer of slime1 which under the microscope appeared as a confused web of transparent threads#hd4 ,this was brushed off with soft brushes at least once a fortnight1 for the slimy covering impeded the access of the water to the limestone4 ,that in this case the ferric oxide was the result of the action of light was proved by the fact that only those blocks which were placed near the windows were discoloured1 and that the discolouration was proportionate to the amount of light which fell upon them#he4 ,again1 after the treatment in the covered tubs some of the blocks became so black that they resembled blocks of coal rather than limestone4 ,after exposure to light for a day or two1 especially when the water had been drawn off1 the discolouration disappeared without leaving any traces4 ,the colour was doubtless due to a minute quantity of iron in the form of sulphide which1 after oxidation in the air and light1 became invisible upon the light yellow limestone4 ,under these circumstances the presence of sulphuretted hydrogen in the water1 possibly produced by bacterial action upon the sulphates1 was attested by the characteristic smell4 ,the enormous number of bacteria which develop in the water constitute a great hindrance to the process of steeping1 and as to boil such a quantity of water as is required for these large objects is out of the question1 frequent changes of water and frequent cleaning of the stone1 wooden blocks1 and tubs are the only remedies4 ,examination of the ,progress of the ,steeping4 ,the water should be changed at first daily1 then by degrees every two1 three1 or four days1 later on weekly only1 until finally once a fortnight is sufficient4 ,to ascertain the progress and completion of the elimination the quantity of chlorine in the wash-water may be determined by a simple method of titration#hf4 ,the following short explanation may be of use1 and the method is easily learnt4 ,if a solution of silver nitrate is poured into a solution of common salt 7sodium chloride71 a white curdy precipitate is produced1 a process which the following equation will explain3 ,na,cl ,ag,n,o#c ,ag,cl ,na,n,o#c4 ,the white precipitate is the silver chloride1 whilst the sodium nitrate which is produced at the same time remains in solution and is therefore not visible4 ,as always definite proportions of the two substances1 silver nitrate and sodium chloride1 react upon one another1 by the use of a solution containing a known amount of silver nitrate we can determine the amount of salt1 and hence of chlorine present4 ,by cautiously inclining a burette 7,fig4 #ac7 divided into tenths of cubic centimetres#hg1 the silver solution should be dropped into a beaker containing a definite volume of the solution to be examined for chlorine2 the level of the silver solution in the burette should be read off before and after pouring out1 and the number of cubic centimetres of the silver solution required to precipitate the chlorine will thus be known4 ,illustration3 ,fig4 #ac4 ,gay-,lussac's ,burette4 #a_/f nat4 size4 ,the process when carried out in this manner has one defect1 for it is necessary to allow the precipitate to settle in order to see clearly whether an additional drop of the silver solution will produce further precipitation1 or whether it will merely cloud the fluid2 this defect can1 however1 be remedied by means of a so-called indicator4 ,a few drops of a concentrated solution of neutral yellow potassium chromate should be added to the fluid to be examined1 which is thereby coloured yellow2 the solution is then shaken or stirred with a glass rod1 while the silver nitrate is dropped in4 ,every drop of the silver solution will cause a red precipitate1 the colour of which however disappears on stirring so long as there is any chlorine present2 only when the silver solution has precipitated all the chlorine does the red colour become permanent1 and thus the change of colour of the whole fluid from yellow to red shows with exactness the complete precipitation of the chlorine4 ,for practical purposes all that is required is the so-called decinormal silver solution1 and from the number of cubic centimetres of this solution which are required to precipitate all the chlorine the total amount of chlorine present can be readily calculated4 ,in steeping smaller objects before examination the whole of the water should be well stirred with a glass rod or poured two or three times from one vessel into another3 #ajj1 #ej or #be cubic centimetres are then poured into a graduated glass or drawn up into a pipette4 ,the water should be drawn up by suction slightly above the level of the mark upon the stem of the pipette1 the upper end of which is immediately closed with the thumb4 ,by slightly raising the thumb the water is allowed to run off until its upper surface is exactly level with the mark4 ,the amount taken is then placed into a beaker 7for #ajj cubic centimetres a beaker of #djj c4c4 capacity should be used71 and1 after the addition of a few drops of a solution of potassium chromate1 is examined by titration4 ,in the treatment of large objects1 for which tubs are required1 the necessary quantity of water may be drawn by means of a long pipette from the bottom of the tub1 where the quantity of salt is always greatest1 or through the tap at the bottom of the tub 7as was done with the blocks from the ,meten ,chamber1 in which case about #a litre was drawn off into a glass out of which #ajj c4c4 were taken for titration74 ,to obtain results which are comparable1 care must be taken that the object is always as nearly as possible in the same quantity of water4 ,after placing the larger blocks in the water1 one examination should be made during the first few days1 when the titration may require #bj c4c4 or more of silver solution4 ,there is no need to examine for chlorine while the water is being frequently changed3 indeed1 in order to economise the silver solution1 this need not be begun until the second month1 when the water is changed every fortnight4 ,as has been stated above1 it is only necessary to read off the number of cubic centimetres of the solution used in the titration1 for the decrease in these figures is a sufficient indication of the progress of the operation1 while the diminution of the chlorine-content may be taken as an indication of the simultaneous removal of the sulphates#hh4 ,in the treatment of small objects in distilled water1 the process may be regarded as complete if the red colour is obtained on the addition of from one to two drops 7i4e4 about #a_/aj to #a_/e cubic centimetre7 of the silver solution4 ,if1 when tap-water is used1 and is being changed at intervals of a fortnight or a month1 the estimations give a constant result between #jf and #aj1 the treatment need not be carried further4 ,the accompanying table shows the figures obtained from three large blocks from the ,meten ,chamber4 ,they represent the number of cubic centimetres of decinormal silver solution used for #ajj c4c4 of the water1 which was changed every fortnight4 ,the first column on the left shows the dates upon which the stones were placed in the tubs3 ---------------------------------------- ----------------------- #c ,feb4 #g ,apr4 #d ,may #b ,june#be ,aug4#bb ,sep4 #d ,nov4 #a ,dec4#ab ,jan4 #ahij #ahia ---------------------------------------- ----------------------- #cj #be #bc #ad #aj #ji #jh #jh ---------------------------------------- ----------------------- #be ,apr4 #i ,may #ah ,july #a ,aug4#be ,nov4#bc ,dec4#af ,feb4#bi ,aug4#ab ,sep4 #ahic #ahid ---------------------------------------- ----------------------- #fj #ef #di #bj #ag #ae #jh #jh ---------------------------------------- ----------------------- #bi ,july#bh ,oct4#be ,nov4#bc ,dec4#bj ,jan4#af ,feb4 #a ,aug4#bi ,aug4#ab ,sep4 #ahic #ahid ---------------------------------------- ----------------------- #cj #bj #ae #ac #aa #jg #jh #jg ---------------------------------------- ----------------------- ,when repeated examinations gave a fairly constant result of #jg-jh cubic centimetre the process was regarded as complete1 for ,berlin tap-water itself contains small quantities of chlorine compounds1 #ajj c4c4 requiring from #jd to #jf c4c4 decinormal silver solution4 ,before using the water from a well or from waterworks1 it should be examined to ascertain the number of cubic centimetres of silver solution required to produce the red colouration4 ,as the amount of chlorine compounds in the water may vary it is advisable to repeat the examination#hi4 ,the following table shows the rapidity with which salts can be completely extracted from small pieces of limestone4 ,the limestones were placed in tap-water in three glass cylinders1 each containing #b litres2 the amount of silver solution required for the water was #jde c4c4 per #ajj c4c4 ---------------------------------------- ------------------------ ,no4 of days of soaking in water #a #a #a #b #b #d ---------------------------------------- ------------------------ #a,weight in grammes #ajgcd c4c4#adaajgjeje;cubic centimetres of decinormal silver solution4 #b,weight in grammes #ffcj c4c4#abjgje --#je;cubic centimetres of decinormal silver solution4 #c,weight in grammes #dgcf c4c4#jhjfje --#je;cubic centimetres of decinormal silver solution4 ---------------------------------------- ----------------------- ,these figures show the numbers of the c4c4 of silver solution used for every #ajj c4c4 of the water1 which was changed after #a1 #b1 etc4 days as shown above4 ,after #i to #aa days therefore the stones could be declared free from salt4 ,if the accuracy of the titration method be considered unnecessary1 either on account of the small number or size of the objects to be treated1 or for reasons of expense 7the outlay required is however very small71 a solution of unknown strength may be used4 ,a comparison between the degree of turbidity produced on mixing the silver nitrate solution with the tap-water1 and that produced with the wash-water1 will enable the progress of the operation to be gauged4 ,advantages and ,disadvantages4 ,although steeping removes the cause of decay1 i4e4 the salts contained in the limestone1 and although permanence may be considered as certain1 there are certainly some disadvantages connected with the process1 especially when the pieces1 on account of their size1 must remain in the water for some length of time4 ,some large and very thick blocks from the ,meten ,chamber required to be soaked for more than a year4 ,the small quantity of carbonic acid which is always found in water dissolves small quantities of calcium carbonate1 thus the sharp contours of prominent parts may become somewhat rounded4 ,limestones which have developed fissures may1 on immersion1 lose small portions which might otherwise have remained attached1 though probably for a while only4 ,in such cases it must be carefully noted from which block1 and from which part of it1 the fragment has broken off1 in order that it may be replaced#ij4 ,limestones which are much cracked1 or which are likely to fall to pieces1 should be wrapped round with gauze1 or held together with twine1 before they are put in the water4 ,in addition to the permanent preservation of the object some other smaller advantages of this method may be mentioned3 for example1 the layer of dust which is often present is removed and thus traces of colours may be brought out by the steeping which had been concealed by it4 ,thus certain remains of colour mentioned by ,lepsius#ia as being still visible in his time upon some of the blocks from the ,meten ,chamber were no longer visible when we took them in hand4 ,moreover traces of green colouring which were visible after the treatment in the eyes of a few large figures in relief were probably evidence that colours had formerly been present4 ,drying4 ,when the steeping is finished the limestone is taken out to be dried4 ,small objects may be placed upon a glass ring1 wooden tripod or some such appliance1 which admits air on all sides1 and may thus be dried by the air only4 ,a piece of paper laid loosely over them will protect them from dust4 ,in winter a hot stove1 or similar source of heat1 affords a satisfactory method of drying1 but wet stones must not of course be placed directly upon the hot iron stove plate lest spots of rust should be produced upon the stone4 ,large blocks are preferably dried in drying chambers in which in summer time a strong draught is obtained by opening windows on opposite sides1 and which in winter are strongly heated and opened every now and then for a short time4 ,the limestones should be laid upon wooden blocks to allow air to pass beneath them1 while they must be guarded from dust both above and at the sides with sheets of paper4 ,several months are often required to dry large blocks completely4 ,impregnation4 ,when limestones have been completely dried1 especially if they are soft1 it is often advisable to impregnate them with one or other of the impregnation agents4 ,to economize material1 large objects may be painted over once or twice with a solution of the material chosen1 but smaller objects should be immersed in the solution until air-bubbles are no longer formed4 ,if there is a supply of tap-water with sufficiently good pressure1 rapid and complete penetration by the fluid can be ensured by placing the object in a vessel containing the necessary fluid under a bell glass1 the air from which is then exhausted by a water air-pump#ib4 ,figure #ad illustrates the application of such an air-pump fixed to the water-tap by means of an india-rubber tube which is firmly bound with wire4 ,an india-rubber stopper perforated to admit a glass tube is fixed in the top of the bell glass1 while the smooth ground edge and the thick ground glass plate upon which it rests are smeared with grease or vaseline4 ,the side tube of the air-pump is connected with the interior of the bell glass by an india-rubber tube which is sufficiently strong to resist the pressure of the outer air1 and thus when the tap is opened the pressure of the flow of water carries with it the air from the bell glass with which the pump is connected4 ,if the water-tap is suddenly turned off when the air is exhausted the pressure of the outer air will force the water into the bell and cause it to mix with the solution of resin or varnish4 ,to prevent this1 a stop-cock or valve should be inserted1 or the water-tap should not be turned off until the stopper of the bell-glass has been cautiously raised4 ,a second glass tube provided with a stop-cock may be passed through the india-rubber cork and connected with a manometer to measure the progressive action of the pump 7,figure #ae74 ,when air-bubbles cease to come from the object under treatment1 the glass tap should be closed and the manometer removed1 after which the glass tap should be again opened and the water-tap closed#ic4 ,illustration3 ,fig4 #ad4 ,air-pump fixed to water-tap4 ,illustration3 ,fig4 #ae4 ,apparatus for impregnation by extraction of air fitted to manometer4 ,if the object is of some length but not too thick1 the bell-glass may be fixed on a strong glass cylinder of a similar diameter having a ground edge 7,fig4 #ae71 into which the object and the impregnating solution are then placed4 ,the following solutions1 amongst others1 may be recommended as suitable for impregnation3 7#a7 ,shellac dissolved in alcohol4 7#b7 ,solution of gum-dammar#id4 #ae grammes of dammar are dissolved in #acj grammes of benzine1 to which is added a solution of #bj grammes of clarified poppy seed oil in turpentine4 ,if the solution becomes too thick it should be diluted with benzine and a small quantity of turpentine4 7#c7 ,rice water or tapioca water#ie4 7#d7 ,dilute size4 7#e7 ,waterglass solution4 7#f7 ,linseed oil dissolved in benzine4 7#g7 ,linseed varnish dissolved in #c parts of benzine or petroleum ether4 7#h7 ,solutions of stearine or paraffin wax in benzine4 7#i7 ,collodion 7free from acid74 ,zapon#if4 7#aj7 ,kessler's fluate4 ,it may be added that1 as a general rule1 solutions for this purpose must be used as dilute as possible1 for two immersions in a dilute solution are preferable to a single soaking in a concentrated one1 which often scarcely penetrates into the pores4 ,as the preparation of solutions of shellac1 gum-dammar1 and of such substances as resin1 stearine1 and paraffin1 necessitates heating1 and as the solvents are very inflammable1 it is advisable to make use of the solution of linseed varnish in benzine4 ,this solution may be obtained at any time at any degree of concentration without the use of heat4 ,although it has the advantage that it hardens more rapidly than a simple solution of linseed oil it has also one disadvantage1 for it gives a somewhat darker colour to light-coloured limestones4 ,no more of the mixture of varnish and benzine should be prepared than is required for the impregnation1 for this solution1 on standing1 throws down a gelatinous precipitate which is not re-dissolved even by heating4 ,as this alteration is accelerated by the action of light1 the mixture should always be kept in a dark place4 ,collodion and zapon#if1 on account of the expense1 should only be used for small objects4 ,after impregnation the objects should be covered with glass jars1 cardboard boxes1 etc41 to prevent the precipitation of moisture upon them1 as the result of the rapid evaporation of such volatile substances as benzine and ether upon exposure to the open air4 ,rice water1 tapioca water1 or size 7the latter of no greater strength than #b7 are only applicable to specimens which are kept in dry rooms1 for in damp rooms they readily become sticky1 and are liable to be attacked by moulds4 ,waterglass solution1 probably because it is generally applied in too concentrated a form1 instead of penetrating the object has a tendency to form a pellicle1 which readily strips off4 ,even dilute solutions1 however1 are said to be unsuitable1 from the liability to the efflorescence of alkali salts4 ,in the case of marble objects and antique statues of porous limestone1 showing colours which are still bright on excavation1 but which would soon fade1 ,rhousopulos#ig recommends impregnation with a very dilute solution 7#a in #ajjj7 of waterglass to preserve the colour4 ,the solution should be as neutral as possible3 in any case not alkaline4 ,this is several times sprayed upon the object1 which is allowed to completely dry between each spraying4 ,a material which is suitable for large objects to which the solution can only be applied upon the surface is ,kessler's fluate#ih1 which is soluble in water1 and which hardens the limestone without completely closing the pores4 ,it offers the additional advantage that it is applicable to thick limestone blocks1 the dryness of which is not certain4 ,the solutions numbered #a-i must only be used when the limestone is dry throughout its mass4 ,the fluate to be used in any particular instance must be decided from the nature of the case4 ,those most generally applicable are magnesium and zinc fluates and the so-called double fluate4 ,the stones from the ,meten ,chamber were hardened in the following manner3 ,the limestone blocks were placed upright and the surface dusted by the air-current from a ,dechend's spray apparatus#ii which was then used to spray them repeatedly with a solution of double fluate of sp4 gr4 #aaf4 ,owing1 however1 to the injurious effect of the fine spray of the fluate upon the nose and lungs the stones were turned to a horizontal position1 and a solution of fluate of sp4 gr4 #ach was applied by means of a large brush until the fluid was no longer absorbed4 ,for the treatment of limestones on which there are remains of colours the use of a solution of shellac1 gum-dammar1 or collodion is recommended4 ,fluates should not be applied until their suitability for the particular purpose has been tested4 ,all specimens should be kept after impregnation in rooms which as far as possible are free from dust1 for the dust which falls upon the surface will set in the varnish whilst it is hardening4 ,,impregnation ,,without ,,previous ,,steeping4 ,if a preliminary examination has shown that specimens of limestone will not bear steeping in water1 recourse can be had to impregnation only4 ,the treatment of such specimens must be thorough1 for merely to paint the fluid upon the surface with a brush almost invariably proves a failure4 ,instead of penetrating the stone the impregnating medium forms a firm coating which is liable to be lifted1 and in parts broken1 by the crystallisation of salts1 and thus allows the destructive processes to continue uninterrupted4 ,aqueous solutions1 e4g4 size1 cannot of course be applied1 and as it is necessary to make a preliminary trial of a fluate spray1 it is generally found preferable to make use of the varnish-benzine mixture4 ,in spite of this1 salts may still make their appearance in the form of a crystalline powdery layer on the surface1 which can be wiped off with a wet sponge2 any moisture must however be removed with a soft dry linen cloth4 ,,removal ,,of ,,incrustations ,,and ,,dust4 ,incrustations of earth1 lime1 or gypsum should be washed off with water or removed by mechanical means1 such as gentle rubbing with the finger4 ,the solvent action of acids upon limestone precludes their use for this purpose4 ,any dust which adheres can be removed by rubbing with stale bread-crumb4 7b7 ,marble and ,alabaster4 ,it is usually only necessary to clean marble with a soft brush and warm water1 with the addition perhaps of some good neutral soap4 ,in rare cases the presence of sulphates may perhaps cause some friability4 ,the crystalline structure of marble renders steeping futile1 and accordingly impregnation is resorted to4 ,the use of ,kessler's fluates may be recommended4 ,adherent pitch or resin is best removed by a mixture of alcohol and ether4 ,alabaster seems to remain permanently sound and may be cleaned in the same way4 7c7 ,earthenware4 ,,steeping4 ,the same line of treatment should be followed as in the case of limestones4 ,a preliminary examination should always be made to test the power of resistance in water1 which is always satisfactory if the clay has been sufficiently baked4 ,in the case of coloured terra-cotta care should be taken to ascertain whether the colours are likely to suffer during steeping4 ,there is no danger of injury if the steeping is not too prolonged2 in fact1 the removal of the dust during the procedure often brings out the colours more clearly4 ,if the ,egyptian ostraca 7clay fragments with black script7 require to be washed they should be carefully watched in order to preserve the script1 and therefore should be placed in the bath in such a way that the lettering is visible4 ,these fragments are usually curved and bear the script upon the convex side1 care should therefore be taken that they are completely immersed1 and that no large air-bubbles prevent the access of the water to any part of the under-surface4 ,the writing is done with either lamp-black or more rarely some form of iron ink1 and is retained mechanically by the porous character of the ostraca4 ,in the latter case the characters may be enhanced by the application of a dilute solution of tannic acid1 which sometimes proves useful also for limestone pieces4 ,if these fragments are sufficiently few in number to allow each to be put into a separate glass vessel1 the washing out of the salts is completed so quickly that there need be little danger of obscuring the script4 ,when large numbers were to be washed and when the script was already indistinct ,i have employed the following method3 ,after examination as to their fitness for immersion the fragments are placed on a wooden grating in a tub1 in which they remain for a couple of days1 during which the water is renewed once4 ,they are then taken out and allowed to dry4 ,all those which still show the script distinctly are separated and their steeping is completed1 but the remainder1 having been completely dried1 perhaps on the top of a warm stove1 are brushed over once or twice with a dilute 7#a3f7 mixture of varnish and benzine in such a way that the surface is only moistened1 and when dry shows no gloss4 ,the pieces thus superficially varnished are kept in a dry place for about two months1 until the varnish is hardened2 the process of washing out the salt is then begun again4 ,the thin coat of varnish fixes the script without interfering with the steeping4 ,the varnish solution must be dilute1 for a thick coating will partially peel off from the object in the course of the steeping1 or will remain in the pores in the form of opaque particles1 and thus render the script illegible4 ,the same difficulty which arose in the treatment of the ,meten limestones was frequently met with in the treatment of these ostraca4 ,those which were of a dark brown colour especially1 and to a less degree also the red and the yellow1 were covered with a slimy growth of algae4 ,as the script is easily destroyed no attempt should be made to remove these algae from the side which bears the script even with the softest brush1 although they should from time to time during steeping be brushed from the underside4 ,the inconvenience caused by algae is1 however1 less marked in the treatment of earthenware1 the light and porous character of which renders prolonged steeping needless1 nor is there the same necessity to continue the steeping for the purpose of chlorine estimation4 ,the following results were obtained in the treatment of #ac fragments1 the average thickness of which was #a cm4 #c_/hth inch1 with an average superficial area of #a_/aj sq4 metre #d inches4 ,the tub in which they were steeped contained #he litres #ah-a_/b gallons of water4 #ajj cubic centimetres of the tap-water used were found to require #je c4c4 of the silver solution1 and on each occasion this quantity of the water was tested4 ---------------------------------------- ---------------------- ,water changed after #a #a #a #a #b #b #b #d #e days ---------------------------------------- ---------------------- #ajj c4c4 of the water used in #cj #ac #aj #jh #ji #jg #jg #jf #jf c4c4 steeping of silver required solution ---------------------------------------- ---------------------- ,the water was changed at first daily1 then every two days1 and so on3 the steeping could therefore be regarded as complete at the end of a fortnight4 ,a small figure of earthenware1 which weighed only #bhi grammes1 was steeped in #a-a_/b litres of distilled water1 and gave the following result for every #ajj c4c4 used3 ,water changed after #b days required #cf c4c4 silver solution4 ,water changed after #c days required #jd c4c4 silver solution4 ,water changed after #d days required #jj c4c4 silver solution4 ,the steeping was1 therefore1 in reality complete after five days1 and1 as the steeping water was thoroughly mixed before the withdrawal of the #ajj c4c41 the total quantity of sodium chloride contained in the figure can be calculated as follows3 ,for the #aeth part 7viz4 #ajj c4c47 of the water #cf #jd1 i4e4 #dj c4c41 of decinormal silver solution were used1 which is equivalent to #ae #dj1 i4e4 #fj c4c41 of silver solution for the whole quantity4 ,now #a c4c4 of this decinormal solution corresponds to #jjjehd gramme of sodium chloride2 the water therefore contained #fj #jjjehd gr41 or #jce gr4 sodium chloride4 ,thus the figure contained altogether #a-a_/e of sodium chloride4 ,in addition to the chlorine compounds1 there was also a considerable quantity of sulphates1 the presence and disappearance of which were tested by adding to a few cubic centimetres of the water a dilute solution of barium nitrate or of barium chloride#ajj4 ,the soluble barium salts give with sulphates a white precipitate or cloudiness of insoluble barium sulphate4 ,if therefore on the addition of a solution of barium nitrate no cloudiness appears1 even after some time1 it may be concluded that sulphates are no longer present in the water4 ,when the ostraca have been washed and dried1 it is often possible to make the script more distinct by varnishing them over with a varnish-benzine mixture 7#a3f74 ,it is advisable to subject friable objects of earthenware to the process of impregnation 7cp4 the impregnation of unbaked clay1 p4 #ha74 ,,the ,,removal ,,of ,,incrustations4 ,incrustations of earth or lime can be easily removed if the earthenware has been well baked1 but trial must first be made with a drop of dilute hydrochloric acid1 whether the earthenware itself is not attacked by the acid4 ,the specimen is then placed upon a glass ring or suspended in water containing #b of hydrochloric acid#aja4 ,this mixture1 which must be renewed every #bd hours1 will remove incrustations which it would be difficult to remove by mechanical means1 while crystals of gypsum of considerable size1 which are often found on clay tablets of ,assyrian origin1 are easily dissolved in from two to four days4 ,figures #af to #ba represent two ,assyrian tablets which have been cleaned by myself in this manner4 ,it will be seen that the cuneiform characters1 which before treatment were almost invisible1 are now distinctly legible4 ,illustration3 ,fig4 #af4 ,fig4 #ag4 ,assyrian clay tablet with incrustations4 ,before and after treatment4 ,illustration3 ,fig4 #ah4 ,fig4 #ai4 ,fig4 #bj4 ,fig4 #ba4 ,assyrian clay tablet before and after treatment4 ,after this treatment with acidulated water the acid must itself be removed by careful washing in pure water4 ,here too a solution of silver nitrate will serve as a test1 for1 so long as any chlorine1 and therefore any hydrochloric acid1 is present in the water1 a white precipitate or cloudiness is produced4 ,the method of titration with yellow potassium chromate is not applicable here1 for the free acid prevents the appearance of the red precipitate4 ,the steeping must therefore be continued in distilled water until the addition of silver nitrate no longer produces any cloudiness4 ,baked earthenware which shows colouring1 or which has incised lines filled with substances containing lime1 must not be steeped in acidulated water1 nor will ostraca bearing inscriptions in iron ink stand this treatment2 these are1 however1 fortunately rare3 in fact amongst several thousand fragments few have shown incrustations of lime or gypsum4 ,should any such be found a cautious attempt should be made to remove the incrustations by some mechanical means4 ,rhousopulos#ajb carries out the cleaning of ,lecythoi#ajc and clay vases1 which are painted in water-colours and which have a thin white incrustation1 by dipping them into a #e solution of pure hydrochloric acid4 ,as soon as the colours show the least sign of running1 or if an efflorescence makes its appearance1 the vase is immediately removed and allowed to dry4 ,it is then dipped into distilled water and allowed to dry a second time4 ,impregnation is not necessary4 ,if the treatment is otherwise successful1 but an earthy layer remains upon the colour1 the spots which are thus affected are lightly touched with the finger whilst the object is still in the liquid4 ,rubbing1 or any sort of mechanical attack1 is absolutely out of the question4 ,this process evidently requires the greatest care and constant attention4 7d7 ,slightly ,baked ,or ,unbaked ,clay4 ,,impregnation4 ,if upon examination it is found that a drop of water softens the clay1 the same line of treatment must be followed as in the case of limestones which exhibit a similar condition 7see p4 #gc71 i4e4 they must be subjected to the process of impregnation#ajd4 ,as the colour of the clay objects is yellow-brown or red-brown1 the varnish benzine mixture will be the most suitable application for the purpose4 ,a considerable number of sun-dried ,assyrian clay tablets treated in this manner have given good results1 and have undergone no change during the last five years1 in fact they may now even be laid in water without crumbling4 ,in the case of slightly baked or unbaked ,babylonian clay tablets the method formerly employed was merely to remove deposits of lime1 clay1 gypsum1 etc41 by lifting or scraping them away with pointed or wedge-shaped tools1 for the soft clay would not stand treatment with water1 still less with #b hydrochloric acid4 ,the difficulty in avoiding damage to the clay surface1 when removing the deposit1 makes this method both tedious and risky4 ,warming to #bjj-cjj;,c4 in a drying oven1 or in an iron box embedded in sand1 seldom aids the removal of incrustations2 moreover1 this treatment has no hardening effect upon the clay1 and thus does not facilitate the removal of the injurious salts by soaking4 ,a further expedient therefore remains1 that of heating the clay to higher temperature1 whereby it is fully baked and rendered capable of resisting subsequent treatment with water or #b hydrochloric acid4 ,at the ,royal ,museum this firing is done in muffle furnaces#aje1 the smaller of which has a capacity of about one cubic foot1 and is heated by six and twelve ,bunsen burners4 ,the temperature is regulated in the same way as in porcelain manufacture by the use of ,seger's cones#aje1 which are placed in the muffle1 where they can be seen through the observation aperture4 ,to avoid cracking the heating must be gradual1 the gas-supply being very gradually increased4 ,the firing must at first be adjusted to cone #jbb #eij;,c42 ,watkin1 ,no4 #a1 #ajid;,f42 the gas is then turned off and the furnace allowed to cool as slowly as possible4 ,to effect this the damper is closed and all openings into the muffle are made up with fire clay4 ,the clay tablet is removed when quite cold 7usually in #ah-bd hours71 and1 as a rule1 much of the incrustation can then be removed by means of a soft brush4 ,should the removal prove difficult1 and a preliminary trial have shown that it will bear the treatment1 the removal of the deposits will be assisted by soaking for two or three days in water4 ,should the tablet prove capable of bearing treatment with #b hydrochloric acid it may remain in the acid for #ab to #ah hours4 ,if necessary the acid may be renewed once2 it must then be thoroughly removed by steeping in ordinary water and finally in distilled water1 until the wash-water is free from chlorides4 ,after steeping1 the tablets will be found somewhat softened and occasionally coated with a slimy growth of algae1 care must therefore be used in changing or taking them from the water4 ,the best way to handle them is to place the fingers of the two hands under the tablet4 ,illustration3 ,fig4 #bb4 ,babylonian clay cone before treatment4 ,illustration3 ,fig4 #bc4 ,babylonian clay cone after treatment--firing1 treatment with hydrochloric acid and steeping4 ,after thoroughly drying the tablets first in the air1 then in the drying oven at a temperature of #bab;,f41 supported on glass rings1 it is well to impregnate them4 ,this can be best carried out by placing them1 while still warm1 into melted paraffin wax1 and raising the temperature to about #bej;,f4 #abj;,c44 ,the wax is allowed to cool to about #afj;,f4 #gj;,c41 when the tablet is removed upon a broad band of gauze1 any excess of wax is drained off1 and the object is wiped with a soft cloth4 ,the benzine-varnish mixture or zapon may also be used for impregnation4 ,if heating in the muffle to ,seger cone #jbb is insufficient to allow of the removal of the incrustations1 or if the condition of the clay does not warrant soaking in water or acid1 the object must be again placed in the muffle and fired to ,seger cone #jaj #iej;,c42 ,watkin1 ,no4 #ac1 #agdb;,f41 and1 if softening occurs upon the application of water or acid after exposure to this temperature1 recourse must be had to a third heating to ,seger cone #je #ajej;,c42 ,watkin1 ,no4 #ah1 #aibb;,f44 ,higher temperatures than this are not advisable1 for the lime1 sodium chloride1 and other salts found in some ,babylonian tablets may partially fuse4 ,during firing therefore the appearance of the object must be carefully watched1 and the temperature lowered at once by reducing the gas-supply1 if signs of fusion are noticed4 ,,additional ,,methods ,,of ,,impregnation4 ,if clay objects have a smooth surface1 it is1 according to the ,merkbuch#ajf1 advisable to impregnate them with ,belmontyl oil#ajg1 for varnish in the course of drying gives a lacquered appearance to the surface4 ,according to the same authority the surface of glazed vessels can be restored by impregnating them several times with a mixture of poppy seed oil and benzine #bj grammes clarified poppy seed oil in #bgj gr4 benzine1 i4e4 #a in #ac-a_/b1 and by subsequently brushing them first with soft1 then with harder brushes4 ,there are1 however1 many other substances used in different collections for impregnation1 a few of which are subjoined4 ,in the ,museum at ,vienna friable clay objects are laid for two or three minutes in a dilute solution of warm size1 and when dry are brushed over with a solution of shellac2 size alone1 or a solution of shellac alone1 is frequently used for impregnation1 or to give a coating4 ,in the ,museum at ,wiesbaden thin specimens are impregnated with a solution of white of egg1 brittle objects with dilute fish glue1 while for hard objects a solution of shellac or melted shellac is used4 7e7 ,fayence4 ,i have been able to wash out the sulphates from several ,egyptian fayence figures in spite of the glaze1 the fissures in which allowed the water to penetrate into the interior4 ,the process of steeping1 which was necessarily somewhat prolonged1 was tested from time to time by the barium nitrate test 7vide p4 #gg74 7f7 ,objects of ,stucco and ,nile-mud4 ,these are rare1 and in almost all cases contain salts4 ,as1 however1 they will not bear steeping1 they must be preserved by means of impregnation only4 ,the varnish-benzine mixture should be used for this purpose4 7g7 ,sandstone and ,granite4 ,these scarcely need any special preservative process1 but ,kessler's fluates are useful for the impregnation of weathered sandstones which are exposed to the open air 7see p4 #gb74 ,they can be cleaned by washing with warm water1 while calcareous incrustations may be removed by hydrochloric acid4 ,a thick coating of oil paint was successfully removed from an ,egyptian statue of sandstone by placing it in an alcoholic solution of soda4 ,oil colours and similar substances may often be removed with ease and completeness from stone1 plaster1 wood1 etc41 by placing the objects in air-tight vessels together with a vessel containing alcohol4 ,the alcohol vaporises1 even at the ordinary room-temperature1 and causes a softening of the paint4 ,the time required for the treatment depends upon its age and hardness4 ,appendix4 ,cement for ,earthenware4 ,restorations4 ,to fix together pieces of broken pottery good ,cologne glue is useful1 but it has the disadvantage that it can only be used when warm4 ,for this reason it is better to use liquid fish-glue ,syndeticon1 which may1 if necessary1 be thinned with a little vinegar4 ,fire-clay dust in waterglass is used in the ,museum at ,breslau4 ,a thick ropy solution of shellac#ajh may also be mentioned1 for the use of which the opposing surfaces must be first moistened with alcohol4 ,gum arabic and dextrin should not be used1 for objects thus cemented readily fall to pieces unless kept in perfectly dry rooms4 ,this1 however1 may also be said of earthenware which contains salts1 if cemented with glue or fish-glue4 ,previous steeping would obviate this difficulty4 ,chalk1 plaster of ,paris1 brick-dust1 or fire-clay dust are often added to the fish-glue1 dextrin1 etc4 ,without giving additional strength to the cement1 these substances may be of use in filling up small gaps between the fragments to be cemented4 ,for filling up larger gaps the ,merkbuch#aji recommends stone cement1 for the preparation of which it gives the following prescription3 ,mix #ejj grammes of ,cologne glue with three sheets of strong white blotting-paper1 or four sheets of white tissue paper1 shredded as small as possible1 and boil until it becomes thick1 stirring the whole into a perfectly smooth pulp4 ,let it boil thoroughly1 and while stirring continually1 and working with a stout wooden rod1 add #b-a_/b kilogrammes of very finely sifted dry purified whiting4 ,after working this mixture thoroughly1 add #hj grammes of linseed oil1 which must be also thoroughly worked in4 ,to preserve the glue add #ej grammes of ,venetian turpentine4 ,this stone cement will take any shade of colour if mixed with lamp-black or coloured earths4 7h7 ,iron4 ,the various methods for the preservation of iron objects which have been or are still in use may be divided into two groups4 ,to the one group belong those methods in which the objects are preserved with their coating of rust1 or with the rust that has penetrated them2 to the other group belong those in which the removal of rust precedes preservation4 ,the former methods must be applied when the iron has been completely converted into rust or when the rust has only left a small metallic core4 ,these methods may of course be used also for all iron antiquities4 ,the methods of the second group can be applied to those objects only which still retain a strong metallic core1 in which case the objects regain the more or less grey or white surface of fresh unoxidized iron4 ,these methods are at present little known1 and therefore but little used1 for owners and the general public are still accustomed to see in the covering of rust the evidence of antiquity with which they are loth to part4 ,in addition to these methods1 there are others which are of an intermediate kind1 either special or a combination of methods from both these groups4 7#a7 ,methods of preserving ,objects of ,iron without removal of the ,rust4 ,,impregnation4 ,the earliest processes1 which are to some extent still in use in some collections1 are simple impregnation methods1 in which the object is either painted once or more with the impregnating medium by means of a brush1 or is placed directly in the medium itself4 ,in either case the penetrating power of the solution used is directly proportional to its fluidity4 ,the following media may be used for the purpose3 7#a7 ,warm size4 7#b7 ,warm isinglass solution4 7#c7 ,solution of waterglass4 7#d7 ,solution of shellac in alcohol4 7#e7 ,rubber solution in carbon bisulphide4 ,the mass after swelling is dissolved in benzine#aaj4 7#f7 ,copal varnish diluted with turpentine4 7#g7 ,copal varnish mixed with linseed oil#aaa4 7#h7 ,linseed oil4 7#i7 ,linseed varnish4 7#aj7 ,linseed varnish mixed with an equal quantity of petroleum4 7#aa7 ,bees'-wax dissolved in turpentine4 7#ab7 ,bees'-wax dissolved in benzine4 7#ac7 ,petroleum4 7#ad7 ,vaseline4 7#ae7 ,melted paraffin4 7#af7 ,oleate of lead3 #ajj grammes of olive oil1 #ajj gr4 of lead oxide1 and #ajj gr4 of water are boiled until all the water has evaporated and the mass has become grey4 ,the mass is extracted by shaking it with alcohol1 and the residue is dissolved in absolute ether1 in the proportion of #ajj gr4 of ether to #e gr4 of the substance4 ,before use it should be diluted with a little ether#aab4 7#ag7 ,speerschneider's mixture4 ,this consists of #h parts of rape oil1 #a part of bees'-wax1 #a part of pine resin1 and #b parts of benzene#aac4 7#ah7 ,collodion1 or the mixture used in the ,museum at ,donaueschingen1 which consists of #cj grammes of collodion1 #b gr4 of camphor1 and #a gr4 of oxalic ether4 ,in addition to these materials1 there are other mixtures of resin1 varnishes1 and bees'-wax1 with their appropriate solvents1 but they do not possess any special advantages as impregnating solutions4 ,after treatment with size or isinglass1 iron objects may be given when dry a coating of linseed oil1 linseed varnish1 solution of shellac1 etc4 ,the materials numbered #g to #aj in the above list should be applied warm to enable the viscid fluids to penetrate the rust1 for the more readily the solution enters the object the better is the result obtained4 ,apart from the fact that they are easily ignited at a high temperature1 they must not be heated beyond #bcj;,f4 #aaj;,c41 otherwise objects which consist largely of rust will fall to pieces#aad4 ,in the process of impregnation a twofold result is aimed at1 viz4 to prevent the rust from crumbling1 and to exclude air from the specimen4 ,the application of heated linseed oil or linseed varnish is founded upon the supposition that these substances enter into a chemical combination with ferric oxide to form a stable compound2 this is1 however1 disputed by some modern authorities#aae4 ,neutral substances offer a safer method for the exclusion of air1 and of these melted paraffin is undoubtedly the best4 ,the paraffin must be quite pure and free from stearine1 as can be ascertained from the melting point2 thus pure paraffin melts at #acj-aej;,f4 #ee-fe;,c41 stearine at #afj;,f4 #gj;,c44 ,paraffin with a melting-point higher than #fe;,c4 should be looked upon with suspicion4 ,in many collections the objects are heated before impregnation with media which are insoluble in water1 or they are exposed to the air for six to twelve months after excavation4 ,this latter proceeding is1 however1 certainly inadvisable if the iron contains chlorine1 and if this is the case not one of these methods produces satisfactory results4 ,on the other hand1 as almost all the iron antiquities which do not contain chlorine compounds may be treated by the methods of the second group1 simple and direct impregnation is passing more and more out of use4 ,before impregnation all soluble substances1 especially chlorine compounds1 must be removed by steeping4 7#b7 ,preservation by ,steeping and ,subsequent ,impregnation4 ,,krause',s ,,method4 ,the water used for steeping should be preferably lukewarm1 and should be changed every twenty-four hours4 ,it is even better1 at least for the first time1 to lay the object in water and then raise it to boiling-point1 a measure which will allow the more ready penetration of the water4 ,as in the case of limestones1 earthenware1 etc4 7p4 #ei71 care must be taken to place the objects as near to the surface of the water as is possible4 ,small objects may be put in glass jars1 large ones in wooden troughs1 tin vessels1 or wooden boxes lined with zinc or lead4 ,any little excrescences on the iron1 which are frequently filled with ferrous chloride1 should be punctured to give the water unimpeded and more speedy access4 ,crumbling objects should be held together by tightly wrapping them in muslin4 ,curators must decide for themselves how far means such as files1 chisels1 or small hammers may be used to remove the rust or earthy material conglomerated by rust4 ,although much recommended1 the method of adding soda or lime water to remove the chlorine as soluble sodium chloride or calcium chloride is1 in our opinion1 inadvisable4 ,both these substances precipitate the iron from the ferrous chloride or ferric chloride 7which are soluble in water7 as insoluble hydroxide of iron1 which more or less closes the interstices1 and thus impedes the access of water to the interior4 ,the process of steeping can here again be controlled by the use of the silver solution 7p4 #fb71 for if there no longer appears any or only very little cloudiness the steeping may be considered complete4 ,the length of time required for steeping depends upon the thickness of the rust and the porosity or existence of cracks in it1 and if the objects are of considerable size1 it may extend over several weeks4 ,after steeping the object should either be dried in the open air1 and later on a warm stove1 or be placed for a few days in alcohol to remove the water1 after which the rapid evaporation of the alcohol will quickly dry it4 ,the steeping of iron objects in warm alcohol has been recommended#aaf1 but if their size is considerable the method is an expensive one4 ,this method has the advantage that the alcohol penetrates the rust sooner than does water1 and also prevents oxidation1 which may be actually produced by the water4 ,it may perhaps be advisable to dilute the alcohol1 the usual strength of which is #ie to #if1 with about an equal volume of water1 for some salts are not readily soluble in pure alcohol4 ,when dry the object is warmed for a few hours in a mixture of equal parts of good linseed varnish and petroleum4 ,the petroleum serves to dilute the varnish1 which can thus more quickly permeate the entire mass of iron and rust4 ,on account of the inflammable nature of the mixture the warming should be done over a water-bath4 ,for small objects a cylinder made of ordinary tin-plate1 measuring from #f to #aj inches #ae to #be cm4 in diameter and #f in4 #ae cm4 in height1 may be used4 ,to increase stability the lower half should be of a smaller diameter1 and fitted into an iron tripod4 ,the same end is attained by soldering a ring round the middle of the cylinder1 which will rest on the ring of the tripod4 ,the cover consists of a number of copper rings gradually diminishing in diameter1 which fit closely into one another1 thus enabling porcelain vessels of various sizes to be used4 ,for larger objects1 such as swords1 two long rectangular troughs 7,fig4 #bd7 of stronger plate should be used4 ,the following sizes will probably be found useful3 one about #dj inches #ajj cm4 long by #d inches #aj cm4 broad1 and #d inches #aj cm4 deep1 and the other slightly larger4 ,handles should be fixed at the upper edges4 ,three iron bars #a inch #b-a_/b cm4 thick and #d inches #aj cm4 in length are laid across the bottom of the larger trough1 on which the smaller is placed4 ,the space between the two vessels is filled with water to a depth of #b inches #f cm44 ,the trough is warmed on a stove1 or better1 where gas can be had1 by means of a number of ,bunsen burners fitted with rose or ring burners1 over which the trough may be supported upon tripods4 ,while heating care must be taken that the water does not boil over1 which can be easily avoided by regulating the gas supply4 ,as the water evaporates further quantities should be added as required4 ,after simmering for about two hours1 the objects should be removed and allowed to drain2 they should then be placed on a tripod1 or on glass rings1 on the warm stove in cold weather1 to accelerate the evaporation of the petroleum and the setting of the varnish4 ,in summer drying chambers may be used2 these are sold by dealers in physical and chemical apparatus1 or can be made at little cost by a tinsmith4 ,illustration3 ,fig4 #bd4 ,water-bath4 #a_/ae nat4 size4 ,if the objects have been steeped in pure alcohol1 or at least towards the end of the treatment in three changes of alcohol1 so that all the water is replaced by alcohol1 they may be dipped directly without drying in the varnish mixture1 for the alcohol evaporates in the varnish bath which is at a temperature of #aid-bjc;,f4 #ij-ie;,c44 ,as the varnish hardens1 the iron thus treated acquires a glazed surface2 other means of impregnation may therefore appear preferable1 e4g4 a solution of gum-dammar or melted paraffin4 ,for impregnation with the dammar solution the object must first be dried1 and the air-pump used in the way described on p4 #fh4 ,on account of the inflammable nature of the benzine heat must not be applied1 nor indeed is it necessary4 ,when impregnating with pure paraffin#aag1 specimens may be lightly wiped with a cloth1 but need not be dried4 ,the paraffin may be heated to #bab-bdh;,f4 #ajj-abj;,c4 without danger1 so long as it is kept from direct contact with the flame4 ,a thermometer should be used1 and1 as soon as the paraffin has melted at a temperature of about #fj;,c41 the object should be placed in it by means of tongs4 ,when the temperature has risen above #bab;,f4 #ajj;,c4 the water is converted into steam1 and causes a brisk ebullition of the melted paraffin4 ,the quantity of paraffin used should1 therefore1 be such that its level remains at the least #b inches #e cm4 below the upper edge of the vessel4 ,when the bubbles have ceased to rise1 thus showing that all the water is expelled1 the paraffin should be allowed to cool to a temperature of #ahj-aij;,f4 #hj-ij;,c44 ,the iron should be taken out with tongs1 and the liquid allowed to run off4 ,it should then be wrapped1 while still at #hj;,c41 in soft blotting-paper or in a piece of old linen to absorb the superfluous paraffin4 ,if the surface of the object is very uneven1 or if there are deep cracks or holes in which the paraffin can collect1 it will1 when cold1 form a white mass1 and should therefore1 while still warm and fluid1 be soaked up with filter paper1 or distributed evenly by means of suitable brushes4 ,the superfluous paraffin may also be absorbed by putting the object in dry sawdust2 any sawdust which remains attached can be removed when cold with benzine1 or it may be scraped from the spots where it has collected with a knife or spatula4 ,any spots where the iron may have become exposed may be covered with a thin coat of paraffin dissolved in benzine4 ,,ekhoff',s ,,method#aah4 ,the objects are laid for two or three months in water which is changed every two or three days1 a small quantity of quicklime being added#aai4 ,after this steeping1 and after some of the rust has been removed mechanically1 the object is lightly dried and put into heavy petroleum of sp4 gr4 #jhe to #jie1 which is then heated up to #bbj;,f4 #aje;,c44 ,a thermometer should be used to ensure this temperature4 ,this temperature being higher than the boiling-point of water1 the water contained in the object evaporates and causes the petroleum to bubble1 as in the method previously described4 ,when all the water has been replaced by the petroleum the bubbling ceases4 ,after the fluid has somewhat cooled down1 the iron is taken out and is allowed to remain for about an hour in sawdust1 which absorbs the superfluous oil4 ,finally1 while gently warming the object over a warm1 but not too hot1 stove1 it is coated over with a mixture of #a part of bees'-wax and #b parts of turpentine1 or better with paraffin dissolved in benzine4 ,heavy petroleum1 which we have found by experience to be a suitable material1 is preferable to varnish in so far as the iron is impregnated by a neutral substance which is practically liquid paraffin1 but has the disadvantage of being highly inflammable and of being difficult to obtain at so high a specific gravity4 ,,straberger',s ,,method4 ,this method1 for the description of which ,i am indebted to ,herr ,straberger1 has proved effective in the preservation of a number of iron antiquities in the ,museum at ,linz on the ,danube4 ,even iron objects1 which had been in bad condition and had undoubtedly contained chlorine1 have after treatment by this method shown no signs of change1 while the dull black surface has an agreeable appearance4 ,straberger places the newly-excavated objects immediately into linseed oil to prevent the access of air4 ,after remaining in the oil for some time they are taken out1 wrapped in cloths saturated with linseed oil1 and removed packed in sawdust4 ,upon arrival they are unwrapped and put into water1 to which a small quantity of soda is added to remove the oil more easily4 ,the water is frequently changed1 and the objects are meanwhile cleaned mechanically with emery paper and hard brushes4 ,any blisters are removed by the aid of a small hammer and chisel4 ,after steeping they are dried and smoked over a candle flame which is allowed to play over the whole surface4 ,the soot is then rubbed off with a cloth or soft brush4 ,objects with a smooth surface may be rubbed with india-rubber4 ,the preservative action of this proceeding depends upon the fact that during the smoking1 in addition to the soot1 oily products of combustion are deposited from the candle flame1 which prevent the access of air and moisture to the iron4 ,objects which are much decayed or cracked should1 when cleaned and thoroughly dry1 be again placed into linseed oil which has been slightly warmed and should remain therein for a few days before being smoked4 ,upon removal from this second oil bath they should be lightly wiped and dried over a moderately warm stove or in the sun4 ,patience is necessary1 and nothing further should be done until the oil has entirely dried in the fine cracks and crevices and firmly binds the mass4 ,the oil crust on the surface is then loosened by soaking in a strong soda solution and wiped off1 after which the object is dried1 smoked over the candle flame1 and the soot wiped or brushed off with a soft brush4 ,the smoking and wiping may be repeated if necessary4 ,herr ,straberger states that his treatment has been successful when impregnation with isinglass and coating with shellac has failed4 ,the methods of ,hartwich and ,jacobi hold an intermediate place between the above methods and those which will be subsequently explained4 ,with the former they have this in common that they do not call for the entire removal of the rust and that they require the use of linseed oil2 on the other hand their application presupposes the existence of a strong metallic core1 otherwise when the rust is removed they will show merely a skeleton of the original object4 ,the existence of a sufficiently substantial metallic core can be easily ascertained from the weight1 for an object1 which consists solely or in great part of the oxide of a metal1 is much lighter than one of the same size which is largely metal4 ,the ring also affords a test1 for an iron object1 of which the greatest part is metallic iron1 gives a clearer note when struck than one which is chiefly rust4 ,a still more certain test is the use of a file or a drill 7comp4 page #ajg74 ,,hartwich',s ,,method#abj4 ,this method is intended for objects of an especially large size1 the hard oxide coating of which does not allow satisfactory steeping4 ,hartwich heats the object to redness1 allows it to cool slowly1 and then scrapes off the outer layer which has been rendered friable by this treatment4 ,the subsequent procedure is that of ,krause's method1 viz4 warming in linseed varnish4 ,,jacobi',s ,,method4 ,the method of preservation of iron antiquities used in the ,saalburg ,museum at ,homburg is described by ,jacobi as follows3 ,the object is heated in the fire of a forge1 which causes the chief part of the rust to flake off1 while any rust which still adheres is removed when cold by water and brushing4 ,the object is again held in the flame with tongs and heated 7smaller objects may be placed on an iron plate72 and during the heating is quickly taken out three or four times and each time brushed over with linseed oil4 ,most of the linseed oil is thus burnt and the deposition of carbon gives to the iron a black colour1 while the oil which has been partially burnt or hardened by the heat produces a slight lustre4 ,this process1 as carried out at ,homburg by a locksmith1 is that which blacksmiths ordinarily use to blacken iron objects and to protect them from rust4 ,the preservation has proved permanent1 and only in rare cases has it been found necessary to repeat the process4 ,these good results are probably due to the fact that the antiquities of iron preserved in that ,museum are for the most part found in good condition1 having very little rust and certainly containing only a very small amount of chlorine4 ,iron articles which contain chlorine but which still have a good metal core1 after washing1 drying1 and a cautious preliminary application of heat1 are ready for treatment by ,jacobi's method4 ,,inlaid ,,iron ,,objects require especially cautious treatment4 ,although ,i have not had any personal experience in the treatment of objects of this kind1 good results have been obtained in several ,museums1 especially in that at ,mainz4 ,the following quotation from the ,merkbuch 7p4 #ge7 describes the method which is applied at ,mainz1 where it probably originated3 ,objects of this kind which are likely to have been originally inlaid with silver1 gold1 copper or brass1 as is frequently the case with objects of the ,merovingian period1 are not placed in alcohol after the steeping1 but are warmed and dipped three or four times into a hot dilute solution of isinglass4 ,the heating is necessary1 otherwise the isinglass will set on the surface and will not penetrate into the interior4 ,when the object has been dried and the isinglass has set1 the layer of rust which covers the inlaid ornaments is scraped off with a graving tool1 and any spongy hollow parts are filled up with a paste made of iron rust and isinglass1 before the inlaid work is cleaned4 ,during the scraping the object is held in the left hand on a little wooden board covered with plush or thick chamois leather1 to which it is fixed as firmly as is necessary by means of a vice4 ,in scraping special care must be taken that the graving tool follows the lines of the designs1 for in scraping across the design it may slip under the flat silver thread and raise it out of its place4 ,when the ornamentation has been completely laid bare1 it is rubbed with emery cloth and then polished with a brush and fine emery powder4 ,the piece is then dipped into a solution of gum-dammar1 and1 when the surface is dry1 emery is again used to remove the varnish1 which gives the silver a slightly yellow colour4 ,the object is then protected from the influence of air and moisture by the transparent retouching varnish of ,sohne frres 7,paris74 ,a modification of ,krefting's method 7p4 #ajh7 has proved eminently successful in the treatment of iron objects inlaid with silver4 ,krause#aba recommends that the article be placed1 with the inlaid surface downwards1 for #bd hours in a mixture of #aj grammes of #dj acetic acid1 #aj grammes of ammonium chloride1 #gj grammes of distilled water1 #aj grammes of aluminium powder4 ,it is then removed from the bath1 carefully brushed and washed1 and1 if the inlaid work is not yet cleaned1 is replaced in the bath4 ,this is repeated until the inlaid work is completely exposed4 ,spots of ferroso-ferric oxide which are difficult to remove may be ground away by an emery wheel1 care being taken that the inlaid surface is held against the lower side of the wheel 7which must be rotated in the reverse direction7 so that it is always in sight4 ,all the methods of this group1 which have been applied to many articles in various ,museums1 exhibit one inherent defect1 for any rust which remains after treatment may cause the continued oxidation of the iron4 ,the effects of this action of rust are1 ,i believe1 extremely small1 and it must at the same time be admitted that iron antiquities1 even if they have been well steeped and afterwards impregnated1 do not always remain in a permanent and sound state of preservation4 ,if in such a case the well-known small watery bubbles should make their appearance1 the steeping has undoubtedly been insufficient4 ,this evil can be remedied by gradually heating the object to redness to destroy the impregnating material1 and by a careful repetition of the steeping and impregnation4 7#c7 ,preservation of ,iron ,antiquities by ,removal of the ,rust4 ,,steffensen',s ,,method 7,,copenhagen74 ,the objects are carefully heated over a flame and are then laid in dilute sulphuric acid4 ,the sulphuric acid dissolves a certain amount of the iron1 and it is found by experience that the chemical action is strongest at those spots where any rust remains1 and that this is detached by the hydrogen which is produced4 ,when the cleaning is sufficient1 the iron is laid in a dilute soda solution to neutralise the acid1 and is afterwards well washed with water and dried in an oven4 ,when dry the iron is brushed over with a solution of bees'-wax 7or better of paraffin7 in benzine1 the evaporation of which leaves a protective coating of bees'-wax or paraffin4 ,,blell',s ,,method4 ,the method proposed by ,blell and applied by him to many of the objects in his collection is distinct from that described above1 although in its earlier stages the principle is the same4 ,the following quotation is taken from the description of his method which the author read before the ,antiquarian ,society#abb at ,knigsberg3 ,if a specimen is found to have a sufficiently strong core of iron it should be heated in the furnace to bright redness and then dipped into water4 ,the expansion of the iron caused by the heat and the subsequent contraction caused by the sudden cooling thoroughly loosens the layer of rust4 ,large iron objects with a strong and firmly attached incrustation of rust will require a repetition of the process4 ,by this means not only is the rust converted into a red powder which is easily rubbed off1 but the object itself is rendered more suitable for the subsequent treatment4 ,at the same time the heating process removes any coating of oil1 fat1 etc41 which may have remained from previous attempts at preservation1 and which would interfere with the further stages of the process4 ,smaller or delicate specimens should be treated in the flame of a spirit-lamp1 but special care must be taken that there is sufficient iron present4 ,sword blades and other tools and weapons with sharp edges should be heated only1 for the sudden cooling may cause cracks in the cutting edges4 ,to complete the removal of the incrustation of rust which has been loosened by the heating process1 or by the heating and sudden cooling1 the object should be placed in a well-stirred mixture composed of one part by weight of sulphuric acid in nine parts of water4 ,bubbles of hydrogen will immediately rise and the rust will begin to separate4 ,in freshly prepared acid objects which are not very rusty will be freed from rust after four to six hours1 those covered with a deeper layer of rust in about twelve hours1 but several days1 or even weeks1 may be necessary4 ,the duration of the process depends upon the strength of the acid and the character of the rust1 viz4 whether it is thick and solid1 or thin and porous1 and whether the iron is of a soft1 or of a hard character4 ,when first making use of this method it is advisable to use dilute acid and to take out the objects several times in the course of the day and examine them1 while during the night they should be taken out of the acid and placed in soft water#abc4 ,for the acid bath and for rinsing it will be found convenient to have two pairs of wooden troughs having the following internal measurements3 7#a7 ,an internal length of #aj inches #be cm4 by #g-a_/b inches #ai cm4 in breadth and #d-c_/d inches #ab cm4 in depth1 which will be useful for the larger number of objects4 7#b7 ,for long narrow objects1 e4g4 sword-blades1 and long spear-heads1 the internal measurements should be #dj inches #ajj cm4 long by #d inches #aj cm4 broad and #c inches #h cm4 deep4 ,small fragile objects are most satisfactorily treated in glass vessels or glazed earthen pots or vases4 ,the acid must have free access to all parts of the object2 if a sword1 for example1 lies flat upon the bottom1 the under-surface apparently remains unacted upon by the acid4 ,this should be remedied by the use of a couple of small wooden supports4 ,frequent rubbing with a cloth and forge scale#abd or coarse sand greatly helps in removing the rust1 but gentler treatment is required for the smaller and more fragile objects4 ,the rust is often very firmly attached in some portions of the object1 and in this case those areas which have been already freed from rust should be coated over with lard1 which is free from salt1 to protect them from further action of the acid1 while the pockets of rust are alternately treated with acid and graving tools4 ,no particle of rust should be allowed to remain1 for sooner or later it will begin to spread1 whatever precautions may be taken4 ,the action of the acid becomes less effective if it has been used for several objects4 ,a little fresh acid should then be added4 ,the more active the sulphuric acid1 the brighter will be the grey colour of the iron after the rust has been removed4 ,if old acid has been used the iron will be of a dirty grey colour1 and should then be placed into fresh acid for a short time until it assumes a clear light grey colour4 ,the third part of the process begins with the removal of the iron from the acid bath and has as its object the removal of every trace of the acid1 otherwise the rust will very quickly return and cover the whole surface4 ,the object is therefore immediately and repeatedly rinsed in soft water and carefully dried2 the cheapest material for this purpose is cotton waste1 but ordinary linen-cloth must be used for objects with jagged edges1 for the threads will catch in the notches and hinder the drying4 ,this should be done without delay1 or a change of the colour from light grey to yellow will betoken a new formation of rust4 ,articles showing a very complicated construction1 which are however rare from the ,iron ,age1 should be packed in perfectly dry hot pinewood sawdust1 while those which are still more difficult to dry1 for example1 coats of chain-mail1 after thorough rinsing1 should be immediately put into a pan with melted lard1 free from salt1 and boiled until the cessation of bubbling shows that all the water has been driven off by evaporation4 ,they are then rubbed dry or are laid in hot sawdust1 after which they are brushed over with melted lard and placed in this condition for at least half an hour in a moderately hot cupboard until the fat has penetrated into the finest pores of the iron4 ,that this has really taken place may be proved by the use of a file4 ,when by this means all trace of sulphuric acid has been removed the fourth stage of the process is reached1 viz4 the removal of the grease from the surface and the subsequent application of some preparation to prevent the access of air and moisture4 ,most of the grease is removed by placing the objects in a warm place on blotting-paper4 ,any grease still remaining on the surface can be entirely removed with a cloth or paint-brush by means of benzine4 ,if no restoration or repair is required nothing more is necessary than to apply the protecting solution4 ,a white varnish has much to recommend it from its protective power1 but as it gives to iron an unsatisfactory gloss1 it is preferable to use a solution of bees'-wax in benzine4 ,having made use of ,blell's method in a number of cases ,i have a few suggestions and modifications to offer4 ,the heating should be carried out carefully and gradually1 lest the sudden conversion of the moisture in the rust into steam should cause small explosions which would scatter pieces of rust4 ,there is no danger of this if the objects are heated in an oven2 they should not therefore be heated in an open flame4 ,for smaller objects ,i use a box six inches #ae centimetres square1 of strong tin-plate loosely covered with an iron lid1 or with a piece of asbestos sheet2 but if the objects are large1 e4g4 swords1 spearheads1 etc41 ,i heat them on a strong piece of tin-plate bent round to form a channel1 and covered with a long piece of asbestos sheet1 the edges of which are bent over the edges of the channel1 to retain the heat as much as possible4 ,it is advisable1 in my experience1 to use the sulphuric acid well diluted1 e4g4 in the proportion of #a to #bj1 and to renew it several times if necessary4 ,in mixing concentrated sulphuric acid with water great caution is required on account of the evolution of heat4 ,the acid should be poured in a thin stream into the water1 but not vice vers1 and the mixture should be constantly stirred with a glass rod4 ,if a glass vessel is used for the mixing1 it must not be too thick lest the heat should cause it to break1 but the larger the proportion of water to the sulphuric acid1 the less considerable will be the rise of temperature4 ,for boring out rust spots which have eaten deeply into the iron a dental drill can be used with success1 and a great variety of drills and milling cutters can be obtained4 ,the rinsing1 which ,blell carries out by moving the object to and fro close under the surface in a vessel full of water1 may be sufficient for thin iron objects1 such as swords1 knives1 spear-heads1 and similar objects4 ,larger specimens should be freed from the acid by putting them into a still more dilute solution1 and1 when necessary1 by steeping for a short time in water4 ,it may also be advisable to put the objects into dilute soda solution to neutralize the sulphuric acid1 but this does not do away with the necessity for steeping in water4 ,the brown coating of rust which may possibly follow the steeping can be removed by the use of steel-wire brushes1 which can now be made of such fine wire that their softness almost equals that of a moderately soft tooth-brush4 ,brass-wire brushes should not be used1 on account of the yellow colour which they give to the iron4 ,i always put the objects directly after steeping into clean fat heated to #bej;,f4 #abj;,c41 for brushing over with fat and warming in a stove often caused a slight tarnish to cover the surface4 ,i have also used paraffin wax instead of fat4 ,for the method of restoring iron antiquities and of filling up large gaps1 the reader should refer to ,blell's detailed account2 it will here suffice to quote his statement that a mixture of iron filings with tin filings can be used for this purpose4 ,these are melted and applied by the aid of a blowpipe4 ,the accompanying illustrations represent iron antiquities which have been treated by ,blell's method3 the sword 7,fig4 #be7 proved1 after reduction1 from its two ridges to be a scramasax2 on the spear-head 7,fig4 #bf7 treatment revealed a small copper ring at the most constricted part1 while the fibula1 which previously had been a mass of rust1 now shows the spiral which had been totally disguised4 ,illustration3 ,fig4 #be4 ,iron sword treated by ,blell's method4 ,illustration3 ,fig4 #bf4 ,iron spear-head treated by ,blell's method4 ,illustration3 ,fig4 #bg4 ,iron fibula treated by ,blell's method4 ,,krefting',s ,,method4 ,the electro-chemical method of ,krefting was originally published in ,aarsberetning fra ,foreningen till ,norske ,fortidsmindesmaerkers ,bevaring1 #ahib 7p4 #ea71 but in ,finska ,fornminnesfreningens ,tidskrift#abe there is a translation into ,german by ,h4 ,appelgren1 and an additional series of observations and experiments by him4 ,his remarks are equally applicable to ,blell's method1 and the following extracts and quotations from this paper give ,krefting's method of procedure and the circumstances under which it should be applied4 ,small fragile objects such as fibulae1 thin clasps and bracelets or those which are much eaten away by rust1 are not suitable for this mode of treatment1 thus3 ,a knife which is much corroded1 and which when taken out of the earth shows a distinctive form 7for example1 that of the ,early ,iron ,age71 may lose so much by the application of the electric current that every distinct sign of its original character is destroyed4 ,the characteristic edges of a spear-head or of an axe of the late ,iron ,age1 or the equally characteristic point of an iron sword1 may1 if the rust has eaten deeply into them1 be unrecognisable when removed from the electrolytic bath4 ,a sword1 the hilt of which is inlaid with copper wire or is plated with silver or gold1 or the blade inlaid with inscriptions in gold1 silver1 or copper1 may be totally destroyed by incautious treatment2 for the ornamentation1 if undermined by rust1 may be detached with the rust from the underlying iron4 ,on the other hand1 objects of sound metallic iron covered with an incrustation of rust about #a_/be inch #a millimtre in thickness may be easily cleaned in this manner1 but if on using a file the metal does not appear at all1 or only at a depth of #a_/h inch #c millimtres1 great caution must be used4 ,if there is reason to believe that there is gold or silver inlaid work undermined by rust1 ,appelgren recommends that the object should1 as a preliminary1 be laid in clean water1 which should be renewed every day4 ,after some time1 three weeks at the most1 sufficient rust will have been cleared away by carefully brushing with a steel brush to lay bare the ornamentation1 at least in part1 and it can then be ascertained whether there is any rust underneath which would1 if ,krefting's method were used1 cause the ornamentation to be detached4 ,the line of treatment is as follows3 ,the metallic iron core is laid bare by filing in several places4 ,the specimen is then wrapped with strips of zinc in such a way that the zinc is in actual contact with the bare metal 7,fig4 #bh74 ,the whole is then placed into a #e solution of caustic soda#abf4 ,appelgren uses a solution of #c-a_/b-d-a_/b lbs4 #a-a_/b-b kilogrammes of caustic soda in #b gallons #aj litres of water4 ,the rust is cleared away by voltaic action2 the iron forms the negative pole1 the zinc the positive of a voltaic cell1 in which the water is resolved into its constituents1 viz4 oxygen and hydrogen4 ,at the negative pole1 i4e4 the iron1 the hydrogen rises up in small bubbles and acts in part by mechanically detaching the rust as in ,blell's method1 in part also by the chemical conversion of the rust into metallic iron1 or into a compound which contains a smaller quantity of oxygen than does ordinary rust4 ,the oxygen combines with the zinc to form zinc oxide1 which is dissolved in the soda solution4 ,the process is usually completed in #bd hours#abg4 ,the black powder which is loosely attached to the iron is best rubbed off with wet sand and fine wire brushes4 ,any hard pieces of black stable rust 7,edelrost71 magnetic oxide of iron1 which have not yielded to the electric current should be removed by means of a small chisel4 ,after rinsing the object thoroughly in water1 it should be placed in melted paraffin at #bdj;,f4 #aae;,c41 which will expel every trace of moisture4 ,on removal the melted paraffin should be allowed to drain off1 and thus leave when cold a protective covering upon the iron#abh4 ,the following points should be observed in the application of the method4 ,vessels of glass or glazed earthenware should be used for the reduction1 while long swords can be put into tall glass cylinders or into wooden troughs1 the interior of which must be coated over with paraffin4 ,the soda solution must be kept in a closed glass bottle#abi4 ,it should be diluted with water until the specific gravity1 as shown by the hydrometer1 is #ajf2 the mixture will then contain about #e per cent4 of caustic soda4 ,during the reduction process the mixture frequently assumes a brownish colour as the result of the presence of organic matter associated with the rust4 ,on account of the dissolved zinc which it contains it cannot be used a second time1 unless regenerated by boiling with quicklime4 ,the solution is1 however1 so cheap that this is scarcely worth the trouble4 ,the objects should be handled with metal tongs1 and should not be touched with the hand until they have at least been dipped or rinsed in water1 for the soda solution has an injurious effect upon the skin4 ,a basin containing vinegar1 dilute hydrochloric or sulphuric acid should always be at hand into which the fingers should be quickly dipped if they have been in contact with the caustic soda4 ,these materials will serve also for cleaning the vessels used in the reduction process4 ,the zinc strips should be #a_/d to #a_/c inch #a_/b cm4 to #a cm4 in breadth1 and should be cut out of a piece of sheet zinc of moderate thickness1 but of sufficient pliability4 ,any firmly fixed rust may be removed by mechanical means1 such as the graver1 drill1 etc41 as has been previously mentioned4 ,if in rinsing a slight layer of oxide appears1 although this is rare1 it should be brushed off with a steel-wire brush4 ,if one portion only of a specimen requires reduction 7the other portion having1 for example1 remains of wood attached1 and therefore being unsuitable for reduction71 that portion only should be wrapped with the zinc and immersed in the solution4 ,the results obtained by ,krefting's preservation-process are quite as surprising as those which are afforded by ,blell's method4 ,figure #bi1 taken from ,appelgren's work1 shows the lower portion of a spear-head before and after treatment1 by which it became apparent that the whole socket was plated with silver1 with two engraved and gilded animal figures4 ,fig4 #cd represents a piece of a sword1 on which an inscription was brought to light by the reduction process4 ,illustration3 ,fig4 #bh4 ,krefting's method4 ,iron spear-head wrapped with strips of zinc4 ,illustration3 ,fig4 #bi4 ,iron spear-head before and after treatment by ,krefting's method4 ,illustration3 ,fig4 #cj4 ,iron pin from ,danes' ,graves1 ,yorks4 ,cp4 ,yorks4 ,phil4 ,soc4 ,report1 #ahig4 ,illustration3 ,fig4 #ca4 ,the same after treatment by ,krefting's method1 still showing chalky accretions4 ,illustration3 ,fig4 #cb4 ,iron object from ,lamel ,hill#acj1 ,york4 ,it appears to have been originally rivetted to wood or leather4 ,illustration3 ,fig4 #cc4 ,after treatment by ,krefting's method4 ,illustration3 ,fig4 #cd4 ,piece of iron sword-blade showing inscription1 after treatment by ,krefting's method4 ,,hartwich',s ,,reduction ,,method#aca4 ,this method is only applicable to small objects1 because it necessitates the subjection of the objects to red-heat in a glass tube in a current of hydrogen4 ,by these means the hydrogen combines with the oxygen of the oxides1 which are thus reduced to metallic iron4 ,owing to the explosive nature of a mixture of hydrogen and air1 this process should only be carried out by one who is conversant with chemical methods1 for results which are equally good can be obtained at less expense by ,krefting's method4 ,for ,hartwich's method a strong core of metal is essential1 for although objects which are entirely oxidized may be thus reduced1 the result will be the formation of a more or less loose iron powder which is frequently in such a fine state of division that by union with the oxygen of the air1 in consequence of the great amount of surface presented1 it becomes red-hot with the formation of ferric oxide as a combustion product4 ,it is advisable to apply a combination of ,blell's or ,krefting's method with one of the first group 7under certain conditions7 to such iron objects as are found1 during the process of preservation1 to be penetrated by black stable rust to such a degree that the complete removal would only leave a kind of iron skeleton4 ,fig4 #ce represents such an iron dagger-sheath#acb1 the dark spots upon it being rust4 ,after heating and cooling down and a short treatment with acid the removal of the rust was proceeded with mechanically1 but was not completed4 ,the object was then well steeped1 and when dry was warmed in the varnish-petroleum mixture#acc4 ,illustration3 ,fig4 #ce4 ,iron dagger-sheath after treatment by a combination of ,blell's and ,krefting's methods4 ,iron objects1 the size of which is inconsiderable1 such as arrow heads1 small rings1 etc41 can be very quickly reduced1 if they still have a well-preserved core1 by heating them for a short time in molten potassium cyanide#acd4 ,the cyanide may be melted in a porcelain crucible supported by wire gauze on a tripod over a good-sized ,bunsen burner1 and the object introduced by the aid of tongs4 ,the reaction is accompanied by vigorous effervescence and is soon complete4 ,it is then taken out and dropped into cold water4 ,by repeatedly boiling in fresh quantities of water it is thoroughly cleansed1 then treated with paraffin wax1 or the water may be expelled by alcohol4 ,it is then dried1 and finally impregnated with zapon4 ,if the cyanide treatment is insufficient1 any remaining rust may be removed by drills or other suitable tools4 ,hitherto this method has only been applied to a small number of objects1 but there is no doubt that its use may be largely extended4 ,owing to the poisonous nature of the cyanide this method should be left to those who possess chemical knowledge4 ,the disadvantage of the process lies in the difficulty of fusing large quantities of the potassium cyanide#ace4 7#d7 ,preservation of ,medieval ,iron ,objects4 ,a complete treatise on this subject would be beyond the limits of a handbook1 the following observations1 therefore1 will be sufficient for our purpose4 ,the rust spots on objects of this kind are frequently only superficial and can be removed either mechanically by rubbing with pumice or emery1 etc41 or chemically by a concentrated solution of sodium sulphide#acf4 ,to prepare this1 sodium sulphide is dissolved in water1 or flowers of sulphur are boiled in a solution of caustic soda4 ,if the object is too large for immersion1 the solution may be applied with a brush1 and if the layer of rust is thick1 the application must be repeated4 ,after treatment the object must be rinsed in water and dried4 ,small articles can be freed from rust by immersion in strong fuming nitric acid#acg1 for strong acid dissolves the rust only1 while it induces in the iron the so-called passive#ach condition in which it is not acted upon even by dilute acids1 and can be safely washed in water4 ,when thoroughly cleaned1 the most suitable protective is some neutral substance such as paraffin wax1 vaseline1 or paraffin dissolved in benzine1 but any of the numerous forms of oil or fat may be used4 7i7 ,bronze and ,copper#aci4 ,well-preserved bronzes with a stable patina1 such as the highly esteemed glossy stable or edel patina1 or that which1 although not glossy1 covers the bronze with a rough and often crystalline coating1 should not be interfered with4 ,such bronzes as need treatment should be subjected either to simple cleaning or to some appropriate method of preservation4 ,,the ,,cleaning ,,of ,,bronzes4 ,bronzes1 the metallic substance of which is more or less intact1 while the surface is hidden under earthy or sandy material cemented together by copper compounds1 may be cleaned either by mechanical or chemical means4 ,when the materials forming the incrustation are more firmly cemented together than they are to the material beneath 7which often still retains a polished surface71 a small hammer may be used1 but more adherent portions require the use of small chisels1 which can be made to order in different shapes or sizes4 ,i have used with advantage hammers with striking surfaces like those shown in ,fig4 #cf4 ,the two on the right are rounded so that they touch the object at one point or on a line only4 ,the process may be facilitated by the use of ,springer's method4 ,a warm thick solution of glue should be spread upon the incrustation covering the bronze4 ,as the glue dries and becomes cool it scales off1 carrying with it some portion at least of the crust1 thus leaving the metal clean4 ,that part of the glue which remains can then be readily detached by gentle strokes with a hammer4 ,the eyes should be protected when using the hammer1 whether on the incrustation or on the glue4 ,illustration3 ,fig4 #cf4 ,hammer heads1 natural size4 ,,other ,,methods4 ,since metallic oxides are scarcely1 if at all1 soluble in water1 washing with water1 even when a brush is used1 will remove only earth or soil which is loosely attached4 ,compounds containing oxygen or oxygen and chlorine are1 however1 more or less soluble in ammonia1 and1 if they are thin and not too compact1 after immersion for some time can be removed with a brush4 ,thick compact layers are loosened with difficulty4 ,immersion in #b-e hydrochloric acid acts more effectively1 while sulphuric acid1 nitric acid1 and concentrated acetic acid have the same action4 ,the frequent use of these reagents is1 however1 strongly to be deprecated1 for it is impossible to remove the acid by simple washing with water after the incrustation has been removed4 ,the bronze should be washed and placed in a very dilute soda solution or in dilute ammonia1 after which it should be again well washed with distilled water4 ,as has been explained in ,part ,i41 it is to chlorine compounds that the destruction of bronzes is chiefly due1 and these are actually produced by the hydrochloric acid treatment4 ,if the bronzes are not thoroughly washed1 and this is no easy matter1 sooner or later efflorescences will make their appearance1 and the process of preservation must be repeated if the destructive action is to be arrested4 ,various attempts have been made to remove the incrustation by raising the bronze to a red heat4 ,this process is not recommended2 for not only does it give to the bronze an unpleasant appearance1 but it detaches any inlaid metal 7gold or silver7 or enamel which may be present4 ,in conclusion1 it may be stated that1 although the process is slow and laborious1 the best results are obtained by careful removal of incrustations by mechanical means4 ,preservation of ,bronze and ,copper ,objects4 7,a47 ,,methods ,,of ,,impregnation4 ,the impregnation of bronzes1 as of the majority of antiquities1 has for some time been carried out by the use of solutions similar to those already enumerated for iron4 ,these are applied directly or after the specimen has been either steeped in water or treated with dilute acids4 ,this latter treatment1 as has been already stated1 is to be avoided1 and if used all acid must be washed out before the object is dried4 ,steeping in water is of little use1 because compounds containing oxygen or chlorine are often insoluble in water1 which will at most only wash off loosely attached dirt or earthy material4 ,the impregnation process may therefore be applied directly1 and this should be done in all cases in which the surface is much corroded1 warty 7,figs4 #g and #h71 or cracked 7,figs4 #cg and #ch71 or in which there is little or no core of metal4 ,impregnation is also the only means of preservation when the formation of oxides has raised inlaid metals or enamel in such a way that the removal of the oxides would detach them4 ,the ,merkbuch#adj recommends poppy seed oil and benzine mixture 7p4 #gj7 or the gum-dammar solution4 ,to obtain thorough impregnation this should be carried out by extraction of the air1 as has been already recommended in the case of limestone 7p4 #fh74 ,the object must also be perfectly dry1 which may be insured either by exposure to moderate heat or by keeping it for some time over anhydrous calcium chloride#ada4 ,the object is placed under a glass bell jar1 the edges of which are smeared with vaseline to ensure contact with the glass plate upon which it rests4 ,the calcium chloride should be placed in an open glass vessel1 beneath the bronze1 but care must be taken that they are not in actual contact4 ,illustration3 ,fig4 #cg4 ,osiris showing cracking and destructive patina4 ,illustration3 ,fig4 #ch4 ,boeotian bridle with cracking patina4 ,immersion of bronzes in paraffin wax at #bdj;,f4 #aae-abj;,c4 gives results which are as good1 if not better1 than those obtained by the use of solutions4 ,should efflorescences make their appearances upon bronzes which have been impregnated1 their further spread may often be successfully prevented by smearing fish-glue on the parts affected4 ,fish-glue1 however1 has not proved a satisfactory material for the complete impregnation or coating of bronzes which are in the last stages of decay4 7,b47 ,,preservation ,,by ,,reduction4 ,it has been previously explained 7pp4 #bh et seq47 that the efflorescences upon bronze known as creeping or malignant patina which may in time cause the complete destruction of the metal are due to the action of sodium chloride4 ,it is found upon all ,egyptian bronzes and upon those from some other localities4 ,the metal1 especially the copper1 is converted into the so-called basic chloride4 ,in the reduction processes an attempt is made to reduce these compounds again to metal1 while the chlorine thus liberated forms chemical compounds1 which may be subsequently washed out with water4 ,there are two methods which effect this reduction1 viz41 that of ,finkener 7,berlin7 and that of ,krefting4 ,the principle of both is electrolytic1 and both bring about the complete removal of the patina and the restoration of a clean metallic surface4 ,to complete this portion of the subject a third method may be mentioned1 viz41 reduction by heat in a stream of hydrogen4 ,this method#adb is1 however1 only applicable to small objects4 ,,finkener',s ,,method4 ,care must be taken when examining the bronze that the metallic-looking mixture of cuprous oxide with other copper compounds is not mistaken for metallic copper4 ,when it has been ascertained that the bronze still has a good metallic core1 and that any inlaid metals which may be present rest on the metal itself and not upon a crust of oxide1 a platinum wire should be tightly wound round it4 ,this should be connected by an insulated copper wire to the zinc or negative pole of the first of #c or #d ,daniell cells1 or1 better1 of two accumulators arranged in series4 ,the object should then be immersed in a #b aqueous solution of potassium cyanide4 ,in the same solution1 as near as possible to the bronze without actual contact1 should be placed a piece of platinum foil connected first by an emerging platinum wire1 and then by an insulated copper wire to the positive pole4 ,the potassium cyanide completes the electric circuit and electrolysis takes place1 whereby the water is split up into its constituents4 ,the oxygen appears in small bubbles upon the platinum foil1 but the hydrogen does not immediately make its appearance at the other pole1 for1 by combination with the chlorine and oxygen contained in the bronzes1 free hydrochloric acid and water are formed4 ,the hydrochloric acid in turn acts upon the potassium cyanide to form potassium chloride and hydrocyanic acid1 both of which substances are dissolved in the water of the bath4 ,the hydrocyanic acid can often be recognised in the room by its characteristic smell of bitter almonds4 ,the process may be expressed by the following equations 7neglecting the water produced by the oxygen of the oxide1 which is of no importance in the process73 ,cu,cl#b #b;,h ,cu #b;,h,cl1 ,h,cl ,,kcn ,k,cl ,,hcn4 ,although the chief portion of the potassium chloride and hydrocyanic acid are dissolved in the bath1 the remaining traces of these substances must be removed by very carefully washing the bronze in water1 after which it should be dried1 and if necessary finally subjected to impregnation4 ,some further observations may be made in connection with the practical application of this process4 ,of course1 other primary batteries may be used instead of the ,daniell cells1 but these latter may be specially recommended for the ease with which they can be procured and for the steadiness of their action4 ,information concerning the method of filling and using them may be obtained at any shop where they are sold4 ,the copper wire and platinum wire should not be too thin1 but must be at least from #a to #b mm4 in thickness3 they should be fastened together by binding-screws1 and care must be taken that both the wire ends and the screws have clean surfaces4 ,glass vessels or glass cylinders are most suitable because the process of reduction can be watched1 but large objects will of course require glazed earthenware baths4 ,if wooden boxes are used they must be coated inside with paraffin wax4 ,the strength of the cyanide solution should be #b4 ,having a large number of reductions to carry out1 ,i keep a #bj stock solution in a large bottle1 one part of which is diluted with nine parts of water when required for use4 ,potassium cyanide is1 as is well known1 a strong poison1 and care should therefore be taken to prevent access to any sore or cut on the hands2 this can be done by the use of india-rubber finger stalls or gloves4 ,if the bronze object is neither too large nor too heavy it may be suspended in the bath by looping the platinum wire over the edge of the vessel4 ,it is a convenient plan to use different coloured wires to distinguish the negative and positive poles of the battery1 but should any doubt arise as to which wire should be connected with the bronze or which with the platinum1 the following test will readily decide the question4 ,moisten a small piece of white filter paper with a drop of a solution of potassium iodide#adc1 and touch the two conducting wires with it simultaneously3 a brown spot will be seen on the paper at the point of contact with one of the wires2 this is the positive wire1 and must therefore be connected with the platinum4 ,if the current is passing through the cyanide bath and the bronze1 bubbles of gas will appear upon the platinum foil1 or the products of the decomposition of the potassium cyanide may change the colour of the bath near the platinum to yellow or brown1 while at the same time cloudy streaks under the bronze will show where the potassium chloride and hydrocyanic acid1 resulting from the reduction of the copper compounds1 are meeting with the cyanide of the bath4 ,if the platinum wire is not firmly fixed round the bronze1 hydrogen may be formed upon it1 and should this occur the wire should be drawn tighter4 ,whilst the reduction is going on it is advisable to renew the potassium cyanide at least once1 or even several times1 if large and greatly oxidized bronzes are under treatment1 for otherwise all the potassium cyanide may be consumed by the changes in progress2 this can be ascertained with certainty by a smell of chlorine4 ,when the bath requires renewal the bronze may be taken out with a pair of metal tongs1 or if too large1 two strong copper wires should be passed underneath it1 the ends of which are wound round a strong glass rod or wooden stick4 ,the bronze should then be well rinsed or brushed with a soft brush before it is put into the fresh bath4 ,bronzes are frequently met with which are much deformed by an earthy or sandy layer cemented by oxide4 ,these incrustations can be partly removed by a preliminary treatment with dilute hydrochloric acid1 but the bronze must be afterwards carefully rinsed with water or even steeped to prevent unnecessary decomposition of the cyanide by the acid4 ,before reduction it is useful to secure thorough penetration by placing the vessel containing the solution and the bronze under a bell glass attached to an air pump1 as has been previously explained 7p4 #fh74 ,during the process of reduction small whitish-green crystalline needles often collect on the platinum foil1 but although in large numbers they are so minute that it has not been possible hitherto to determine their composition2 they seem to contain copper and cyanogen4 ,after some time the platinum becomes covered with a whitish-green or brownish deposit1 which should be removed by rinsing in water and brushing2 if this should not succeed the platinum must be dipped in hydrochloric acid1 rinsed with water1 and rubbed with fine sand4 ,the glass vessel may be cleaned in the same way4 ,the reduction is complete when all the chlorine1 previously combined with the metal1 has combined with the hydrogen produced by the electrolysis of the water4 ,there being no further chlorine with which the hydrogen produced by the continued action of the current may unite1 the completion of the process is marked by the appearance of bubbles of that gas upon the surface of the bronze4 ,the bubbles which rise from beneath often mark out the outlines of the object upon the surface of the bath4 ,before the bronze is washed it should be placed in a fresh cyanide bath1 but of #a strength only4 ,for large and especially for thick objects1 this bath must be renewed several times1 so as to allow the washing process to begin in the bath itself whilst the current is still passing through it4 ,care should also be taken that every side of the object in turn faces the platinum foil for some time1 for if one side remains turned toward the platinum throughout the process1 it will sometimes assume the red tint of copper1 while the rest of the bronze retains a somewhat dark colour4 ,when finally removed from the reducing bath1 after the black metallic powder has been thoroughly cleaned off with water and a soft brush1 the object should be suspended for a short time in water at the ordinary temperature1 or so fixed that there is a good depth of water beneath it2 it should then be washed in hot water4 ,when the bronze is first placed in water1 whether hot or lukewarm1 small bubbles of hydrogen will continue to rise for some time1 while at the same time a whitish1 or sometimes grey1 gelatinous precipitate1 consisting of a hydrated oxide of tin#add1 will often fall from it4 ,the grey colour is caused by the admixture of small particles of lead or copper4 ,at first ,i renew the water two or three times a day1 then once in twenty-four hours1 and finally at longer intervals1 using distilled water throughout for small objects1 but for larger specimens for the final washings only4 ,for the earlier washings at any rate ,i use warm water4 ,cyanides as well as chlorides give a white precipitate with silver nitrate2 this reagent will therefore serve to indicate the progress of the operation4 ,if at the end of a fortnight in the case of small bronzes1 or in three to six weeks for large objects1 the water shows no cloudiness1 or if upon the addition of yellow potassium chromate it instantly assumes a red colour 7p4 #fb71 the steeping may be considered complete4 ,some ,egyptian bronzes1 especially those which contain a large proportion of lead1 after steeping exhibit a whitish crystalline coating of lead carbonate or small hemispherical groups of crystals scattered over the surface of the metal1 especially where the pores are large2 when dry these can easily be removed4 ,an extended experience points to the conclusion that bronzes should be dried at once1 and as quickly as possible4 ,they should be wiped with soft cloths and then dried in a drying chamber or upon glass or metal rings on a stove4 ,a simple form of drying chamber can be made with copper or iron plate of sufficient thickness1 with a loose lid provided with a hole fitted with a cork1 through which a thermometer passes4 ,this can be heated over a ,bunsen burner1 but the temperature should not exceed #bcj;,f4 #aaj;,c44 ,small objects may be freed from water by immersion in alcohol for twenty-four hours before drying4 ,the completion of the process may be gauged by the yellowish or reddish yellow colour which the bronzes should assume when they have been dried and wiped with a cloth or brushed2 brushes made of the finest steel wire may be used for this purpose4 ,a bright colour is but rarely seen on bronzes which contain lead4 ,egyptian bronzes frequently contain as much as #bj of lead1 and such bronzes have nearly always a dull-grey or blackish appearance4 ,a similar colour is seen on bronzes which contain no lead1 but which are very porous1 and are in an advanced state of decomposition4 ,in such cases the finely divided particles of reduced metal are retained upon the rough surface of the bronze1 and as all metals1 when sufficiently finely divided1 form a blackish powder without any metallic lustre1 the whole object then appears almost black4 ,it is difficult1 and in many cases impossible1 to remove this dust1 especially that retained in the pores4 ,metal dust is injurious to the lungs1 and if recourse is had to brushing1 an efficient extractor for the removal of the dust-filled air is required#ade2 but brushing and the use of bellows in addition frequently prove insufficient4 ,washing the objects with benzine is more effectual1 but a trustworthy method of giving the bronze a better appearance is to place it into melted paraffin wax#adf at #bejto #bhe;,f4 #abj to #adj;,c44 ,yet the use of paraffin wax should be avoided if possible1 for in spite of the most careful washing blue efflorescences may sometimes appear upon thick bronzes in the course of a year4 ,if this should happen they must be washed out at once1 and the bronze can again be submitted to the cyanide-reduction process4 ,if however paraffin wax had been applied an attempt would have to be made to remove it by immersing the bronze in benzine or a mixture of ether and alcohol1 or by heating1 before the reduction process could be repeated4 ,illustration3 ,fig4 #ci4 ,bronze bull showing warty patina4 ,illustration3 ,fig4 #dj4 ,the same after reduction by ,finkener's method#adg4 ,there is no doubt that these bright-blue efflorescences are the result of an incomplete reduction1 which in many cases can scarcely be remedied1 for it is often impossible thoroughly to wash objects of great thickness4 ,thin bronzes1 bronze plate1 and copper plate remain free from efflorescences4 ,moreover1 many bronzes1 especially ,egyptian ones1 have a hard1 non-metallic core1 which in the casting has been partly fused or at least hard-burnt1 and resists the effects of the washing4 ,illustration3 ,fig4 #da4 ,bronze axe-blade before treatment by ,finkener's method 7,aeg4 #acbjc74 ,illustration3 ,fig4 #db4 ,the same side after treatment4 ,illustration3 ,fig4 #dc4 ,reverse side of axe-blade after treatment4 ,it is occasionally found that a bronze cannot stand the process of reduction1 either because there is only a thin layer of metal over a stout core1 or because the metal is permeated with cuprous oxide1 which when tested with a file has a metallic appearance4 ,the bronze must therefore be continually watched whilst it is in the cyanide bath1 and if necessary should be taken out even before the reduction is complete4 ,this should be done if large pieces or large quantities of a powdery precipitate fall from the bronze1 or if it is found that a needle readily pierces the oxidized layer4 ,a specimen of this kind must be taken from the bath1 carefully steeped1 dried1 and impregnated#adh4 ,it is not to be expected that bronzes which are in an advanced state of decomposition 7e4g4 ,figs4 #i-ab7 can be so transformed by reduction as to appear as they did when they left the artist's hand4 ,for1 although the decomposed oxidized layer is now reduced to metal1 this no longer forms a coherent mass1 but a loose powder1 which1 being deprived of its essential constituents1 chlorine1 oxygen and carbonic acid1 no longer retains its coherency1 but falls to the bottom4 ,only in the interior and in the pores is the reduced metal retained4 ,in addition to the preservation of articles by the removal of the injurious chlorine compounds 7as is also the case with ,blell's and with ,krefting's method for iron antiquities71 the process may result in the discovery of inlaid work1 inscriptions or ornamentation1 the presence of which was not suspected4 ,the accompanying illustrations 7,figs4 #ci and #dj7 show bronzes before and after the preservation process1 while the axe-blade shown in ,figs4 #da-dc illustrates equally clearly the advantages which accrue from the treatment4 ,not less striking is the result of the treatment in the case of the dagger-sheath shown in ,figs4 #dd and #de by which the design was discovered4 ,reference may here be made to a case described elsewhere#adi1 in which reduction proved that what had been thought a single bronze object consisted in reality of two pieces which did not belong to each other1 but were fitted together by means of a bottle cork of modern date6 ,in another instance a bronze was found upon reduction to be brazed with a hard solder containing zinc1 which was thus quite inconsistent with the age ascribed to the object4 ,illustration3 ,fig4 #dd4 ,fig4 #de4 ,dagger sheath before and after treatment by ,finkener's method4 ,a short digression may be here made in order to discuss the question whether the composition of the bronzes undergoes any alteration4 ,three analyses#aej of ,egyptian bronzes before and after reduction by ,finkener's method show that the change in composition is so slight as to be immaterial4 ,it is of course obvious that greater differences will be seen in the results of the analyses before and after reduction of bronzes which are in an advanced state of oxidation1 for in this case chlorine1 oxygen1 water1 and carbonic acid constitute an appreciable proportion of the total weight4 ,but even in these cases the analysis made after the reduction shows very slight variation from that of the original metal4 ---------------------------------------- ---------------- ,osiris ,osiris ,ibis ---------------------------------------- ---------------- ,before ,after ,before ,after ,before ,after ,reduction ,tin #baf #bbg #dcj #dba #hff #hdf ,copper #gghc #ggde #giff #gigd #hhec #hhge ,lead #aibc #aihf #aeea #aeeh #afi #aie ,iron #jab #jad #jbh #jbd #jba #jbj ,nickel ,cobalt #jbi #jbd #jbj #jag #jcj #jbi ,arsenic #jag #jbc #jag present #jcb present ,antimony trace trace trace --- #jbj present ---------------------------------------- ----------------- ,the two latter bronzes were tested qualitatively only for arsenic and antimony1 and when the three objects were washed the hydrated tin-oxide described on p4 #acj was only found in the case of the ,ibis4 ,in this connection it should not be forgotten that slight differences in the quantities may be due to errors in the analysis as well as to a want of homogeneity in the alloy4 ,,krefting',s ,,method4 ,this method is similar to that used for the reduction of iron 7see page #ajh74 ,the layer of oxidized material is removed in several places by filing1 hammering1 or rubbing with emery cloth until the metal is exposed4 ,the object is then wrapped round with strips of zinc1 and placed in a #e solution of caustic soda4 ,the hydrochloric acid produced in the process of reduction acts upon the soda to form sodium chloride4 ,here too the greatest care must be taken that the steeping is sufficient4 ,personally ,i prefer ,finkener's method1 for potassium cyanide is more easily washed out than soda1 and also1 although poisonous1 is less caustic4 ,krefting's method however has proved of considerable success in some cases1 notably in the treatment of some #dj-ej1jjj ,roman copper coins at the ,berlin ,museum4 ,these were1 with few exceptions1 covered with a crystalline layer resembling green malachite or blue azurite and were quite illegible4 ,various unsatisfactory attempts were made to clean them with ammonia1 with warm and cold acids of different kinds1 with acid and iron nails1 and by electric current both in an acid solution and in a solution of potassium cyanide4 ,the following method finally proved satisfactory#aea3 ,krefting's ,method ,applied to ,oxidized ,copper ,coins4 ,a thin plate of zinc with a bright metallic surface is perforated with a brad-awl1 having a diameter of from #b to #e mm41 until there are about #ej or #fj holes in each square metre4 ,this is placed with the sharp edges of the holes uppermost on a row of glass rings 7or crystallizing dishes will serve the purpose7 #bj mm4 in height resting upon the bottom of a large glass vessel4 ,the coins1 which in this case were #bj mm4 in diameter1 were then placed on the zinc plate1 so that #g or #h of them occupy a space of #a square decimetre4 ,another similarly perforated plate is laid upon them1 and upon this more coins are arranged in the same way1 and so on until there are six or eight double layers4 ,a perforated zinc plate is then placed on the top with the sharp edges of the holes turned downwards1 and over this a few zinc plates which have been previously used4 ,the whole pile is surmounted with weights or stones resting upon glass rings or inverted glass dishes in order to press the sharp edges of the holes into the closest possible contact with the coins4 ,a #e solution of caustic soda is then poured over the whole1 the immediate result of which is an evolution of gas4 ,the reduction of the coins is usually complete in fifteen to eighteen hours1 after which they should be well washed4 ,after several rinsings in cold water they are placed1 about #ajjj at a time1 in a large vessel fitted with a perforated false bottom containing hot water1 which should be renewed three or four times every day4 ,after four days the coins are wiped with a cloth and thoroughly dried on a warm oven plate or in a drying chamber at a temperature of about #bab;,f4 #ajj;,c44 ,they are then brushed with a bristle brush before a dust extractor1 a procedure rendered necessary by the fine metallic dust from the coins1 which then assume a light or dark brown colour such as is seen on copper coins which are in actual circulation4 ,the practice of placing the coins whilst still wet into melted paraffin wax at #bfj;,f4 #abj-acj;,c41 which gives a dark appearance even to the brightest1 has the disadvantage that the wax prevents the use of sealing-wax for taking impressions1 and is therefore not recommended4 ,the reaction is analogous to that which occurs in the reduction of iron4 ,the copper of the coin forms in the alkaline solution an electric couple with the zinc1 and the hydrogen which forms at the copper end reduces the copper compounds covering the coins to metallic copper1 and thereby loosens them1 while the zinc oxide which is simultaneously formed is dissolved in the soda solution4 ,in actual practice a part only of the zinc oxide is dissolved1 while the remainder forms a white coating on the zinc#aeb4 ,experience shows that a #d-e solution is the most suitable for this method of reduction1 which gives the most favourable results when these details are followed4 ,if for example the zinc plate is laid immediately on the bottom of the glass trough1 if the coins are laid too close together on the plate1 or if there are more than #f to #h double layers in a trough1 the process of reduction is often incomplete1 and it is then necessary to treat the coins a second time4 ,it is scarcely necessary to mention that larger coins must be placed at proportionately greater distances from each other4 ,the #dj-ej1jjj coins which were thus treated had originally been tinned1 but the tin only remained at a few places4 ,when the coins were washed immediately after the reduction1 this tin could still be clearly distinguished1 but on further washing1 drying1 and brushing1 it ceased to be visible on account of the dark colour imparted to it by the finely powdered copper4 ,in one or two cases lead appeared on the surface of the coin1 but was easily removed by mechanical means4 ,illustration3 ,fig4 #df4 ,roman coins before treatment4 ,illustration3 ,fig4 #dg4 ,roman coins after treatment by ,krefting's method4 ,cleaning ,copper ,coins by ,melted ,lead4 ,although the results obtained by this method are less satisfactory than those produced by the preceding1 it has the advantage of simplicity#aec4 ,using a pair of tongs1 dip the coins one by one into melted lead until the crackling1 which begins at once1 has ceased1 which occurs in from #c to #aj seconds4 ,the hand should be protected with a glove from the spluttering molten lead4 ,the coin is then thrown into cold water1 cleaned1 and placed until the next day in hot milk4 ,it may be necessary to repeat the process when the coin has become cold4 ,by this method an olive colour is imparted to the coin which many antiquaries prefer to dark brown1 but personally ,i prefer ,krefting's method because it renders the inscription and designs far more distinct4 ,a coin which after the treatment with melted lead has remained so covered with cupric oxide as to be still illegible can seldom be improved by a repetition of the treatment1 whereas had the zinc treatment been applied in the first instance the result would probably have been satisfactory4 ,this conclusion seems to be justified by the extremely small percentage of coins which1 in my experience1 have remained illegible after the treatment by electrical methods4 7,c47 ,preservation of ,bronzes by the ,exclusion of ,air4 ,in those cases in which the advanced state of decomposition renders the reduction process either inapplicable or at any rate inadvisable1 or in which the decay is not likely to be arrested by impregnation1 a further method of preservation remains1 viz4 the complete exclusion of air and moisture4 ,if air is completely freed from moisture the oxygen can no longer act in conjunction with the copper chloride upon the still intact metal 7see page #bi et seq471 and the condition of the bronze will consequently remain unchanged4 ,a bronze1 for example1 which shows much decay should be placed after impregnation under a hermetically sealed bell glass1 and beneath or near it should be placed some dehydrating agent1 of which anhydrous calcium chloride is the most suitable 7see note1 p4 #abc74 ,to exclude the air completely the bell glass should have a projecting ground edge1 which should be smeared with vaseline or grease and pressed firmly upon a thick well polished glass plate4 ,the dehydrating agent may be placed in a glass vessel or dish in such a way as to be unseen1 or it may be covered with two or three thicknesses of dark gauze or with black cardboard laid loosely over it4 ,if an object is too large for a bell glass1 or if several objects are to be exhibited together1 a square plate-glass case with iron framework1 made air-tight with putty1 may be used as shown in the illustration 7,fig4 #dh74 ,the lower part1 containing calcium chloride1 is partitioned off by a perforated plate covered with black gauze#aed4 ,a hygrometer was placed behind the head1 the indicator of which has remained at zero since it was first fixed several years ago1 and the bronze has not hitherto shown any sign of change1 although the inlaid gold is in parts raised from the metal by a light-green oxychloride4 ,the cost of these cases is considerable1 but for valuable objects this should not be considered4 ,in the place of calcium chloride1 sticks or lumps of caustic soda may be used with advantage1 for this substance absorbs both moisture and carbonic acid4 ,illustration3 ,fig4 #dh4 ,method of mounting objects in air-tight cases4 ,this method of preservation is of course applicable not only to decomposed bronzes but to all valuable antiquities1 whatever the material may be4 ,appendix4 ,methods of ,bringing out ,worn ,lettering upon ,coins4 ,these methods are founded upon the fact that the sunken areas of the coin are1 by the pressure of the die in stamping1 rendered denser than the raised portions1 such as the inscription4 ,the earliest method is that published by ,brewster1 reported by ,spke#aee4 ,the coins when cleaned are placed upon red-hot iron1 which causes the oxidation of the entire surface of the coin4 ,the thin film of oxides varies in colour according to the duration and the intensity of the heat4 ,the oxidation of the letters of the inscription differs from that of the surrounding parts1 and is recognisable by a difference in colour4 ,drude#aef1 treating more especially of silver coins1 remarks that the inscription is rendered legible by heating them to redness over a ,bunsen-burner4 ,it then1 according to ,prometheus#aeg1 when viewed in a dark room1 appears dark on a bright ground1 especially if the coin has been previously polished and then roughened again by slightly etching it with acid4 ,in conclusion1 the method of ,roux#aeh may be quoted3 ,the smooth-worn and polished coin is placed in a solution of copper sulphate or of some other metallic salt1 and suspended between the electrodes of one or more cells of a battery 7any other form of continuous current will serve the purpose74 ,if the current is weak1 the electrodes must be near to the coin4 ,the stronger the current the more rapidly the impression appears4 ,on the side which faces the anode or positive plate the impression is metallic2 on the other side1 after gently wiping off the less firmly adherent part of the oxide1 the impression appears in grey lines4 ,these markings can be fixed by varnishing them with a thin alcoholic solution of shellac4 ,to render the impression legible on both sides1 the coin should be placed upon the four upturned feet of an insulating stand4 ,the larger the coin the deeper must be the layer of solution above and below the coin4 ,the depth below should be equal to the radius of the coin4 ,this can perhaps be most conveniently carried out by placing that electrode in immediate contact with the coin which upon immersion in the solution becomes tarnished with the metal1 i4e4 the cathode or negative pole4 ,other portions which it is not intended to treat should be first covered with varnish4 ,the striking success of this method is due to the fact that that portion of the metal which has been compressed by the stamp is a better electrical conductor than the rest2 no success could therefore be expected from the use of this process for the restoration of such objects as worn engraved copper-plates1 etc4 7j7 ,silver4 ,preservative treatment of silver is scarcely necessary 7cp4 pp4 #di-eb71 except in those cases in which the silver is alloyed with a large percentage of copper1 and which show efflorescences similar to those which appear upon bronzes containing chlorine4 ,electrolytic reduction will be found to be the most suitable method of treatment in such cases4 ,to treat silver coins they should be placed in contact with iron nails in lemon juice4 ,instead of the citric acid1 which is the active principle in this process1 other diluted acids and other metals1 e4g4 zinc1 may be employed4 ,flinders ,petrie#aei has shown that the reduction can also be effected by a weak solution of common salt4 ,silver chloride is soluble in ammonia1 and thin layers may be removed by the application of ammonia by means of a soft brush4 ,thorough rinsing with pure water1 drying with soft cloths1 and cautious warming are always essential4 ,an excellent reducing agent for single coins1 the characters of which are rendered illegible by a layer of silver chloride1 is molten potassium cyanide1 or a mixture of this substance with sodium or potassium carbonate4 ,in a short time the silver chloride is decomposed and removed from the smooth surface of the coin4 ,after boiling out with water1 steeping in alcohol1 drying1 and brushing with a soft brush1 the coins may be coated with zapon4 ,coins treated in this way appear to be less brittle than those reduced by ,krefting's method4 ,more troublesome but less dangerous1 because potassium cyanide is not used1 is the treatment of silver coins with a fused mixture of potassium and sodium carbonates4 ,in this case the silver chloride is converted into silver carbonate1 which is then decomposed with #ej acetic acid4 ,further treatment by washing1 drying1 and impregnation is carried out as previously described4 ,silver which has become friable 7p4 #ea7 can be rendered more compact by cautiously heating it to redness4 ,it will however be advisable to entrust heating and mechanical treatment of objects which are much bent to some skilled silversmith1 whose experience may prevent disaster4 ,silver objects which are largely converted into friable chloride1 especially if they are much expanded1 or if large portions have broken away in the process of removing the chloride1 will hardly bear any other treatment than that of impregnation with gum-dammar solution or with paraffin wax4 ,as silver chloride is easily fused such articles should not be subjected to heat4 ,earthy matter can often be removed with a neutral soap and warm water1 while calcareous accretions can be dissolved by a #b solution of hydrochloric acid4 ,silver which has been blackened by silver sulphide may be laid in a warm #b solution of potassium cyanide4 ,all objects should be subsequently well washed with warm water4 7k7 ,lead and ,tin4 ,objects of pure lead and pure tin are rare4 ,if much oxidized they should be washed with warm water1 dried1 and impregnated with a gum-dammar solution or with paraffin wax 7pp4 #gj and #ia74 ,if in a good state of preservation they may be freed from any earthy or calcareous coating or from lead carbonate by the cautious use of very dilute nitric acid followed by steeping in water4 ,ceresole#afj cleans oxidized leaden seals with #aj acetic acid1 neutralises the acid with ammonia1 and after five minutes in alcohol coats them thinly with wax4 ,the seals are preserved between glass dishes 7,petri dishes71 the space between the dishes being filled with cement4 ,i employ ,krefting's method for leaden medals1 using either zinc and very dilute sulphuric acid1 or zinc dust and caustic soda4 ,occasionally the zinc dust becomes firmly cemented by oxide to the surface of the lead1 and1 if this is the case1 great care must be used in removing it4 ,the washing process also requires care4 ,a very efficacious method is to allow a stream of warm distilled water1 from which the dissolved air has been driven off by boiling1 to flow over the object in a porcelain dish4 ,i now omit any impregnation with paraffin wax1 and instead recommend removal of the water by alcohol1 drying1 and coating with zapon4 ,to preserve the specimens after treatment1 more especially from the injurious action of perspiration from the hands1 they are placed between dishes of glass or of celluloid#afa4 7l7 ,gold4 ,objects of pure gold usually need only be cleaned with soap and water and a soft brush2 lime may be removed by the application of a #b solution of hydrochloric acid4 ,a coating of silver chloride occurring on gold which contains a large percentage of silver may be removed by ammonia1 or1 in certain cases1 by the alternate use of dilute hydrochloric acid and ammonia4 ,a layer of red ferric oxide 7see p4 #ec7 is of frequent occurrence upon gold objects1 and may be removed by warming the object in a stronger solution of hydrochloric acid1 but soft brushes will often serve the same purpose4 ,pure gold being very soft1 only the softest so-called silver brushes should be used1 and all pressure or bending should be avoided4 ,if friable the object should be carefully impregnated with a solution of gum-dammar 7p4 #gj74 7m7 ,glass and ,enamel4 ,if covered with a film of dirt1 or if when in a collection objects of glass or enamel undergo any alteration1 they should be washed or steeped in lukewarm water4 ,when dry they should be treated with pure olive oil or poppy-seed oil1 which may be diluted with benzine4 ,the oil helps to restore the lustre to the glass and to bring out the colour of the enamel4 ,when thus treated the objects should be carefully protected from dust4 ,a decomposition of ancient glass when deposited in a museum has been hitherto only rarely observed1 but allusion may be here made to the so-called 'sweating' of glass which is a question of considerable importance in ,industrial-,art collections4 ,in this case preservation is insured by washing with distilled water1 drying1 and coating with zapon4 ,further particulars may be obtained from the paper by ,pazaurek#afb4 ,,ii4 ,preservation of ,organic ,substances4 7n7 ,bones1 ,horns1 ,ivory4 ,many curators dry carefully and impregnate them with a gum-dammar solution or shellac2 isinglass or glue are however preferable1 for these aqueous solutions may be used for the treatment of damp objects1 which could scarcely be dried without cracking4 ,in order to permeate the object these solutions must be very dilute1 and are most advantageously applied at a temperature of about #abj;,f4 #ej;,c44 ,the impregnation may also be effected in rarefied air under a bell glass 7p4 #fh74 ,friable bones and similar objects which might fall to pieces in the solution during impregnation should be bound with strips of gauze or with string before immersion2 they are easily removed when cold4 ,to prevent the formation of mould a small quantity of dissolved corrosive sublimate#afc is added to the glue1 or when dry after impregnation the objects may be covered with a solution of shellac or resin4 ,impregnation is of very general application1 and is frequently used for the preservation of fossil and pleistocene bones4 7o7 ,leather4 ,at ,copenhagen the method used to render leather soft and pliable is to place it in train oil for an hour and then dry it with filter-paper4 ,lanoline may also be used with success#afd4 ,poppy-seed oil in benzine 7p4 #hf7 is said to produce good results1 but the ,merkbuch recommends the preservation of leather in this condition in alcohol#afe4 7p7 ,textile ,fabrics1 ,hair4 ,earth and soil may be removed by mechanical means1 and1 occasionally1 careful washing may be possible4 ,the objects should be dried and impregnated with a gum-dammar solution 7p4 #gj71 poppy-seed oil 7p4 #hf71 or a solution of india-rubber 7p4 #ij71 or they may be preserved in alcohol 7p4 #aei74 ,some textile fabrics in the ,copenhagen ,museum owe their excellent state of preservation to ,steffensen's treatment1 i4e4 impregnation with a solution of india-rubber in turpentine with the addition of bees'-wax4 ,the following account of the treatment of textile fabrics from the ,lake-,dwellings is due to ,herr ,heierli1 of ,zrich3 ,the pieces as they were taken up were laid on the ground and thus slowly allowed to dry in the air4 ,they were then placed between glass plates1 the edges of which were pasted over with paper4 ,old pieces which had been dry for a long time1 and which had become tender and friable1 were laid on the ground and watered from time to time until they were soaked through2 they were then treated in the manner already described4 ,egyptian textile fabrics preserved between glass plates often deposit a thin layer of salt on the glass1 but this is easily wiped off 7see p4 #aee74 ,it must first be ascertained by a previous trial in each case whether the salt can be removed by steeping in water or in alcohol and water4 ,hair found in peat has always a dark-brown colour from impregnation with peaty matter4 ,the method proposed by ,bille ,gram#aff for restoring the natural colour consists of repeated and alternate treatment with very dilute alkali solution and acid at about #abj;,f4 #ej;,c44 ,when the liquid ceases to show coloration the natural colour of the hair is restored4 7q7 ,feathers4 ,these do not require any treatment beyond protection against insects1 which is attained by immersion in an alcoholic solution of corrosive sublimate1 or by spraying with corrosive sublimate in either alcoholic or aqueous solution4 ,of course the poisonous nature of corrosive sublimate necessitates caution in its use and it should be always labelled as such4 ,the use of naphthalene is not always successful1 and white scales of naphthalene are apt to make their appearance2 nor does finely powdered pepper sprinkled on the feathers1 either alone or mixed with finely powdered alum1 give satisfactory results4 7r7 ,papyrus4 ,the method of cleaning and preserving papyrus in use in the ,egyptian department of the ,royal ,museums at ,berlin is as follows3 ,those pieces which are folded together or rolled are carefully straightened1 and1 if very friable1 they are first placed between damp filter paper to render them uniformly pliable4 ,dust and dirt are removed with soft paint-brushes1 crystals of salt which are often found#afg are picked off with forceps4 ,any growths of fungus are carefully scraped off with a knife4 ,the papyrus thus prepared is then placed between two thick polished glass plates1 the two opposing surfaces of which are covered with a very thin layer of vaseline4 ,air is frequently admitted to dry the papyrus1 while the pressure of the glass plates tends to smooth it out1 and after it has been so treated it is mounted between thin glass plates1 the edges of which are pasted over with paper covered with an oil paint4 ,a papyrus preserved between glass plates often shows round the edges a whitish border about two millimetres in breadth1 and on separation the glass plates show a slight film of the same white material on the surface which had been in contact with the papyrus4 ,the formation of this film1 which consists chiefly of common salt and is easily wiped off1 may be prevented by previously washing the papyrus in distilled water1 a proceeding which experience has shown to be harmless4 ,as the papyrus will swim on the surface it should first be immersed in alcohol until soaked through2 the process of steeping is then quite simple4 ,the thinness of papyrus enables the steeping to be completed after #bd to #dh hours by two changes of the water1 and care must be taken lest a too prolonged steeping should obliterate the lettering4 ,the water assumes a yellowish or brown tint and the papyrus becomes somewhat lighter in colour on drying4 ,papyrus may also be preserved by zapon 7see ,appendix71 but this method has no advantage over that of mounting between glass plates4 7s7 ,wood4 ,to preserve adequately articles of moist wood 7and they are generally in this condition when first excavated71 preliminary measures to prevent their drying in the air must be taken immediately after they are dug out of the earth4 ,if found in water1 as for instance articles from pile-dwellings1 they should be conveyed in water2 moist objects should be wrapped in several thicknesses of moist cloth1 and the whole wrapped in gutta-percha membrane1 or in a layer of moist moss4 ,the cracks which arise in wooden objects which have become dried may frequently be closed up by laying them in lukewarm water4 ,as the earliest attempts at preservation were probably made upon wooden objects there is scarcely a collection in which a number of methods are not employed4 ,one exception only is known to me1 and here1 after a plaster of ,paris cast has been taken1 the object is simply allowed to shrink4 ,the methods proposed and carried out are so different and so numerous1 especially as regards the liquid used for impregnation1 and in such variety1 that it is only necessary to deal with the most important4 ,these may be divided into two classes1 viz4 dry and wet4 7#a7 ,dry ,preservation of ,wood4 ,moist or wet objects are placed in thin size or in a solution of isinglass till they are impregnated1 after which they are dried gradually in a shady place4 ,a solution of shellac1 or varnish diluted with petroleum or benzine1 is then put on with a brush4 ,sometimes the objects are placed directly into a mixture of varnish and petroleum1 or they are impregnated with melted paraffin4 ,the former is preferable as a means of impregnation if there are cracks or holes1 for the superfluous solution readily drips from the wood when it is taken out1 while paraffin sets too soon to drain out of the cracks1 and thus imparts an unnatural white appearance to the wood4 ,owing to the large size of the vessels which would be otherwise required1 paraffin is only useful for small or medium-sized objects1 but when making use of varnish one end of a large object#afh may be placed in the mixture while the solution is repeatedly poured over the object4 ,after two or three days the opposite end should be placed in the solution4 ,by repeating this process every part of the object will soon be thoroughly impregnated4 ,objects of still greater size1 such as a ,viking's ship1 can only be preserved by painting the surface4 ,in such cases it is advisable to begin with dilute varnish so as to allow the impregnating solution to penetrate as deeply as possible into the material1 instead of merely forming a skin4 ,a solution of waterglass has in one instance been used for the preservation of a large boat1 but the result is not satisfactory4 ,,leiner',s ,,method#afi4 ,the wooden articles are laid in glycerine mixed with a small percentage of carbolic acid4 ,the length of time during which they remain in the glycerine depends upon their size4 ,when taken out they are lightly wiped and preserved without further treatment4 ,if a growth of mould should occur it may be washed off4 ,objects thus treated retain their moist condition and should therefore be very carefully protected from dust4 ,,speerschneider',s ,,method#agj 7cp4 p4 #ia74 ,small specimens are heated for two hours in a mixture of #h parts of rape-seed oil1 #a part of bees'-wax1 #a part of pine resin1 and #b parts of benzene4 ,larger objects require a proportionately longer heating1 but the mixture must not be allowed to actually boil4 ,the moisture rises as steam and causes the solution to bubble4 ,the bubbling however continues after the moisture has been driven off2 great care must therefore be taken that the heating is not so prolonged as to cause the object to shrink4 ,the highly inflammable nature of the mixture renders great caution necessary1 and should it ignite1 a lid1 which should always be in readiness1 should be put on the vessel4 ,after impregnation the objects are wrapped in blotting-paper and laid in ashes for four days to prevent the access of air4 ,the aim is doubtless to insure thorough absorption of the superfluous liquid which remains upon the object1 which exposure to air would prevent by causing the mixture to set too rapidly4 ,the same mixture can be used repeatedly1 but each time two-thirds of the original quantity of benzene must be added4 ,,herbst',s ,,method#aga4 ,the moist objects are boiled in a saturated solution of alum for two hours 7hot water dissolves about #c-a_/b times its weight of alum71 but if they are of some thickness the time must be proportionately longer4 ,they are then taken out1 and when the alum in crystallizing has made them more or less firm1 the crystals adhering to the surface are washed off with warm water4 ,when thoroughly dry the wood is brushed over with hot linseed oil1 which operation is repeated until no more oil is absorbed4 ,a final thin coating of varnish or shellac is then given4 ,according to ,steffensen1 the method followed at ,copenhagen is to lay the objects in warm thin size for a quarter of an hour after impregnation with alum4 ,this alum-method is there used for objects of oak1 although the ,merkbuch 7p4 #fj7 states that only the varnish-petroleum mixture should be used for impregnating this class of object4 7#b7 ,preservation of ,wooden ,objects in ,liquids4 ,the expense entailed by this method renders it applicable only to articles of small size4 ,the preservation of small objects in a flat vessel1 the bottom of which is covered with glycerine1 has the disadvantage that glycerine extracts organic substances and thus assumes a brown colour4 ,if glycerine is used the object should undergo a thorough preliminary steeping1 and the glycerine should be renewed until it remains colourless4 ,closed cylinders filled with glycerine or a mixture of glycerine and water are not convenient because wood nearly always floats in the liquid4 ,this may be remedied however by the addition of alcohol4 ,,jenner',s ,,method#agb4 ,when the objects have been thoroughly cleaned with water1 pure alcohol1 diluted with water until the specific gravity at #ed;,f4 #abe;,c4 reaches #jif1 is poured over them4 ,after six or eight weeks the alcohol is poured off and replaced by fresh alcohol of the same specific gravity4 ,this alcohol is examined in a year's time1 and should always show a specific gravity of #jif4 ,the alcohol which has been poured off may be filtered1 and if necessary decolourized by animal charcoal2 when the specific gravity has been again raised to #jif1 by the addition of fresh alcohol1 it may be used again4 ,the same process is applicable to textile fabrics1 yarn1 and leather4 ,protection against ,wood-worms1 etc4 ,all the methods mentioned above will destroy insects and their larvae4 ,in cases in which it is either impossible or undesirable to use immersion or external application1 as for instance in the treatment of objects of dry wood1 the larvae may be destroyed by dropping petroleum1 an aqueous solution of potassium arsenite1 or corrosive sublimate1 into the various small openings4 ,this will also help to prevent further attacks4 ,if solutions are not applied insects may be destroyed by the vapour of carbon bi-sulphide or of crude benzene4 ,these liquids1 which are sufficiently volatile at the ordinary temperature1 should be placed1 together with the objects to be treated1 in a closed box4 ,i have used a similar method for the destruction of wood-worms in ,egyptian coffins4 ,the coffin is placed in a large wooden box lined with tin plate4 ,the lid1 also lined with tin1 is provided with projecting edges1 to which strips of felt are glued4 ,the weight of the lid by compressing the felt is sufficient to render the box air-tight4 ,six or eight glass vessels containing crude benzene are placed at the bottom of the chest and of the coffin itself4 ,it need scarcely be added that the box must not be opened near a fire or light1 as the vapour forms an explosive mixture with air2 it is in fact advisable to have no light or fire in the room4 ,insects can also be killed by naphthalene vapour1 but as naphthalene is insufficiently volatile at ordinary temperatures1 the method above described is more convenient#agc4 ,preservation and ,cleaning of ,coloured ,wooden ,objects4 ,for objects of this kind materials should not be used which1 like varnish1 tend to darken and so to damage the colours4 ,gum-dammar solution 7page #gj7 answers the purpose1 but colourless collodion is better4 ,colours which are soluble in water 7as is frequently the case with wooden objects from ,egypt7 cannot of course be cleaned with water1 but benzine may be applied by means of soft cloths or brushes4 ,resinous or pitch-like substances may often be removed from coloured objects by turpentine mixed with benzine or ether4 ,a method of cleaning gilded or brightly coloured ecclesiastical figures which is used in the ,breslau ,museum is the application of a mixture of copaiba balsam and ammonia4 ,this method is similar to that used to clean paintings#agd1 the action of the solution being that of a mild soap4 ,antiquities which were originally uncoloured1 but which have been subsequently painted1 may be cleared of paint by means of a solution of caustic soda in water or alcohol4 7t7 ,amber4 ,after the mechanical removal of any adherent earth and dust1 the specimen should be rubbed carefully backwards and forwards between the fingers covered with a soft woollen glove4 ,particles of soil should be picked out of any holes and indentations by using a strong horse hair#age4 ,it is then preserved by impregnation with a solution of shellac1 poppy-seed oil1 or isinglass 7pp4 #gj and #hf74 ,the following particulars of the method used in ,messrs ,stantien and ,becker's collection of amber have been supplied by ,prof4 ,klebs3 ,amber is preserved best in distilled water3 ,i add a very small quantity of glycerine and a still smaller amount of alcohol4 ,a proportion of alcohol greater than #a is injurious to the amber4 ,a thick layer of gelatine containing glycerine is an excellent medium for the preservation of large objects if they are kept free from dust4 ,this layer should be washed off and renewed every few years4 ,the ,care of ,antiquities after ,preservative ,treatment4 ,in addition to the protection from dust afforded by closed glass cases1 it is also important to protect objects from the action of direct sunlight1 especially during the summer months4 ,there is1 for instance1 no doubt that the decay of bronzes1 even of those with a patina which is apparently sound1 is hastened by the great variations of temperature1 caused by the rays of the sun falling directly upon them4 ,similarly objects which have been preserved by the application of solutions of resin or varnish should be protected from the direct access of sunlight1 for the sudden warming may easily cause cracks4 ,nor should antiquities be kept near the heating apparatus4 ,there is another precaution1 to which too little attention has been paid1 viz4 the protection of objects as far as possible from even diffused daylight4 ,although no investigations upon the extent of the injurious action of light have as yet been published1 light is not without influence upon the outward appearance1 and therefore also upon the material condition of antiquities of organic origin4 ,but even inorganic objects1 such as pigments1 glass1 enamel1 amber1 etc41 are affected by light2 it is therefore certainly advisable to protect antiquities of all kinds from light during the time in which they are not exhibited to the public4 ,the public is effectually prevented from fingering antiquities which are enclosed in glass cases1 but it may be well to remind those who have to handle them in the course of their duties that contact with the bare hand can only be harmful1 even though fingering is understood to be beneficial to modern bronzes by inducing the formation of patina4 ,the bright surface of metallic iron which results from treatment by ,blell's or by ,krefting's method1 especially if there is a thin coating of paraffin1 should not be touched at all with the bare hand1 but only with a cloth or a glove4 ,bronzes1 whether intact or restored1 and iron objects1 should never be in direct contact with those which show efflorescences4 ,the usual custom is to attach labels of painted cardboard or metal by means of thin metal wire4 ,the tendency to rust makes iron wire unsuitable1 especially for objects containing salt1 which are quickly affected2 thus light coloured earthenware may soon be covered with spots of rust4 ,copper wire and nickel wire are liable to be similarly attacked4 ,many years ago it was noticed#agf in the ,ethnological ,museum at ,berlin that nickel wire when in contact with silver objects which were covered with silver chloride was destroyed by the formation of a deliquescent green nickel salt4 ,silver or platinum wire forms the most suitable means of attachment1 but if the expense of these is too great1 copper or nickel wire may be used1 except in the cases mentioned above4 ,small objects of any kind1 which one still frequently finds kept in open cases1 are better preserved in upright glass cylinders with glass stoppers1 or in cheaper glass tubes1 one end of which is fused and the other closed with a cork4 ,conclusion4 ,the methods of preservation which have been described in the preceding pages may be thus tabulated and summarised3 ,methods4 ,application4 ,steeping in water1 drying ,limestone1 and impregnation4 ,earthenware1 ,iron1 much corroded4 ,direct impregnation4 7#a7 ,unbaked earthenware1 etc41 7#b7 ,bronze objects with little or no metallic core1 or showing a cracked or warty surface1 7#c7 ,objects of wood and of other organic substances4 ,removal of compounds of oxygen or chlorine 7a7 by chemical process1 ,iron objects in a good metallic condition1 7b7 by electrolytic process4 7#a7 ,iron objects with a sound metallic core1 7#b7 ,bronze objects with a sound metallic core4 ,mounted thoroughly dry and ,valuable bronzes in an advanced hermetically sealed4 state of decomposition4 ,there will be no difficulty in the choice of methods for limestone or earthenware1 whether kiln-dried or sun-dried1 for a simple experiment will prove whether steeping is likely to cause injury or disintegration4 ,the methods are themselves simple and inexpensive4 ,for organic substances the chief question is the choice of the most suitable medium for impregnation4 ,iron and bronze present some difficulty1 although the use of a file will readily show whether reduction is feasible4 ,the simplicity of the apparatus required for ,krefting's method gives it an advantage over other methods1 at any rate for iron objects4 ,objection has been taken to the methods of reduction1 because they give to the objects thus treated an appearance to which the public are not accustomed4 ,it may be safely asserted however that this appearance more truly represents the object when in actual use1 than the oxidized and rust-covered specimens to which we are accustomed in antiquarian collections4 ,to those who value an antique object for the crust that covers it1 all methods of restoration must be objectionable4 ,such persons ought to object to the removal of the incrustations which hide the cuneiform inscriptions on clay tablets4 ,on the other hand1 those who regard these methods with approval should go a step further and confide their collections to experienced hands for some form of treatment which may bring to light inscriptions and inlaid work which will greatly enhance their value4 ,to spread the knowledge of these methods and to invite the co-operation of others is the aim of this book4 ,as to the best method to be used in each particular case it is unnecessary to lay down any hard and fast rule1 for this can only be learned by observation and experience4 ,,appendix ,a4 ,,method ,,of ,,taking ,,squeezes ,,of ,,inscriptions1 ,,etc4 ,for this purpose a proper brush is required with strong bristles1 closely set as in a scrubbing brush2 the brush should have a firmly fixed handle1 preferably slightly curving upwards to save the knuckles from being bruised upon the stone4 ,a so-called silver brush will serve the purpose4 ,the paper should be stout and stiff enough to resist the blows of the brush without tearing4 ,an admirable paper1 which possesses these qualities1 is specially prepared for the purpose by the ,o4,w4 ,company1 #ajj1 ,great ,russell ,street1 ,london1 ,w4 ,as a substitute for the specially prepared paper stout packing paper may be used with satisfactory results4 ,the stone should be tilted if possible at an angle of about #de1 and the surface bearing the inscription should be well washed or carefully scraped free of dirt and foreign matter and should be rendered thoroughly wet4 ,a piece of the special paper of suitable size should be soaked in water for a minute or more4 ,it should then be carefully applied to the surface of the stone in such a way as to prevent air-bubbles4 ,this may be assisted by gently smoothing it with the hand or back of the brush4 ,when close adhesion has been secured1 and all air-bubbles removed 7this can sometimes be done by pricking through the paper with a pin71 the paper should be sharply beaten with the brush1 the blows being delivered from the wrist and not from the shoulder until it begins to show a fluffy appearance4 ,it should then be peeled off and allowed to dry1 after which it may be rolled or folded without danger of injury to the embossed inscription4 ,should the paper tear1 another piece soaked as before may be placed on the top and beaten until it becomes incorporated with the first4 ,if the letters are large and deep1 or if the surface is much cracked1 two or more sheets superimposed should be used4 ,in the case of large inscriptions it is advisable to take impressions by sections1 care being taken that each sheet slightly overlaps the preceding one to prevent the possible omission of some of the letters4 ,it is also useful to take at the same time a pen or pencil copy of the inscription1 for a comparison of the copy and the squeeze will often prevent errors in deciphering4 ,the squeezes can be very well deciphered by artificial light1 while doubtful letters may sometimes become clear on holding up the sheet to the light4 ,the reverse side of the squeeze1 upon which the inscription stands in relief1 may afford great assistance when read by the aid of a mirror4 ,a photograph of the squeeze will often reveal more than a photograph of the inscription itself4 ,the method is described by ,s4 ,reinach in his ,trait d'pigraphie ,grecque 7,introduction1 p4 ,,xx471 where he also refers to ,hbner1 ,ueber mechanische ,copien von ,inschriften1 #ahga4 ,,appendix ,b4 ,,zapon4 ,further particulars may be given of the new preparation known as ,zapon4 ,this substance is now made on a large scale1 and can be obtained from the ,british ,xylonite ,co41 ,brantham ,works1 ,manningtree 7,xylonite lacquer ,f4 #ffca74 ,the following excerpt is from a short communication in ,prometheus 7,,xv4 #aijd1 pp4 #dhe and #dii71 which deals with the preservation of wax seals and of glass4 ,zapon1 the invention of ,crane1 of ,shorthills1 ,u4,s4,a41 has been used for #bj years past for the protection of metals from oxidation and the action of sulphuretted hydrogen4 ,although the products of the various manufacturing firms differ in composition1 zapon is essentially a solution of nitro-cellulose in various solvents4 ,the nitrated cellulose1 i4e4 gun-cotton 7pyroxyline71 is generally1 with the addition of camphor1 dissolved in a mixture of amyl acetate 7hence the peardrop-like smell7 to which distillation products of petroleum1 etc41 are added4 ,it comes into the market as a faintly yellow1 slightly oily liquid4 ,its use as a preservative depends upon the fact that the evaporation of the solvent leaves behind it a fine transparent coating of gun-cotton 7pyroxyline74 ,zapon for preservative purposes must have a neutral reaction1 and must not under any circumstances redden litmus paper4 ,its use in this connection is due to ,schill1 who also recognised its suitability for other materials1 as1 for example1 for plaster casts1 the treatment of which is eminently simple1 for it consists in dipping small casts1 or in painting larger ones with a soft brush4 ,it is advisable to begin at the top and apply it from above downwards1 using a clean dry cloth to wipe off any excess of the fluid which collects in the deeper parts of the cast4 ,if zapon containing about #d of gun-cotton is used1 the coating left on drying is scarcely visible2 with a #e solution a certain degree of polish results4 ,casts treated with zapon are less easily damaged by dust than those untreated1 and may be cleaned with soap and water without injury to their surface1 provided that a soft brush is used1 but brushes which are stiff enough to injure the zapon coating will damage the contours of the statue4 ,it should only be used for objects kept under cover1 for rain and wide variations of temperature will attack them almost as readily as untreated casts4 ,it can be used with equal success for antiquities of stone1 clay1 baked or unbaked1 or for plaster after the soluble salts have been thoroughly removed by steeping1 for if this has not been done the salts will soon crystallize out and loosen the protective coating4 ,for objects which are free from salts impregnation with zapon possesses the advantage that it renders them less liable to damage from handling or dust1 whilst the appearance is scarcely altered1 if at all4 ,this applies also to antiquities of metal1 for unless the injurious chlorine compounds are removed by simple steeping1 or reduction and subsequent steeping1 treatment with zapon is useless4 ,to bronzes1 which in spite of mechanical cleaning show a somewhat unpleasant grey non-metallic appearance1 zapon often imparts a distinct metallic lustre4 ,to enhance this lustre by a second vigorous application is not recommended1 for this gives the impression of a varnish4 ,to protect articles of silver from the blackening influence of sulphuretted hydrogen1 zapon is very useful1 but does not afford absolute protection unless it has been thickly applied4 ,in collections of armour much use may be found for this material4 ,the objects are dipped and then placed in a drying oven at #aje;,f4 #dj;,c4 to secure rapid drying and uniform distribution4 ,the amyl acetate or other solvent is best conducted away1 as it evaporates1 into a flue or into the open1 although the vapours can hardly be considered dangerous to health4 ,the following references will afford some information on the use of zapon in the preservation of ,archives3 ,e4 ,schill1 ,anleitung zur ,erhaltung und ,ausbesserung von ,handschriften durch ,zapon-,imprgnierung1 ,dresden1 #ahii4 ,o4 ,posse1 ,handschriften ,konservirung1 ,dresden1 #ahii4 ,g4 ,sello1 ,das ,zapon in der ,archivpraxis 7,korrespondenzblatt des ,gesamtvereins der deutschen ,geschichts- und ,alterthumsvereine1 ,l41 #aijb1 p4 #aie74 ,schoengen1 ,over hat ,zapon 7,nederl4 ,archivenblad1 #aijb1 #aijc1 ,nos4 #a and #c74 ,j4 ,perl1 ,das ,archiv-,zapon 7,korrespondenzblatt1 ,,lii41 #aijd1 pp4 #aai and #dce74 ,g4 ,sello1 ,die bei der ,zaponverwendung in der ,archivpraxis gemachten ,erfahrungen 7,korrespondenzblatt1 ,,lii41 #aijd1 p4 #dci74 ,,index4 ,acetic acid #aej ,air-pump #fh1 #ie1 #abi ,akermann #i ,alabaster #gd ,alcohol #hg1 #ic1 #ie1 #acb1 #aee1 #afa1 #afb ,jenner's method #aei preservation of leather #aec removal of oil by #hg ,algae #aj1 #fj1 #gf1 #he ,alum #aed1 #aeh ,amber #ee1 #afb ,ammonia action upon bronze #ah1 #be1 #ca1 #aba action upon silver #adh1 #aej ,analyses bronzes #bb-bg1 #dg1 #ach iron rust #ab patina #bc1 #ci salt crystals #aee silver #ea silver chloride #ea ,appelgren on application of ,krefting's method #ajh1 #aae ,arche #bg ,archives1 preservation of1 by zapon #agj ,armour1 iron1 treatment of #aje1 #afi ,assyrian tablets1 treatment of #gh1 #ha ,atacamite #ba1 #bb1 #bf1 #bi ,azurite #ag1 #ba1 #cf1 #aci ,bacteria1 influence of1 on iron #aj influence of1 on bronze #bh1 #df ,barium chloride #gg ,barium nitrate test #fa1 #gg1 #hf ,barth #aee ,bassett1 analysis of bronze #be ,bees'-wax #ij1 #ig1 #ajb1 #ajf1 #aec1 #aeh ,bell-glass1 use of #fh1 #ie1 #abi1 #aeb ,belmontyl oil #hf ,benzene #ia1 #aeh1 #afj ,benzine #gj1 #hf1 #ij1 #ie1 #if1 #ajf1 #aca1 #afa ,berthelot #bh1 #eb ,bibra on patina #bj on silver #eb ,bille ,gram #aed ,bischoff #da ,blell #ac1 #ia ,blell's method 7iron7 #ajb ,bolle #afa ,bones1 influence of contact with #ad preservation of #ee1 #aeb ,book-bindings1 treatment of #aeb ,brewster's method 7coins7 #adf ,bronze #ae1 #abj action of ammonia upon #ah1 #be1 #ca1 #aca analyses of #bc-bg analyses after reduction #ach ,fellenberg's classification of #ae cleaning of #abj drying of #abc1 #aca impregnation of #abb incrustations1 removal of #aba glue1 treatment by #aba1 #abe hammers #abj heating #aba hydrochloric acid #aba inlaid metals upon #abb ,springer's method #aba lead in bronze #bd1 #acj preservation of1 by exclusion of air #add preservation of1 by carbolic acid #abj reduction of #abe ,finkener's method #abe ,krefting's method #aci ,krefting's method 7coins7 #adj ,villenoisy's classification of #cb ,brushes1 wire #ajg1 #aae1 #aca1 #ada silver brushes #aea1 #aff ,bucholz1 experiment #ah ,bunsen #ed ,calcium chloride #abc1 #adf ,carbolic acid #abj1 #aeg ,carbonic acid1 influence of1 on iron #h1 #i influence of1 on bronze #ca ,carbon bisulphide #ij1 #afj ,caries of bronzes #bf ,casts 7plaster71 zapon for #afi ,caustic soda #aaj1 #aae1 #aai1 #aci1 #adj1 #afa ,celluloid #aej ,cement for pottery #hg for stone #hh ,ceresole1 treatment of lead #aej ,chevreul #ba ,chlamydothrix #aj ,chlorine1 destructive action of #ab1 #bf1 #da1 #df1 #ajj1 #aba estimation of #gf ,church1 analysis of silver #ej ,citric acid #adh ,clay1 baked #d1ha ,clay tablets1 treatment of #gh ,clay vases1 sodium sulphate in #f treatment of #hj ,coffey1 analysis of ,irish celts #bf ,coins1 treatment of #aci ,brewster's method #adf ,krefting's method #adj ,roux' method #adg treatment of1 by melted lead #adc ,collodion #ga1 #ia1 #afa ,copaiba balsam #afa ,copal varnish #ij ,copper #ae1 #di1 #abj absence of edel-patina #di carbonate #ba1 #cc chloride #ag1 #ba1 #eb oxychloride #ag1 #ba1 #bi1 #da preservation of #abb stannate #ca1 #cc sulphide #ba1 #bd1 #cc ,copper crystals of bronzes #ah ,corrosive sublimate #aeb1 #aed1 #afj ,covelline #bc ,crenothrix #aj1 #fj ,crum ,brown #g ,cuboni #bg1 #df1 #dh ,cuneiform tablets #f1 #gh ,cupric oxide #ah1 #bb1 #cc1 #cg ,cuprite #ah ,cuprous oxide #ag1 #ba1 #bd1 #bh1 #cg1 #da1 #eb ,cyanogen #abi ,damp1 influence of #bi1 #dc1 #dg1 #di ,daniell cells #abf ,davy #ag ,dechend's apparatus #gc ,dextrin #hh ,dowris find1 analysis of bronze from #bf ,drude #adg ,dunstan1 on rusting #i ,dust extractor #aca1 #ada ,dust1 protection from #afb ,earthenware baked1 impregnation of #gh baked1 steeping of #gd unbaked1 impregnation of #ha unbaked1 treatment of #ha with colouring #gi ,edelrost #ad ,edel-patina #di1 #abj ,egypt1 soil of #a dry climate of #b1 #ef ,egyptian bronzes #acj1 #acd1 #ach absence of edel-patina in #db high chlorine-content in #db lead in #bd1 #cc1 #acj ,egyptian coffins #afj ,egyptian coloured objects #afa ,egyptian textile fabrics #aed ,egyptian ostraca #d1 #eg efflorescences upon #d treatment of #ge ,ekhoff's method 7iron7 #if ,electric current a cause of rust #i ,electric muffle furnace #hd ,electrolysis #aaa1 #abf1 #adg1 #adh ,elster #bc ,enamel #aea ,ephesus1 bronze from #be ,ether #gd1 #ij1 #acc1 #afa ,fat #ajf1 #ajg ,fayence #f1 #hf ,feathers #aed ,fellenberg #ae ,finkener's method 7bronze7 #abe ,fire-clay #hd1 #hh ,fire-clay dust cement #hh ,fish-glue #hf1 #hh ,flinders ,petrie #a1 #ga1 #hg1 #aai on impregnation of earthenware #ha on reduction of silver #adh ,fluates #ga ,forge scale #h1 #ad1 #ajd ,formalin #fj1 #aeb ,friedel #df ,gallionella #aj ,gelatine #afb ,glass1 changes in #ed1 #aea ,glue #hg1 #hh1 #abj1 #aea ,glycerine #aeg1 #aei1 #afb ,gold1 changes in #ec treatment of #aej existence of1 in silver objects #ej ferric oxide upon #ec1 #aea ,granite #hg ,gum arabic #hh ,gum dammar #gj1 #ie1 #aja1 #adi1 #aea1 #afa ,gypsum #gd1 #ha ,haidinger1 on patina #ba ,hair #ee1 #aec ,hammers #abj ,hartwich's method 7iron7 #aag ,hassack1 on patina #bg ,heat-recorders #hd ,herbst's method 7wood7 #aeh ,hierli1 on textile fabrics #aec ,hildesheim silver-find #di1 #ea ,horn1 changes in #ee treatment of #aea ,horn-silver #di1 #ea ,hnefeld #ag ,hydrated ferric oxide #fj ,hydrated tin oxide #acj1 #ach1 #aci ,hydrocyanic acid #abf ,hydrochloric acid #gh1 #hd1 #he1 #hg1 #aaa1 #aaf1 #aba1 #abf1 #abi1 #adi1 #aej ,hydrogen1 reduction of bronzes in 7,finkener's method7 #bb1 #abe ,hydrogen1 reduction of iron in 7,hartwich's method7 #aag ,impregnation media bronze and iron #ij limestone #gj ,incrustations1 bronzes #cg1 #abj1 #abh earthenware #gh limestone #gd silver #adi ,india-rubber solution #ij1 #aec ,ink upon ostraca #ge ,inlaid metals #ajj1 #acf ,inscriptions1 squeezes of #aff ,insects1 attacks of #aed1 #afj1 #afa ,iridescence of glass #ed ,iron #g1 #hi absence of antiquities of iron in ,egypt #ad acid bath for #ajc alcohol1 steeping in #ic1 #ie bone-ash1 influence of #ad chain-mail #aje ferric chloride #ab1 #ic ferric hydroxide #g1 #ic ferric oxide #ad ferric oxide on gold #ec1 #aea ferroso-ferric oxide #h1 #ad1 #aja ferrous chloride #ac1 #ib ferrous oxide #ad ferrous phosphate #ad ferrous sulphide #fj heating of iron #ib1 #ii1 #ajf impregnation of iron #ic impregnation media for iron #ij inlaid work upon iron #ajj linseed-oil for iron #ia medieval iron objects #he methods of treatment3 ,blell's method #ajb ,ekhoff's method #if ,hartwich's method #ii1 #aag ,jacobi's method #ii ,krause's method #ib ,krefting's method #ajh ,steffensen's method #ajb ,straberger's method #ig ,passivity of iron #aai ,reduction by heat #ii ,reduction by potassium cyanide #aah ,reduction by potassium sulphocyanide #aai ,rusting1 see rust ,irvine #h ,isinglass #ij1 #ih1 #ajj1 #aea1 #aef1 #afb ,ivory #ee1 #aea ,jackson #aj ,jacobi #ad ,jacobi's method 7iron7 #ii ,jenner's method 7wood7 #aei ,karabacek #a ,kessler's fluate #ga1 #gb1 #gd ,kisa #adc ,klebs1 on amber #afb ,krause's method 7inlaid iron7 #aja ,krefting1 analysis of rust #ab experiments of #aj1 #de method for bronze #aci1 #adj method for iron #aja1 #ajh1 #aah method for lead #aej theory of rust #h ,krhnke #i1 #dh ,lanoline #aeb ,lead1 changes in #ca1 #ec treatment of #adi treatment of coins with #adc ,lead carbonate #ec1 #aej ,lead oxide #cc1 #ij ,lead stannate #ca ,leaden objects1 ,ceresole on #aej ,leather #aeb preservation of1 at ,salzburg #ef ,lechat #cj ,lecythoi1 treatment of #hj ,leiner's method 7wood7 #aeg ,lemery #aj ,lepsius #fg ,light1 influence of #aj1 #fj1 #afb ,lime1 incrustations of #gd ,limestone #eg action of salts upon #b changes in #b drying of #fg dust1 removal of #eh impregnation of #ea1 #fh impregnation media for #gj steeping #eh1 #ff disadvantages of #fg test of progress of #fb ,linseed oil #ga1 #ij1 #ia1 #ig1 #ii ,linseed varnish #ij1 #ia1 #ic1 #ii ,magnesium sulphate #e ,malachite #ag1 #ah1 #ba1 #cf1 #aci ,marble #gb1 #gd ,medieval iron objects #aai ,mdm1 analysis of bronze from #bf ,mtaux malades #bi ,meten chamber description of #b limestone blocks from #ef1 #fg impregnation of #gc steeping of #ei1 #fd table of results of steeping #fe ,milbauer #aai ,mitzopulos1 on patina #bd on silver #ea ,mond1 on patina #bg1 #df1 #dh ,moody1 on rusting of iron #i ,moulds1 attacks of #gb1 #aeg ,muffle furnace #hd ,mycene1 copper alloys from #bd silver from #ea ,naphthalene #aed1 #afa ,natterer1 analysis of ,ephesian statuette #be ,neufeld #aj ,nickel wire for labels #afc ,nile mud1 objects of #hg ,nitric acid1 action upon iron #aai ,oak1 objects of #aei ,oil colours1 removal of #hg ,oleate of lead #ij ,olive oil #ij1 #aea ,olshausen vii1 #aa1 #dh1 #ee ,organic substances changes in #ed influence of1 on patina #ca treatment of #aea ,ostraca1 see ,egypt ,oxygen1 influence of #ed ,paint1 removal of #hg1 #afa ,papyrus #aed crystals from #aee treatment of #aee zapon useful for #aef ,paraffin wax #ga1 #he1 #ia1 #ie1 #ig1 #aae1 #aah1 #abe1 #acb1 #ada1 #adi1 #aeg ,patina composition of #af heat1 action of upon #bh1 #abb varieties of black #cc blue #cb cracking #abb creeping or malignant #bh1 #abe edel-patina #cd1 #abj green #af warty #ch ,peat1 influence of bronzes #ae1 #cc iron #ac organic substances #ee hair #aed ,pepper 7for feathers7 #aed ,petroleum #ic1 #if1 #ig1 #aeg ,petroleum ether #ga ,phosphoric acid #ad ,picht #ag ,pile-dwellings antiquities from #ec1 #aef horn and wool #ee textile fabrics #aec ,plaster of ,paris #hh1 #aef ,pole paper #abg ,poppy-seed oil mixture #gj1 #hf1 #aea1 #afb ,potassium arsenite #afj carbonate #adh1 #adi chromate #fb1 #acj cyanide #aah1 #abf1 #adh1 #adi iodide #abf sulphate #a sulphocyanide #aai ,priwoznik1 on patina #bc ,quicklime #if1 #aae ,reduction bronze #abe iron #ii1 #aah1 #aai ,rein1 on ,japanese bronze #cf ,reinach1 on inscriptions #afg ,resin #ia1 #aeh1 #afb ,resin1 removal of #gd1 #afa ,reuss1 on patina #ag ,rhousopulos treatment of bronze #aaa treatment of earthenware #hj treatment of iron #aaa treatment of marble and limestone #gb ,rice water #ga1 #gb ,rogna1 variety of patina #bf ,roux1 method of cleaning coins #adg ,rubber solution #ij1 #aec ,rust bacteria1 a cause of #aj edel-rost #ad1 #aaa1 #aah removal by acid #ajc removal by sodium sulphide #aai theories of causation #g ,salt crystals1 analysis of #aee ,salzer #ic1 #ie ,sandstone1 treatment of #hg ,schertel #ea ,schill #afh ,schliemann #bf ,schuler1 analysis of patina #bd1 #dh ,schulz1 analysis of bronze #ach ,seger cones #hb ,setlik #aaj ,shellac #gj1 #hf1 #hh1 #ij1 #adg1 #afb ,silver1 analysis of #ej1 #ea changes in #di1 #adi electrolytic treatment of #adh preservation of #adh ,silver brushes #aea1 #aff ,silver chloride #di1 #ea1 #eb1 #adh ,silver nitrate solution #fa1 #gf1 #gh1 #ic1 #acj ,silver subchloride #di1 #ea ,silver sulphide #ej1 #adi1 #afh ,simon #h ,size #ga1 #gb1 #hf1 #ij1 #aef ,soda #hg1 #ic1 #ig1 #ih1 #ajb1 #ajf1 #aae ,sodium chloride #a1 #d1 #e1 #aj1 #dg1 #ef1 #fa1 #he1 #ic1 #adh ,sodium nitrate #f ,sodium sulphide #aai ,speerschneider's method #ia1 #aeh ,spennrath #h ,spray apparatus #gc ,springer's method #abj ,squeezes of inscriptions #aff ,stapff #h ,stavenhagen #df ,stearine #ga1 #ib ,stearine glaze #aeb ,steel wire brushes #ajg ,steeping baked clay #he bronze #acj earthenware #gd iron #ib limestone #ei ,steffensen's method 7iron7 #ajb textile fabrics #aec wood #aei ,stolba #ba ,stone cement #hh ,straberger #afb ,straberger's method 7iron7 #ig ,stucco #hg ,sulphates1 test for #fa1 #gg1 #hf ,sulphur1 influence of #ca ,sulphuretted hydrogen #bd1 #ca1 #fa1 #afi ,sulphuric acid #ac1 #ajb1 #ajg1 #aaf1 #abc ,sunlight1 see ,light ,spke #adf ,syndeticon #hg ,tannic acid1 influence of #ac ,tapioca water #ga1 #gb ,terra-cotta #gd ,terreil #bc ,test for progress of steeping #fa ,textile fabrics #aec ,tin1 changes in #ca1 #ec treatment of #adi ,tin oxide #bb1 #cg1 #da1 #ec ,tin1 proportion of1 in patina #bf1 #dh ,titration #e1 #fa test in connection with #fa ,tolomei #h ,train oil #aeb ,turpentine #gj1 #ij1 #aec1 #afa ,unbaked clay #ha ,varnish-benzine mixture #ga1 #gd1 #ge1 #gh1 #ha1 #he1 #hg ,vaseline #ij ,verdigris #af ,villenoisy1 on patina #cj classification of #cb ,vivianite #ad ,volney #a ,voss v1 #afc ,wagner #aj ,wall-saltpetre #g ,warrington #ea ,water-bath #id ,waterglass #ga1 #gb1 #hh1 #ij1 #aeg ,watkin's heat-recorder #hd ,white of egg solution #hf1 #aec ,wibel #af1 #ag ,wire for labels #afc ,wood1 treatment of ,herbst's method #aeh ,jenner's method #aei ,leiner's method #aeg ,speerschneider's method #aeh coloured wood #afa large objects1 varnish for #aeg ,wood-worms #afj ,wool1 changes in #ee preservation of #aec ,yarn #afj ,yorkshire1 analysis of bronze from #bf iron objects from #aac1 #aad ,zapon #ga1 #ha1 #aah1 #acb1 #adi1 #aej1 #aef1 #afh ,zinc #ca1 #aaj1 #aaf1 #ach1 #aci1 #adj1 #aej ,zinc oxide #ca1 #aaa1 #ada ,zylonite lacquer1 see ,zapon ,,cambridge3 ,,printed ,,by ,,john ,,clay1 ,m4,a4 ,,at ,,the ,,university ,,press4 ,,footnotes3 #a ,lexikon d4 gesamten ,technik1 ,vol4 ,i4 p4 #beg4 ,o4 ,lueger4 #b ,merkbuch4 ,the excavation and preservation of ,antiquities1 #bnd edition1 ,berlin1 #ahid4 #c ,mittheilungen aus der ,sammlung der ,papyrus ,erzherzog ,rainer4 ,vol4 ,i4 p4 #aah4 ,see also ,flinders ,petrie1 ,archaeological ,journal1 ,vol4 ,,xlv4 #ahhh1 p4 #hh4 #d ,aeg4 #aje4 ,this and similar notes have reference to the catalogue of the ,egyptian 7,aeg47 or ,antiquarian 7,ant47 sections of the ,berlin ,royal ,museums4 ,the limestone blocks were brought from the ,mastaba of ,meten1 at ,abusir near ,memphis1 explored by ,lepsius in #ahdf4 ,meten was one of the chief officials under ,king ,snefru1 ,b4,c4 #bhjj4 ,the inscriptions relate to his possessions and official career1 while the pictorial representations depict hunting scenes and the offering of the gifts for the dead4 ,the statue of ,meten was found in the grave and is now in the ,egyptian department 7,no4 #aajf7 of the ,royal ,museum4 ,comp4 ,ausfhrliches ,verzeichniss der aegyptischen ,alterthmer1 ,berlin1 #ahii4 #e ,aeg4 ,p4 #dgcj #f ,aeg4 ,v4 ,a4 #bhdf4 #g ,aeg4 ,p4 #dgci4 #h ,it may be here mentioned that1 as is well known to chemists1 the efflorescences which often go by the name of wall-saltpetre1 in most cases do not contain any saltpetre1 but consist of sodium sulphate4 #i ,crum ,brown1 ,chem4 ,centralblatt1 #ahij1 ,i4 p4 #bab2 ,e4 ,simon1 ,ueber ,rostbildung u4 ,eisenanstriche1 p4 #d4 #aj ,j4 ,spennrath1 ,verhandlungen d4 ,vereins zur ,befrd4 d4 ,gewerbefleisses1 #ahie1 p4 #bde4 #aa ,christiania ,videnskabs-,selskabs ,forhandlinger for #ahib1 ,no4 #af1 p4 #h4 #ab ,chemische ,zeitung4 ,repetitorium1 #ahie1 p4 #bhi4 #ac ,chem4 ,centralblatt1 #ahie1 ,i4 p4 #dda4 #ad ,id41 #ahia1 ,i4 p4 #hfj4 #ae ,berg- und ,httenmnnische ,zeitung1 #ahhb1 p4 #dfi4 #af ,it may not be out of place here to give the main conclusions1 drawn from a long series of experiments by ,prof4 ,w4 ,r4 ,dunstan 7,proc4 ,chem4 ,soc41 ,,xix4 #aej1 #aijc74 7a7 ,pure iron is not oxidised in the presence of gases and water-vapour only1 but for the appearance of rust the presence of water in the liquid state is necessary4 7b7 ,the reagents which prevent the rusting of iron are those in the presence of which hydrogen peroxide is decomposed1 and which are consequently inimical to its formation3 among such reagents the following are given--sodium chloride1 sodium sulphate1 ferrous sulphate and potassium nitrate4 7c7 ,the action of ,h#b,o#b on metallic iron leads to the production of red basic ferric hydroxide1 which is identical with ordinary rust4 ,the composition of rust may therefore be represented by the formula ,fe#b,o#b7,,oh7#b1 the reaction being represented by the equations3 ,fe ,o#b ,h#b,o ,fe,o ,h#b,o#b4 #b;,fe,o ,h#b,o#b ,fe#b,o#b7,,oh7#b4 ,these views are however combated by ,moody 7,proc4 ,chem4 ,soc41 ,,xix4 #aeg and #bci7 who concludes that aerial rusting must be regarded as a change involving the interaction of iron and carbonic acid and the subsequent formation of rust by oxidation of the ferrous salt4 ,he also states that those salts which do not combine with and which are not decomposed by ,,co#b have no retarding influence on the formation of rust1 e4g4 sodium chloride1 sodium sulphate1 etc4 ,on the other hand substances which absorb and combine with carbonic oxide 7e4g4 sodium carbonate or hydroxide1 ammonium carbonate1 calcium hydroxide71 or which are decomposed by carbonic acid 7potassium and sodium nitrites71 inhibit rusting1 which may therefore be regarded as a change involving the interaction of iron and acid and the subsequent formation of rust by the oxidation of the ferrous salt4 ,o4 ,krhnke 7,wochensch4 ,brauerei1 ,,xvii4 #bcc7 gives the following equations3 ,fe #b;,,co#b ,h#b,o ,fe7,,hco#c7b ,h#b4 #b;,fe7,,hco#c7b ,o ,h#b,o #b;,fe7,,oh7#b #d;,,co#b4 ,comp4 also ,dammer1 ,handbuch der anorg4 ,chem41 ,vols4 ,,iii4 and ,,iv4 7supplement74 ,considerable attention has also been directed to the influence of bacteria upon iron4 ,thus the growth of ,crenothrix may cause much trouble in waterworks1 vide ,centralblatt fr ,bakterien und ,parasitenkunde1 ,,ii4 #ab1 #fha4 ,a variety1 ,chlamydothrix 7,gallionella7 ferruginea 7,mig47 appears to play an important part in the formation of rust 7comp4 ,zopf1 ,crenothrix polyspora die ,ursache der ,berliner ,wasser-,calamitt1 ,berlin1 #ahgi4 ,de ,vries1 ,unter4 der ,crenothrix ,commission1 ,rotterdam1 #ahhg and #ahij74 ,neufeld 7,chem4 ,centralblatt1 #aijd1 ,i4 #afba--;abstracted from ,zeitschrift fr ,untersuchung der ,nhrungs- und ,genussmittel1 ,,vii4 #dgh7 gives particulars of three varieties3 ,crenothrix polyspora1 which separates iron2 ,cr4 ochracea1 which separates aluminium and some iron2 and ,cr4 manganifera1 which separates manganese4 ,jackson 7,journal of ,society of ,chemical ,industry1 #aijb1 p4 #fha7 gives micro-photographs of these varieties4 ,microscopically the masses of ,crenothrix are seen enclosed in a gelatinous sheath1 in which is imbedded the precipitated metallic hydrate4 ,it is anarobic and its action is favoured by absence of light4 ,in the absence of dissolved oxygen1 the bacillus appears to take its iron from the pipes4 ,cr4 polyspora is found however 7,zeitschrift fr analytische ,chemie1 ,,xlii4 #eij7 to separate the iron not from the ferrous carbonate 7,fe,c,o#c7 but from iron organically combined4 ,see also ,winogradsky1 ,ueber ,eisenbakterien1 ,bot4 ,zeit41 #ahhh1 and ,chem4 ,centralbl4 #aijd1 ,,ii4 #accb4 ,transl4 #ag ,wagner in ,dingler's ,polyt4 ,journal1 ,,ccxviii4 p4 #gj4 ,axel ,krefting in the above-quoted ,forhandlinger1 p4 #d4 #ah ,olshausen often noticed on freshly excavated antiquities of various kinds a peculiar smell of resin or gum1 especially after treatment with hydrochloric acid 7,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahhd1 p4 #ebj74 ,it may be supposed that this odour is due to the traces of hydrocarbons present4 #ai ,termed by ,e4 ,friedel ,dunstperlen4 ,eintheilungsplan d4 ,mrk4 ,prov4-,museums1 p4 #i4 #bj ,om ,konserviring af ,jordfundne ,jernsager1 in ,aarsberetning fra ,foreningen till norske ,fortidsmindesmaerkers ,bevaring1 #ahib1 p4 #eb4 #ba ,krause1 ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahhb1 p4 #ecc4 #bb ,private communication4 #bc ,sitzungsberichte der ,alterthumsgesellschaft ,prussia1 #ahha-b1 p4 #i4 #bd ,merkbuch1 ,alterthmer aufzugraben und aufzubewahren1 #bnd edition1 p4 #ga4 #be ,this fact was noticed by ,sir ,thomas ,browne1 #afeh1 cp4 ,hydriotaphia1 cap4 iii4 ,transl4 #bf ,in this work the ,patina on antiquities only is considered2 with that on modern bronzes we are not concerned4 #bg ,mittheilungen d4 naturforsch4 ,gesell4 in ,bern1 #ahfe1 p4 #ab4 #bh ,mitth4 d4 naturforsch4 ,gesellschaft in ,bern1 #ahfj1 p4 #fi4 #bi ,jahrbuch fr ,mineralogie1 #ahfj1 p4 #hac4 #cj ,malachite1 ,cu,c,o#c1 ,cu7,,oh7#b4 #ca ,azurite1 #b;,cu,c,o#c1 ,cu7,,oh7#b4 #cb ,jahrbuch fr ,mineralogie1 #ahfe1 p4 #djj4 #cc ,the extract which here follows is in part verbatim4 #cd ,annalen der ,chemie u4 ,pharmacie1 #ahec1 ,vol4 ,,lxxxv4 p4 #bec4 #ce ,von ,bibra1 ,die ,bronzen und ,kupferlegirungen1 p4 #bjf et seq4 #cf ,see the very full quotation from ,wibel's work given above4 #cg ,i have not been able to find anything on this point in the literature of the subject4 #ch ,atacamite1 ,cu,cl#b1 #c;,cu7,,oh7#b4 #ci ,cf4 ,comptes rendus1 #ahef1 ,,xliii4 p4 #gce4 #dj ,journal f4 praktische ,chemie1 ,,xciv4 #ahfe1 p4 #cad4 #da ,verhandl4 d4 ,ver4 z4 ,befrd4 d4 ,gewerbf41 #ahfi1 p4 #ahb4 #db ,dingler1 ,polyt4 ,journal1 #ahgh1 ,vol4 ,,cciv4 p4 #dhc4 #dc ,berg- u4 ,httenmnnische ,zeitung1 ,vol4 ,,xxxvii4 #ahgh1 p4 #cbi4 #dd ,dingler1 ,polyt4 ,journal1 #ahgi1 ,vol4 ,,ccxxxii4 p4 #ccc4 #de ,several other analyses of bronzes from various sources have been recently published4 ,thus ,natterer 7,monatshefte fr ,chemie1 ,,xxi4 #bef1 #aijj2 also ,chem4 ,centralblatt1 #aijj1 ,i4 #abfb7 examined a corroded bronze statuette from ,ephesus4 ,the bronze contained3--,tin #fji1 lead #dhg1 and copper #hifd1 with traces of zinc4 ,bassett 7,proc4 ,chem4 ,soc41 #aijc1 ,,xix4 #ie7 gives an analysis of the base of an ,egyptian statuette1 found in the ,nile ,delta1 probably dating from #bjj-ajj ,b4,c4 ,the base was hollow but filled with lead1 and was covered with a thick green coating1 which in parts entirely replaced the original metal4 ,table ,i4 ,cu #ejfe ,pb #fgd ,sn #bid ,fe #jae ,ni1 ,mn1 etc4 #jaa ,cl #aega ,si,o#b 7as sand7 #aad ,h#b,o #aajg 7,,nh#d7 #jaa ------- #hhfb ,table ,,ii4 ,cu,cl#b #bicd ,cu,o #dfaj ,h#b,o #aajg ,sn,o#b #cgc ,pb,o #gbf ,fe#b,o#c #jbb ,ni,o1 etc4 #jad ,si,o#b #aad 7,,nh#d7;,cl #jcb ------- #iicb ,in the second column the chlorine has been calculated as copper chloride1 the remaining copper and other metals as oxides4 ,traces of calcium were also found1 but the amount of sodium was so small that it could only be detected by the flame test4 ,if all the copper had been present as basic chloride 7atacamite ,cu,cl#b1 #c;,cu,o1 #c;,h#b,o71 this would require #bfhd ,cu,cl#b1 #dgeg ,cu,o1 and #ajgh ,h#b,o4 ,it would therefore appear that the substance produced by corrosion is less basic than atacamite1 and that ammonium chloride may have played a more important part than sodium chloride in the formation of copper chloride1 for in this case the sodium was only found in amount too small for estimation4 ,an analysis of the earliest piece of bronze known1 i4e4 that from ,mdm1 ,egypt 7#cgjj ,b4,c471 gives #hd of tin 7inner core #ia7 to #hih of copper with a small quantity of arsenic4 ,an analysis of a celt from the ,dowris find 7,king's ,county1 ,ireland1 #ahbe7 gave copper1 #hebc2 tin #acaa2 lead #aad1 with traces of sulphur and carbon4 ,the waste material from the same place yielded #hi copper1 #aa tin1 with traces only of lead1 iron and silver4 ,on the other hand an early bronze celt 7,butterwick1 ,e4,r41 ,yorks47 showed a smaller quantity of tin--#ajgd1 compared with #hgig of copper4 7,guide to ,bronze ,age ,antiquities1 ,british ,museum47 ,mr ,george ,coffey has also published 7,brit4 ,assoc4 ,reports1 #ahii1 p4 #hgc7 a tabulated series of analyses of ,irish celts which proved to be composed of practically pure copper4 ,transl4 #df ,schliemann1 ,ilios1 pp4 #ebg and #ega4 #dg ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahhb1 p4 #ecg4 #dh ,dingler1 ,polyt4 ,journal1 #ahhd1 ,vol4 ,,ccliii4 p4 #ead4 #di ,it should be observed that the change in the proportions according to ,schuler 7see page #bd7 is only true of the analysis1 ,column ,,iii4 ,in ,columns ,i and ,,ii the amount of metallic copper of the patina is indeed smaller1 but so is also that of lead and especially of tin4 ,but this may be due to a faulty method in the determination of tin noticed by ,olshausen 7v4 ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahig1 p4 #cdi74 ,the different proportion of the copper compounds in the patina should also be noted1 ,schuler giving carbonate and hydrate in the proportion #a3a1 ,arche and ,hassack once as #a3b1 and again as the result of two analyses as #a3c4 #ej ,atti della ,reale ,accademia dei ,lincei1 #ahic1 p4 #dih4 #ea tude sur les mtaux dcouverts dans les fouilles de ,dahchour in ,fouilles ,dahchour4 ,march-,june1 #ahid1 p4 #aca et seq4 ,j4 de ,morgan4 ,see also ,comptes rendus1 #ahid1 ,i4 #aah1 p4 #gfh4 #eb ,revue archologique1 v4 #bh1 #ahif1 pp4 #fg and #bjb4 ,in the publication for the second half of the same year ,lechat maintains the assertion 7comp4 ,elster1 p4 #bc7 that in many cases the antique patina is due to the artist4 #ec ,ant4 ,misc4 #gchb4 #ed ,j4 ,j4 ,rein1 ,japan1 ,vol4 ,,ii4 p4 #ebh4 #ee ,ant4 ,misc4 #hegi4 #ef ,according to ,graham-,otto1 ,lehrbuch der ,chemie1 ,vol4 ,,iii4 p4 #hdi1 cuprous oxide is decomposed by dilute acids which contain oxygen2 the cupric oxide is dissolved and metallic copper remains4 #eg ,buto1 ,aeg4 #aahfg4 #eh ,ant4 ,fr4 #bi4 #ei ,the extraordinary deformation produced by this type of patina may be judged from the fact that the features in this instance were so obscured that the nature of the specimen was not recognised and it had accordingly been mounted upside down4 ,transl4 #fj ,ant4 ,fr4 #ec4 #fa ,ant4 ,fr4 #ec4 #fb ,bischoff1 ,das ,kupfer und seine ,legirung1 p4 #dc4 ,layard1 ,discoveries in the ruins of ,nineveh and ,babylon1 p4 #aia4 ,fellenberg1 ,mittheilungen d4 naturforsch4 ,ges4 in ,bern1 #ahfj1 p4 #fh4 #fc ,christiania ,videnskabs-,selskabs ,forhandlinger for #ahib1 #af1 p4 #e4 #fd ,having been broken off and soldered1 the base was not subjected to treatment4 ,transl4 #fe ,e4 ,friedel1 ,eintheilungsplan des mrk4 ,provinzialmuseums1 #ahhb1 p4 #bj4 #ff ,aeg4 #bcdh4 #fg ,aeg4 #acghg4 #fh ,olshausen1 ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahhd1 p4 #ecb1 and #ahig1 pp4 #cdf-g4 ,krhnke1 ,chem4 ,untersuchungen an vorgeschichtl4 ,bronzen ,schleswig-,holsteins1 p4 #da4 ,see also quotation from ,schuler1 p4 #be4 #fi ,this celebrated hoard was found ,oct4 #i1 #ahfh1 on the ,galgenberg1 near ,hildesheim 7,hanover71 #aj feet below the surface4 ,it consisted of more than #fj pieces1 including plates1 dishes1 tripods1 etc41 the most notable being a crater1 #ae-a_/b inches in height1 ornamented with graceful scroll-work1 and a cylix with an ,athene in high relief4 ,the workmanship points to a date not later than the first century ,a4,d4 ,cp4 ,wieseler1 ,der ,hildesheimer ,silberfund1 ,bonn1 #ahfi4 ,darcel1 ,trsor de ,hildesheim1 #ahgj4 ,transl4 #gj ,compare also the analysis by ,schertel1 p4 #ea4 #ga ,polytechn4 ,centralblatt1 #ahga1 p4 #iaf4 #gb ,polytechn4 ,centralblatt1 #ahga1 p4 #iag4 #gc ,berg- u4 ,httenmnn4 ,zeitung1 #ahgh1 ,no4 #cg1 p4 #cbg4 #gd ,dingler1 ,polyt4 ,journal1 #ahga1 ,vol4 ,,cci4 p4 #eb4 #ge v4 ,e4 v4 ,bibra1 ,ueber alte ,eisen- u4 ,silberfunde1 p4 #gd4 #gf ,morgan1 ,fouilles ,dahchour1 p4 #ace4 #gg ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahig1 p4 #cdh4 #gh ,krause1 ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahhc1 p4 #cfj4 #gi ,muspratt's ,chemistry1 ,vol4 ,,iii4 p4 #achi4 #hj ,verhandl4 d4 ,berl4 anthropol4 ,ges41 #ahhi1 pp4 #bdc and #bdd4 #ha ,id4 #ahib1 p4 #ddi4 #hb ,id4 #ahig1 p4 #cdg4 #hc ,at that time obtained from the ,stralau waterworks4 #hd ,this was not the well-known ,crenothrix only4 ,cp4 ,polytechn4 ,centralblatt1 #ahia-ib1 p4 #aie4 7,see footnote1 p4 #aj47 #he ,it has been found that the formation of this layer of slime may be avoided by the use of tubs which are lined with sheet zinc4 ,the addition of #aj-bj cubic centimetres of formalin #dj solution of formaldehyde to every hundred gallons of water also prevents or restrains the formation of slime4 ,it is not necessary to add formalin each time the water is changed4 #hf ,since chlorine compounds 7especially common salt7 form the predominating substance in the soluble salts contained in limestones their removal may be considered a proof that other salts 7e4g4 sulphates7 have also been removed4 ,hence it is sufficient to prove the disappearance of chlorine4 ,in the rare cases in which sulphates only are present1 a test similar to that mentioned on p4 #gg1 applied to clay objects1 should be used4 ,if the water used for soaking salt-containing limestone1 earthenware1 etc41 gives no precipitate1 or only turbidity with the silver solution1 the determination of chlorine by titration is not applicable4 #hg ,though some other kinds of burette may be easier to use1 that here recommended 7that of ,gay-,lussac7 is the most convenient for reasons into which we need not enter4 ,the following precautions should be observed3 where the burette is not closed by a cork1 let a few drops out first to wash away crystals of silver nitrate which may have formed at the mouth4 ,the silver solution should be kept in well stoppered bottles4 ,when filling the burette a glass funnel should be used1 so that the cork used for closing the burette is not wetted with the silver solution4 ,before reading off wait until the level of the fluid is constant1 in order that any solution on the sides of the glass tube may have time to run down4 #hh ,see note1 p4 #fa4 #hi ,i have found that the amount of chlorine is smaller in winter than in summer4 ,in the summer of #ahid1 #ajj c4c4 tap-water from the ,stralau ,waterworks often required #jh c4c4 silver solution3 but at that time stronger disinfectants were used on account of the cholera1 and this may have caused the increase of chlorine2 for since then1 and even at the present time 7winter #ahih71 #ajj c4c4 tap-water requires #je to #jf c4c4 silver solution4 #ij ,it may be here observed that objects of limestone or of earthenware may be numbered or marked at the back in black iron ink1 which does not disappear even after prolonged steeping in water4 #ia ,lepsius1 ,denkmler aus ,aegypten und ,aethiopien4 #ib ,it is scarcely necessary to add that any other form of air-pump may be used4 #ic ,a powerful pressure of water in combination with a well-acting pump may cause the fluid to evaporate with such rapidity as to produce bubbles1 but these bubbles are easily distinguished by their size from the minute bubbles of air4 ,to avoid this ebullition1 the air should not be pumped out too rapidly4 #id ,merkbuch1 p4 #fb4 #ie ,flinders ,petrie1 ,archaeological ,journal1 ,part #de1 #ahhh1 p4 #hh4 #if ,zapon3 for further information and references see ,appendix4 #ig ,chemische ,zeitschrift1 ii4 #aijc1 p4 #bjc4 #ih ,for particulars of the composition and action of ,kessler's ,fluates 7salts of ,hydrofluosilicic acid7 see ,h4 ,hauenstein1 ,die kessler'schen ,fluate 7#bnd ed41 ,berlin1 #ahie74 ,the depot is ,h4 ,hauenstein1 ,berlin ,n4 ,reinickendorferstrasse1 #b;b4 #ii ,ger4 ,patent1 ,no4 #cajcb4 ,the apparatus was one of those used in the moulding room of the ,royal ,museums for the impregnation of plaster moulds and casts4 #ajj ,in applying the above test it is advisable to add one or two drops of nitric acid before the addition of the barium salt4 ,in this case1 too1 should any other than distilled water be used for steeping1 a preliminary examination should be made to determine the presence or absence of sulphates4 #aja ,pure hydrochloric acid is usually sold in two strengths4 ,concentrated acid has a strength of about #cb1 whilst the diluted hydrochloric acid of the ,pharmacopoeia is about #aj4 ,the former should therefore be diluted with about #ae1 the latter with about #d volumes of water4 ,transl4 #ajb ,chemische ,zeitschrift1 ,,ii4 #aijc1 p4 #gfa4 #ajc ,lecythoi3 slender narrow-necked painted vessels which were frequently burnt or buried with the dead2 cp4 ,aristophanes1 ,ecclesiazusae1 #iif3 hos tois nekroisi zgraphei tas lkythous4 ,transl4 #ajd ,the method of washing objects of unbaked clay suggested by ,flinders ,petrie in the ,archaeological ,journal 7,,xlv4 #ahhh7 is in my experience impracticable4 #aje ,muffle furnaces may be obtained from ,messrs ,fletcher1 ,russell and ,co41 ,warrington4 ,if electricity is available1 the electric muffle may be used4 ,these may be obtained from ,messrs ,a4 ,gallenkamp and ,co41 #ai1 ,sun ,street1 ,finsbury ,square1 ,london4 ,the ,heat-recorders supplied by ,h4 ,watkin1 #bbe1 ,waterloo ,road1 ,burslem1 will be found very convenient in place of ,seger's cones1 which may be obtained from ,messrs ,brady and ,martin1 ,northumberland ,road1 ,newcastle-on-,tyne4 ,transl4 #ajf ,merkbuch1 p4 #gh4 #ajg ,a paraffin prepared from ,burmese petroleum4 ,transl4 #ajh ,flinders ,petrie1 ,archaeological ,journal1 ,,xlv4 #ahhh1 p4 #hi4 #aji ,merkbuch1 p4 #gi4 #aaj ,it is important to avoid confusion and mistakes arising from the similarity of the terms benzine and benzene4 ,benzene 7,benzol7 is the specific coal-tar product which has the formula ,c#f;,h#f4 ,benzine 7,benzin7 is a light-boiling petroleum distillate1 lighter than lamp oil1 and with a varying boiling-point4 ,it consists of a number of saturated hydrocarbons of the methane series4 ,it is also called benzoline or petroleum naphtha4 ,transl4 #aaa ,appelgren1 ,finskt ,museum1 #ahie1 p4 #ef4 #aab ,a communication from ,herr ,schjerning1 ,copenhagen4 #aac ,speerschneider1 ,antiquarisk ,tidsskrift1 #aheh-fj1 p4 #agh4 #aad ,blell1 ,sitzungsberichte der ,prussia1 #ahha-hb1 p4 #bd4 #aae ,krefting1 ,aarsb4 fra foreningen t4 norske fortidsmindesm4 bevar4 #ahib1 p4 #ed4 #aaf ,salzer1 ,chem4 ,zeitung1 ,,xi4 #ahhg1 p4 #egd4 #aag ,probably first recommended by ,salzer1 ,chemiker ,zeitung1 ,,xi4 #ahhe1 p4 #egd4 #aah ,kongl4 ,vitterhets ,historie och ,antiqvitets ,akademiens ,mnadsblad1 #ahhe1 p4 #acd4 #aai ,the addition of the lime is not advisable1 comp4 p4 #ic4 #abj ,chemiker ,zeitung1 ,,xi4 #ahhe1 p4 #fje4 #aba ,zeitschrift f4 ,ethnologie1 ,,xxxiii4 #aijb1 p4 #dca1 and ,,xxxiv4 #aijc1 p4 #gia4 #abb ,sitzungsberichte1 #ahha-hb1 p4 #aj et seq41 and #af et seq4 #abc ,in this acid treatment bare hands may be used1 but care must be taken to avoid splashing clothes or linen1 which will cause red or yellow spots4 ,these are best removed by the immediate application of ammonia1 but the yellow spots can only be removed by oxalic acid4 #abd ,germ4 ,hammerschlag4 ,the iron scales which chip off from heated iron at a forge or blacksmith's shop4 ,transl4 #abe ,no4 #ag1 #ahig1 p4 #ccc et seq4 #abf ,a number of modifications in the metals employed and the composition of the bath have been suggested4 ,setlik 7,chemiker ,zeitung1 ,,xxvii4 #aijc1 p4 #ded7 imbeds iron objects which have a very weak core in a zinc-wire basket immersed in a magma of zinc dust and caustic soda4 ,personally ,i should prefer not to attempt a reduction process in such cases1 but should rely rather upon mechanical removal of the rust1 soaking and impregnation4 ,for the treatment of bronzes this observer prefers the ,finkener method 7q4 v47 and suggests caustic soda1 sodium chloride1 or ammonia chloride1 instead of potassium cyanide as the electrolyte4 ,rhousopulos 7,chemische ,zeitschrift1 ,,ii4 #aijc1 pp4 #bjb and #cfd7 uses zinc and hydrochloric acid1 and when dry gives to the bronze a coating of wax4 ,i should deprecate the use of either of these substances1 the hydrochloric acid because of the difficulty of completely removing it by steeping and the danger of subsequent decomposition of the bronze1 the wax because the contained fatty acids may act upon the metal4 #abg ,the period required for complete reduction is1 in our experience1 often considerably longer4 ,we have sometimes found an #h soda solution more satisfactory4 ,transl4 #abh ,krefting's method affords an excellent illustration of the truth of my remarks in the preface that the literature upon these preservation-methods is very scattered and in consequence has been hitherto but little studied4 ,in #ahib1 when visiting the ,museum at ,christiania1 ,i had the opportunity of examining some iron objects which had been treated by ,krefting's method4 ,i then obtained his address1 and ,herr ,krefting kindly communicated his method to me by letter1 and in the following year forwarded a reprint of his article referred to above4 ,in #ahhg he had described his method to ,appelgren by letter1 but at that time he treated the object after reduction1 washing1 and drying1 by impregnating it with a paraffin-petroleum solution4 ,in #ahig ,appelgren published this method1 with drying and impregnation1 in ignorance of ,krefting's publication in #ahic4 #abi ,the bottle should not be closed by a glass stopper1 but by a rubber bung1 or by a cork coated with paraffin or wrapped round with parchment4 ,soda solution attacks glass1 and especially ground glass2 thus the stopper may become so firmly fixed into the neck of the bottle as to render its removal impossible4 #acj ,excavated by ,dr ,thurnam1 #ahdh 7vide ,archaeolog4 ,journal1 ,vol4 ,,vi4 p4 #bg74 ,transl4 #aca ,chemiker ,zeitung1 ,,xi4 #ahhg1 p4 #fje4 #acb ,ant4 ,fr4 #aaed a4 #acc ,i should now use paraffin for impregnation4 7,author's note47 #acd ,great caution must be used to prevent inhalation of the gas1 which is extremely poisonous4 ,transl4 #ace ,instead of potassium cyanide1 ,i have made experimental use of the much more readily fusible potassium sulphocyanide4 ,this converts the iron compounds into iron sulphide1 which is easily got rid of4 ,the sulphide which still adheres to the iron and imparts a not unpleasing blackish colour to the object appears to be stable4 ,the rest of the treatment is similar to that above described4 ,having so far only experimented with a few specimens ,i am not yet in a position to offer any judgment as to the practicability of the process4 7,author1 #aijd47 ,for practical objections to this method1 which we do not consider satisfactory owing to the instability of the products resulting from the reaction1 and the difficulty in removing them by the subsequent washing1 see ,milbauer1 ,zeit4 f4 anorg4 ,chem4 ,,xlii4 #aijd1 p4 #dcc 7,journ4 ,chem4 ,soc4 ,abstracts1 i4 #aba71 where it is stated that treatment of ,fe#b,o#c at #djj;,c4 leads to the formation of ,k#b;,fe#b,s#d4 ,transl4 #acf ,stolba1 ,chemiker ,zeitung1 ,,xx4 #ahif1 ,repertorium1 p4 #bdj4 ,sodium sulphide has a very deleterious action upon the skin and fingernails which should be protected when using this substance4 ,transl4 #acg ,flinders ,petrie1 ,archaeological ,journal1 ,vol4 ,,xlv4 #ahhh1 p4 #hh4 #ach ,cp4 ,mugdan1 ,zeit4 ,elektrochem4 #aijc1 ix4 p4 #ddb4 #aci ,a method used by the explorers of the ,palestine ,exploration ,committee for the preservation of much decayed bronzes1 as1 for instance1 those from wells and cisterns1 is to place them immediately they are discovered into a strong solution 7#a in #aj7 of carbolic acid4 ,transl4 #adj ,merkbuch1 p4 #fh4 #ada ,instead of calcium chloride strong sulphuric acid may be used for dehydration1 but the dry chloride is more simple1 and less dangerous4 ,if kept in corked bottles1 the corks should be covered with paraffin wax to prevent access of moisture4 #adb ,first put forward by ,chevreul 7see pp4 #bb and #aag74 #adc ,the so-called 'pole paper' is supplied by most dealers in electrical apparatus4 ,transl4 #add ,in such a case the hydrated oxide of tin is either present as such in the oxidized bronze1 or it is a product of the reduction which has been prevented from falling to the bottom by the high sp4 gr4 of the potassium cyanide solution4 ,it is also possible that finely divided tin in the reduced bronze may decompose the warm water into oxygen and hydrogen1 forming a hydrated oxide of tin4 ,such a reaction would account for the formation of hydrogen4 ,the hydrogen might at the same time remain occluded until allowed to separate by the cessation of the current and the temperature of the water4 #ade ,such1 for instance1 as is obtained by attaching a suitable nozzle to a fall pipe where there is sufficient water-pressure2 v4 e4g4 ,polytechn4 ,centralblatt1 #ahia-ib1 p4 #aii4 #adf ,i now consider it a better plan not to employ the method of coating with paraffin wax4 ,i thoroughly soak and then dry the reduced bronze with a cloth1 and place it in #if alcohol4 ,this must be renewed after a time1 and for large bronzes a third or even a fourth renewal is advisable4 ,the bronze is again wiped and introduced into a drying oven raised to about #bab;,f4 #ajj;,c44 ,the unsightly grey colour and rough surface may be much improved by using a brush of the finest wire or very fine emery cloth4 ,the object is finally impregnated with zapon 7see ,appendix74 7,author's note1 #aijd47 #adg ,the base was not treated owing to the advanced destruction of the metal4 ,transl4 #adh ,in only about #b of the bronzes treated in the laboratory of the ,royal ,museums at ,berlin has it been found necessary to interrupt the reduction4 #adi ,polytechn4 ,centralblatt1 #ahia-ib1 p4 #bjj4 #aej ,these analyses were made by ,schulz in the ,laboratory of the ,royal ,museums4 #aea ,i quote here the greater part of an article published in ,dingler's ,polytechn4 ,journal1 #ahif1 ,vol4 ,,ccci4 p4 #dd4 ,the reduction of about #gjjj ,danish copper coins1 undertaken while the above was in the press1 gave similarly good results4 #aeb ,the zinc1 which in the course of the reduction process may become coated with a thin layer of metallic copper1 may be used again4 ,it should be first put through dilute sulphuric acid 7in the proportion of #a3b71 then washed1 rubbed with a steel wire brush and again washed4 ,but it must in such cases be used again while still wet1 for if allowed to dry it becomes coated with a layer of oxide and requires to be re-polished4 #aec ,publications de la socit pour la recherche et la conservation des monuments historiques dans le grandduch de ,luxembourg1 ,vol4 ,x4 ,as ,i have been unable to consult the original1 ,i have here inserted a communication sent to me by ,dr ,kisa of ,cologne4 ,i have tried this method on a few coins4 #aed ,in another instance--that of a ,minotaur group ,ant4 ,misc4 #gchb--the calcium chloride is contained in four shallow glass troughs which are placed round the marble pedestal of the bronze and are loosely covered with a black card4 #aee ,grote1 ,bltter fr ,mnzkunde1 #ahce1 ,i4 ,no4 #ca1 ,,vi4 #aef ,zeitschrift fr ,numismatik1 ,vol4 ,,xvii4 #ahij1 p4 #ajj4 #aeg ,prometheus1 ,,viii4 #ahig1 p4 #cea4 ,a report on the other methods is here given4 #aeh ,zeitschrift fr ,numismatik1 ,vol4 ,,xx4 #ahig1 p4 #cbe4 #aei ,archaeological ,journal1 ,,xlv4 #ahhh1 p4 #hg4 #afj ,riv4 ,ital4 ,numism4 #aijc1 p4 #ca2 also ,chemiker ,zeitung1 ,,xxvii4 #aijc1 p4 #hbe4 #afa ,in this connection however it must be remembered that celluloid gives off traces of acid for a long time4 ,this may possibly involve risk of injury to certain specimens4 ,transl4 #afb ,mittheilungen des ,nordbhmischen ,gewerbe ,museum1 #aijc1 p4 #ajd4 #afc ,a few drops of formalin will serve the same purpose4 ,transl4 #afd ,lanoline1 especially if applied warm1 retains the flexibility of the leather very satisfactorily4 ,it may be here mentioned that the leather of old book-bindings may be preserved by the application1 by means of a soft brush1 of a mixture of white wax with a small quantity of white vaseline and paraffin wax1 brought to a pasty consistency with benzine or turpentine4 ,the ',stearine ,glaze' used for the same purpose is made by boiling one part of caustic soda with eight parts of stearic acid and #ej parts of water till dissolved1 then mixing another #aej parts of cold water and stirring until the whole sets to a jelly4 ,either of these media should be applied very thinly and then polished with a brush or flannel4 ,if the cover is very bad1 considerable improvement is effected by repeated applications of the stearine glaze so as to fill up the damaged surface of the leather4 ,in some cases the addition of some dye such as logwood1 or one or other of the acid coal-tar dyes1 is advantageous4 ,lanoline1 or wool fat1 i4e4 lanoline without the water1 is useful1 but gives a dull surface to the leather4 ,in some cases a thin coating of diluted white of egg1 to which a few drops of clove oil1 or some other essential oil1 has been added as an antiseptic is beneficial4 ,transl4 #afe ,on preservation in alcohol see p4 #aei under the heading ',wood4' #aff ,aarb4 for nordisk ,oldkynd4 og ,historie1 #ahia1 p4 #aab4 #afg ,according to an analysis published by ,l4 v4 ,barth in an account of the collection of papyri belonging to the ,archduke ,rainer1 ,part ,i4 p4 #abj1 the salt crystals1 after removal of the insoluble constituents1 consisted of3 ,potassium sulphate #jh ,potassium and sodium chlorides #ibj ,calcium sulphate #df ,magnesium chloride #bh ,organic substances #jb #afh ,merkbuch1 p4 #fj4 #afi ,communicated by ,herr ,leiner of ,constance4 #agj ,antiquarisk ,tidsskrift1 #aheh-fj1 p4 #agf4 #aga ,id41 p4 #agd4 #agb ,olshausen1 ,verh4 der ,berl4 anthropol4 ,ges4 #ahhe1 p4 #bdb1 an oral communication from ,herr v4 ,jenner4 #agc ,attention may be drawn to a paper which 7,dec4 #aijd7 will shortly be published by the ,imperial ,commission for ,monuments of ,art and ,history in ,vienna4 ,at a meeting in ,vienna a paper was given by ,bolle on the animal enemies of paper1 leather1 and wood1 and their destruction by means of carbon bisulphide4 ,carbon bisulphide is an infallible poison and has no effect upon colours when used in a perfectly dry state4 ,this may be carried out by a preliminary displacement of the air by carbonic acid which is readily obtained in the liquid form in cylinders4 ,benzine would probably act equally well1 but would require a longer time for its action4 ,references to other methods such as the employment of a vacuum or of heat will be found in the same publication4 #agd ,keim1 ,technische ,mittheilungen fr ,malerei1 #ahhh1 p4 #d4 #age ,communication from ,herr ,straberger of ,linz on the ,danube4 #agf ,communication by ,dr ,voss4