摘要:

THE QUARTERLY JOURNAL OF THE CHEMICAL SOCIETY OF LONDON. 6lYmmiht Df @rnblimtim THOMAS GRAHAM' F.RS. W. A. MILLER M.D. FR.S. A. W. HOFMANN PH.D. F.R.S. J. STENHOUSE LL.D. F.R.S. LONDON HIPPOLYTE BAILLIERE 219 REGENT STREET AND 290 BROADWAY NEW YORK U.S. PARIS J. B. BAILLIERE RUE HAUTEFEUILLE MADRID BAILLY BAILLIERE CALLE DEL PKINCIPE. 1857. LONDON PRINTED BY HARRISON AND SONS ST. MARTIN’S LANE. W.C. COK TENTS OF T H E N I N TH VO L U 31E. YAQE On aome new Colouring Matters Derivatives of Dinitrobenzole Dinitronaphtha- line &c. By Arthur H. Church and William H. Perkin ............................ 1 Action of Chloride of Cyanogen on Kaphthalamine. By William 8.Perkin .... 8 Note on the Solubility of Sulphate of Baryta in Hydroch!oric Acid.By Henry M. Noad Ph.D. .................................................................................. 15 On the Source of the Water of the Deep Wells in the Chalk under London. By Dugald Campbell ..................................................................... ... 21 Proceedings at the Meetings ofthe Chemical Society ......................................... 28 Notices of Papers contained in other Journals :-Chemical Report on the mbde of detecting Vegetable Substances mixed with Coffee for the purpose of Adulteration. By T. Graham F.R.S. 3. Stenhouse F. R.S. and Dugald Campbell F.C.S. ......................................................... 33 On circ*imstancesmodifying theaction of Chemical Affinity.By 3. H. OIadstone Ph.D.,F.R.8.............................................................................................. 54 Contributions to the History of Nitric Acid with especial reference to the Valuation of Nitre. By F. A. Abel and C. L. Bloxam .............................. 97 Note on a New Method of making Ferricyanide of Potaesium and a Para-cyanogen Compound. By Lyon Playfair C.B.,F.R.S. ................................ 128 By Frederick Quthrie. P1i.D. ............................................................................ 131 On the Action of Heat upon t.he Oxychloride of Copper (Ataeamite) . By Frederick Field ............................................................................................140 Analysis of a Meteoric Stone from tho desert of Atacama .By Frederick Field 143 Some Experiments illustrative of the Reciprocal Decomposition of Salts. By J .H. Gladstone Ph.D. F.R.S. ................................................................. 144 Report of the Council of the Chemical Society ...................................................... 157 Balance-sheet of the Chemical Society .................................................................... 162 Proceedings of the Meetings of the Chemical Society ............................................ 163 i v CONTENTS . PAGE On the Sdphovinates. and on Amylophosphoric acid and thc Amylophosphates . Notices of Papers contained in other Journals :-On the Constitution and Propertiea of Omno.By Thomas Andrews. M.D. F.R.S.,M.R.I.A ....................................................................................... 168 On tho Formation and Preparation of Formic Acid . By M. Berthelot .................. 182 Chemical Notices . By H.Limpricht .................................................................. 184 On Anisic Alcohol . By 8.Cannizzari and C.Bertagnini ....................................... 190 On Cadmium.ethy1 . By J . A . Wanklyn ................................................................ 193 On a Coal-Gas Carbon and Nitric Acid Voltaic Battery . By Jamepl L. and L . Wheeler ....................................................................................................... 198 Description of a Self-acting Washing Bottle .By William Stephens Clark ........ 200 On the Composition of some Varieties of Foreign Iron . By F. A . Abel ............ 202 Notices of Papers contained in other Journals :-On Insolinic Acid . By A. W. Hofinann ............................................................ 210 On Lophine . By A. Oijssmannand E. Atkinson ................................................ 220 Examination of select Vegetable Products from India By John Stenhouse LL.D.,F.R.S........................................................................................... 226 Researches on the Action of Sulphuric Acid upon the Amidcs and Nitriles together with remarks upon the Conjugate Sulpho.acids . By George B. Buckton Esq. F.L.S. F.C.S. and A . W.Hofmann LL.D. Ph.D. F.R.S. &c . 241 Chemical Notices . By H. Limpricht ................................................................. 264 On a New Mode of Formation of Hydride of Bcnzoyl. By II. Kolbe .................... 266 On somo Compounds of Bewoyl. By C.w1 Voit .................................................. 265 CONTENTS . v PAGE On some Conitituenh of Opium. By T. Anderson ............................................. 273 On the Compounds of Stibethyl. By W. Merck ................................................... 278 On the Stibamgls . By F. BerlB ........................................................................ 282 On Methyluramineand its Derivatives. By V. Dedgnes.... .............................. 286 On the Reciprocal Precipitations of the Metals . By M. Odling. M.B. L.R.C.P. 289 Proceedings of the meetings of the Chemical Society ............................................ 298 Titles of Chemical Papers in British and Foreign Journals ................................ 301 Index ..................................................................................................... 373

ISSN:1743-6893    

DOI:10.1039/QJ85709FP001

出版商:RSC    

年代:1857

数据来源: RSC

摘要:

NR. W. 11. PERKIN ON THE ACTION OF 11.-Action of Chloride of Cyanogen on Naphthalamirie. By ~VILLIAM H. PERKIN. MM. CAHOURSand CLOEZ,in their investigations on naph-thalamine observed that it combined with chloride of cyanogen forming the hydrochlorate of a new base. They however did not investigate this subject any further; and as it was interest-ing to know whether compounds similar to those obtained from nielaniline might be produced I undertook at the request of Dr. I€of m an n to examine this reaction more minutely. Preparation of Naphthalamine. -The preparation of naphtha-lamine is effected by distilling nitronaphthaline wit'h iron and acetic acid according to the process of Z in in modified by B 6ch am p. This process yields the base in considerable quantity but in an impure condition.To purify this it must be dissolved in hydro- chloric acid and water and filtered from all insoluble impurities; the filtrate is then evaporated to dryness and distilled wit,h lime when the base comes over nearly pure and perfectly anhydrous. Prepamtion of fifenaphthalamine. -In subjecting naphthala- mine to the action of chloride of cyanogen I adopted the same arrangement that Dr. Hofmann had used in the preparation of melaniline ;namely a series of tubes filled with the alkaloid through which the chloride of cyanogen was drawn by means of an aspirator. However in this case it is necessary to support the action from the comniencement by the application of heat naphtha- lamine being a solid substance. When the gas is passect into the fused anlryclrous nnphthalamine oliemicnl ILC tiitii is at oiicc rcnclcrccl pcrce1)tible by a rapid cleva- CIILORJDE OF CYANOGEK ON NAPHTIilALAD.IINX3 tion of the temperature and the gradual thickening of the liquid which prevents the gas from passing freely.To complete the re- action heat must be carefully applied sufficient to keep the eom- pound in a state of fusion. On cooling the naphthalamine is found converted into a black resinous mass which consists principally of the hydrochlorate of a base which I propose to call menaphthalamine. On boiling this mass in a large quantity of water it almost entirely dissolves. On adding potassa or ammonia to the filtered liquid a white precipitate is produced which is freed from chloride of potassium or ammonium by washing with water and recrystallised once or twice from alcohol from which it is deposited in small white needles.This base when dried at 100" C. and burnt with protoxide of copper gave the following numbers :-I 0.249 grm. of menaphthalamine gave 0.7385 , carbonic acid 0.1275 , water. II. 0.2840 , menaphthalamine gave 0.8425 , carbonic acid 0.1410 , water. These numbers lead to the following percentage composi-tion :-I. 11. Carbon . 80.88 80-90 Hydrogen . . 5.40 5.50 Two analyses of the platinum-salt gave a mean of 19.065 per cent. of platinum. Equivalent deduced from the platinum-salt = 31 1.24 Theoretical equivalent . . = 311*00 These results lead to the formula c*,HI N39 which require the following values :-Theory.Mean of -m'-experiments. 42 equiv. of carbon. . 252.0 81.0 80.89 17 eqiiiv. of hydrogen . 1'7.0 5.4 5*45 3 equiv. of nitrogen . 42.0 13-6 -__-3 1 1 -0 100-0 MR. W. R. PERIZIN ON THE ACTION OF This show that the formation of menaphthalamine is perfectly analogous to that of melaniline and metoluidine 2 equiv. of naphthalamine and 1 equiv. of chloride of cyanogen yielding 1 equiv. of the hydrochlorate of menaphthalamine. 2C,,H,N + C2NC1 = C, H,,N,,HCl LpH M Naphthalamine. Chloride of EIgdrochlorate of cyanogen. menaphthalamine. Propertiesqf Mena~~t~a~a~~~e~ -This base when pure crys-tallises in small white needles which are not coloured by exposure to the atmosphere.Menaphthalamine is odourless ; it has a bitter taste ; fuses at about 200"C. into atransparent slightly yellowish oil. If the tem- perature be raised above 260"C. decomposition ensues pure naphthalamine distils over and a brown mass remains in the retort. In the case of melaniline the residue had the formula C5 H, N, which may be regarded as a compound of aniline-mellone with 3 equiv. of aniline. It is probable that the menaphthalamine residue has an analo- gous composition. Menaphthalamine is almost insoluble in water and only moderately soluble in alcohol and ether. It changes the colour of red litmus-paper. Chromic acid acts but slowly upon it. COMBINATIONS OF MENAPHTHALAMINE. This base forms salts with all acids many of which are amorphous or very slightly crystalline.They are all sparingly soluble in water. The salts have no action on litmus-paper. They are pre- cipitated by acids and saline solutions ; potassa and ammonia de- compose them the base being separated in the form of a pure white powder. Hydrochlorate of Me~a~~z~~~a~arn~n~.a white -This salt is amorphous compound which becomes slightly red when exposed to air and moisture. It is moderately soluble in water and very soluble in alcohol and ether when heated it is decomposed hydrochlorate of naphthalamine subliming and leaving a black residue in the rctort. C EILORIDE OF CYANOGEN ON XAPIITIIALAMINE. A determination of hydrochloric acid gave the following result -0.4422 grm. of hydrochlorate gave 0.682 , chloride of silver corresponding to 10.44 per cent.of hydrochloric acid. This number leads to the formula which requires the following values -Theory. Experiment. 1 equivalent of menaphthalamine= 311*O 8 9.6 -1.equivalent of hydrochloric acid= --36.5 10.4 1044 -347.5 100a Sulphate. -This salt is best obtained by neutralising sulphuric acid with menaphthalamine. It is a white perfectly amorphous salt moderately soluble in alcohol and ether which on evapora- tion deposit it in the form of a white powder. Nitrate. -This salt which is the finest of all the menaphthala- mine salts may be prepared by adding menaphthalamine to very dilute boiling nitric acid. This solution on standing deposits the nitrate in small white prisms nearly insoluble in cold water but very soluble in alcohol and ether.Phosphate.-It is a white crystalline salt very soluble in alcohol and ether. Binoxalate. -This salt is best obtained by boiling menaphtha- lamine with an excess of oxalic acid. From this solution the salt crystallises in small tufts of white needles which are not easily soluble in water but moderately soluble in alcohol and ether. Wydrobromate and Bydriodate. -These salts are crystalline and very soluble in alcohol. ~~drochloropZatinate.-This compound is best prepared by adding an alcoholic solution of bichloride of platinum to a warm alcoholic solution of the hydrochlorate of menaphthalamine; from this solution small yellow crystalline scales are deposited. If however the aqueous solutions are employed it is immediately precipitated as an amorphous powder which is almost white but soon becomes slightly green.*-,- XR. W. H. PERKIN ON THE ACTION OF Two determinations of the platinum gave the following nuni- bers :-I. 0.229 grm. of the salt gave 0.0435 , , platinum. 11. 0.19975 , , salt gave 0.0377’5 , , platinum. Theory. Experiment. --- 1. 11. Percentage of platinum in the 1908 1gr0.1 1.9.09 platinum-salt . ./! Terchloride of gold gives with menaphthalamine-salts a blue precipitate. METAMORPHOSES OF MENAPHTHALAMINE. Menaphthalamine when exposed to the action of various agents undergoes a variety of transformationa many of whicli I have not been able to study. Action of SaZphzcric Acid.-When Nordhausen sulphuric acid is brought in contact with menaphthalamine it becomes pasty owing to the formation of the sulphate; but if a gent.le heat be applied it becomes perfectly liquid. This liquid on being diluted with water and treated with carbonat,e of lead produces a soluble lead-salt of a new acid which decomposes partially every time it is evaporated. On passing sulphuretted hydrogen through a solution of the lead-salt a colourless solution is obtained (with precipitation of the lead as sulphide). When this liquid is evaporated the new acid is decomposed into a soluble alkaline body and an insoluble neutral one. Action of Fuming Nitric Acid. -This pcid acts violently on menaphthalamine producing a variety of substitution-products.Chlorine bromine and iodine seem to produce neutral com- pounds. Action of Cyanogen.-If cyanogen is passed through an alcoholic or ethereal solution of menaphthalamine it becomes first yellow and then red nothing being deposited on standing ;but if the base is made into a thin paste with ether and cyanogen passed through it it all dissolves ;and on standing the solution deposits a slightly crystalline body of a light buff colour which may be purified by washing with ether. CHLORIDE OF CYANOGEN ON NAPIIT I{ ALAMINE. A conibustion of a specimen dried at 100" C. gavethe following results :-0.2'74 grm. of the substance gave 0.764 , carbonic acid and 0.1292 , water which gives the following percentage composition :-Carbon .. 76*00 Hydrogen . . 4-71 This may be translated into the formula '46 N5 as may be seen by the following table :-Theory. Experimerit. ,-m-L4.+-. 46 equiv. of' carbon . . 276 76 *OO 76-00 17 4.69 4.7 1 17 , hydrogen '70 19.31 -5 , nitrogen _I 363 1oo*oo This compound therefore like dicyanomelaniline is formed by the combination of two equivalents of cyanogen with one of menaphthalamine. c42 H17 N3 + 2c2 = c46 H17 N5 -\-71--/ ---? Menaphthalamine. Cyanogen. New compound. DTCYMENAPHTEIALAMINE (which name I propose for this com- pound) is a slightly buff-coloured body which crystallises with diEculty ; it is moderately soluble in alcohol and ether but inso- luble in water. It is a base though a very unstable one ; it dissolves readily in dilute acids and may be reprecipitated by ammonia if added directly after solution ; but like cyaniline and dicyanomelaniline this base cannot remain in acid solutions without undergoing com- plete decomposition.If this base be dissolved in hydrochloric acid and the solution allowed to stand for a few moments it be- comes cloudy and a yellow substance begins to appear which is not the hydrochlorate of dicymenaphthalamine. The best process for the preparation of this new compound consists in adding dilute hydrochloric acid to a warm alcoholic solution of dicymennphthalamine. On standing it is deposited in 14 ACTION OF CHLORIDE OF CYANOGEN ON NAPHTIIALAMINE. small scales of a yellow colour. The mother-liquors from the preparation of this compound always contained ammonia.The analysis of this compound dried at 100" C. gave the follow- ing results :-0.212 grm. of substance gave 0.590 , carbonic wid and 0+080 , water. These numbers lead to the following percentage composition :-Cc<Lrb on . . . = '15.6 Hydrogen . *-4-2 which may be translated into the formula as is evident from the following coinparison of the theoretical with the experimental values :- Theory. Experimcnt. 46 equiv. of carbon . . 276.0 75.66 75% 15 , hydrogen . 15.0 4-10 4*2 3 4 , , nitrogen oxygen . . 42.0 32-0- 11-50 8-74 - 365-0 100*00 This substance which I propose to call MENAPHTHOXIMIDE is perfectly analogous in its properties to melanoximide.Its formation is as illustrated by the following equation,- C, HI N + 4H0 + 2€ICI=C, H, N 0 + 2NH4C1. L.I-LR/\-' --' Dicymenaphthalamine. Menaphthoximide. This substance is insoluble in water and very slightly in alcohol and ether from which it may be crystallised but with difficulty. Menaphthoximide may be regarded as binoxalate of menaphtha- lamine minus 4 equivalents of water,-a view which is supported by experiment. On addition of potassa to this compound menaph- thalamine is reproduced and the mother-liquor is found to contain oxalic acid. The action of acids upon menaphthoximide is precisely the same as in the case of melanoximide namely it is converted into oxalic DR. 13. M. NOAD ON SULPRATE OF RARYTA. acid menaphthalamine and a white neutral body to which I intend to return at some future period.Action of Heat on Menaphthoximide.-When menaphthoximide is heated to 245" C. it fuses; if the temperature be raised to 260" C. it decomposes with evolution of a white vapour having a most peculiar and powerful odour. I believe that this reaction is analogous to that which melanoximide undergoes when sub mitted to the influence of heat and that the substance produced corresponds t,o Dr. Hof m an n 's anilocyanic acid,- in fact that it is the naphthalamine term corresponding to cyanic acid or naphthalocyanic acid; but I have not been able to obtain this compound in sufficient quantity to establish this supposition by experiment. I hope however to return to the examination of this most interesting subject as soon as possible. In conclusion I have to thank Dr. Hofmann for the advice and assistance he has afforded me during the prosecution of this investigation.

ISSN:1743-6893    

DOI:10.1039/QJ8570900008

出版商:RSC    

年代:1857

数据来源: RSC

摘要:

DR. 13. M. NOAD ON SULPRATE OF RARYTA. III.-Note on the Solubility of Sulphate of Baryta in Zydroehloric Acid. By HENRY&f. NOAD,Ph.D. LECTURER ON CHEMISTRY AT ST. GEORGE’S HOSPITAL. IN the Proceedings of the Royal Society vol. viii. p. 532 there is an abstract of a paper “On Chemical Affinity and the Solu- bility of SuIphate of Baryta in Acid Liquors,” by Mr. F. Crace Calvert. The author says that cc the insolubility of this salt is affected even by the weakest nitric or hydrochloric acids,” and that <‘in future the practice of rendering liquors acid with either of these acids must be discontinued when sulphates are to be determined.” In the abstract of Mr. Calvert’s memoir as it appears in the cc Proceedings,” the only experiments quoted relate to t>he solubility of sulphate of baryta in nitric acid; whether he extended his researches to hydrochloric acid it is not stated; it is to be concluded that he did so since in a practical point of view it is of far greater consequence to establish the fact and the degree of the solubility of this sulphate in t,he lrttter acid than in DE.13. M. NOAD ON THE SOLUlfILITY OF the former the great majority of sulphur and of sulphuric acid determinations in mineral analyses being made in liquids contain- ing excess of hydrochloric acid. That sulphate of baryta is soluble to some extent in nitric acid or at any rate that sulphuric acid may exist in nitric acid both ttrong and dilute and still no precipitate or even cloudiness be produced by the addition of a barytic salt has I believe been known for some time to many chemists.Speaking for myself T have certainly been aware of the fact for upwards of two years. I do not claim it as n discovery of my own though I am quite unable to say from whom I derived my information. I have reason to believe however that the discovery originated with Mr. Nicholson though the first public announcement of it is probably in Mr. Calvert’s paper. It is easy to prove that almost all the fuming nitric acid of commerce contains sulphuric acid though it may retain a perfect transparency when largely diluted with water and treated with a barytic salt. All that is necessary is to evaporate an ounce or so of the acid in a platinum capsule down to about a drachm the11 add water and nitrate or chloride of barium upon which a greater or less turbidity ill ensue.That very grave errors have been committed in sulphur detcrniinations in organic compounds iir consequence of a want of the knowledge of this important filcr cannot be doubted fuming nitric acid having been very general?y employed as the oxidising agent to convert the sulphur into sul- phuric acid thousands of mineral analyses must for the same reason be considered erroneous as regards the determination of this particular element; and I consider myself fortunate that I was made aware of the almost invariable irnpurity of nitric acid previous to the commencement of my own iron and cinder ana- lyses and thus have been enabled to guard against it.It is quite otherwise however as regards hydrochloric acid ; and I must certainly confess that I read the abstract of Mr Calvert’s paper with considerable clisconifort ;for if his statement be true then my own and many thousand other sulphur determinations have been made in vain since in separating sulphur from phosphorus in crude iron and forge cinders I hare almost invariably done so in an acid solution and that acid has been hydrochloric. Being thus so immediately interested and in the absence of all experimental evidence in the abstract of Mr. Calvert’s paper it was natural that I should forthwith commence a series of experiments to satisfy myself as to the justice or injustice of Rir. Cnlvcrt’s con- SULPHATE OF BARYTA IN HYDROCHLORIC ACID.clusions; it being sufficiently evident that if the insolubility of sulphate of baryta is affected by the weakest hydrochloric acid the usual course of mineral analyses must be somewhat modified. The results of my experiments I beg briefly to lay before the Society; they have proved the groundlessness of my fears and may have the effect of relieving the minds of some other prac- tical chemists as they have relieved mine. They show that though under certain circumstances the insolubility of sulphate of baryta is affected by weak hydrochloric acid yet that the error likely to be thereby introduced into analysis is either altogether nil or so exceedingly small as to be in most cases unworthy of considera-tion. FIRST SERIES OF EXPERIRIENTS.Twelve liquors were prepared of uniform bulk,- the first con-sisted of 1000 grain measures of distilled water; the second of 900 grains of water+ 100 grain measures of hydrochloric acid sp. gr. 1153 ; the third of 800 grains of water + 200 grain mea-mres of the same acid ; the fourth of 700 grains water +300 grain measures of acid; the fifth of 600 grains water+400 grain mea- aures of acid ; t@he sixth of 500 grains water +500 grain measures of acid ; the seventh of 400 water +600 acid ; the eighth of 300 water -/-700 acid ; the ninth of 200 water + 800 acid ; the tenth of 100 water +900 acid ; the eleventh of 1000 grain-measures of the acid without any water 5 grains of neutral and thoroughly dried sulphate of potash were dissolved in each of these liquors; and while boiling solutions of 10 grains of nitrate of baryta in 300 grains of water were poured into each; they were allowed to remain at rwt for twenty-four hours then filtered and the sul- phate of baryta washed dried ignited and weighed.In the twelfth experiment the 5 grains of sulphate of potash were dis- solved in 500 grain measures of hydrochloric acid and the LO grains of nitrate of baryta were boiled for some time with another 500 grain measures of the acid ; little if any of the salt was dis- solved but abundance of chlorine was disengaged and the liquor became dark yellow from the absorption of nitrous vapour. The acid liquor was decanted and added to the acid solution of the potash salt sufficient boiling water was then added to dissolve the bwyta-salt and the liquors were then mixed boiled and the sulphate of baryta allowed to subside.The quantities of barytic sulphate obtained in the twelve experiments are given in the following table. The quantity of nitrate of baryta required theo- VOL. IX.-NO. XXXIII .c 18 DR. H. 31. KOAD ON TIIE SOLUBILITY OF retically to precipitate 5 grains of‘ sulphate of potash is 7.5 grains and the quantity of sulphate of baryta produced should be 6.70 grains. L rrl 8 & (u CH 8 P $ Pi 1. 2. 1000 900 0 100 5 grs.do. 10 grs.do. 6 *74 6.70 3. 800 200 do. do. 6.7’1 4. TOO 300 do. do. 6.72 5. 600 400 do. do. 6.69 6. 7. 500 400 500 600 do. do. do do. 6.71 6.78 8. 300 700 do. do. 6.77 9.200 800 do. do. 6.76 10. 100 900 do. do. 6.78 11. 0 1000 do. do. 6.78 12. 500 do. do. 6.78 It is seen that so far from there being a loss of sulphate of baryta there is in the last six experiments a small apparent excess ; this doubtless arose from a small portion of undecomposed nitrate having been carried down mechanically in the strongly acid liquor with the sulphate from which it was not subsequently thoroughly removed by washing. It is well known that nitrate of baryta does adhere most pertinaciously to the sulphate when thus carried down and requires long-continued washing to detach it; it is also well known that nitrate of baryta is very sparingly soluble in highly acid liquids. The precipitates were in all cases washed with the same quantity of boiling water and the experi- ments show clearly I think that in this particular bulk of liquid -viz.about 1000 grains measure,- the precipitation of sulphuric acid is complete in whatever proportion hydrochloric acid exists,- whether it forms the entire volume of the liquid or whether it is absent altogether. SULPHATE OF BABYTA IN HYDROCHLORIC ACID But Mr. Calvert says cc The solubility of sulphate of baryta .is affected in a higher degree by the bulk of the acid than by its strength?” and the table that he gives for nitric acid fully proves this to be the case. It became necessary to examine this position in relation to hydrochloric acid. SECOND SERIES OF EXPERIMENTS 5 grains of sulphate of potash were dissolved in 9000 grains of distilled water +1000 grains of hydrochloric acid sp.gr. 1153 and precipitated as before while boiling with a solution of 10 grains of nitrate of baryta. Three precisely similar experi- ments were made and the following quantities of sulphate of baryta were obtained :- I. TI. 1x1. 5.81 . . 5.72 . . 5.90 Mean 5.81 grs. Here then there is a distinct loss of *89 gr. of sulphate of baryta but does this arise from a solution of the salt in the acid liquor or is it the result of dilution? To determine this point the same quantities of sulphate of potash were dissolved in the same bulks of acid and water but double the quantity viz. 20 grains of the precipitant? were employed the proportions of sulphate of baryta now obtained in three experiments were- I.If. 111. 652 . . 6-51 6.50 Mean . 6.51 grs. Loss . . *19gr. Three other solutions were then made and precipitated by 30 grs. of nitrate of baryta. The quantities of sulphate of baryta obtained were -1. 11. 111. 6.71 . 6.69 . . 6.71 the exact theoretical quantity. I must observe that in these last six experiments the washings were continued for some hours in order to avoid any possible error arising from the adhering of a portion of the precipitant to the precipitated salt. By the side of these last experiments I placed two others in one of which the 5 grains of sulphate of potash were dissolved in 10,000 grains of boiling distilled water and in the other in c2 20 DR H. M. NOAD ON SULPHATE OF BARYTA.20,000 grains no acid being added in either case the quantities of sulphate of baryta obtained were- I. IT. 6-73 grs. . . . 6.72 grs. Lastly the following experiment was made -5 grains of sulphate of potash were dissolved in a small quan-tity of water and precipitated by 10 grains of' nitrate of baryta; 10,000 grain measures of a mixture of 9 parts water and 1 part hydrochloric acid were then added and the whole was boiled for 20 minutes; after 24 hours the resulting sulphate of baryta was weighed. Two precisely simila rexperiments were made with the following results -I. 11. 4.4 grs. . . 4.5 grs. Here then was a loss of 2.3 grains of sulphate of baryta one- third of the entire quantity that should have been obtained.The solubility of sulphate of baryta in a large bulk of dilute hydro- chloric acid is proved conclusively by this experiment but in a practical point of view it is not a matter of any importance; since in the first place it is not usual to attempt precipitations in such bulky liquids but always to concentrate a;s far as possible; and in the second place it is always the practice to add considerable excess of the precipitant which as has been shown above coun-teracts the tendency of the barytic sulphate to dissolve in the acid liquor. On the whole then I tlhink that we may without fear continue to make our sulphur determinations in strong hydro- chloric acid liquors and that the only thing that the analyst has to guard against is the possible existence of' sulphuric acid in the nitric acid he may employ as his oxidising agent.While on the subject of sulphur determinations I may allude to a method 1have lately adopted for estimating the amount of this element in crude iron which with certain precautions gives very accurate results and which possesses the great advantage of enabling the operator to work upon much larger quantities of material than in any of the tisual methods. The pounded iron ia digested in a flask with dilute hydrochloric acid and the gases evolved passed through three W ol fe's bottles each containing il solution of arsenious acid; the whole of the sulphur of the metal passes over as sulphuretted hydrogen and is estimated as As S,; I have convinced myself by repeated experiments that the whole of MR.D. CAMPBELL ON WELLS IN CHALK CNDER LONDON. 21 the sulphur is thus obtained in combination with the arsenic and that the phosphorus which the crude iron invariably contains though it is partly liberated at the same time in the form of phos-phuretted hydrogen does not interfere with the accuracy of the result. In what form the phosphorus combines with the arae- nious acid or whether it combines with it at all I intend to make the subject of a special investigntion; at present but little is known of the compounds of phosphorus with arsenic. I have however satisfied myself that no insoluble compound is formed under the circumstances of the above experiment. The only precautions to be observed are-lst not to add too much hydro- chloric acid to the water in which the arsenious acid is dis-solved the tersulphide not being so insoluble in hydrochloric acid as is generally supposed; nevertheless the solubility of arsenious acid in water is so greatly increased by the addition of a little hydrochloric acid that a! snzall quantity may be added with advantage; 2nd.the evolved gases must pass through at least three Wolfe’s bottles and it may occssionally be advisable to add a fourth; and Srdly the connections between the bottles must be of sheet and not of vulcanised India rubber it being almost impossible to keep the latter perfectly tight under the pressure to which they are subjected. I have occasionally em- ployed solutions of nitrate and acetate of lead in the place of arsenious acid but the objection to these salts is the great difficulty of washing thoroughly the bulky sulphide of lead the results are however when carefully obtained quite trust- IVorthy.

ISSN:1743-6893    

DOI:10.1039/QJ8570900015

出版商:RSC    

年代:1857

数据来源: RSC

摘要:

MR. D. CAMPBELL ON WELLS IN CHALK CNDER LONDON. 21 IV.-On the Source of the ;Water of the deep Wells in the Chnlh zcfzder London. By DUGALD CAMPBELL. THEsource of the supply of water to the deep wells in the chalk below London is a subject which has occupied the attention of many persons and has been discussed in several Societies on more than one occasion; but although this Society has recorded in its Journal the analysis of the water of several of the deep wells still the origin of the source of their supply has not been considered much by the Society. c3 22 MR. D. CAMPBELL ON THE SOURCE OF THE WATER OF On this occasion I purpose to give in as short a manner as I can some of the views which have hitherto been maintained as to the origin or source of the water ; and I shall endeavour to point out from the results of my experiments upon the water that its true source has not yet been suggested.One of the theories most strenuously maintained and apparently the most popular is that the wells under London are partly sup- plied from the infiltration of sea-water and partly from the infil- tration of water from the chalk in the upper strata; and this view is supposed to be substantiated in a great measure by the che- mical character of the water. The advocates of this theory say that in the water of a11 the chalk- wells in or around London which are below Trinity high water inark the quantity of solid saline matter is very large whereas in the water of those wells which are above Trinity high water mark there is comparatively a small quantity of solid saline matter.What they mean by solid saline matter are salts of potash and soda. They take the water of the Trafalgar-square wells,-which as far as my experience goes contains the largest amount of solid saline matter of any water of the deep wells,--as a type of the water from below Trinity high water mark and the water from wells at Watford in the upper chalk as a type of the water above Trinity high water mark. They also say that the large amount of saline matter together with the small amount of carbonate of lime or chalk in the deep well-water,-just the opposite of what is found in the shallow chalk well-waters -is another proof of the strong impregnation of the chalk-water with sea-water.They likewise insist that this view is considerably strengthened by the fact that there is a gradual increase of the solid saline inatter in the water of the London deep wells which would not be the case were the water derived entirely from the upper strata and had no supply whatever from the sea In order to show that the saline matter in the deep well-water is on the increase Professor Br and e 's analysis of the Trafidgar- square water is quoted in comparison with Messrs. Abel and R ow n e y 's analysis. According to Mr. Brand e in 1846 the solid contents per gallon were 66.1 grains consisting of 59.9 grains of soda salts and 3.1 grains of carbonate of lime with 2.4 grains of carbonate of magnesia ;by Messrs. Ab e 1 and R o w n e y 's analysis in 1849 the solid contents per gallon were 68.24 grains,-showing an increase on the whole of 2-14 grains of solid matter per gallon ; THE DEEP WELLS IN THE CHALK UNDER LONDON.23 and ‘c this increase was principally due to salts derivable from sea- water there being only 0.17 grain increase in the carbonate of lime,” I may just mention that in Mr. Brande’s analysis no volati- lised or orgnnic matter is given; and were this supplied I believe there would be little difference in the amounts of solid contents in the two analyses; indeed were the orgmic matter estimated by the method generally employed at that time and still I believe retained by many analysts it would amount to more than 2.14 grs,,-the excess of solid contents found by Messrs.Ab el and Rowney over that found by Mr. Brande. This method of estimating the organic matter in water to which I have alluded was to evaporate a portion to dryness weigh the residue and afterwards heat it to low redness till it ceased to lose weight when the difference from its furmer weight would be considered the organic matter. Tn 1850 my attention was directed to the Trafalgar-square water and I then found that the solid contents including organic matter were per gallon 61.60 grains or 6.64 grains per gallon less than when it was examined by Messrs. Abel and Eowney in 1849. In the Society of Civil Engineers last July it was again stated that the salts were increasing in the yater of the Trafalgar-square deep wells and I then directed my attention to the subject pro- cured specimens of the water and made an analysis of it when I found that what had been stated was not the case and the saline contents were less than when I examined it in 1850.Perhaps I nzay be allowed a digression here to state that before this I had analysed the water from many of the deep wells in different parts of London and in all I had found a large amount of soda-salts and a small though wcighable quantity of potash-salts varying in potash from 0.327 grain in a gallon to as much as 1.33 grain; but I was scarcely prepared to find the Trafalgar-square water to have the same character Messrs. Abel and Rowney having found 13.6’7 grains of sulphate of potash in a gallon;* however on procuring a copy of the minutes of the Proceedings of the Civil Engineers vol.ix. I for the first time saw Mr. Brande’s analysis and either he had not detected any potash-salts in the water or they were in such small quantities as not to be con-sidered by him worth noticing for they are not given in the analysis. * Chern. SOC.Qu. J. i. 97 ctsey. c4 24 MR. D. CAMPBELL ON THE SOURCE OF THE WATER OF I have placed in a table my analysis of the Trafalgar-square well- water together with an analysis of the Watford chalk-water and also an analysis by Dr. Schweitzer of the water of the English Channel; so that at one glance a comparison of their composition may readily be made in order the better to test the different views which have been set forth as to the source of the supply of the deep well-water in the chalk under London.TABLEOF ANALYSES. Trafalgar-sq. Watford Eng. Channel water water sea-water, Substances found. grs. in a galloc grs. in a gallon grains in a at 60' Fah. at 60° Fah. gallon Carbonate of soda -10.58 Sulphate of soda -21 *34 0*70 Chloride of sodium -19.04 1.39 1894-13 Carbonate of potash -1-05 Chloride of potassium -53.55 Carbonate of magnesia 2.07 Sulphate of magnesia -160.65 Chloride of magnesium 256.62 Bromide of magnesium 2.03 Carbonate of lime -2.74 18*20 2.3 1 Sulphate of lime -98 *42 Nitrate of lime -1*'r6 Phosphate of iron and lime --0.97 Silica --0.40 0.8 1 Volatilised matter -0.6 6 0%1 Total -58-85 23.67 2467.71 In the analysis I have combined the acids with the bases but not before getting as good an insight into the constitution of the water as can be obtained by taking its degree of hardness and alkalinity before and likewise after submitting it to the softening process of Dr.C 1 ark. I may observe that the volatile or organic matter is obtained as follows :-The water is evaporated to dryness in a platinum THE DEEP WELLS IN THE CHALK UNDER LONDON. capsule and the solid contents dried until they cease to lose weight at the temperature of 260' Fah. ; the weight is then noted and the capsule heated to low redness until no more loss of weight takes place; the contents are then saturated with fresh car-bonic acid water and dried at 260"; and this operation of satu- rating with carbonic acid water and drying is repeated until an uniform weight is obtained the diflerence between this and the first weight before heating to low redness is volatilised or organic matter.This is not an exact method of estiinating volatile or organic matter there being none; still I think it is the most correct known ; for if the residues after evaporating the water are simply heated to redness and weighed no two results are ob- tained alike from the same water. The process given is better in this respect besides the water originally is not caustic whilst a solution of the residue iu water which has been heated to redness generally is -indicating that it has been deprived of acid. In the residues from water I find carbonic nitric and even sulphuric acid affected by the heating to redness.Restoring the carbonate as described was suggested by Dr. Clark. The results which I obtained as I stated before show that the salts in the water have decreased,since 1850 2.75 grs. per gallon and since 1846 altogether 9-39 grs. per gallon,-a result rather fatal to the statement that the salts are increasing in the water and also to the idea ofa percolation of sea-water into the wells. But I think it is only necessary to compare an analysis of the deep well-water with that of a proper chalk-water together with an analysis of sea-water as in the table I have given to be con- vinced that the deep well-water is no mixture of chalk and sea- water ; and it is quite clear without making an experiment that under no circumstances could a mixture of sea-water with chalk- water in any proportion produce the deep well-water.To account for the presence of carbonate and sulphate of soda alone in the deep well-water without going further into the matter is impos-sible. As a modification of the first view given it has been suggested that the water may still be a mixture of chalk-water and sea-water only the sea-water has undergone a change by percolating through the challi strata before reaching the wells. There can be no doubt that the first portions of sea-water passing through chalk would be deprived of their salt to a great extent if not entirely ; but as the chalk became saturated with sea-water the water would in passing through increase in its saline properties and in time 26 MR.D. CAMPBELL ON THE SOURCE OF' THE WATER OF tvauld become sea-water. But this I have shown is not the case besides the analysis of the three waters will not admit of this view ; for common salt is not decomposed in an ordinary way by carbonate of lime or sulphate of lime. But granting for a moment for the sake of argument that by some means which we know not of it underwent decomposition still the chlorine which was originally combined with the decomposed chloride of sodium -and it is not a small quantity -is not to be traced in the analysis of the deep well-water but has entirely disappeared out of it,-a thing I would consider chemically impossible. An observation I have made and which I do not think has been noticed before by anyone writing upon the subject is that the deeper wells in the chalk contain more saline matter in a gallon than the shallow ones -rather a strong fact I consider against the view of the infiltration of sea-water into the wells for sea- water should become less saline in proportion to the thickness of chalk it has to percolate through and not more sa 1' me.Another view of the source of the deep well-water which has been supported by no mean chemical authority is that it is ordinary chalk-water which has been decomposed by percolating through the chalk strata and has no sea-water in its composition. The explanation given of how it is changed is as follows:-Silicate of soda is found in the chalk through which the water percolates; this silicate is decomposed by the carbonate of lime in the water insoluble silicate of lime deposits and the carbonate of soda gets into solution in its place.This may be very well to account for the increase of the car- bonate of soda and decrease of carbonate of lime in the deep well- water but it does not in any way afford a solution for the presence of chloride of sodium and sulpliate of soda in such large quantities as these salts are found in the deep well-water. My own conviction is that the water does not originally come from an ordinary chalk stratum; indeed I believe that the deep wells have a separate and independent source and are not sup- plied from the upper chalk-water at all. This view has been strengthened by my having observed a pecu1iarit.y in the water of the deep wells not hitherto I think noticed,-namely that there is scarcely the slightest if any indication of nitrates in the proper deep well-water ; whereas a€lwaters from the upper chalk which I have examined and these are not a few contain a notable quantity of nitrates,-indeed it is a characteristic of a proper chalk-water to do so The Watford water one of the purest chalk-waters to be THE DEEP WELLS IN THE CHALK UNDER LONDON.met with gave on an average of several examinations 1.76 grain of nitrates per gallon as noted in the table. As the deep well-water contains phosphates (an observation which was made by Nr. Gr ah am*) and as phosphates are generally associated with animal or vegetable substances I should have expected an increase of nitrates in this water over the ordinary chalk-water from the oxidation of nitrogenous matter accompany- ing the phosphates; but the freedom from nitrates especially under the circumstances is certainly very peculiar and the in- ferences to be drawn from it are that either the phosphates in the water are not originally derived from an organic source or if they are that large quantities of water must have passed through the strata in which these organic remains were deposited and thus have washed away the more soluble nitrates from amongst them.This I believe is really what has taken place. Before forming an opinion myself of the source of the deep well-water in the chalk I thought it was necessary to examine if possible the water from the different strata which form the London Basin; and for this purpose I procured what I was told was a specimen of water from the plastic clay or tertiary strata and from that part of the strata whieh immediately Overlies the chalk.I did not make a full analysis but only estimated certain substances in it; my results however showed this water to have a great similarity in many respects to the deep well-water but they differed so much from analyses already published upon the water that I thought perhaps I might not have had a genuine specimen given to me; and as it is a point too intimately connected with this subject to be entirely passed over I deferred proceeding further until I had a little more leisure and unt4il I could procure and examine other specimens and if possible from wells in the strata in different localities when I hap with the kind permission of the Society again to bring the subject before their notice. * Chem. Soe. Mem. ii. 392.

ISSN:1743-6893    

DOI:10.1039/QJ8570900021

出版商:RSC    

年代:1857

数据来源: RSC

摘要:

PROCEEDINGS AT TEE MEETINGS OF THE CI€EMICRL SOCIETY. January 21 1856. The MASTERof the MINT Vice-president in the Chair. The following donations were announced :-The Journal of the Society of Arts :” from the S0ciet.y. cc The Journal of the Photographic Society :” from the Society. (6 The Literary Gazette :” from the Publishers. 66 The Pharmaceutical Journal :” from the Editor. cC The Journal of the Franklin Institute :” from the Institute. <<The American Journal of Science and Art:” from the Editors. cc On the Action of Water upon certain Sulphomethylates :” by A. H. Church. From the Author. cc On the Spontaneous Decomposition of certain Sulpho-methylates:” by A. H. Church. From the Author. Dr. H. E. Roscoe was elected a Fellow of the Society.Dr. W. A. Miller delivered a discourse On some points in the practice of the Assay of Gold and Silver.” February 4,1856. Dr. W. A. MILL E R ,President in the Chair. The following donations were announced :-cc Elements of Chemistry Theoretical and Practical,” Second Part by Dr. W. A. Miller. From the Author. 6c Report of the Commission appointed to markeInquiries into PROCEEDINGS OF THE CHEMICAL SOCIETY. the state of the Manufacture of Iron and Brass Ordnance :” from I?. A. Abel. Jc The Journal of the Society of Arts :” from the Society. cc The Journal of the Photographic Society 2’from the Society. “The Literary Gazette :” from the Publishers. cc The Pharmaceutical Journal :” from the Editor. cc The Memoirs and Proceedings of the Academy of Sciences of Madrid for the years 1851 1852 and 1853:” from the Academy.The following papers were read :-cc Contributions to the I-Iistory of Nitric Acid with especial reference to the Valuation of Nitre:” by F. A. Abel and C. L. Bloxam. 6c Note on the Solubility of Sulphate of Baryta in Hydrochloric Acid:” by Henry M. Noad Ph.D. Dr. A. W. Hofmann made a verbal communication cc On a New Class of Alcohols.” February 18 1856 Dr. W.A. MILLER,President in the Chair. The following donations were announced :.-cc The Literary Gazette :” from the Publishers cc The Journal of the Society of Arts :” from the Society cc The Journal of the Franklin Institute :” from the Institute. cc The Report of the Council of the Art-Union of London for 1856 :” from the Art-Union.cc The Almanack of the Art-Union of Londan for 1856 :” from the Art-Union. ‘‘On the supposed Influence of the Hot-Blast in augmenting the quantity of Phosphorus in Pig-Iron :” by David S. Price Ph.D* and Edward Chambers Nicholson. From the Authors. Nathan Mercer Esq. of Liverpool was elected a Fellow of the Society. Dr. A. W. Hofmann delivered a discourse cc On some Pu’ew Bases containing Phosphorus.” PROCEEDINGS OF THE CHEMICAL SOCIETY. March 3 1856. Dr. A.W. WILLIAMSON, Vice-President in the Chair. The following donations were announced :-cc The Literary Gazette :” from the Publishers. c6 The Journal of the Photographic Society :” from the Society. cc The Journal of the Society of Arts :” from the Society.cc The Pharmaceutical Journal :” from the Editor The following gentlemen were elected Fellows of the Society :-G. C.Foster B.A. University College London. Arthur Herbert Church Esq. 9 Bedford Row Gray’s Inn Augustus Beauchamp Northcote Esq. 37 Argyle Square. The following papers were read :-cc On the Source of the Water of the deep Wells in the Chalk under London:” by Dugald Campbell. cc On the Action of Chloride of Cyanogen on Naphthalamine :” by William H. Perkin. On some New Colouring Matters Derivatives of Dinitro-benzole Dinitronaphthaline &c. :” by A. H. Church and W. H. Perkin. March 17 1856. Dr. W. A.MILLER,President in the Chair The following donations were announced :-“The Literary Gazette :” from the Publishers.The Journal of the Society of Allits :” from the Society. cc The Journal of the Franklin Institute C’ from the Institute. cc Bericht der kaiserlichen Akademie der Wissenschaften zu Wien :” from the Academy Dr. J. H. Gladstone delivered a discourse 66 On some Laws of Chemical Combination.’’ PROCEEDINGS OF THE CHENICAL SOCIETY. ANNIVERSARY MEETING March 31 1856. Dr. W. A. MILLER President in the Chair. The Report of the Council and the Audited Account of the Treasurer were read. It was Resolved,- cc That in By-Law 2 < Of Honorary and Foreign Members,’ the first sentence of the second paragraph be altered and in future stand as follows :-The number of Foreign Members shall not exceed twenty-five.’ ” Blr.W. Ferguson and Mr. A. B. Northcote having been appointed Scrutators the meeting proceeded to the election of Council and Officers for the ensuing year and the following gentlemen were declared to have been duly elected :-PRESIDENT. W. A. Miller M.D. F.R.S. VICE-PRESIDENTS (WHO HAVE FILLED THE OFFICE OF PRESIDENT). W. T. Brande F.R.S. Thomas Graham F.R. S. C G. B. Daubeny M.D. F.R.S. Colonel Philip Yorke F.R.S. VICE-PRESIDENTS. B. C. Brodie F.R.S. G. D. Longstaff M.D. Warren De laRue Ph.D. F.R. S. A.W.Williamson,Ph.D. F.R. S. SECRETARIES. Theophilus Redwood Ph.D. William Odling M.B. FOREIGN SECRETARY. A. W. Hofinann Ph.D. F.R.S. TREASURER Robert Porrett F.R. S OTHER MEMBERS OF THE COUNCIL F. A Abel Esq.William Herapath Esq. C. L. Bloxam Esq. Charles Heisch Esq. G. B. Buckton Esq. H. Bence Jones M.D. F.R.S. Dugald Campbell Esq. Hugh Lee Pattinson F.R.S. J. €3. Gilbert Ph.I). John Stenhouse LL.D. F.R.S. W. C. Henry N.D. F.R.S. John Thoinas Way Esq. PROCEEDINGS OF THE CHEMICAL SOCIETY. It was moved by Dr. A. W. Williamson seconded by Robert Porrett Esq. and Resolved,- <‘That Professor Benjamin Collins Brodie h&ing re-signed the office of Secretary this meeting desires to express their regret at the loss of his services and request the President to convey to him in the form he may think most suitable their thanks for the zeal he has manifested in promoting the interests of the Chemical Society; and at the same time to congratulate him on the more extensive sphere of action to which he has lately been appointed.” The thanks of the meeting were voted to the President Officers and‘Council for their services during the past year

ISSN:1743-6893    

DOI:10.1039/QJ8570900028

出版商:RSC    

年代:1857

数据来源: RSC

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NOTICES OF PAPERS CONTAINED IN OTHER JOURNALS. BY HENRY WATTS B.A. F.C.S. Cheinlcall Report on the Mode of Detecting Vegetable Substances mixed with Coffee for the purpose of Adulteration. By T.Graham F.E.S. J. Stenhouse F.R.S. and D.Campbell F.C.S. THEadulteration of coffee in the condition of the original bean unground and unroasted could only be effected by tthe substitution of a different seed and would form the subject of an inquiry entirety botanical. But it is proper to remark that the coffee-bean is liable to be rendered entirely worthless without any injury to its structure when kept in a wet or damp state for some time,- apparently from the readiness with which the soluble constituents of the bean spontaneously ferment. Coffee damaged by sea-water has been found to retain neither the aroma nor bitter flavour of the seed and to have lost the whole of its characteristic principle caffeine.The entire soluble matter which can be extracted from the damaged seeds by boiling water is greatly reduced and does not exceed 12 per cent. of their weight while the presence of the salts of sea-water is always sufficiently obvious. The coffee-bean in its fresh unprepared state is tough and ground with difficulty. It yields an infusion without aroma which is bitter and is said to act more powerfully on the nerves than roasted coffee. This seed however is always roasted before being made use of and it is in that state and with its structure more or less obliterated by grinding that it must be identified and its purity established by chemical means of investigation.In consequence of torrefaction coffee is materially altered and acquires new properties. The woody tissue of the fresh bean is VOL. 1X.-NO. XXXIII D horny and differs from ordinary woody fibre in its composition and is also said not to yield sugar when treated wit,h sulphurie acid. By the roasting this woody tissue undergoes a partial decomposition and becomes friable and the difficulty of pul-verising the seed and exhausting it by water is removed. There is produced at the same time a soluble brown bitter matter due in part to a gummy substance pre-existing in the coffee altered like starch by torrefaction but principally to the conversion into cararnel of a quantity of sugar in the coffee-bean amounting to 6 or 7 per cent.of its weight. A still more characteristic product of the roasting of coffee is that which gives it aroma. This principle when separated from the infusion of coffee by distillation is found to be a brown liquid oil heavier than water soluble in ether and has received the name of CGfeone (Boutron and Fr6my). Caffeone is slightly soluble in boiling water ; a quantity of caffeone which is almost insensible mill aromatise two or three pints of water. In common with all the valuable constituents of coffee caffeone is found to come from the soluble portion of the roasted seed. The caffeic acid of the green coffee is also changed by the roasting into an acid of different properties. Of the crystallisable cageine a small portion may be lost from its volatility in roasting.No seed appears to be known which roasted and yulverised forms a true equivalent and sufficient substitute for coffee either in the physiological properties or chemical composition of its soluble extract. A great variety of seeds were tried in France as substitutes for coffee during the continuance of the Continental blockade including in addition to maize barley oats and the other cereals the seeds of the yellow flag (Irispseudo-acurus) grey pea (Cz'cer arietiamz) the milk vetch or Andalusian astra-galus (Astragalus boeticus) the Bibiscus escuZe?ztus holly Spanish broom acorns chesnuts the small lupin (Lzipinus angustfulia) peas haricots horse-beans sunflower pips of the gooseberry and grape eglantine (Rosa villosa) and the capsules of box (Buxus sempervirens).Of the seeds enumerated the yellow flag a com-mon marsh plant in England appears to have offered tjhe only similarity to coffee; but it is doubtful whether the resemblance extended beyond the aroma of this seed when roasted which is certainly suggestive of coffee. The search made among the seeds of other plants for a substi-tute for the coffee-berry may then be said to have entirely failed. The divergence of the root-substitutes from true coffee is still greater in every property except one The roots which have been most used are those of chicory (Cichorium intybms) carrot THE ADULTERATION OF COFPEE beet rush-nut (Cyprus esculentus) earth-nut (A~dtis hypogGa) scratch-weed (Gallium aparine) fern (Polypodium$lix mas) and butchers' broom (Ruscus aculeatus).The roots of chicory and of beet and carrot which are all extensively used in Germany are similarly prepared being cut into thin slices dried in a stove and then passed through a coffee- roaster,-generally with the addition of about 2 per cent. of butter and sometimes of a red powder to give the colour of coffee. It is to be remarked of the roots that they are generally used rather as an addition. to coffee than as a substitute for it. In one property these roots all agree and we have no doubt that it has led to this common application of them chicory beet carrot &c. are all remarkable for containing a large quantity of sugm easily caramelised by heat.They acquire when roasted the bitter of burnt sugar with a somewhat similar aroma. NOWthe taste of this bitter appears to be one of the strongest and most general of our gustatory preferences. It equally recommends toast-water and the varieties of brown beer or porter in the preparation of which a portion of malt is used with its sugar caramelised by heat. The caramel bitter is in fact a stock flavour which we find modified by the most various accessories in different beverages and even in solid articles of diet in a cooked state. It is not surprising therefore that the chicory root containing as it does about 30 per cent. of sugar more than one-half of which is caramelised in roasting should obtain extensive fmour as an addition to coffee.Fresh chicory has a certain bitterness or rather acridity but this is overpowered in the torrefiecl root by the caramel bitter and this rootl may be adequately replaced by the bland beet or carrot similarly prepared. No one of these roots contains any constituent which associates it with coffee except sugar :-in other respects they are entirely different. The preparation of roasted chicory appears to have originated in Holland upwards of a century ago but remained secret till 1801. It is now prepared on a great scale both on the Continent and in England. The quantity of chicory-po wder consumed annually in France is known to amount 6,000,000 kilogrammes. In the chemical examination of ground coffee with the view to discover if it is mixed with the vegetable substances which have been named or with others the characteristic constituents of the coffee are less immediately available than certain properties of the infusion of a physical character.This arises from the circum- stance that although it is easy to discover the presence of caffeic acid and caffeine yet the determination of the exact quantity of these substances in an infusion is both difficult and tedions. There is reason also to believe that the proportion of' caffeic acid DZ and caffeine varies considerably in different samples of coffee so that the quantities of these substances (when found) could not show exactly the proportion of pure coffee in a mixture. It will be most advantageous to discuss here the general properties of the coffee infusion in the first instance as they are most easily ob- served; and a single character of this kind in some instances and two or three in others will generally be sufficient to establish adulteration when it has been practised.The higher chemical inquiries will then follow. 1. When hot water is applied to the powder of chicory and other roots it softens immediately from the facility with which water is imbibed while the grains of coffee remain hard and gritty in the same circumstances. Ground chicory is highly hygroscopic. Roasted grain such as wheat and barley gives an infusion with hot water which is mucilaginous and thick while the infusion of coffee is remarkably thin and limpid. The grain infusion gene- rally contains starch and gives when cool a blue colouration with iodine while the infusions of both coffee and chicory appear to be entirely destitute of starch.2. The more deep and rapid coloration of water by chicory and the allid roots than by coffee affords a useful indication in a preliminary examination. The roasted grains also appear to colour water more deeply than coffee does. The relative colouring power of coffee chicory and a variety of other vegetable sub- stances used in the adulteration of coffee was determined with considerable precision by infusing equal quantities of each in water as in the preparation of coffee filtering the infusions through paper and observing the colour in glass tubes of equal diameter-about 1 inch.The solutions required to be very dilute. It was also necessary to have a standard of comparison and for this purpose caramel carefully prepared from cane-sugar was had recourse to. The standard solution of caramel consisted of 1 grain of that substance dissolved in 2000 grains of water. To produce the same intensity of colour as the standard solution a larger proportion than 1 grain of all the other substances required to be dissolved in 2000 grains of water. The proportion necessary is expressed in Table I. The substances are a11 roasted as they would be used to mix with coffee. THE ADULTERATION OF COFFEE. TABLEI. Weight of substance (roasted) dissolved in 2000 parts of water to produce an equal depth of colour. Caramel .* ’i* Mangold-wurzel . Bouka (a coffee substitute) Sparke’s vinegar colouring Black malt . . . . . . . 1.66 1.66 lei4 1.82 White turnips Carrots . . . . 2.0 2.0 Chicory (darkest Yorkshire) 2.22 Parsnips . . 2.5 Maize . . 2.86 Rye . . 2.86 Dandelion root . . 3-33 Red beet . . 3-33 Bread raspings . 3-64 Acorns . . 5.00 Over-roasted coffee . . 5.46 Highly-roasted coffee . 5-77 Medium-roasted coffee . 6.95 Another specimen of coffee . 6.66 White lupin seed . . 10*00 Peas . . 13.33 Beans 13.33 Spent tan . 33. Brown malt . . 40. It will be seen from the preceding table that 2922 parts of chicory have the same colouring power as 5.77 grains of highly-roasted and 6.95 grains of medium-roasted coffee or of 13-33 grains of roasted peas and 40 parts of brown malt.The same results are given in a different form in Table 11. TABLE11. Colouring power of various substances (roasted) dissolved in an equal quantity of water. Caramel . . loooo Mangold-wurzel . 602-4 Bouka (a coffee substitute) . 602.4 Sparke’s vinegar colouring . 574.7 1 Black malt . . 549-45 White turnips . * . 500. Carrots . 500-Chicory (darkest Yorkshire) . 450.45 03 NESSRS. GKAHAM STENHOUSE AND CAMPBELL ON Parsnips . 400. Maize . 350* Rye 350* Dandelion root 300.3 Red beet 300.3 Bread raspings . 274*72 Acorns . 200. Over-roasted coffce . 183.15 Highly-roasted coffiie . 173.31 R4edium-roasted coffee . 143.88 Another speciiiien of coff'ee . 150.15 White lupin seed .100. Peas 73.18 Beans . 75*18 Spent tan 30* Brown malt . 25-The number for chicory (450) indicates that that substance possesses nearly half the colouring power of caramel (1000) ;while highly- roasted coffee (173) is about one-sixth of caramel. Maize and rye with probably all the other cereals rise to 550 and have therefore a high colouring power quite double that of coffee; while peas and beans (75) are on the other side and possess only about half the colourixig power of coffee for equal weights of the substances compared. The preceding solutions were prepared at 212" and chicory then exhibits about three times the colouring power of coffee. But when the solutions are prepared without heat the disparity is still greater.In cold water chicory exceeded coffee about four and a half times in colouring power. When a few grains of roasted chicory or any other sweet root are dropped into a glass of cold water without being stirred a yellowish-brown colour diffuses rapidly through the liquid while the pure coffee gives no sensible colour to the water in similar circumstances. 3. Another property of infusions which is still more precise and valuable is their specific gravity. The proportion of substance found most suitable for an extensive comparison was 1 in 10 of water. The substances were not exhausted by water but simply placed in about a pint of cold water in the preceding proportion by weight and the temperature raised to 212O and retained at that point €or not more than half a minute.The infusions were then filtered through paper. The substances as usual are roasted and ground equally fine with t,he exception of the last three in the table. THE ADULTERATION OF COFFEE. TABLE111. Specific gravity of solutions at 60' F. 1part of substance to 10 parts of water. Spent tan LupinseedAcorns . . . . 1002*14 . 1007*3 . 1005.7 Peas . . 1007*3 Mocha coffee . 1008*0 Beans . . 1008*4 Neilgherry coffee . Plantation Ceylon coffee Java coffee . . . 1008.4 . 1008-7 . 1008.7 Jainaica coffee . . 1008+7 Costa Rica coffee . . 1008*98 Native Ceylon coffee Costa Itica coffee . . . 1009*0 . 1009.5 13rown innlt . . 1010*9 Parsnips . . * 1014.3 Carrots 1017*1 Boulsa . 1018.5 English chicory (Yorkshire) .1019.1 Black malt . . 10219 lurnips . m . 1021.4 Eye meal . . 1021% English chicory . . . 1021.7 Dandelion root . 1021.9 Red beet. . 1022-1 Foreign chicory . 1022.6 Guernsey chicory . 1023.2 Mangold-wurzel . . 1023.5 Maize . . 1025*3 Bread raspings * . 1026.3 British gum . . 10379 Gum artlbic . . 1038.6 Cane sugar . . 1040*Y Starch sugar . . 1042.8 The leguminous seeds it appears give a low specific gravity,-- peas 1007*3 and beans 1008*4. The coffees are also remarkably low varying from Mocha coffee 1008*0 to Costa Rica 1009.5 ; while chicory rises greatly ranging in different samples between 1019-1 and 1023*2. The cereals are equally high or still higher in the scale of gravity ;rye-rneal being 102 1.6 and maize 1025*3.The low gravity of the coffee infusion therefore distinguishes it sharply from the two most important classes of adulterating sub-stances,-the roots and cereals. D4 40 MESSRS. GRAHAM STENHOUSE AND CAMPBELL ON 4. The action of other solvents besides water may be shortly referred to. Agitated four times successively in ten times their weight of ether the substances to be mentioned gave different proportions of matter soluble in that menstruum :-Roasted beans . 1.81 per cent. of oil and resin maize. . 5-15 ,, ff JJ Y> , chicory(Yorkshire) 6.83 , 1 Y coFee(Mocha) . 15.93 ,, y9 9 Y9 including probably nearly 1 per cent. of caffeine. It tlw appears that coffee yields much more soluble matter to ether than beans maize or chicory which represent the three classes of leguminous seeds cereals alnd sweet roots.The fat obtained from chicory was no doubt principally composed of the sweet American or Australian tallow added by English manu-facturers to the root in roasting to prevent burning. The experi- ment with ether is easily made and may in particular circumstances prove valuable. The solubility of the same substances in proof spirit was observed the substance being exhausted four times in succession by ten times its weight of proof spirit at the boiling temperature. Roasted beans gave 17.5 per cent. of a dry blackish lustrous extract. Roasted maize gave 50.2 per cent. of an extract much like the preceding. Roasted chicory (Yorkshire) gave 67-76 per cent.of extract of a lighter colour than the preceding but otherwise very similar. Roasted coffee (Mocha) gave 26-35 per cent. of extract much like the first two in external appearance. These operations are remarkably tedious while the experiments with ether on the contrary are easy and simple. The results with proof spirit are not sufficiently characteristic to recommend its application. 5. Fermentation by means of yeast gives a decisive proof of the adulteration of coffee by many vegetable substances particu- larly by chicory and the other saccharine roots. In our fermentation experiments 2000 grains of the coffee or other substances were weighed out and treated successively with I+ pint of cold water l-$pint of water about 174" and a little additional water for washing the solid residue upon a filter of fine calico.About 3 pints of infusion were thus obtained which were mixed with 250 grains of brewers' yeast weighed after being pressed in a calico bag. The fermentation was continued for forty-eight hours at a temperature of from 80" to 90". The fermented liquor was afterwards distilled and about 6000 grains THE ADULTERATION OF COFFEE. brought over. The last vinous liquor was rectified a second time about 3000 grains being now collected; and the alcohol was inferred from the density of this distillate. The substances were examined for sugar both before and after being roasted as it was interesting to observe the extent to which the sugar is caramelised by torrefaction in the different substances.The sugar of coffee is found to be reduced by roasting from 6 to 7 per cent. in raw coffee to from 0-to 1.12 per cent. in the roasted,-or to be almost entirely destroyed; while in other sub-stances the sugar is more generally reduced by precisely similar treatment to from one-half to one-third of its original proportion. It is difficult to account for this dissimilarity unless a portion of the sugar of raw coffee exists in a state of conjugate combination like the sugar in tannin amygdalin salicin &c. our attempts to isolate such a conjugate body however from raw coffee have not yet proved successful and its existence is therefore hypothetical. XTe succeeded on the other hand in crystallising out cane-sugar from an infusion of raw coffee.It was decided by proper experi- ments that the fermentation of sugnr mas not interfered with by the empyreumatic products or essential oil of roasted coffee. The sugar was determined which exists in the most dissimilar varieties of coffee the wild and cultivated beans the beans from Ceylon and the West Indies from Arabia and the Neilgherry Hills. Twelve different samples were examined each both before and after roasting. TABLEIT. Sugar found in coffee before and after torrefaction. Sugar per Cent. 7- Raw.. Roasted. 1. Plantation Ceylon . 7.52 1.14 2. 1 3 . 7-48 0-63 3. . 7-70 0.0 19 99 4. YY . . 7.10 0.0 99 5. Native Ceylon . . 5-70 0-46 6. Java . . 6-73 0.48 7. Costa Rica .* . 6-72 0.49 . . 6-81 0.40 8. 9 1 Y 9. Jamaica . . . 7.78 0-0 10. Mocha . . 7-40 0.50 11. . 6.40 0.0 YY 12. Neilgherry . . 6.20 0.0 The sugar in coffee appears to be increased by cultivation,-the proportion in Native Ceylon being 5.7 per cent. and in Plantation Ceylon from 7.1 to 7.7 per cent. 42 MESSRS. GRAHAM STENBOTJSE AND CAMPBELL ON The proportion of sugar in the dried roots is high at first and continues after roasting still very notable. TABLEV. Sugar in chicory and other sweet roots before and after torrefaction. Sugar per Cent. I---49-,- Raw. Roasted. Foreign chicory . 23.76 11.98 Guernsey chicory . . 30.49 15-96 English chicory . . 35.23 17.98 9 , (Yorkshire) .32.06 9.86 Mangold-wurzel . . 23-68 9.96 Carrots (ordinary) . . 31-98 11-53 Turnips , . . 30.48 9.65 Beet root (red) . . 24-06 17-24 Dandelion root . 21996 9.08 Parsnips . * . 21.70 6-98 Bouka (a coffee substitute) . -5-82 It thus appears that roasted chicory as it is sold for mixing with coffee retains from 9-86 to 17'98 per cent. of undecomposed sugar. In none of the other sweet roots which are occasionally substituted for chicory such as mangold-wnrzel beet turnip or carrot does the proportion of sugar retained af'ter torrefaction 611 under 9 per cent. with the exception of pwsnip in which the sugar falls to 6.98 per cent. The coffee substitute (' Bouka," falls into this class and appears to be a mixture of true coffee with a torrefied sweet root.The last group is composed of the leguminous and certain other seeds with the cereals. The sugar was determined for most of these substances in the roasted form of the grain only which alone affects the question of adulteration. TABLEVI. Sugar in various seeds before and after torrefaction. Sugar per Cent. -,"--=--. Raw. Roasted. Acorns . . 3.64 2-70 Horse-beans -1 *62 Peas (grey) . -1*08 Maize .-0.82 Rye-meal . .-1.96 Bread-raspings -1-78 Lupin-seed . -0*74 Brown malt . . 8-48 -Black malt . -1*66 THE ADULTERATION OF COFFEE. In the roasted seeds enumerated the proportion of sugar is sensible but not sufficiently considerable to give the means of distinguishing leguminous seeds and cereals from coffee.In roasted acorns the sugar rises to -2.7 per cent. and black malt it will be observed still retains 1.66 per cent. of fermentable matter. The fermentation test 0x1 the other hand is adapted to detect adulteration by chicory and the sweet roots and will we believe from its certainty and facility of application prove eminently useful for that purpose. 6. Coffee and the various vegetable substances used in its adulteration may be incinerated on a platinum or porcelain capsule and leave an earthy ash of which the composition is often charac- teristic of the plant. Valuable information may be obtained without making a formal analysis of the ash by simply digesting it in strong hydrochloric acid. The earth which remains undis- solved after this treatment is silica Now coffee we find is remarkably distinguished from the roots and cereals by the small quantity of silica it affords.The quantity of that earth found in coffee is so small that it may be doubted whether coffee contains any silica except what may accidentally adhere to the coffee beans when collected in the form of sand. The proportion of silica found in the twelve samples of coffee of Table IV. was as follows :-TABLE VII Silica in roasted coffee. Per Cent. in Ash. > 2 Sample 1 . . . 0 o*. 0. 3 3 . 0.26 Y 4 * 0.02 9 5 0.17 Y9 6 . . 0.28 9 11 ' . 0. 1 12 . 0.09 The only case in which the silica approaches to half a per cent. of the ash is Sample 8 ; and in another sample of the same coffee which was properly screened before roasting the silica of the ash fell to 0.On the other hand the silica and sand insoluble in acids of four samples of roasted chicory amounted to so much as 10.69 44 MESSRS. GRAHSBI STENIIOUSE AND CAMPBELL ON 13.13 30.71 and 35.85 per cent. of the ash. It may be added that the portion of this silica soluble in alkali was in the same samples 2.61 3-81 10.52 and 12-75 parts; the portion of silica insoluble in alkali 8.08 9.32 20.19 and 23.10 parts. The whole silica in roasted dandelion root amounted to 11.26 per cent. of the ash. In other cultivated roots the proportion of silica does not appear to be so large as in chicory. The silica is always expressed with reference to 100 parts of the ash.Messrs. Way and Ogston find in the root of the carrot from 0.76 to 1.92 silica; in beet from 1.4 to 4.11 silica; and in turnip from 0.96 to 2.75 silica. The proportion of silica appears to be low in certain grains and seeds although rarely descending to the insignificant proportion of the coffee-bean,-and to be very high in other grains. We find in the ashes of acorns 1.01 per cent. of silica ;in maize 198 per cent. of silica; in the white lupin of the Levant 0.87 per cent. of silica. I\;lessrs. Ogston and Way report from 2.05 to 5-46 silica for wheat ;froin 23.6 to 70*77 silica for barley ;from 38.48 to 50.03 for oats; and 9.22 for rye. It appears therefore that the presence of 1 per cent. or upwards of silica in the ashes of coffee is a proof of adulteration; that the adulterating substances which increase the proportion of silica most considerably are oats and barley then chicory and dandelion which are followed by rye :wheat beet turnip and carrot would produce a small and less decisive effect.There will now be presented complete analyses made for this inquiry of the ashes of seven varieties of coffee and four different samples of chicory. TABLEVIII Analyses of the ashes of coffee and chicory. COFFEE. Native Costa Ja-Neil-zeylon *Java. Rica. maica. Uocha gherry. -i-I-Potash . . . * . 55.10 52'72 54.00 53.20 53.72 51.52 55.80 Soda . . . .. ----Lime . . . .. 4'10 4-55 4'11 4-61 6'1g 5.87 5-68 Magnesia . . * . 8-42 8-46 8'20 8'66 8-37 8-87 8-49 Sesquioxide of iron ..0'45 0-98 0'73 0'63 0'44 0'44 0%1 Sulphuric acid . .. 3'62 4-48 3'49 3'82 3.10 5-26 3.09 Chlorine . . .. 1.11 0.45 0'26 1.00 0.72 0'59 0'60 Carbonic acid . .. 17'47 16'93 18'13 16'34 16.54 16'98 14.92 Phosphoric acid . .. 10.36 11.60 11'05 10'80 11'13 10.15 10'85 Silica . . . * . ----I Sand . . . .. ---. Total amount . * . .00-63100'20 00'18 99'68 10004 TTIE ADULTERATION OF COFFEE. CHICORY. DEDUCTING SAND AND SILICA. Darkest English(Sorkshire) English. Foreign. Guernsey. Potash . . .. 38-53 27'85 46.07 46-27 Soda ... .. 9'34 16'90 3-17 5'49 Lime .. . .. 10.79 10.81 7-78 7-65 Magnesia . . Sesquioxide of iron Sulphuric acid . Chlorine .. .. .. .. .. 6-06 4.38 11'38 5.67 8'08 3-50 11.78 5'23 5'33 8-29 8.38 5.03 5'55 5'08 8.67 6'58 Carbonic acid ... 2.04 3'22 4-36 4.60 Phosphoric acid . Silica ... * . .. 12-27 12.61 I 11-00 9.59- Sand .. . Total amount . .. 100.46 1 99'98 99-41. 99.48 DEDUCTING SAND AND NOT SILICA. Darkest English English. Foreign. Guernsey. (Yorkshire) Potash ......37'07 27'13 40-20 41'41 Soda .. .... 8-99 16'46 2-77 4.92 Lime ...... 10.38 10-53 6.79 6.8 5 Magnesia ..... 5'83 7'87 4.66 4.97 Sesquioxide of iron ... 4-22 3'41 7.24 4'55 SuIphuric acid .*.. 10.95 11'48 7.32 7.76 Chlorine ..... 5'46 5-10 4.39 5-89 Carbonic acid .... 1.97 3-14 3%1 4'1 2 Phosphoric acid ... 11.81 12-29 9'60 8.59 Silica . . .... 3.8 1 2-61 12.75 10.52 Sand ...... --Total amount ....100.49 100*02 99'53 99.58 NOT DEDUCTING SAND AND SILICA.Darkest English English. Foreign. Guernsey. I (Yorkshire) Potash ...... 33'48 24'98 29'56 32.07 Soda . . .... 8.12 15-10 2'04 3.8 1 Lime .... . * 9 $38 9'60 5-00 5.3 1 Magnesia ..... 5.27 7'22 3'42 3-85 Sesquioxide of iron ... 3.8 1 3'13 5'32 3-52 Sulphuric acid .... 10-29 10.53 5.38 6.01 Chlorine ..... 4.93 4-68 3'23 4'5 6 Carbonic acid . ... 1.78 2.88 2'80 3'19 Phosphoric acid .... 10'66 11.27 7.06 6-65 Silica ... ... 3.8 1 2'61 12-75 10-52 Sand . . .* . . 9'32 8.08 23'10 20.19 Total amount ....j100'85 99-98 100'66 99.68 46 MESSRS. GRAHAM STENHOUSE AND CAMPBELL ON The first difference which appears upon comparing the two sets of analyses is the absence of soda in coffee and its presence in chicory to the extent of from 2.04 to 15-1 per cent.of the ash. The united amount of potash and soda does not differ much in the two substances. In chicory the lime is greater and the magnesia less than in coffee. The sesquioxide of iron is strikingly different being always under 1 per cent. in coffee by our experi- ments and ranging from 3.13 to 5.32 per cent. in chicory. The ash of chicory is on this account red to the eye when compared with that of coffee. The difference in chlorine is also important, the highest proportion observed in coffee-ash being 1*I1 per cent. and the lowest proportion in chicory-ash 3.28 per cent. Coffee gives an ash which is highly carbonated the carbonic acid varying from 14.92 to 18-13 per cent. ; while the ash of chicory is only slightly carbonated containing from 1.78 to 3.19 per cent.of carbonic acid. The proportion of phosphoric acid is pretty similar in the two kinds of ash. The disparity in the silica has been already referred to. The differences most available in the two kinds of ash as dis- tinctive tests for coffee and chicory appear to be the following :-In coffee-ash. In chicory-ash. Silica and sand . 10.69 to 35-85 I___ Carbonic acid . 14.92 to 18.13 1.78 to 3.19 Sesquioxide of iron 0.44 to 098 3.13 to 5.32 Chlorine . . 0.26 to 1.11 3.28 to 4-93 Another series of ash analyses was executed comprising the ash of the white lupin of the Levant-a seed which from its chemical properties and low price is not unliliely to be substi- tuted for coffee-the ash of acorns of maize and of parsnin and dandelion roots.TABLEIX. Analyses of ashes of certain seeds and roots DEDUCTING SILICA &C. Lupins. I1 Acorns. Maize. Parsnips. hidelion root. Potash. Soda . . . 33.83 17'90 55'49 0.63 31528- 56-86- 20.22 34.87 Lime . . . 7.81 6.98 3.11 6.88 12-81 Magnesia . . Sesquioxide of iron Chlorine . . 623 -2-12 4.36 0.54 2-53 14.95 0.8 5 0.50 6.52 0.53 2.10 1 -47 1 *42 4.32 Sulphuric acid Carbonic acid . . 6'85 0.56 4-53 13.82 4'20- 4.09 1150 2.66 6.99 Phosphoric acid . Silica &c. . . 25.74 - 11'26- 45'29- 13.91- 12.63 e - Total amount 101-04 1 100'44 100.21 102'39 97 *45 THE ADULTERATION OF COFFEE. Analyses of ashes of certain seeds and roots Lupins. Acorns. Naize. Parsnips. Dandelion f-root.i- Potash. Soda . . . . . . . . . . 33'54 17'75 54-93 0-63 30-74 - 56'54 -. 17.95 30.95 Lime . . . . . . 7.75 6'01 3'06 6'85 11.43 3Iagnesia . . Sesquioxide of iron Chlorine . . . . . . . . . . . 6-18 -2.11 4'32 0.54 2.51 14.7'2 0.84 0.50 6'49 0.53 2.09 1.31 1.27 3 84 Snlphnric acid Carbonic acid . . . . . . .) . 6-80 0.56 4-79 13.69 4.13- 4.07 11-44 2-37 6 21 Pliosphoric acid Silica &c. . . . . . . . . 25.53 0.87 11.15 1-01. 44'50 1.78 13%4 0-57 11.21 11.26 -____I_ I- Total amount . .. . . 101'09 99.58 10027 102'42 97.80 In the ash only of the dandelion root is the silica sufficiently large in quantity to make a good distinction from coffee. Lupins and maize are distinguished from coffee by their low proportion of carbonic acid. The white lupin both of the Levant and England we find to contain a notable quantity of manganese.The oxide of iron is everywhere too low to be serviceable. Chlorine appears as low in maize as in coffee but the proportion of that element is doubled in lupins acorns parsnips,--and nearly quadrupled in dandelion a high proportion of phosphoric acid distinguishes maize and we may add all the other cereals from coffee. The ash of the turnip root contains according to Way and Ogston from 9-54 to 14.82 per cent. of carbonic acid which is very different from chicory and nearly as high as in coffee. The sesquioxide of iron of turnip is also given even lower than in coffee -from 0.14 to 0.66 per cent. Chlorine appears to be as abundant in the turnip in the form of chloride of sodium as in the chicory root.According to the same excellent authorities in beet-root-ash the carbonic acid varies from 15.23 to 21.61 per cent. and is therefore quite as high as in coffee-ash; the sesquioxide of iron from 0.52 to 3.7'4 per cent. small as in coffee ; the chlorine very large and distinctive being represented by from 14.18 to 49-51 per cent. of chloride of sodium. In the ash of the carrot the carbonic acid is from 15.15 to 19.11 per cent. ; the sesquioxide of iron from 0.59 to 1.66 per cent. ; chlorine nearly as in chicory being represented by from 4.91 to 7.65 per cent. of chloride of sodium (Way and 0g st on). 48 MESSRS. GEARAM STENHOUSE AND CAMPBELL ON 7. The action of the inore ordinary cheniical reagents upon infusions of coffee and chicory may now be noted.The indi- cations thus obtained with coffee are unfortunately rendered much less characteristic by the torrefaction of the seed. e TABLE X. Action of certain chemical reagents up04 infusions of coffee and chicory. Roasted lCaw Coffee. Roasted Coffee. Raw Chicory. Chicory. Potassa . . A bright red-Brownish-yel-Not altered. Not altered. dish- ye110 w low liquid liquid and no and no pre- precipitate. cipitate. Lime-water. . Pale- yellow Reddish-brown Not altered. Not altered. liquid ; on with shade of standing be- purple and coming green no precipitate at ths surface; no precipitate Acetate of copper Dirty-green Brownish-green PaIe-green Gelatinous precipitate.precipitate. precipitate. precipitateofa reddish-brown colour. Perchloride of iron Deep greenish- Very dark Blackish-brown. No effect. black precipi- greenish-blacb coloured liquid tate. precipitate. Nitric acid . . Bright red-co- Clear port-wine No effect. No effect at loured liquid. coloured liquid first ; on standing, port-wine colour. Sulphuric acid . Dirty blackish- Dark blackish- Deep blackish- Brownish-brown-colourec brown-colourec brown-colourec black liquid. liquid. liquid. liquid. Hydrochloric acid Pale brownish- Port-wine-co-No effect. Slightly dark- yellow liquid. loured liquid. ensthe liquid. In allowing a solution of unroasted coffee to stand its green colour becomes gradually deeper. This change is due to oxidation and the formation of tlie viridic acid of Roc h 1e d e r.It is greatly promoted by the presence of an alkali an excess of lime brings out this colour very strongly in a day or two,-giving at first however a bright yellow colour. Subacetate of lead gives in unroasted coffee a yellow precipitate which does not become green. An excess of aceta-teof copper gives a green precipitate THE ADULTERATION OF COFFEE. in abundance which is brightened by the addition of an alkali. This copper precipitate has been used as a green pigment. The reactions above described are however much altered and obscured by the roasting of the coffee and are therefore of little service for our present purpose. It has already been stated that iodine produces no blue coloration in the infusion of either coffee or chicory.If the reagents named act clearly in a different manner upon any infusion from what they do upon pure coffee a presumption of’adulteration is obtained but the indications must be of a positive and specific nature fully to establish adulteration. 8. Coffee was submitted to the usual process of distillation with soda-lime for the determination of its nitrogen. The proportion of nitrogen per cent was in coffee Sample 1 (Table VIT.), roasted 2-93; in Sample 2 roasted 2.62 ; in Sample 3 raw 2.53 roasted 2.70; in Sample 4 raw 2.71 ; in Sample 5 raw 2-50 roasted 2.49 The proportion of nitrogen in roasted coffee appears therefore to lie between 2$-and 3 per cent. The nitrogen in a specimen of foreign chicory amounted in the raw chicory to 1*51per cent.; in the same roasted 1.42 per cent. The same of English growth gave in the raw state 1.86 per cent. of nitrogen; and in the roasted state 1*74per cent. The proportion of nitrogen in coffee is therefore greater than in chicory ; but the difference is not sufficiently marked to distin-guish the two substances easily from each other. The conclusion may however be drawn that less than 2 per cent of nitrogen in coffee is a strong presumption of adulteration. We may now advert to the peculiar and characteristic sub- stances found in coffee and the aid to be derived from them in the discovery of adulteration. 9. Professor Rochleder who has devoted great attention to the analysis of coffee gives the following enumeration of the sub- stances found in the raw coffee-bean with the formulsc of their element4ary composition :-C.H. 0. N. Woody fibre . . . . 12 10 10 Cane sugar . . . . 12 11 11 Palinitic acid . . . 32 32 4 Fat Oleic acid . . 36 34 4 Glycerine . . .686 Leguinin . . . . 48 36 14 6 Caffeic acid . . . .16 7 6 Caffeine . . . . 16 10 4 4 VOL. IX.--NO. XXXIII. E 50 MESSRS. GRAHAM STENROUSE AND CA3lPBELL ON To these Rochleder had lately added citric acid (C12H5011 + 3HO) in the small proportion of 2 grains in a pound of coffee ; also a trace too small to be estimated by weight of viridic acid (C14H60,). This last substance is the acid obtained by exposing solutions of the neutral and basic caffeates to the influence of' the air.Tne green colour of raw coffee is believed by Eoc hl eder to be owing to a small quantity of viridate of lime. The evidence upon which Rochleder rests the existence of palmitic and citric acids in coffee does not appear to us quite decisive. The formula given by that chemist for both caffeic and viridic acids are doubtful. It is also stated by I3 o chleder that when dried caffeic acid is submitted to destructive distillation a small quantity of crystals were obtaiiied which he considered to be pyrocatechine. The ex- periment repeated by us on II considerable scale gave a negative result. Eochleder finds caffeic acid in Paraguay tea (&'ex Para-guayensis) as well as in coffee. This statement we must also doubt.The acid of the Paraguay tea has been examined by us and found to have a certain resemblance to caffeic acid but not to be identical with it. Free caffeic acid when strongly heated in an open vessel emits the peculiar odour of roasted coffee ; but the acid from Paraguay tea emits a perfectly different odour when similarly treated. The sugar of coffee may be inferred to exist in a peculiar con- dition as was before hinted from the fact that when the coffee is roasted none of its sugar appears to be converted into grape- sugar as it does not affect Trommer's test; while when 7 grains of cane-sugar were added to 100 grains of coffee and the whole roasted in the usual way abundant indications of grape-sugar were obtained by the same test. M. Payen gives the proportional quantities of the different substances which he finds in raw coffee as follows :-Cellular tissue .. . . . 34.000 Hygroscopic water . . . . . 12.000 Fats . . 10. to 13.000 Starch sugar dextrin and vegetable acids 15.500 Chlorogenate of potash and caffeine Free caffeine . . Legumin . . Nitrogenous portion . . . . . . 3.500 . 0*800 . 1.000 3.000 Thick insoluble ethereal oil . . 0.001 Aromatic oil . . . 0.002 Mineral constituents potash lime mag- nesia phosphorus sulphur silica and traces of chlorine . . . . 6.697 THE ADULTERATION OP COFFEE. Payen's cltlorogenic acid is the same as the caffeic acid of Rochleder and Pfaff. Payen believed that he had obtained from coffee a crystalline double salt of this acid containing potash and caffeine; but this observation has not been confirmed.The proportion of fat in the coffee bean is remarkably high being generally stated at 10 or above 10 per cent. We €ound at least 8.9 per cent. of fat readily extracted by ether. In chicory the proportion of natural fat is scarcely appreciable; but it is brought up by the fat added in the process of roasting the chicory. 10. Some uncertainty existing respecting the proportion of the active principle caffeine in coffee the point was particularly in- quired into. The following process was adopted :-The raw coffee was ground fine having been previously well dried at 212" to facilitate that operation. A decoction was then made of 1000 grains by the repeated application of boiling water so as to exhaust the coffee of all soluble matter.The solution was con- centrated a little by evaporation. The acid of the coffee and certain other substances were now entirely precipitated by t8he addition first of the neutral acetate of lead and then of the subacetate of lead. These insoluble matters were removed from the liquid by filtration. The excess of lead in solution was then thrown down by means of hydrosulphuric acid. The liquid after this preparation was evaporated to dryness and the dry matter left was exhausted by means of strong spirit of wine (sp. gr. 0.840). The alcoholic solution was concentrated by evaporation and allowed to stand in a nearly syrupy state for about ten days in order to crystallise The crystals which are caffeine were collected upon a small filter and compressed power- fully to remove the mother liquor.These crystals were redis-solved in a small quantity of water the solution evaporated and crystallised anew. It gave almost nothing but caffeine in long silky white needles with little or no colour. The proportion of caffeine obtained in five experiments made upon different samples of coffee was as follows :-CAFFEINE IN RAW COFFEE In Native Ceylon . . 0.80 per cent. 9 9 9 0.80 91 9) Y> YY 3 . 1.01 I YY ,,Plantation Ceylon . 0.54 Yf Y? 9 3 Y . 0.83 39 9 The caffeine of the wild coffee appears to exceed that of the cultivated plant ; the mean proportion of caffeine in Native Ceylon being 0.87 per cent.and in Plantation Ceylon 0.69 per cent. E2 52 MESSRS. GRAHAM STENI-IOUSE AND CAICIPBELL ON The mean average of the whole five samples is 0.80 per cent. of caffeine. Probably the actual quantity of caffeine in the coffee bean is from 0.75 to 1 per cent. allowance being made for losses in the separation. The proportion of theine (or caffeine) in tea is considerably greater and more easily extracted. Two pounds of fine strong Congou yielded 2-9s grains of theine or 2-09 per cent. When it is merely desired to extract caffeine from raw or roasted coffee without reference to quantity the general process for the extraction of organic bases by means of ether suffices. Lime is added to the infusion of coffee which is then evaporated to dryness upon a water-bath.The extract may be divided by means of clean sand and then agitated with ether. The caffeine ciystallises as the ether evaporates or it may be re-dissolved in water and crystallised %gain. We believe that the caffeine from 10 per cent. of coffee in it mixture might be extracted in sufficient quantity for its identification by the preceding simple process Caffeine when once obtained is fully recognised by its easy sublimation and also by its action with nitric acid in which it resembles uric acid. When the solution of caffeine in nitric acid is evaporated to dryness and exposed to ammonitlcal gas it is covered by a pink blush like murexide. The only other substances besides coffee in which caffeine is known to exist are tea Paraguay tea and a species of chocolate made from the Gaurana oficinalis or Paullinia sorbilis.11. Chemists generally are disposed to refer the flavour and peculiar properties of coffee as a beverage more to its acid-the cafeic acid (particularly after that substance is modified in its properties by roasting) than to any other constituent of the seed Roc h le d er considers this acid as belonging to the tannin class of substances and calls it tanno-caffeic acid. But as caffeic acid does not precipitate gelatine it is deficient in the most characteristic quality of the tannic acids. CafTeic acid in the present state of our knowledge appears to be confined to the coffee plant. We have observed a property of caffeic acid which facilitates the detection of that substance and consequently of coffee in a mixture.Caffeic acid appears to be analogous to kinic acid the acid of cinchona barks for it yields kinone when oxidated by means of sulphuric acid and binoxide of manganese. To observe this property the coffee is boiled with water and a little slaked lime the infusion filtered and evaporated down to the consistence of a syrup. The syrupy liquid is then mixed in a retort with fbur times its weight of binoxide of manganese and 1 part of oil of vitriol diluted with an equal bulk of water. Sufficient heat is THE ADULTERATION OF COFFEE. produced by the action of sulphuric acid upon the other materiale to bring over the greater portion of the kinone and the lamp need not be applied till towards the close of the operation.The dis- tillate consists of yellow crystals of kinone which usually coat the neck and sides of the retort and a bright yellow liquid which is a saturated aqueous solution of kinone with a considerable quantity of formic acid. Kinone is easily discernible by its volatility and peculiarly acrid odour which greatly resembles that of chlorine. The solution of kinone gives with ainmonia a sepia-black colour and becomes reddish-brown with hydrosulphuric acid. It is de- dorised by sulphurous acid. The beautiful green hydrokinone is obtained by exactly nentraliaing the solution of the yellow kinone with sulphurous acid great care being taken not to intro-duce the latter in excess. The peculiar acid of Paraguay tea agrees with caffeic acid (to which it is no doubt related) in yielding kinone to similar oxidising agencies so does the acid of the leaves of common holly (Ilex aquifoZiunz) tea and the whole of the cinchona tribe.The prune tribe of plants including the sloe cherry laurel &c. the seeds of which yield prussic acid all contain amygdalin or some similar principle. Now all of these when oxidised in the same manner as the former class yield oil of bitter almonds and so can be recognised. The willow and poplar tribe on the other hand yield oil of Spirea ulrnarin (salicylous acid) a wry characteristic substance. The tests for kinone can be applied in a few minutes and they are sufficient to indicate the presence of 10 or 12 per cent. of coffee in a mixture.12. The root of chicory presents no feature of a marked nature beyond its large proportion of sugar and the composition of its ash which have both been sufficiently adverted to. The pro- portion of fat naturally in the root is quite insignificant. In an infusion of the fresh undried root neutral acetate of lead appears to throw down the whole acids of chicory and the subacetate of lead produces no further precipitate in the liquid. But the root appears to undergo a considerable modification by being dried at a temperatiire not exceeding 212'. Its infusion now gives a second precipitate with subacetate of lead following the neutral acetate. Both of these precipitates can be well enough washed; but when the attempt was made to decompose either of them by means of hydrosulphuric acid a mucilaginous liquid was obtained from which the sulphide of lead does not fall unless with a con-siderable addition of alcohol.The acid precipitates appear most indeterminate and afford nothing crystalline. A great deal of pectin-looking subEtance is present. Chicory also appears to B3 DR. GLADSTONE ON CIRCUMSTANCES possess about one-fourth of t.he quantity of inulin that is con-tained in the dahlia root and starch in no other form the infusion of' chicory giving only a brown with iodine and no blue. Chicory appears to contain no oxalic malic citric or any other crys- tallisable organic acid. The other sweet roots beet turnip &c. also like chicory present little that is tangible in their chemical properties.But the high colour of the infusions of all these roots when roasted the great density of their solutions and their fer-mentability afford sufficient means for distinguishing them from coffee and for discovering their admixture with that substance. The properties of a great variety of other vegetable substances which might possibly be eiqloyed in the adulteration of coffee are exhibited in the early tables of this Report. On Circumstances modifying tlie Action of Chemical A=nity.* By J. H. Gladstone Ph.D. F.R.S. ITis among the facts in chemical science which admit of no dis-pute that a substance frequently shows a greater tendency to combine with one body than with another. This has usually received the appellation cc elective attraction,” or cc elective affinity.” It is also perhaps universally allowed that the manifestations of this elective affinity are greatly inff uenced by the insolubility or the volat.ility of the original substances or of the resulting com- pounds.The degree of temperature the respective masses of thc different substances the presence of other bodies and many cir- cumstances beside these are supposed to modify the result. The attempt has frequently been made to construct tables showing the relative strength of affinity of different substances for some particular body and Guyton de Morveau even en-deavoured to give a nunierical expression to them. In treating of this subject the elabomte disquisition of I3ergman cc De Attrac- tionibus Electivis,” must be referrcd to ; in which he illustrates at once the chemical fact and the meaning of the term by supposing A to be a substance united to c and that on the addition of b the c is excluded and the union of the latter substance with A is brought about; in which case he says b has 8 stronger elective attraction for A than c has.Re in common with most chemists both of his own and of later times takes it for granted that if b decomposes Ac it does so completely. The Swedish chemist * Phil. Trans 1855 p. 17% MODIFYING THE ACTION OF CHEMICAL AFFINITY. 55 gives the results of nearly 2000 reactions in one table the first column of which exhibits the following substances arranged according to their affinity for sulphuric acid commencing with what he conceived the most powerful :-baryta potash soda lime magnesia ammonia zinc manganese iron lead tin cobalt copper nickel bismuth arsenic mercury antimony silver gold platinum alumina sesquioxide of iron water phlogiston.The suitability of some of the methods employed for arriving at these results has never as far as I know been questioned; for instaiice that zinc has a stronger affinity for sulphuric acid than manganese or iron or lead has because it will separate any one of these metals from its solution in the said acid. Other methods however are more open to objection,-such for example as that which led Ber gman to place baryta at the head of the series because it took sulphuric acid from every other base. To such deductions as this drawn from precipitation it may be objected that the tendency of the two bodies to combine has arisen more or less from the insolubility of the compound.Berthollet adopted this view and in his (‘Recherches sur les Lois de l’AfKnit6” he endeavoured to prove Ec que les affinit6s 4lectives n’agissent pas comme des forces absolues par lesquelles une substance seroit d6plac6e par une autre clans line combinaison ; mais que dnns toutes les compositions et les d4compositions qni sont dues & l’affinit6 Blcctive il se fait un partage de l’objet de la combinaison entre les substances dont l’action est oppos6e et que les proportions de ce partage sont d&erminees non seulement par 1’6nergie de l’affinit6 de ces sub- stances mais aussi par la quantit6 avec laquelle elles agksent de sorte que la quantit6 peut suppl6er B la force de l’afinit6 pour produire un meme degr6 de saturation.” These two conflicting views were much diecussed at the time when they were propounded ; the attention subsequently paid to the laws of stokhiometry has removed much of the difficulty in which the subject was then involved ; Ga y-L u ssac has pointed out the erroneous idea of cohesion that obscured the reasoning of Bert holle t ; and yet the amount of truth contained in either of these opposite opinions remains still an open question.It is now some years since I first began to reason and occasion- ally to experiment upon this subject. Since that time nil al agut i has published a paper bearing upon it which will be referred to subsequently ; Bu n s en and D e b u s have experimented and in- dependently arrived at a very remarkable law ; and William son has on more than one occasion vindicated the views of Ber-th 011et.Bu n sen * exploded together carbonic oxide hydrogen or * Ann. Ch. Pharm. lxxxv. 137. E4 DR. GLADSTONE ON CIRCUMSTANCES cyanogen with oxygen and after varying his experiments greatly deduced conclusions tending to show a siniple atomic relation be- tween the products of the combustion and a sudden transition from one ratio to another as the proportions of the original gases were varied. De bus * examined the phenomena presented in the precipitation of a mixture of the hydrates of lime and baryta by carbonic acid and of the hydrochlorates of these earths by carbonate of soda and arrived at analogous results.In each of these cases however the first products of the chemical combination were removed at once from the field of action. It is evidently quite another case when the products themselves remain free to react. A. mixture of tswo salts in solu- tion which do not produce a precipitate affords a case where this requisite is fulfilled. Let AB and CD be such salts. According to the one view when mixed they will either remain without mutual action or should the affinities so preponderate they will become simply AD and CB the excess of either original salt remaining inactive. According to the other view A will divide itself in certain proportions between B and D while C will do the same in the inverse ratio the said proportions being determined not solely by the differences of energy in the affinities but also by the differences of the quantities of the bodies.Again supposing the latter view to be correct another question will arise,-Does the amount of AD or CB produced increase in a gradual manner with the relative increase of AB; or do sudden transitions take place under these circumstances such as Bunsen and Debus observed in their experiments ? It mas to the elucidation of these questions that I applied myself. In the majority of instances it is impossible to ascertain what has taken place when a mixture of the kind alluded to has been made; but the physical properties of sab will sometimes give an indication.Colour seemed to offer the best means of solving the problem; yet even here a difficulty arose from the fact that many bases such as nickel give the same-coloured solution when combined with different acids and vice versd. Ses-quioxide of iron however appeared to promise good results since many of its salts are intensely coloured while others are almost colourless. FERRIC SULPHOCYANIDE. If a soluble sulphocyanide be mixed with a ferric salt a red solution results indicating the formation of the ferric sulpho- cyanide. Suppose three equivalents of the sulphocyanide be * Ann. Ch. Pharm. lxxxv 103 ;Ixxxvi. 156 ;Ixxxvii. 238. MODIFYING THE ACTION OF CHEMICAL AFFINlTY. 57 inixed with one equivalent of the metallic salt we have the exact proportions theoretically necessary for the production of Fe, 3S Cy.The first question to be solved is,-In such a case does the whole of the iron and of the sulphocyanogen combine as ferric sulphocyanide or does it not? If Bergman’s view be correct the decomposition will be in accordance with the following simple formula (Ed standing for any salt radical and M for any metal)- Fe2 Rd,+ SMS,Cy=Fe, 3S2Cy+3MRd; and it will not matter what metal is represented by M or what salt radical by Rd provided only that a double decomposition does take place. Besides which the addition of a larger quantity of either one of the original compounds will not increase the colour ; for there is but one sesquisulphocyanide of iron and the whole of the iron or of the sulphocyanogen (as the case may be) has been already saturated.If however B e r t h o 11 e t ’ s view be correct t+he decomposition will not be so complete as to form merely Fe, 3S2Cy and 334 Rd but in addition to these two salts there will be certain portions of the two original salts still remaining as such in the solution. This will become manifest by an amount of colour being obtained which is not equal to what would have been produced had the whole of the iron entered into combination with the sulphocyanogen and the requirements of the theory will lead us moreover to expect that the amount of ferric sulphocyanide (and consequently the depth of colour) will depend in s great measure on the nature of M or Rd and will be increased by each addition of‘either the soluble sulphocyanide or the ferric salt.The following were the preliniinaries for the complete deter- mination of this question :-Aqueous sohtions of the ferric chloride nitrate sulphate acetate and citmte were prepared of known strength; as also of sulphocyanide of potassium barium and mercury ; of hydro-sulphocyanic acid and of various potash salts. In order to compare the depth of coloixr produced on the ad-mixture of these solutions it was necessary to have vessels of colourless glass of a uniform character. Ordinary precipitating glasses holding about five ounces were found peculiarly fitted for the purpose being blown and not moulded they are very trans- lucent ; they are easily obtained devoid of colour ; and although not strictly uniform in size it was easy to pick out a sufficient number which would furnish every requisite for the experiment.This was tested by dividing a coloured solution into two equal parts and pouring one-half into one glass and the other half into another if the two solutions appeared then of a perfect equality of tint nothing more could be desired. When two or more coloured solutions were to be compared the best method was DR. GLADSTONE ON CIRCUlCISTANCES found to be to place the glasses containing them on a stand before the window across the pane of which was stretched a piece of tissue-paper about three inches in depth. The experiments were almost always performed when the sun was shining but not on the window itself as that was found to be disadvantageous.By observing the coloured solutions against the evenly illuminated tissue-paper most exact results could be obtained especially after a little practice. If the object was to observe the amount of dilu-tion necessary to reduce one coloured solution to the same tint as another distilled water was added and thoroughly mixed with it until equal bulks of the two solutions appeared alike. The amount of water added was of course easily measured in a graduated vessel. hIy own observation was always checked by that of my assistant; and if we differed I generally adopted his view since having no idea of what result was to be expected his judgment was the more impartial. I may also state in this place that it was found unnecessary to let a freshly mixed solution containing a sulphocyanide stand any length of time for it assumed instantane- ously its proper amount of colour two mixtures similarly pre- pared were always found to be of precisely the same shade; and everything conspired to give me great and increasing confidence in the validity of testimony drawn from the colour of a solution.The first object to be determined evidently was whether on mixing three equivalents of sulphocyanide of potassium with one equivalent of the ferric salt say the chloride the full depth of colour possible from the combination of all the sulphocyanogen with all the iron was actually obtained. That this was not the case was seen at once for on adding to such a mixture either inore sulphocyanide of potassium or more chloride of iron the colour was increased.This showed also the influence of mass which will be exhibited quantitatively in due course; but before doing so it is necessary to advert to another part of the inquiry v1z. -The dependence of the amount of the coloured salt on the natzcre of the other substances present in the solutioii but which are not im-mediately concerned in its formation. -In order to investigate this point solutions of each of the ferric salts containing exactly the same amount of iron were mixed with the sulphocyanide of potassium solution in the proportion of one equiv. of the f’ormer to three of the latter. The five mixtures were equally diluted. At n glance it was evident that a widely different amount of red sulphocyanide of iron had been formed.The solution containing the ferric citrate was still green; that containing the acetate was red but by no means deep in colour and of a yellowish tint; while those containing the sulphate nitrate or chloride were of an intense red. The following are the relative amounts of dilu- MODIFYING THE ACTION OF CHEiMICAL AFFINITY. 59 tion required to bring these four last-mentioned solutions to the same tint:- 3 equivalents sulphocyan. potassium + 1 equivalent ferric nitrate diluted to 100 parts. 3 equivalents sulphocyan. potassium + 1 equivalent ferric chloride diluted to 89.4 parts. 3 equivalents sulyhocyan. potassium + 1 equivalent ferric sulphate diluted to 65-2 parts. 3 equivalents sulphocyan.potassium + 1 equivalent ferric acetate diluted to 20 parts. The numbers 100,89.4 65-2 and 20 therefore represent the rela- tive amounts of the ferric sulphocyanide contained in these several mixtures." In reference to the mixture of ferric citrate with sulphocyanide of potassium the question presents itself -Does absolutely no interchange take place between them or does a partial though very minute formation of ferric sulphocyanide occur in accordance both with the law of Berthollet and the analogy of the other cases ? The latter conclusion will appear probable from the fol-lowing observations. Although the yellowish-green tint of the citrate still remains after the addition of three equivalents of the sulphocyanide six equivalents almost remove it and a larger quantity renders the solution colourless.No red colour ever appears in a very dilute solution but this destruction of the green appears to point to the presence of a sufficient amount of the com- plementary colour to neutralise it ; and if sulpliocpanide of potas-* After this papcr had been read the following note was appended :-That two or more solutions of the same salt in the same solvent and of equal depth of colour are of the same strength requires no proof. Hence I apprehend no objection can be raised against the conclusion that the gross amounts of salt dissolved in the different solutions are directly proportional to their volume. But it may be objected that though this is true of the solutions when diluted to an equality of colour it is not necessarily true of the solutions before they were diluted for the solvent may exercise some chemical action on the coloured salt absolutely increasing or diminishing its quantity.Should such be the case it appears to me actually the most correct plan of proceeding to reckon the result when the solutions of the coloured salt are of equal strength?-that is to say when the solvent is in each case in the same proportion to the dissolved salt ; for the disturbing influence of the solvent is thus practically got rid of by its reduction to an equality in all-the solutions com-pared. There is however 9~ more serious objection,-namely that the solvent may act dif- ferently on the coloured salt according to the nature or the quantity of the colour- less salts present at the same time in the several solutions ; or that these salts may act differently according to the amount of solvent with which they are conjoined.That this may be the case to a slight extent is very possible but the experiment recorded on page 79 shows that it was too inconsiderable to be appreciated in the cases there submitted to examination. As this is an important matter I have repeated the experiment in a great variety of ways and have satisfied my mind that the amount of error arising from this cause must be quite insignificant-at any rate as far as the ferric sulphocyanide is concerned. The slight differences that do occur are rather in the character than in the intemity of the colour. DR.GLADSTONE ON CIRCUMSTANCES sium be added in large excess to a strong solution of citrate of iron an unmistakeable red ensues. SimiIar experiments were tried in which the same ferric salt was employed but different snlphocyanides. Two portions of nitrate of iron each representing one equivalent were mixed the one with six equivalents of sulphocyanide of barium the other with a corresponding amount of the potassium salt. A deep red resulted in both iwtances but 1000 gr. meas. of the solution con- taining the potassium compound required the dilution of that con- taining the bariuni salt to only 880 gr. meas. to bring it to an equality of colour. The solution of sulphocyanide of mercury produced a scarcely perceptible reddening when added to the ferric nitrate.These experiments suffice to show that on mixing together solutions of soluble sulphocyanides and of ferric salts the amount of sesquisulphocyanide of iron formed depends in a great measure on the nature of the substances previously combined with the sulphocyanogen and with the metallic oxide. The question naturally arises,-Does the converse of this hold good? If a solution of sesquisulphocyanide of iron be mixed with some other salt not capable of forming a precipitate with it will that also cause the distribution of the elements into four salts manifesting itself by a diminution of the colour? and if so will that vary according to the nature of the other salt ? I. 11. III. IV. Volumc of original solution + salt added . 70 m.64 m. 34 m 60 m. Mixture containing the nitrate . . . Mixture containing the chloride . . Mixture containing the sulphate . . Mixture containing the acetate . . Mixture containing the citrate . . . 80 90 150 270 trace of red 77 90 160 220 green 41 56 124 164 62 68 85 120 Six equal portions of as pure sesq~iisulphocyanide of iron as could be prepared were taken one was kept as a standard; to the other five were added respectively equal portions of the nitrate hydrochlorate sulphate acetate and citrate of potash. In each case the colour was reduced. Column I. in the annexed table shows the amount to which the standard had to be diluted before it was brought down to an equality in colour with the different mixtures. Column 11. represents a similar experiment in which a red mixture of one equivalent of sesquichloride of iron and twelve equivalents of sulpliocysnide of potassium was employed MODIFYING THE ACTION OF CHEXICAL AFFINITY.instead of the actual ferric sulphocyanide. In 111. a mixture of ferric sulphate and sulphocyanide of potassium was employed ; in IV. the same with a large excess of sulphuric acid. These experiments might be varied ud injnitzirn all proving the influence on the resulting colour of the nature of a substance mixed with the ferric sulphocyanide. Other organic acids such as the oxalic and the tartaric were found to reduce the red very rapidly." As might be expected also the diversity of effect is not confined to differences in the acid present. The addition of a protosalt of iron has a very great effect in reducing the colour of the ferric sulphocyanide baryta and lime salts act powerfully.A solution of chloride of mercury (as was observed long agoj very speedily removes the colour. The colour of a mixture not dependent on the manner in which the constititents were orzjinally arranged.-On more closely exa- mining the above results it will be seen that whether ferric citrate be mixed with sulphocyanide of' potassium or ferric sul- yhocyanide with citrate of potash the resulting liquids contain but the merest trace of the red salt; it appears also that the deepest colour is obtained on mixing either ferric nitrate with sulphocyanide of potassium or ferric sulphocyanide with nitrate of' potash ; whilst the mixt.ures containing compounds of acetic sulphuric and hydrochloric acids are intermediate in colour in regular order.Mercury also seems to exert the most powerful affinity for sulphocyanogen in whatever way they are brought together. This suggests the conclusion that the amount of sul- phocyanide of iron in a mixture of salts does not depend on the manner in which the different substances were at first combined. The experiment above described was incapable of affording a quantitative demonstration of this as a perfectly pure and definite sulphocyanide of iron was not obtained; but the following ar- rangement was made to put it to a rigid test. Two mixtnres were made of the solutions of known strength so that each contained one equivalent of ferric oxide three equivalents of potash three equivalents of nitric acid and three equivalents of' sulphuric acid.To each was added 1.5 equiv. of sulphocyanide of potassium. The colours resulting in the two cases were so nearly identical that the first diluted to 1770 gr. meas. just equalled the second diluted to 1820 gr. meas. Another 1.5 equiv. of sulphocyanide of potassium was added to each. The two solutions appeared now identical in colour ; they certainly did not differ by 1 degree in 80. The amount of sulphocyanide of potassium in each was then doubled the resulting colours could not be distinguished from each other. It appears there- * Pelouze has observed the diffcrent effects of different acids Ann. Chim. et Yhys. xliv. 216. DR.GLADSTONE ON CIRCUiSfSTANCES fore that it makes no difference whether there be mixed in soh tion The iiguence of the mass of one of the substances that produce the coloured salt.-The influence of mass has yet to be considered quantitatively For this purpose two mixtures were prepared each containing one equiv. of the ferric nitrate and three equivs. of the sulphocyanide of potassium solution. They were both diluted so as to occupy the same volume. The one was kept as a standard of comparison ; with the other additional portions of sulphocyanide of potassium were mixed; and as that increased the colour it was diluted till brought to an equality with the standard solution. Ferric Sulphocyan. Rcd salt Ferric Sulphocyan. Red salt nitrate.of potassium. produced. nitrate. of potassium. produced. 1 equiv.+ 3 equivs. 88 1 equiv.+ 63 equivs. 356 1 equiv. + 6 equivs 127 1 equiv.+-99 equivs. 419 1 equiv.3-9.6 equivs. 156 1 equiv. +135 equivs. 457 1 equiv. +12.6 equivs. 176 1 equiv. +189 equivs. 508 1 equiv. + 'I. 6 -2 equivs. 195 1 equiv. +243 equivs. 539 1 equiv. +19 *2 equivs. 213 1 equiv. +297 equivs. 560 1 equiv. +28.2 equivs. 266 1 equiv. +375 equivs. 587 1 equiv. +46.2 equivs. 318 On comparing these numbers it will be at once evident that each addition of the sulphocyanide produced relatively a smaller increase of colour. In the full paper these results and those of a similar character which follow are represented by curves of which the ordinates express the proportionate amount of red salt.and the absciss;xz the number of equivalents of the sulphocyanide added. The influence of mass was again tried by means of additional portions of ferric nitrate instead of additional sulphocyanide of potassium. The following are the results of the observations reduced as before :-1 ~~ Sulphocyan. Ferric Red saIt Sulphocyan. Ferric Red salt of potassium. nitrate. produced. of potassium. nitrate. produced. 3 eqnivs. +1 equiv. 88 3 equivs. + 5 equivs. 138 3 equivs. +2 equivs. 110.5 3 equivs. + 6 equivs. 144 3 equivs. +3 equivs. 122 3 equivs. +10equivs. 161 3 equivs. +4 equivs. 131 3 equivs. + 14 equivs. 174 MODIFYING THE ACTION OF CHEMICAL AFFINITY. 63 It is not difficult to bring this experiment into uniformity with the preceding so as to form in fact a continuation of it one equiv.of ferric nitrate being combined with less than three equivs. of sulphocyanide of potassium. For expressing the number of equi- valents of the iron salt by x and the comparative amount of ferric sulphocganide by y the general formula of the terms in the above table will be K denoting the potassium and F the iron salt,- 31C +xF =y which may evidently be reduced to a unity of F by dividing by x thus -F+-K=Y. 3 xx On this principle the experiment may be thus tabulated:-- Ferric Sulphocyan. Red salt Ferric Sulphocyan. Ited salt nitrate. of potassium. produced. nitrate of potassium. produced. 1 equiv. +3 equivs. 88 1 equiv. +0*6 equiv. 27.6 L equiv. + 1.5 equiv.55.25 1 equiv. +0.5 equiv. 24 1 equiv.+l equiv. 40.66 1 equiv. +0.3 equiv. 16-1 1 equiv. +0.75 equiv. 32-75 1 equiv. +0.21 equiv. 12.43 It need scarcely be explained that had the whole of the sul- phocyanogen present in the above experiment united itself with the iron the second term would have indicated 44 degrees instead of 55-25 the third 29.33 and so on. In order to confirm by a more direct experiment the result just arrived at two mixtures were made consisting of 1 equiv. of ferric nitrate and 0.24 equiv. of sulphocyanide of potassium. The experiment was conducted as in the previous cases. ~1 Ferric Sulphocyan. Red salt Ferric Sulphncyan. Red salt nitrate. of potassium. produced. nitrate. of potassium. produced. 1 equiv. -l-0.24 equiv.1 equiv. + 3.57 equivs 97.8 1 equiv. $-0.48 equiv. 29.7 1 equiv. i-4.44 equivs. 108.2 19 1 1equiv. +0*78 equiv. 394 1 equiv.+ 5.58 equivs 119 1 equiv. + 1.05 equiv. 48.7 1 equiv. + 7.08 equivs. 134.3 1 equiv. + 1*31 equiv. 60.2 1 equiv.+ 8.64 equiva. 147.3 1 equiv. + 1*83equiv. 69 1 1 equiv. + 10.29 equivs. 158.1 1 equiv. +2.2'2 equivs. 76.5 1 1 equiv. + 11-79 equivs. 167% 1 equiv +2-88equivs. I 86*3 DR. GLADSTONE ON CIRCUMSTAWCES The regularity of this increase of colour (as exhibited to the eye in the curves) is a proof that no law obtains under the cir- cumstances of the experiment similar to that observed and enun- ciated by Bunsen. There is nowhere any sudden increase in the amount of ferric sulphocyanide formed. If the partition of the bases and ac+ids in the mixture really take place at first in atomic proportions it is evident that being at full liberty to act and react the salts arrange themselves according to their respective mass without reference to their respective atomic weights.The effect of mass on the formation of ferric sulphocyanide in a mixture of salts where other substances replaced the nitric acid or the potash was also tried. The two following tables represent similar experiments with the ferric sulphate and chloride. Ferric Sulphocyan Red salt Ferric Sulphocyan. Red salt sulphate. of potassium produced. sulphate. of potassium produced. 1 equiv.+ 3 equivs. 88 1 equiv. + 45 equivs. 318 1 equiv.+ 6 equivs. 128 1 equiv;. + 57 equivs. 355 1equiv.+ 9 equivs.153 1equiv. t 69 equivs. 390 1 equiv +12 equivs. 177 1 equiv. + 81 equivs. 418 1 equiv. +15 equivs. 198 1 equiv. + 93 equivs. 440 1 equiv. +20 equivs. 223 1 equiv. +105 equivs. 458 1 equiv. f24 equivs. 241 1equiv. +123 equivs. 486 1 equiv. +30 equivs. 263 1 eqtiiv. +147 equivs. 513 1equiv. $. 36 equivs. 288 1 equiv. +195 equivs. 538 il I Ferric Sulphocyan. Red salt ' Ferric Sulphocyan. 1 Red salt chloride. of potassium. produced chloride. of potassium. produced. 1 equiv.+ 3 equivs. 88 1 equiv. + 65.4 equivs. 338 I equiv. + 9 equivs. 148 1equiv. + 83.4 equivs. 370 1 equiv. +15 equivs. 190 1 equiv. +107.4 equivs. 400 1 equiv. +21 equivs. 216 1 equiv. +131*4equivs. 428 1 equiv. +28.8 equivs. 246 1 equiv. + 155.4 equivs. 456 1 equiv.+4 1 *4equivs. 286 1 equiv. +19 1.4 equivs. 488 1 equiv. +53.4 equivs. 312 1 equiv. +239.4 equivs. 528 A glance at these tables will show that although the actual amount of ferric sulphocyanide produced from the same quan- tity of the sescjuinitrate chloride or sulphate of iron varies greatly MODIFY IKG TI-IE ACTION OF CHEMICAL AFFINITY. 65 yet the increase of colour on the addition of more sulphocyanide of potassium maintains a somewhat similar ratio in each case. The variations that do exist arise I am disposed to think mainly from errors in the experiment; and this opinion is founded not only on the observations above detailed but upon others of a shorter range which it was not considered necessary to record especially as the three given were the last of their respective kinds which I made and on that account I believe worthy of the greater reliance.None of the others I may remark differed materially from them. I have in vain endeavoured by the aid of my friend hlr. Henry Watts to find an equation which will resolve the curves deduced from the above observations. They do not appear to belong to the second order. For the purpose of seeing whether the same ratio was main- tained where a much smaller proportion of red sulphocyanide was formed the experiment was repeated with the ferric acetate. Ferric Sulphocyan. Red salt Ferric Sulphocy an. Red salt acetate. of potassium. produced. acetate. of potassium. produced. 1 equiv. +1 equiv. 62.4 1 equiv. +11 equivs. 232 1 equiv.+3 equivs. 88 1 equiv. +13 equivs. 304 1 equiv. +5 equivs. 108 1 equiv. +15 equivs. 352 1 equiv. +7 equivs. 133 1 equiv. +19 equivs. 398 1 equiv. +9 equivs. 18'7 Here we have not only an entirely different ratio but one of an irregular character. It is evident there is some interfering action ; what that is will be seen when the ferric acetate itself is made the subject of experiment. A similar experiment on the influence of' mass was tried with hydrogen in the place of potassium. Ferric Hydrosulpho-Red salt Ferric Hydrosulpho-Red salt nitrate. cyanic acid. producFd. nitrate. cyanic acid. produced. 1 equiv. + 2 equivs. 66 1 equiv. +20 equivs. 288 1 equiv. + 4 equivs. 108 1 equiv. +24 equivs.' 325 1 equiv.+ 6 equivs. 142 1 equiv. +30 equivs.353 1 equiv. + 8 eyuivs. 168 1 equiv.+38 equivs. 400 1 equiv. +12 equivs. 217 1 equiv. +46 equivs. 1 equiv. +16 equivs. 25'7 1 VOL. IX.-ETO. XXXIII F DR. GLADSTONE ON CLECUMSTANCES The ratio here is regular but more rapid than in the cuse of the potassium salt. Method of cleterminim~fhe actual amoiint of the colourcrcl snlt it4 a given mixture.-From the experiments above recorded it woulci seem probable that no amount of sulphocyanide of potassium added to a ferric salt will absolutely convert the whole of it into the sesquisulphocyanide of iron. Yet we can easily judge where this result will be very nearly attained. Thus 400 equivalents of the sulphocyanide,added to one of the ferric nitrate must give a close approximation.A somewhat larger quantity will do the same with the sulphate. Indeed it was found by experiment that 500 equivalents of the sulphocyanide added to each of the three prin- cipal ferric compounds caused as nearly as possible the same in- tensity of colour. Such a mixture was made assumed to be the praper tint for an equivalent of the ferric sulphocyanide and employed as a standard. Mixtures were then made of three equivalents of sulphocyanide of potassium with one equivalent of the various ferric salts each occupying 330 gr. meas. The standard red was then diluted till it was equal in colour t9 these several mixtures. The annexed table gives the different amounts of dilution required 1 eq. ferric nitrate + 3 eq. sulphocy. of potas. 1’700 gr.ni. 1eq. ferric chloride +3 eq. sulphocy. of potas. I900 gr. m. 1eq. ferric sulphate +3 eq. sulphocy. of potas. 2650 gr. in. 1eq. ferric acetate+3 eq. sulphocy. of potas. 7000 gr. m. (about). This affords us the elements requisite for a calculation of the actual amount of ferric sulpbocyanide present in each of these mixtures ; and had it been desirable aIniost every observation given above might have been thus reckoned. The ratio between the volumes of the diluted standard ferric sulphocyenide and that of any one of the other red mixtures (330 gr. meas.) gives the ratio between one equivalent and the fractional prt existing in the said mixture. The four observations calculated on this prin- ciple give the following results :-1 equiv. ferric nitrate + 3 equivs.sulphocyanide of potassium give 0.1941 equivalent ferric sulphocyanide. 1 equiv. ferric chloride -j-3 equivs. sulphocyanide. of potassium give 0.1737 equivalent ferric sulphocyanide. 1 equiv. ferric sulphate +3 equivs. sulphocyanide of potassium give 0.1245 equivalent ferric sulphocyanide. 1 equiv. ferric acetate +3 equius. sulphocyanide of potassium give 0.047 1 equiyalent ferric sulphocyanide (about). If this mode of reckoning involve no fallacy the proportion between these four numbers should be the same as that given near MODIFYING THE ACTION OF CHEMICAL AFFINITY. 6 7 the conmencement of this inquiry where the colours produced on a different occasion by adding three equivalents of sulpho-cyanide of potassium to one equivalent of the ferric salts were directly compared.That they do agree almost exactly will be seen from the following table where column I. gives the numbers of the former experiment and column 11.those of the last calcu- lation reduced to the same unit of comparison. I. 11. 1 equiv. ferric nitrate+3 equivs. 100 100 cyanide of potassium . 1 equiv. ferric chloride +3 equivs. cyanide of potassium . . 89.4 89.5 1 equiv. ferric sulphate +3 equivs. cyanide of potassium . 65.2 64*2 1 equiv. ferric acetate+3 equivs. . 20 24.21 cyanide of potassium This close agreement proves not only the correctness of the two independent experiments but also the correctness of this method of reckoning the amount of the coloured salt in any given mixture.Zntuence of the mass of a substance present in the sohtion but which is not one of the cor&ituents of the coloured salt.-It has already been remarked that the addition of a colourless salt will reduce the dour of a solution of ferric sulphocyanide. The influence of mass in this kind of action remains to be examined. A mixture was made of ferric sulphate and sulphocyanide of potassium. The red solution that resulted contained of course sulphate of potash. Successive portions of a solution of this salt were added and the amount of decomposition effected was de-termined by means similar to those employed in previous experi- ments. ~~ Sulphate Water added Sulphate Water added of potash to comparative of potash to comparative ad& d .solution. added. solution. 5 measures =22 measures. 30 measures= 92 measures. 10 measures =38 measures. 40 measures =115 measures. 15 measures =52 measures. 60 measures= 155 measures. 20 measures =67 measures. This action then proceeds in a gradually decreasing ratio. F2 DK. GLADSTONE ON CIRCUMSTANCES These very diversified experinients have put to a rigid test the truth of B er t h o11 e t' s view. Whatever were the circumstances under which the reactions were tried they invariably showed that the results were dependent both upon the nature and upon the quantity of all the substances in solution. FERRIC GALLATE. A solution of gallic acid was iiiade of known strength. Equal portions of it were added to equal portions of the different ferric salts.f equivalent ferric nitrate with 1 equivalent gallic acid gave 100 parts of black salt. 1 equivalent ferric chloride with 1 equivalent gallic acid gave 88 parts of black salt. 1 equivalent ferric sulphate with I equivalent gallic acid gave 70 parts of black salt. 1 equivalent ferric citrate with 1 equivalent gallic acid gave 1O? parts of black salt. The mixture containing the citrate could not be accurately compared on account of its greenish hue. That made from the acetate was of an intense blue. When single equivalents of nitrate of iron and gallic acid .yere mixed a solution resulted in which the gallic acid had to such an extent combined with the sesquioxide of iron that the addition of several equivalents of' either one of the constituent substances caused a scarcely perceptible increase of colour.The ferric chloride was then tried. Ferric Gallic Black salt i~ Ferric Gallic Black salt ! chloride acid. produced. chloride. acid. produced. I II I equiv.+l equiv. 88 1 1 equiv.+4 equivs. I 128 1 equiv. +2 equivs. 108 1 equiv. +6 equivs. 133 1 equiv. +3 equivs 120 I 1' The citrate afforded a better opportunity of obtaining a nume-rical result representing the influence of the mass of one of the constituents. MODIFYING TRE ACTION OF CHEMICAL AFFINITY. 69 1 ll i Ferric Gallic 1 Black salt // Ferric Gallic Black salt citrate. acid. produced. citrate. acid. produced. I ll 1 equiv. + 5 equivs. 155 1 1 equiv. + 13 equivs.I 297 1 equiv.+ 7 equivs. 200 1 I equiv.+l7 equivs. 353 1 equiv. 4. 9 equive. 237 ' 1 equiv. +25 equivs 445 1 equiv. + 11 equivs. 270 1 equiv. + 33 equivs. 509 I 1 Experiments were also tried with gallate of potash in the place of gallic acid. 1 eq. fer. nit. + I eq. gal. of pot. gave 100 parts of black salt. 1 eq. fer. chl. + 1 eq. gal. of pot. gave 97 parts of black salt. 1 eq. fer. sulph. + 1 eq. gal. of pot. gave 68 parts of black salt. 1 eq. fer. citr. i-I eq. gal. of pot. gave a blue solution. 1 eq. fer. acet + 1 eq. gal. of pot. gave a precipitate. A mixture of single equivalents of gallate of potash and ferric nitrate gave nearly but apparently not quite the same depth of colour as when an equivalent of gallic acid was mixed with the same iron salt.Ferric gallate was prepared by dissolving the hydrate$ ses quioxide of iron in gallic acid. It was divided into two equal parts to one of which successive portions of hydrochloric acid were added while the other was diluted after each addition till it had been reduced to the colour of the acid mixture Water added Hydrochloric Water added to Hydrochloric to comparative acid added. comparative /I acid added. solution. solution. 1 measure =3.4 nieasures. 3.25 measures= 10.1 measures. 2 measures=6 *6 measures. 4.5 measures=12*O measures. It requires no further experiments to show that the ferric gallate bears the same testimony as the- sulphocyanide. FERRIC MECONATE. Similar experiments were made with meconic acid and the iron salts.After mixing these substances it was found necessary to F3 DR. GLADSTONE ON CIRCUMSTANCES allow the solutions to stand a minute or two before observation in order that the full colour might be developed. I eq. ferric nitrate + 1 eq. meconic acid (380 C, H O,,) gave 100 parts of red salt. 1eq. ferric chloride + 1 eq. meconic acid (3H0 C, H OI4)gave 96 parts of red salt. 1 eq. ferric sulphate+ I eq. meconic acid (3H0 C, H O,,) gave 72 parts of red salt. I eq. ferric citrate + 1 eq. meconic acid (3H0 C, H O,,) gave 42 parts of red salt. 1 eq. ferric acetate + 1 eq. meconic acid (3H0 C, W O,,) gave a red precipitate. The influence of successive additions of meconic acid to r?l mixture of single equivalents of that substance and ferric nitrate was tried.- I Ferric nitrat,e Meconic acid. Red salt produced. Ferric nitrate. Meconic acid. Red salt produced. t 1 equiv.+l equiv. 1 equiv. t2 equivs. f equiv. +3 equivs. 88 80 76 1 equiv. +4 equivs.1 equiv. +6 equivs. 1 equiv. +8 equivs. 75 73 74 _I___ Here instead of finding an increase of colour as might have been expected by analogy there is a distinct though small de- crease. On examining the action more fully and by repeated experiments it was found that the maximum colour was obtained when the ferric nitrate and the meconic acid were mixed in single equivalents (or rather in the proportion of 12 atoms of the former to 11 of the latter); that the addition of more ferric nitrate to such a mixture did not notably increase the colour; that the addition to it of 0.25 equivalent of meconic acid made little change ; and that a greater addition caused a decided diminution of the tint.A mixture of one equivalent of meconic acid with one equiva- lent of sesquichloride of iron was examined in a similar manner. The addition of meconic acid was found in this case also to dimi- nish the colour. The effect of successive additions of the ferric salt was more particularly tried MODIFYING TBE ACTION OF CHEXICAL AFFINITY. 'I1 /I Meconic Ferric 'nea salt Meconic Ferric Red salt acid. chloride. produced. 1 acid. chloride. produced, I1 I 99 1 equiv. + 1 equiv. 88 i 1 equiv.+ 5 equivs. 1 equiv. + 1*2 equiv 96 ! 1 equiv. + 'i equivs. 93 99 1 equiv.+1*8equiv. 108 ' 1 equiv.+ 9 equivs. 1 equiv. +2.6 equivs. 118 1 equiv. +13 equivs. 119 1 equiv. +3.8 equivs. 106 It is evident that there is some action which twice changes the order of' this series. When ferric sulphate and meconic acid are mixed it requires about seven atoms of the former to five of the latter to produce the greatest intensity of colour. It then just about equals in tint the mixture of five atoms of the ferric nitrate with the same amount of meconic acid and made up to the same volume. No amount of ferric citrate added to the above-mentioned amount of meconic acid is capable of bringing the colour up to that of the former inixtmes. These experiments were repeated with meconate of potash instead of the acid. 1eq.fer. nitrate +3K0 C, H 0, gave 100 parts of red salt. I eq. fer. chloride +3KO C, H 0, gave 73 parts of red salt. 1 eq. fer. sulphate+ 3K0 C, H 0, gave 84 parts of red salt. 1 eq. fer. citrate +3KO C14 H 0,,gave a trace of red salt. f eq. fec acetate +3KO C, H 0,,gave a red precipitate. These proportions differ considerably from those observed where meconic acid itself was employed. The effect of successive additions of meconate of potash to the ferric nitrate was also tried. 11 Ferric Meconate Red salt Ferric Meconate Red salt nitrate. of potash. produced. nitrate. of potash. produced. 1 II I 1 equiv.+0*33 equiv. 34 1 equiv.+l equiv. 88 1 equiv. +0.5 eyuiv. 50 1 equiv. +1.2 equiv. 84 1 equiv. +0% equiv. 74 1 equiv. +1.5 equiv. 69 Here the greatest intensity of colour evidently occurs when about single equivalents are mixed the addition of a larger quantity of meconate of potash producing a rapid diminution of the colour.F4 DR. GLADSTONE ON CIRCUMSTANCES The same was observed in respect to the ferric chloride. When single equivalents had been mixed the addition of more ferric salt was not found to make any great difference in colour. This action however was examined quantitatively by means of the citrate. Meconate Ferric Red salt Meconate Ferric Red salt of potash. citrate. produced. of potash. citrate. produced.' 1 equiv. +0.8 equiv. 1 equiv. + 1-2 equiv. 1 equiv. + 1.8 equiv. 1 equiv. +2.6 equivs. 97 80 69 74 1 equiv. +3.8 equivs. 1 equiv. +5 equivs. 1 1 equiv.+7 equivs.1 equiv. +9.2 equivs. 102 125 154 165 ~ Imagining that the rapid decrease of colour manifested when meconate of potash was idded in excess to the ferric salt might be due to the formation of some paler double compound I added the potash salt to a solution of pure meconate. The colour was greatly diminished. These results show satisfactorily enough that the amount of meconate of iron formed depends upon the nature of the various substances in solution ;but their testimony in respect to the mass of these substances is obscured by the formation of these double compounds. Thinking to avoid this by always using the same amount of meconic acid and iron and yet to exhibit the effect of mass the following experiments were performed. Pure meconate of iron was treated with acetate of potash; it was quickly re- duced to a pale yellow.Oxalate or phosphate of potash had the same effect. A strong solution of sulphate of soda was tried :-u sc 5 measures = 16 measures. 40 measures = 58 measures. 10 measures = 26 measures. 60 measures = 80 measures. 20 measures = 36 measures. Another solution of meconate of iron wa similarly treated with dilute hydrochloric acid :- MODIFYING THE ACTION OF CHEMICAL AFFINITY. 73 ~ydrochloric Water added to Hydrochloric comparative comparative acid added. solution. acid added. solution. 2 measures = 3.6 measures. 7 measures = 15 measures. 3 measures = 5 measures. 9 measures = 20 measures. 5 measures = 10 measures. I It is evident that although a reduction of the amount of ferric meconate always takes place there is some cause interfering with the regularity of the decrease of colour.The amount of ferric meconate depends therefore upon the nature and upon the quantity of all the substances present at the same time in the solution ; but the regularity of the action of mass which was observed with the sulphocyanide and gallate is not confirmed in this instance. FERRIC PYROMECONATE. Thinking that the irregularity in the influence of mass might be more or less connected with the tribasic character of meconic acid it occurred to me that an examination of ferric pyromeconate would be desirable since pyrorneconic acid is monobasic and yet strikes an intense red with the sesquioxide of iron and in many other respects resembles the substance from which it is derived.1equivalent ferric nitrate + 3 equivalents pyromeconic acid gave 100 parts of red salt. 1 equivalent ferric chloride +3 equidents pyrorneconic acid gave 86 parts of red salt. 1 equivalent ferric sulphate +3 equivalents pyromeconic acid gave 39 parts of red salt. 1 equivalent ferric citrate + 3 equivalents pyrorneconic acid gave 27 parts of red salt. 1 equivalent ferric acetate + 3 equivalents pyrorneconic acid gave a red precipitate. 1 equivalent ferric nitrate +3 equivs. pyromeconate of potash gave 100 parts of red salt. 1 equivalent ferric chloride +3 equivs pyromeconate of potash gave 74 parts of red salt. 1 equivalent ferric sulphate +3 equivs.pyronieconate of potash gave 36 parts of red salt. 1 equivalent ferric citrate + 3 equivs. pyrorneconate of potash gave 26 parts of red salt. 1 equivalent ferric acetate +3 equivs. pyromeconate of potash gave a red precipitate. DR. GLADSTONE ON CIRCUMSTANCES On trying the influence of mass it was found that the addition of pyromeconic acid rapidly dirrtinished the colour of ferric pyro- meconate; and that the colour was the deepest when the base was in large excess. Thinking that the effect of a coloiirless salt upon the red pyro- meconate might display more clearly the influence of mass ;L mixture of ferric chloride and pyroxneconic acid was experimented on with a solution of sulphate of potash :--Sulphnte of Water added to Sulphate of Water added to comparative potash added comparative potash added.solution. solution. 3.7 measures= 12.5 measures. 20 measures = 37.5 measures. 11.2 measures= 27.5 measures. iI 30 measures == 4'7.5 measures The rnonobasic pyromeconate appears therefore to be similar in its testiiiiony to the tribasic meconate. FERRIC ACETATE. Twelve equivalents of acetate of potash were added to one equivalent of each of the ferric salts and gave the following proportions :-1 equivalent ferric nitrate +-12 equivalents acetate of potash gave 100 parts of red salt. 1 equivalent ferric chloride + 12 equivalents acetate of potash gave 139 parts of red salt. 1 equivalent ferric sulphate +12 equivalents acetate of potash gave 112 parts of red salt.1 equivalent ferric citrate + 12 equivalents acetate of potash gave no red salt. These proportions differ greatly from those which have been previously observed. The effect of successive additions of acetate of potash was tried:-Ferric Acetate Acetate Red salt nitrate. of potash. of potash. produced. I!. I 1 equiv.+ 3 equivs. 87 1 equiv.+ 6 equivs. 64 1 1 equiv. + 9 equivs. 61 1 equiv. +12 equivs. 102 11 1 equiv. +48 equivs 52 '1 1 equiv. + 15 equivs. 96 1 equiv.+63 equivs. 46 HODIFYMG THE ACTION OF CHEXICAL AFFINITY. 75 Here again as in the case of the meconate there is something producing a great irregularity of action. To a mixture of one equivalent of ferric nitrate and three of acetate of potash successive portions of the iron salt were added.They rendered the mixture much paler reducing it at last almost to the colour of the nitrate itself In order to ascertain whether these changes of colour were due to the formation of double salts containing both iron and potash three equal portions of the ferric acetate employed in the previous experiments were treated respectively with solutions of acetate of potash acetic acid and water. The potash salt caused a slight increase of colotir and the pure acid a great decrease as compared with the effect of mere dilution It is clear that there exist different combinations of acetic acid and sesyuioxide of iron; indeed it has been observed before by others that a highly coloured solution of ferric acetate will spontaneously deposit red oxide and become almost colourless.The ferric acetate then confirms 113 e r t h o11 e t ’s view but like the meconate its testimony in respect to the influence of the mass is equivocal. FEBRIC FERROCYANIDE The ferric ferrocyanide although insoluble in pure water is soluble in the presence of oxalic acid giving a deep blue. A mixture was made of a known amount of ferrocyanide of potas-sium with that acid and it was added to the various ferric salts. The blue from the nitrate chloride or sulphate was very intense; the mixture containing the acetate was colourless the first minute but gradually became blue; while that containing the citrate also deepened in tint on standing. After remaining about two hours the coloured mixtures were in the following proportions :-I equiv.ferric nitrate +3 equivs ferrocyanide of potassium gave 100 parts of blue salt. 1 equiv. ferric chloride +3 equivs. ferrocyanide of potassium gave 8’7 parts of blue salt. 1 equiv. ferric sulphate +3 equivs. ferrocyanide of potassium gave 89 parts of blue salt. 1 equiv. ferric acetate +3 equivs. ferrocyanide of potassium gave 45 parts of blue salt. 1 equiv. ferric citrate +3 equivs. ferrocyanide of potassium gave 60 parts of blue salt. The effect of mass was also tried. The addition of more ferro-cyanide of potassium to a mixture of one equivalent of ferric DR. GLADSTONE ON CiRCUMSTANCES nitrate and three of the ferrocyanide produced no appreciable increase of colour. With the citrate however the following numerical results were obtained :-Ferric Ferrocyanide Blue salt Ferric Perrocyanide Blue salt citrate.of potassium. 1 produced. Ij citrate. of potassium. produced. 1 equiv. +3 equivs. 1 equiv.+ 9 equivs. 113 1 equiv. +6 equivs. 1 equiv. +I5 equivs. 120 Acetate or citrate of potash added to a mixture of ferric nitrate and ferrocyanide of potassium in oxalic acid produces no percep- tible change at the moment of mixing; but a decrease of colour becomes apparent after a few minutes and continues becoming more and more marked for some hours. The ferrocyanide then bears a similar test,imony to the truth of Berth o11 e t' s position to what the ferric sulphocyanide and gal- late do. FERRIC COMENAMATE. Single equivalents of comenamic acid (C,,H,NO +4HO) were mixed with single equivalents of the different ferric salts.With the nitrate chloride and sulphate it gave a most intense purple with the citrate a wine-red solution and with the acetate a pre-cipitate. The three purple solutions were about equally. deep in colour ; they were unaffected by the addition of any amount of iron salt but were reddened by the addition of comenamic acid. The mixture containing the citrate was uninfluenced in t2he character of the tint and almost so in the depth of it by the addition of any amount of either the acid or the iron salt. It was quite evident from this that comenamic acid bas a great tendencp to combine with sesquioxide of iron in place of water and that it is capable of forming two distinct compounds.Indeed it was found that one equivalent or less of coxnenamic acid uniformly gave with one equivalent of nitrate of iron a deep bluish-purple compound ; and that two equivalents or more gave a wine-red compound; whilst any proportion inkermediate between one and two equiva- lents gave an intermediate tint. Comenamate of potash and of ammonia gave similar results to comenamic acid itself; but the colour produced with the citrate at least was not so deep. The following were the ratios :-1 equivalent ferric citrate + 1 equivalent comeiiamic acid gave 5 parts of' red salt. MODIFYING THE ACTION OF CHEMICAL AFFINITY. 77 1 equivalent ferric citrste + 1 equivalent conien of ammonia gave 4 parts of red salt.1 equivalent ferric citrate -+ 1 equivalent comen. of potash pve 2.9 parts of red salt. The addition of citrate of iron to a mixture of single equivalents of it and comenamate of potash caused an increase of colour but no amount turned the solution purple. Comenamic acid then is able to overcome the great affinity of citric acid for ferric oxide only so far as to produce the more acid salt. The purple coinenamate was reddened instantly by citrate of potash yet a large addition of that substance did not wholly destroy the colour. That comenamic acid has not so great an affinity for sesquioxide of iron as to be unaffected by the presence of nitric hydrochloric or sulphuric acid was easily demonstrated. The following expe- riment illustrates the action of such a substance.To a solution consisting of single equivalents of ferric chloride and comenamic acid successive portions of hydrochloric acid were added. The original mixture was bluish-purple. Hydrochloric Colour of mixture. acid added. I 3 measures. Bluish purple but paler by an amount equiv. to 25 measures of water. 6 measures. Bluish purple but paler by an amount equiv to 40 measures of water. 9 measures. Bluish purple but paler by an amount equiv. to 54 measures of water. 15 measures. Visibly redder and paler by an amount equiv. to 80? measures of water. 21 measures. Red purple. 31 measures. Pink. 55 measures. Still perceptibly pink. The affinity then of comenamic acid for sesquioxide of iron though very great is influenced both by the nature and by tLhe quantity of other substances present in the same solution.FERRIC BROMIDE. Experiments were also made on the ferric bromide. The iron salts were employed wit,hout dilution as the bromide itself is but little redder than the chloride. Three equivalents of hydrobromic DR. GLADSTONE ON CIRCUBISTANCES acid added to one of ferric nitrate procluced a distinct red; added to the ferric citrate they produced little change in the colour. Yet the broniiiic has evidently a gent tendency to combine with the iron; for though thc addition of LZ larger quantity of hydro-bromic acid to the nitrate did perceptibly increase the colour a maximum effect seemed attained when only about twelve equivalents were added.The addition of twelve equivalents in the case of the citrate produced likewise a red tint similar to that from the nitrate. Bromide of potassiuni did not redden the ferric citrate. Numerical results could not be obtained on account of the paleness of the colour THE FERRIC SALTS IN GENERAL. Efecect of mass of solz;ent.-In connection with these experiments on ferric salts it became a matter of interest to ascertain whether changes in the mass of water itself had any influence on the com- position of the salts contained in these coloured solutions. The only methods which occurred to me of obtaining an answer to this inquiry were to ascertain whether dilution caused any greater or less decrease of colour in some substances than in others of the same tint; and whether the decrease of colour by dilution was uniform in the same salt by whatever mixture it might be produced.It has frequently be& rioticed that a red solution of ferric sulphocyanide is reduced by the addition of water more than the simple dilution seemed capable of accounting for and more than the red meconate is. To ascertain whether this is really the case two solutions the one of ferric sulphocyanide the other of ferric meconate were made up to the same depth of colour and the same volume each occupying 200 grain measures ; they were then equally diluted 200 gr. m. of the sulphocyanide equalled in colour 200 gr. m. of the meconate. 400 gr. m. of the sulphocyanide equalled in colour 730 gr. m. of the meconate.720 gr. m. of the sulphocyanide equalled in colour 2460 gr. m. of the meeonate. 1440 gr. m. of the sulphocyanide equalled in colour '1540gr. m. of the meconate. The disparity here is very great and takes place at an increasing ratio. It seemed desirable to test if possible whether this diversity was due entirely to the sulphocyanide or whether the meconate MODIFYING THE ACTION 0%'CREllrlICAL AFFINITY ?!! might not also be departing from the ratio of decrease in colour which mere dilution would cause. For this purpose five solutioiis were taken of equal bulk and of the same depth of colour. They consisted respectively of meconate of iron a mix-ture of ferric chloride and sulphocyanide of potassium port wine and water red ink and infusion of cochineal.These solutions though not identical in colour were sufficiently near for the pur- pose. On repeated dilution of each with equal amounts of water they all retained the same colour relatively except the sulpho- cyanide which became yellowish and much lighter. It may fairly be concluded then without predicting anything as to the action of water on dry salts that large quantities of water have no specific action on meconate of iron but that in some way they affect the sulphocyanide. Is this a mere physical effect upon the particular colour ; or does some change take place in tphe composition of the salt itself? In order to test whether this action of water was influenced by the presence of other substances red solutions of equal voluine and equal depth of colour were prepared by the following admixtures :-ferric chloride with sulphocyanide of potassium in large excess ; sulphocyanide of potassium with ferric chloride in large excess; ferric nitrate with sulphocyanide of potassium; the same salts with the addition of a large quantity of sulphate of potash ; sulphocyanide of potas- sium with ferric acetate ; ferrous and ferric sulphocyanide with sulphocyanide of lead ; and nearly pure sesquisulphocy anide of iron.On repeated dilution with equal amounts of water thcse all appeared to retain the same relative colour. It seems then as far as this experiment can prove it, that the action of water whatever it be is exerted equally upon red sul-phocyanide of iron with whatever other substance it may be mixed.This removes any doubt that might have rested from this cause on some of the original experiments with ferric sulphocya- nide and the fact that those experiments were always coIiq)ara- tive leaves little ground for any possible objection. An experiment was likewise tried in order to determine whether the presence of other substances bad any influence in the dilution of meconate of iron. Solutions were taken of pure ferric meconate and of mixtures of ferric chloride with meconic acid ; of the same with meconate of potash both in large excess and otherwise ;of ferric nitrate with meconic acid ;of the same with meconate of potash ;and of ferric citrate with meconic acid. On repeated dilution with equal amounts of water no notable differ- ence was observed in the relative depths of colour of these several solutions except in the case of the citrate which on standing for some hours after dilution lost colour considerably.The red also was of a more pure crimson where there was nitric acid. DR. GLADSTONE ON CIRCUJIS'I'ASCES Pyrotneconate of iron prepared by doiible decomposition was affected in colcw by dilution in a similar manner to themeconate. Water too seemed to have the same effect on the blue ferrocya- nide as on ammoniacal sulphate of copper. In these cases how-ever the salts compared were not of precisely the same tint. Relative strength of a@nity. -Having considered the evidence borne by eight coloured and soluble ferric salts as to the truth of certain views of the laws that regulate chemical combination we have found their testimony on the main points uniform.We niay now go further and by examining the results above given determine the relative degree of affinity exerted by t,he different acids for sesquioxide of iron as compared with potash. The following is the order of affinity of the different acids experimented with for sesquioxide of iron and an equivalent amount of potash :-Least affinity for sesquioxide of iron as coinpared with potash. Hydrosulphocyanic acid Nitric acid . . . 1 4 Hydrochloric acid Sulphuric acid . Gallic acid . . . . 5 7lo? Pyromeconic acid? Meconic acid ? . . Acetic acid . . 20? Hydrobromic acid Comenamic acid . . Citric acid . . 100 Hydroferrocyanic acid .. l70? Greatest affinity for sesquioxide of iron as compared with potash. The numbers in the preceding table are deduced from the experimental data but they must be considered as only rough approximations to the truth. The notes of interrogation indicate that the means of determination were themselves open to doubt. Efeect of dzflerences of temperature.-The experiments narrated in this paper were all performed at the ordinary temperature The slight changes that may have taken place in that respect from one day to another were incapable of affecting visibly the coloured solutions. Much greater variations had a perceptible effect but whether this ever arose from changes in the balance of afKnities 1 am not prepared to say. I now pass on to consider the testimony borne by other coloured salts not ferric compounds in respect to the question at issue.MODIFYING THE ACTION OF CT3ERTICAL AFFTNITY. 81 GOLD SALTS. The bromide of gold is of an intense scarlet whilst the chloride is of a yellow colour. Pure chloride of gold free from hydrochloric acid was prepared. To a portion of this three equivalents of bromide of potassiuni were aclded. The formation of the scarlet terbromide of gold was so complete that the addition of either of the salts employed caused singly too small an increase of colour to be readily appre- ciated Is it to be considered then that the decomposition in this case has been complete ? may it be represented thus-Au C1 +3K Br-Au Br +3K Cl ? This was more rigidly tested by adding chloride of potassium in large excess to bromide of gold.Strong chloride Water added to Strong chloride Water added to of potassium comparative of potassium comparative added. solution. added solution. 5 measures = 30 measures. 35 measures = 105 measures. 10 measures = 48 measures. 50 measures = 135 measures. 20 measures = 70 measures. '75 measures = 180 measures. Some difficulty was felt in determining the last numbers of this experiment from the fact that the chloride of'potassium had by its great excess converted nearly the whole of the bromide of gold into the yellow chloride or still paler double chloride. It was found that bromide of gold was reduced in colour by very small quantities of hydrochloric acid or even of the common yellow crystals of the chloride of gold which are as is well known the hydrochlorate of that salt.These gold salts then have afforded a good example of the influence of mass in gradually counterbalancing and overcoming a strong affinity. PLATINUM SALTS. Neutral bichloride of platinum and different amounts of iodide of potassium were mixed in a series of vessels diluted to an equality of bulk and allowed to stand some hours for the colour bo develop itself properly -a precaution which in this instance was necessnry. The following were the appearances noted :-VOL. IXS-NO. XXXIII. G DR. GLADSTONI? ON CIRCUMSTANCES Richloride Iodide of of platinum. potassium. Character of mixture. I -f 1 equiv.+ 0.5 equiv. Very pale brown solution. 1 equiv. + 1 equiv. Reddish brown and opdescent. 1 equiv.+ 2 equivs. The same but deeper. 1 equiv.+ 3 equivs. The same; some biniodide of platinum deposited on the glass. 1 equiv. + 4 equivs. Red ; opalescence slight ; biniodide of platinum deposited. 1 equiv. + 6 equivs. Bright red ; scarcely any opalescence or deposit. 1 equiv. + 8 equivs. Brighter red ;no opalescence or deposit. 1 equiv. + 10 equivs. Still brighter red. I eyuiv. + 15 equivs. Still brighter. The formation of the insoluble iodide of platinum renders some of these cases less distinct in their testimony than the instances previously considered. The opalescence too was doubtless owing to a minute trace of solid matter. This however is per- fectly clear that the two salts though they have mutually de- composed each other have not done so in the atomic proportions; not according to the schemes Pt C1 +2I<I= Pt I +2KC1 and Pt C1,+3I(I=Pt I, 1<1+2KCl.It has required in fact about four equivalents of iodide of potas- sium to produce the maximum amount of the platinic iodide; and the latter terms of the series exhibit a still increasing amount of the intensely red double iodide of platinum and potassium. It may be expected that the double chloride is one of the salts pro- duced in such a mixture. Successive additions of a strong solu- tion of chloride of potassium to amixture of one equivalent of bichloride of platinum with two of iodide of potassium were found to reduce the colour greatly making it' browner.COPPER S-4LTS. Soluble copper salts are I believe all of a blue colour when dissolved in a large amount of water; but a strong solution of the chloride and of one or two others is green. It has frequently been observed that on the addition of strong hydrochloric acid to a concentrated solution of sulphrite of copper R green colour takes the phce of blue; and it has been naturally concluded that MODIFYIWG THE ACTION OF CHEMICAL AFFINITY. 83 chloride of copper was then formed. This reaction was likewise investigated. Sulphate Hydrochloric Colour of mixture. of'copper. acid. 1 equiv.+ 1 equiv. Blue. L equiv.+ 2 equivs. Blue with a tinge of green. I equiv.+ 3 equiva. Dull green. 1 equiv.+ 4 equivs.Dull green. 1 equiv.+ 6equivs. Bright green. 1 equiv.+ 8 equivs. Bright green. 1 equiv. + 16 equivs. Very bright green. From this it is evident that single equivalents of sulphate of copper and of hydrochloric acid are not resolved wholly (nor indeed to any great extent) into chloride of copper and sulphuric acid; and that the relative mass of the two substances influences the result. In order to observe the influence of the mass of water the following experiments were instituted. Eight portions were taken of a saturated solution of sulphate of copper at 60" F. and were mixed with progressively increasing amounts of strong hydrochloric acid solution. The colours produced were noted. They are given in colunm I. of the subjoined table.Each of the mixtures was then diluted with half its volume of water. The resulting shades are given in column IT. Column 111.represents the shades when t,he water was doubled; column IV. when the solutions were of three tpimes tbeir original volume :-I I Sulph. Hydroch IV. cop. sol. ac. sol. 50 mea. + 10 mea. Perfectly blue. Perfectly blue. Pure blue. 50 mea. + 12'5 mea. Greenish blue. Blue. Pure blue. 50 mea. + 15 mea. Distinctly green Blue with trace of Pure blue. green. 50 mea. +20 mea. Clear green. Just a shade greener. Pure blue. 50 mea. t30 mea. Bright green. Dull bluish green. Pure blue. 50 me&.4-40 mea. Bright green. Green Blue with a trace of green. 50 mea. + 50 mea. Brighter green. Blue with a trace tinguishable. of green.50 mea. + 70 mea. Still brighter. Green Blue with a trace I of green. G2 DR. GLADSTOKE ON CIBCUMSTAXCES It is not bo be inferred that the sulphate of copper was in larger quantity in column IV. than in column I. for water acts according to its mass upon pure chloride of copper converting it from green into a blue compound. To seven portions of the st,andard solution of sulp'nate of copper each measuring 50 parts were added respectively 10 20 30 40 50 70 and 100 parts of a saturated solution of chloride of sodium. There resulted a series of tints passing gradually from blue to almost pure green without any sudden transition. A strong solution of chloride of zinc added to a solution of sulphate of copper also produced a greenish colour which increased as more chloride was added.Knowing the disposition of oxide of lead and acetic acid to combine it occurred to me that chloride of lead might decompose the acetate of copper very readily. Accordingly two equal portions of the blue acetate were mixed with equivalent amounts of chloride of lend and chloride of sodium in solution; and it was indeed found that the former caused a greater diminution of the colour than the latter did. In this experiment much water was necessarily employed but chloride of copper always gives a far paler blue solution than an equivalent amount of the acetate does. These reactions with copper salts bear additional testimony therefore to the truth of the previous views.+ MOLPBDOTi S SALTS.As the molybdous fluoride gives a purple and the chloride a green solution these salts offered another means of testing whether complete or partial decomposition ensued on the mixing of binary compounds. Molybdous oxide was dissolved in hydrofluoric acid and the resulting purple solution was treated with hydrochloric acid. It changed gradually to a greenish blue; and on adding more hydrochloric acid to a positive green. Time entered 8s an appreciable element into this change. The converse of t>his experiment was also tried. The molybdous oxide dissolved in hydrochloric acid of a green colour. The addi- tion of hydrofluoric acid to this gave at the first moment a rich * After this paper had been read the following note was added :-Changes in the state of combination of an element may be rendered visible by a change in the intensity of a colour even where no change in its character occurs.Thus oxide of copper dissolved in acetic acid gi es a much more intense blue than when the same amount is dissolved in sulphiiric acid. This fact was taken advantage of in the fol-lowing experiment which affords additional evidencc of the truth of my main deduc- tion. Sulphuric acid was added to a solution of acetate of copper ; it reduced the colour greatly. Thc experiment was reversed acetic arid being added to a solution of sulphate of copper ; it clecpcned the colour but considerable excess of the acid nw required to make a very cvidwt difference. MODIFYING THE ACTION OF CEEXICAL AFFINITY. purple which was immediately succeeded by a white precipitate insoluble in any excess of hydrofluoric acid but.readily soluble in hydrochloric acid with reproduction of the green. MANGANESE SALTS. Intermediate between the protoxide of manganese and the non- basic oxides there exists a brownish-red salifiable compound of the formula Mn,O,. It is described in Gnielin’s Handbook under the designation ‘(manganoso-nianganic oxide.” Its solution in hot phosphoric acid or cold oil of vitriol is red but it dissolves in other acids with a deep brown colour. I prepared the sulphate and hydrochlorate of this base and found that the addition of hydrochloric acid in excess caused a change in the colour of the sulphate from red to reddish brown and eventually brown; while on the other hand the addition of sulphuric or phosphoric acid in excess to a solution of the brown chloride converted it into the red salt.Thus it appears that the oxide in question has no such affinity for either one of these acids but that it is displaced more or less by the other. BLUE GALLATE OF IRON. Gallic acid when added to iron salts is apt to strike a deep blue colour from the formation of a very stable compound of the organic acid with both the basic oxides of iron at once. A blue solution was prepared by mixing solutions of gallic acid and of green vitriol that had been exposed to the air. The effect of sulphuric acid was tried. Water added Sulphuric Water added Sulphuric acid added. to comparative acid added. to comparative solution.solution. I measure = 9 measures. 10 measures = 63 measures. 2 measures =18 measures. 14 measures =105 measures. 4measures =34 measures. 16 measures =136 measures. 6 measures=46 measures. 18 measures =174 measures. 8 measures= 55 measures. 20 measures == 204 measures. This experiment suffices to prove the influence upon the pro- duction of this blue gallate both of the nature and quantity of other substances present in the solution at the same time. G3 DR. GLADSTONE ON CIRCUMSTANCES QUININE SALTS. In his elaborate paper cc On the Change of Refrangibility of Light,”” Professor Stokes has shown that various acid salts of quinine exhibit that remarkable internal dispersion of light which is now known by the name C~fluorescence.” He mentions the acid sulphatc phosphate nitrate acetate citrate tartrate oxalate and hydrocyanate as giving rise to the phenomenon; while qui- nine dissolved in hydrochloric acid did not present any such ap-pearance.He found moreover that the addition of hydrochloric acid or chloride of sodium to one of the fluorescent salts de- stroyed the colour. Hence he concluded and no doubt correctly that in these cases muriate of quinine was formed; and to obviate the objection that possibly the non-fluorescent salt in solution might be a sort of double salt in which the quinine was combined with the hydrochloric and the other acid in atomic proportion he devised the following elegant experiment. To a strong warm solution of neutral sulphate of quinine which displays no fluo- rescence a very small quantity of hydrochloric acid was added ; it produced the blue appearance :more hydrochloric acid was added; the blue was destroyed.This seemed intelligible only on the supposition that the small quantity of acid first added displaced an equivalent amount of sulphuric acid which combining with the undecomposed sulphate formed the acid salt which displays fluorescence to such a remarkable degree; and that the larger quantity of hydrochloric acid decomposed this again setting free the sulphuric acid and leaving the quinine in solution as hydro- chlorat e. From the manner in which Professor Stokes describes and commeiits on these experiments it is evident that he imagined (as most others would have done) that the decomposition was perfect and that in the particular experiment just mentioned every par- ticle of the quinine existed in the solution in the form of hydro- chlorate on account of the stronger affinity of that acid for the base.He states moreover that even sulphuric acid is incapable of developing the blue colour in a solution of quinine in hydro- chloric acid.” If this be true it evidently militates against the conclusions that double decomposition does not take place per- fectly in solution unless aided by the insolubility or volatility of one or more of the compounds produced and that great mass counterbalances weak affinity. Accordingly I repeated the ex- perimen ts quantitutivei‘y and peiformed some additional ones.? * Philosophical Transactions 1852. t Since writing the above my attention has been drawn to a paragraph in Pro- fessor Stokes’s second paper (Philosophical Transactions for 1853 p. 394.) in which he reniarks that the nentriil hydrochloratc of quinine is riot absolutely non-fluorescent as first stated and that tlic hydroqanntc is like the hyclrochloratc. MODIFYING THE ACTION OF CHEMICAL AFFINITY. 87 Sulphate of Hydrochloric Character of fluorescence. quinine. acid. 1 equiv.+ 0.5 equiv. A deep blue entering far into the liquid. 1 equiv. + 1 equiv. A more intense blue and confined to the edges. 1 equiv. + 1.5 equiv. Much as the preceding. 1 equiv.+ 2 equivs. Rather fainter blue. 1equiv.+ 3 equivs. Decreasing. 1 equiv.+ 4 equivs. Still decreasing.1 equiv.+ 6 equivs. Fainter. 1 equiv. + 8 equivs. Still fainter. 1 equiv. +12 equivs. Very faint. 1equiv.+2O equivs. Just visible. 1 equiv. +30 equivs. As above. 1 equiv.+50 equivs. Invisible except under the most favour- able circumstances. It will be seen at once that the double decoinposition between the sulphate of quinine and the hydrochloric acid was not perfect. Had it been so the first line of the experiment would have been represented by the formula -and the largest possible amount of fluorescence would have been obtained while the second line would have been according to the formula -C44H28N204 HO SO +HC1= C~~H~~NZO@ HC1+ €10,SO, * and there would have been no fluorescence visible with this or any higher proportion of hydrochloric acid.But instead of single equivalents of sulphste of quinine and hydrochloric acid giving a non-fluorescent mixture the blueness was only then attaining its maximum. Chloride of sodium was found to have even less power of decreasing the blue colour than an equivalent amount of the acid has. Neutral hydrochlorate of quinine was prepared. Its solution diluted showed a mere trace of blue which was removed on t.he addition of a drop or two of free hydrochloric acid. Portions of this solution were mixed with all the acids mentioned by Stokes as giving fluorescent compounds with quinine. The acldition of a4 YE. GLADSTONE ON CIRCUMSTANCES sulphuric nitric phosphoric acetic or oxalic acid instantly repro- duced the blue colour in a very marked manner.Citric or tartaric acid added in very large excess also produced the blue but it was faint. I failed to detect any change on the addition of a con-siderable amount of hydrocyanic acid. Similarly a solution of sulphate of soda in considerable excess was added to an acid solution of hydrochlorate of quinine. A very perceptible amount of blue made its appearance. This also is in perfect consonance with what might theoretically be ex-pected and indicates that not only had the commixture of sulphate of soda converted t2 portion of the hydrochlorate of' quinine into sulphate but the free hydrochloric acid had decomposed some of the sulphate of soda liberating sulphuric acid which had corn-bined with the quinine salt to form the bisulphate.That a mix-ture of neutral sulphate of quinine with sulphate of soda does not give the blue tint unless some free acid be added was verified by previous experiment. Stokes also states that iodide or bromide of potassium added to a solution of bisulphate of quinine or the acid phosphate de- stroys the fluorescence. On examining these reactions I found that these haloid salts behaved precisely as the chloride did. This accumulation of evidence all goes to prove that quinine follows the same laws as the substances previously considered. CONPOUND ETHERS. Compound ethers may be regarded as organic saIts in which certain compound radicals take the place of metals and it is to be expected that they will follow the same general laws as the binary compounds that have been previously examined.Their insolu- bility in water precludes the use of aqueous solutions of the sub- stances intended to act upon them; but alcohol affords a con-venient medium for the reaction; and when this is employed results are obtained which are perfectly analogous to those already described in the case of' different metallic salts. The following experiment may be taken as an example. A large excess of oxalic acid was dissolved in alcohol along with acetic ether warmed and allowed to stand for some hours. The mixture was then submitted to gentle distillation and there passed over acetic ether mixed with alcohol and with oxalic ether. The oxalic acid had therefore clisplitwd st certain amount of acetic acid; but though it existed in such large excess that it began to crystallise out it had not displaced the whole.MODIFYIXG THE ACTION OF CHEJIICAL AFFINITY. 89 GENERAL INFERENCES FRON THE PRECEDING EXPERIMENTS. The concurrent testimony of the diversified experiments here detailed is in favour of the view that when two binary compounds are mixed in solution there ensues a partition of the two electro- positive between the two electro-negative elements according to certain proportions regulated both by the difference of strength in the affinities and by the relative quantities of the different bodies. The reverse of this does indeed appear at first sight to be the case in certain instances; as for instance when equivalent portions of sulphocyanide of potassium and ferric citrate are mixed or of chloride of gold and bromide of potassium.But it makes all the difference whether there be a small though inappreciable quamtity of the other salt formed at the same time or whether the decomposition be absolute; and a consideration of the whole series of experiments and of the influence of mass in these very instances will leave I think a strong conviction on the mind that such cases differ from the others only in degree and that if we possessed the means of observing minuter differences of colour we should find evidence of traces of the original salts still remain- ing. But of this each reader will form his independent judgment. Among those instances where evidently four salts were produced by the mixture of two the following substances took part in the reaction :-Iron (in both basic conditions) gold platinum merciiry copper zinc lead molybdenum manganese baryta lime potash soda ammonia hydrogen ethyl quinine.Sulphuric nitric phosphoric hydrochloric hydrobromic hy- driodic hydrofluoric hydrosulphocyanic hydroferrocyanic acetic oxalic citric tartaric gallic meconic pyromeconic and come- namic acids It must be borne in mind that when in studying the mutual action of AB and CD we have determined the laws according to which A and D combine we have equally ascertained them in reference to C and B ; that is to say to take a particular instance if we find on mixing ferric nitrate and sulphocyanide of potassium that ferric sulphocyanide is formed in certain proportions accord- ing to the relative force of affinity and mass we have determined this also in respect to the nitric acid and the potash.We know indeed that for every portion of ferric sulphocyanide produced an exactly equivalent portion of nitrate of potash must be formed. And not only this but in any such mixture where we know the original amounts of the two salts and the amount of any one of the four into which they are resolved we have the data for deter-mining the amounts of the other three likewise. Suppose (which is about the truth) that one equivalent of ferric nitsate mixed with DR. GLADSTONE ON CIRCUMSTANCES three equivalents of sulphocyanide of potassiuni produce one-fifth of an equivalent of ferric sulphocyanide the following is the only formula which can represent the reaction.The amounts are mul-tiplied by five to avoid decimals 5(Fe20, 3NO,)+ 15KS2Cy=Fe, 3s2Cy+ 12KS2Cy +4(Fe20, 3N0,) +3(Ko NO,) or more simply 5AB +5CD= AD +4AB +4CD +CB. Of course this method of reckoning is inapplicable where poly- basic acids are concerned. TESTIMONY FROM OTHER CHEMICAL PHENONENA. There are many chemical phenomena beside those connected with colour which bear testimony respecting the question whether two salts in solution resolve themselves into four. The testimony of prec+pitation. -The idea that when double decomposition occurs the acids and bases make a perfectl ex- change arose doubtless from what is constantly observed when a precipitate ensues.In that case A combines wholly with D and C with B. Yet this will be the inevitable result under the one theory as well as under the other. A mixture of single equiva- lents of nitrate of baryta and sulphate of potash may be taken as an illustration. Here as has frequently been shown if Ber- thollet's views be correct at the first moment of mixing a portion of the baryta combines with sulphuric acid but that com- pound being insoluble is instantly put out of the field of action and the resulting mixture redly consists of nitrate of baryta nitrate of potash and sulpliate of potash which of course gives rise to a redistribution of the bases and acids and a further pro- duction of insoluble sulphate of baryta and so on till the amount of nitrate of baryta remaining is infinitesimally sniall ; while at the same time the whole of the potash must necessarily combine with the whole of the nitric acid.It is scarcely necessary to observe that this division and precipitation will take place con- tinuously until complete; and that it may be so rapid as to elude our notice." The fact then t.hat precipitation when it occurs is complete decides nothing as to the relative merits of the two * Yet it is easily conceivable that when the affinity for each other of the two substances that produce the insoluble compound is very weak the action may last some time and become evident to our senses. Is not this actually the case when sulphate of lime in solution is added to nitrate of strontia or carbonate of soda to chloride of calcium or an alkaline carbonate to tartrate of yttria or oxalate of ammonia to sulphate of magnesia kc.? BLODIFYING THE ACTION OF CHENICAL AFFINITY. theories of elective affinity. Yet there is an important difference to be noted. On Bergman’s supposition it can hardly be imagined but that cases will sometimes occur where A has SO strong an affinity for B or C so powerful an attraction for D that on mixing AB and CD no interchange will take place although AD may be an insoluble body On Berthollet’s supposition the insoluble compound will always be wholly precipitated when- ever by the interchange of acids and bases such a compound can be formed even though it be against the preponderating direction of the affinities.Now this can be put at once to the test of ex-perience and what is the testimony of the thousands of double decompositions which chemists are in the habit of meeting with? Graham * says cc It is a general law to which there is no ex-ception that two soluble salts cannot be mixed without the occur- rence of decomposition if one of the products that may be formed is an insoluble salt.” G m e 1in 1 -even when arguing against Bertholle t’s views admits the same fact adding ‘‘the only case which appears to present an exception is that observed by Th. S c h e re r $ and this requires further examination.” The case which depends on the insolubility of oxalate of yttria broke down on careful investigation. It is then a law without a single known exception that if AB CD El? &c.by any interchange of bases and acids can possibly produce an insoluble substance that insoluble compound does actually make its appearance. This seems to me almost con- clusive evidence that the interchange always takes place originally to a greater or less degree; for I cannot believe with one chemist of high repute that cc when bodies are brought into intimate con- tact all the forces which exist not only in themselves but in all their possible compounds are called into action at the same time,” unless indeed it be by these compounds being actually formed. The following experiments may illustrate more fully the truth of the explanation of complete precipitation which has been given above. I.Strong solutions of sulphocyanide of potassium and ferric sulpliate were mixed. The resulting intensely red liquid was dividedsinto two equal parts. The one portion was largely diluted with water; and to the other portion a little strong alcohol was added which caused the precipitation of suiphate of potash while ferric sulphocyanide was dissolved. The alcohol was poured off and diluted with water till of the same volume as the first portion. It was far deeper in colour indicating evidently that the in- solubility of sulphate of potash in alcohol had removed it out of the sphere of action and had caused a much larger proportion of * Elements of Chemistry. t IIanclbooB of Chcmistry. t Yoggendorff li. 470. DR. GLADSTONE ON CIRCUMSTANCES ferric sulphocyanide to be formed than would otherwise have been produced.Only a small quantity of alcohol was employed and it was mixed with a large amount of water in order to obviate as much as possible the objection that the same amount of ferric sul-phocyanide might appear darker in alcoholic than in aqueous solution which is indeed the fact. 11. Another red solution was prepared by mixing sulphocyanide of potassium and ferric sulphate and it was divided into two equal portions. To one of these hydrochloric acid was added which of course reduced the colour somewhat. To each was then added an equal portion of neutral phosphate of soda. The acid solution re- mained red though paler than before ;the neutral solution became colourless and turbid from the formation of a flocculent precipitate of ferric phosphate.That the insolubility of this salt in the neutral solution was the cause of the complete combination of the oxide of iron with the phosphoric acid was further elucidated by adding phosphoric acid to the colourless mixture which restored i~ faint red tint to the solution doubtless because it had set free some of the sulphuric acid which redissolving the ferric phos-phate allowed of the formation of a small amount of the red sul phocy anide. 111. A mixture of three parts of ferric citrate and four of ferrocyanide of potassium was prepared and divided into two equal parts. To the one there was added a few drops of hydro- chloric acid to the other a few drops of oxalic acid. In the one case the ferric ferrocyanide being insoluble in hydrochloric acid was precipitated leaving no trace of iron in the solution; in the other case there was a blue solution but the whole of the iron was not in the condition of ferric ferrocyanide for the addition of more prussiate of potash caused it to become bluer.That this was due not to the affinity of the oxalic acid for the ferric oxide but to that of the citric acid will be evident from the fact ascer- tained by the previous experiments on the ferrocyanide that this result would not have been obtained had the nitrate been em-ployed. The testimony of voZatiZisation.-The argument that has been employed in the case of precipitation will apply nzutatis mutundis with equal force in the case of volatilisation I am not acquainted with any exceptional instance.The testimony of cr.ystaZZisution.--It will sometimes happen that certain quantities of AB and CL) are mixed in an amount of water which is insufficient to keep in perfect solution AD should the whole of A combine with the whole of D although the salt itself is a soluble one. In such a case if ISergm an's view be correct either no AD will form however concentrated the solution or should doiiblc decomposition ensue it will form to the fullest MODIFYINQ THE ACTION OF CIIEMICAL L~FFJKITT. 93 extent possible and may be expected to crystallise out at once with something like the rapidity with which precipitation usually ttikes place. If however B er t hol 1 e t’s theory be a true expres- sion of the fact a certain amount of AD will always be formed but it may remain dissolved in the liquid although if the whole of A had entered into combination with D it nzust have separated yet on concentration AD mill make its appearance ; and should this or anything else determine the formatioii of crystals or should they ensue on the primary mixing the crystallisable salt is pro tanto put out of the field of‘action and a redistribution of the acids and bases will take place with further crystallisation until an equilibrium is obtained.Now the latter of these deductions describes what actually does take place but there are several cir- cumstances attending cry stallisation from a mixture of salts which are not readily explained and which I have as yet but imperfectly investigated.The testimony of Ma 1ng ti’s experiments.-M a 1 a g u ti * ex-amined the present question by taking two salts both of which were soluble in water but only one of which was soluble in alcohol mixing them in equivalent proportions in water and then pouring the aqueous solution into a large quantity of alcohol. Notwithstanding an objection recognised by the experimenter three important results may be arrived at :-Ist that two salts on being mixed resolve themselves into four ; 2nd that this partition takes place in a definite manner; 3rd that the proportions of the resulting salts are independent of the manner in which the differ- ent elements were originally combined. The testimorriy of substances acted m by one of the compou~€s liberated in a mixture of salts.-ft is to be expected that if two binary compounds be mixed the formation of a new compound though it remain in solution may often be ascertained by certain chemical powers which it is capable of exerting.Instances of this are not wanting. Thus gold as every one knows is not attacked by hydrochloric or nitric acid singly but is dissolved by a com- bination of the two; neutral potash salts of course have no action upon it; and yet gold dissolves readily in a mixture of either nitrate of potash and hydrochloric acid or of chloride of potassium and nitric acid; whence it appears to me the conclusion may be fairly drawn that in both mixtures the potash relinquishes a portion of the acid with which it was originally combined or (which is the same thing) that it divides itself between the two.Such experiments as this have no quantitative value since the liberated substance immediately enters into a new eombination * ‘‘ Exposition de quelyues faits relatifs iL l’action rikiproquc des scls solubles,” Ann. de Chim. et de Yhys. 3 t. xxxvii. p. 198. DR. GLADSTOSE ON CIRCUMSTAIKCES which must give rise to a fresh distribution of the different elements and so on until no more of the active substance can be produced. A mere solvent action of the liberated body would be preferable to an action where poshive chemical combination or decomposition takes place ;but such cases scarcely exist. Among the actions which appear to answer this requirement most fully is when a salt insoluble in water is dissolved in an acid as for in-stance ferric phosphate in hydrochloric acid; yet even here a partial decomposition in all probability ensues.The only in- structive numerical results which I have obtained were by mixing a saturated solution of oxalate of lime in hydrochloric acid with various proportions of acetate of potash or soda. The hydrochloric acid combining with the alkali caused a deposition of' oxalate of litne since that salt is not soluble in the acetic acid that was liberated at the same time. Acetate of soda series. Acetate of potash series. Salt added. Ixalate of lime deposited Salt added. halate of lime deposited. 3 measures. 6 measures 0.075 grm. 0.10 grm. 20 meas.40 meas. 0.359 grm. 0.345 grm. 9 measures. 12 measures. 18 measures. 30 measures. 45 measures. 90 measures. 0.11 grrn. 0-13.5 grin. O*f4*5grm. 0.11 grrn. 0*14.5 grm. 0.19 grm. 80 meas. 120 meas. 160 meas. 240 meas. 0.410 grm. 0.445 grm. 0.503 grm. 0.564 grm. Notwithstanding certain irregularities in these series of num-bers it is sufficiently evident in both instances that the amount of oxalate deposited increased with the amount of acetate added though not in direct ratio. Supposed exceptions and limitations. -With this mass of evidence and that of a very diversified character the question arises,-Are we justified in concluding that the principles which are so general are universal in their application ? Are there no exceptions ? Is there no limitation ? As to exceptions in the whole range of my experiments upon this subject I have never met with a single instance of two sub-stances having so strong an affinity for one another that they combined to the exclusion of other bodies of like kind and present in the same solution even if in large excess.Sometimes this rests not on demonstrative but upon moral evidence as for instance when sulphocyanide of potassium and dissolved ferric ferrocyanide are mixed where unquestionably the amount of ferric sulpho- cyanide produced must be quite inappreciable; yet that some is produced may be safely inferred I think from the fact that sulpho- cyanide of potassium does give a red with the ferric acetate and acetate of potash is capable of decomposing the ferric ferrocyanide to a well-marked extent.During the controversy that ensued after the publication of Ber t h o11 e t ’s treatise many reactions were brought forward to prove the falsity of his views. Most of these were directed against certain positions of the French philosopher which were certainly untenable while others were founded on a rnisapprehension of the question at issue. Those which appear the most formidable against the conclusions arrived at in this paper are that boracic acid or carbonic acid or hydrosulphuric acid is incapable of de- composing in the least degree sulphate of potash or any analogous salt; and that chloride of sodium is not affected at all by iodine. The proof of these statements rests in each instance upon the testimony of blue litmus paper.In the first case the vegetable colour is not reddened; which is supposed to prove that no sul- phuric acid has been liberated; yet if any had been set free there must have been formed at the same instant an equivalent. amount of borate or carbonate or hydrosulphate of potash each of which has an alkaline reaction and would have restored the blue or rather prevented the litmus from reddening. So in the case of the common salt and iodine (where by the way only one base is con- cerned) the chlorine supposing it liberated would not have bleached the litmus but would have combined at the moment of its separation with some of the iodine present to form the ter- chloride of iodine which has a natural reaction. That very little decomposition does take place in these instances I have no doubt but that there is actually none is not proved.The action of water requires fuller investigation. CONCLUSIONS. The general conclusions arrived at in this paper may be summed up as follows:-I. mere two or more binary compounds are mixed under such circumstances that all the resulting bodies are free to act and react each electro-positive eletnent arranges itself in combination with each electro-negative element in certain constant proportions. IT. These proportions are independent of the manner in which the different elements were originally combined. DR. GLADSTONE ON CI-IEMICAT AFFIXPU’TTY. 111. These proportions are not merely the resultant of tlie various strengths of affinitF of the several substances for one another, but are dependent also on the mass of each of the sub-stances in the mixture.IV. An alteration in the mass of any of the binary compounds present alters the amount of every one of the other binary com-pounds and that in a regularly progressive ratio; sudden tran- sitions only occurring where a substance is present which is capable of combining with another in more than one proportion. V. This equilibrium of affinities arranges itself in most cases in an inappreciably short space of time but in certain instances the elements do not attain their final state of combination for hours or even days. VI. The phenonienn that present themselves where precipitation volatiiisation crystallisation and perhaps other actions occur are of an opposite character simply because one of the substances is thus removed from the field of action and the equilibrium that was first established is thus destroyed.VII. There is consequently a fundamental error in all attempts to determine the relative strength of affinity by precipitation; in all methods of quantitative analysis founded on the colour of a solution in which colourless salts are also present; and in all con- clusions as to what compounds exist in a solution drawn from such empirical rules as that “the strongest base combines with the strongest acid.”

ISSN:1743-6893    

DOI:10.1039/QJ8570900033

出版商:RSC    

年代:1857

数据来源: RSC

摘要:

INDEX. A. Abel F. A. on the composition of aome varieties of foreign iron 202 Abel F. A. and C. L. Bloxam con-tributions to the hiatory of nitric acid with especial reference to the valuation of nitre 97. Acetaldehyde 188. Acetate of biamidobenzoic acid 272. -of etibtriethyl 281. Acetamide and acetonitrile action of sul-phuric acid on 243. Acetonitrile preparation of 242. Acid amidobenzoic (benzamic) 269. -amylophoric on by F. Outhrie 134. -amylophosphoric preparation of free 139. -anisoic 186. -benzamic preparation of 264. -biamidobenzoic 271. -binitrobenzoic preparation of 270. -chromic action of on datiscetine 233. -disulphanilic 261. -disulphometholic 245. -disulphometholic identity of with methionic acid 263.-disulphobenzolic 255. -disulphetholic 250 252. -disulphopropiolic 253. -formic on the formation and pre- paration of 182. ~ hydrochloric note on the eolubility of sulphate of baryta in by H. M. Noad 15. -insolinic on by A. W. Hofmann 210. -methionic identity of with disul- phometholic acid 263. -nitric action of on datiscine and datiscetine 232. -action of upon opiauyl 274. -action of fuming on menaph-thalamine 22. -contributions to the history of with especial reference to the valuation of nitre by F. A. Abel and C. L. Bloxnm 97. Acid nitrobenzoic preparation of 268. -oxalic preparation of formic acid from 182. -sulphanilic 260. -sulphobutyric 253. -sulphopropionic 253. -sulphuric action of upon acetoni- trile and acetamide 243.-action of dilute on datiscine 228. -action of and peroxide of lead upon opianyl 276. -action of on benzonitrile 255. --on the action of upon the amides and nitriles by 0.B. Buck t o n and A. W. Hofmann 241. -action of on menaphthala-mine 12. .-action of on aniline 259. -thioformic 185. Acids C,H,O4 preparation of aldehydes from the 187. -conjugate sulpho- remarks on by G. B. Buckton and A. W. Hofmann 256. Acorns snaIysis of the ash of 46. AEnity on circumstances modifying the action of chemical by J. H. Glad-stone 54. Alcohol anisic on by S.Cannizzsro and C. Bertagnini 190. Aldehydes preparation of from the acids C,H,O, 187. Aldehyde-ammonia a compound pro-duced from and chloride of benzoyl 265.Amides and nitriles on the action of ad-phuric acid on the by G. B. Buck t on and A. W. Hofmann 241. Amidobenzoates (benzamates) 269. Ammonia action of upon iodide of sti- bethyl 278. -amylophosphate of 139. Ammonium disulphetholate of 251. -disulphometholate of 246. -examination of the mother-liquor of disulphometholate of 247. -sulphobutyrate of 253. -sulphacetate of 247. -sulphopropionnte of 252. 374 INDEX. Amylophosphates on the by F. 0uth r i e 134. And e r son T. on some constituents of opium 273. Andrews T. on the composition and properties of ozone 168. Aniline action of sulphuric acid on 259. Anisic alcohol on by S. Cannizzaro and C.Bertagnini 190. Anisoate of baryts 187. -of silver 187. -of soda 186. Antimony and copper reciprocal precipi- tation of 291. Ashes analysis of the of certain seeds and roots 46. -analysis of the of coffee and chicory 46. Atacamite on the action of heat on by F. Field 140. Atkinson E. and A. Goasman on lophine 220 Balance sheet of the Chemical Society 162. Barium disulphanilate of 260. -sulphanilate of 260. -disulphetholate of 251. -disulphobenzolate of 255. -disulphopropiolate of 253. -insolinate of 212. -sulphacetate of 247. -aulphobenzoate of 255. -aulphobutyrate ofJ263. -sulphopropionate of 253. Bai.yt.a amidobenzoate of 269. -amylophosphate of 138. -anisoate of 187. -note on the golubility of sulphste of in hydrochloric acid by H.M. Noad 15. Benzonitrile action of sulphuric acid on 255. -preparation of 254. Benxoyl on a new mode of formation of hydride of by H. K o 1b e 266. -8 compound produced from alde- hyde ammonia and chloride of 265. -on some compounds of by C ar 1 V o it 268. -sulphocyanide of 264. Bertagnini C. and S. Cannixzaro on anisic alcohol 190. Berlt? F. on the stibamyls 282. Berthelot. M. on the formation and preparation of formic acid 182. Binitrobenxamide 271. Binitrobenzoate of ethyl 270. Bismuth and copper reciprocal precipi- tation of 291. Bloxam C. L. and F. A. Abel con- tributions to the history of nitric acid with especial reference to the valuation of nitre 97. Bowman J.E. obituary notice of 159. Bromide of stibtriamyl 284. -of stibtriethyl 281. Bromopianyl 276. Buckton G1. B. and A. W. Hofmann researches on the action of sulphuric acid on the amides and nitriles toge- ther with remarks upon the conjugate sulpho-acids 241. C. Cadmium and copper reciprocal precipi- tation of 292. -and iron reciprocal precipitation of 293. -_ and lead reciprocal precipitation of, 293. -and tin reciprocal precipitation of 293. Cadmium-ethyl on by J. W an k 1y n 193. Caffeine quantity of in raw coffee 51. Calcium insolinate of 213. Campbell D. T. Graham and J. S t en ho u se chemical report on the mode of detecting vegetable substances mixed with coffee for the purposes of adulteration 33.Campbell D. on the source of the water of the deep wells in the chalk under London 21. Cannizzaro S. and C. Bertagnini on anisic alcohol 190. Caprylaldehyde 189. Carbonate of stibtriethyl 280. Carbonic oxide formation of formic acid from 182. Chemical aEnity on circumstances modi- fying the action of by J. H. Qlad-stone 54. Chemical notices by H. L imp richt 184. Chicory action of chemical reagents on infusion of 48. -analysis of the ash of 46. -characters of 53. -quantity of sugar in 42. 2hloride of benzoyl a compound pro- duced from aldehyde-ammonia and 265. -of cyanogen action of on naphtha-lamine 8. -of iodine action of upon opianyl, 276. -of stibtriamyl 283. -of stibtriethyl 281. 1NI:EY.375 Chlorine action of upon opianyl 275. Chloropianyl 275. Church A. H. and W.H. Perkin on some new colouring matters deri-vatives of dinitrobenzole dinitronaph- thaline &c. 1. Clark W. S. description of a self-acting washing bottle 200. Coal-gas carbon and nitric acid voltaic battery by J. L. and L. Wheeler 198. Coffee analysis of the ash of 44. -chemical report on the mode of detecting vegetable substances mixed with for the purposes of adulteration by T. Graham J. Stenhouse and D. Campbell 33. -silica in roasted 43. -action of chemical reagents on in-fusion of 48. -quantity of sugar in 41. -quantity of caffeine in raw 51. -bean composition of the raw 49. Colouring matters on some new deriva- tives of dinitrobenzole dinitronaph-thaline &c.by A. H. Church and W. H. Perkin 1. -I powerfi table of of the various vege- table substances (roasted) dissolved in an equal quantity of water 37. Conjugate sulpho-acids remarks on the by G.B. Buckton and A. W. Hof-rn ann 256. Copper and antimony reciprocal precipi- tation of 291. -and bismuth reciprocal precipi- tation of 231. -cmd cadmium reciprocal precipita- tion of 292. -and lead reciprocal precipitation of 292. -and silver reciprocal precipitation of 290. and tin reciprocal precipitation of 291. Copper disulphometholate of 246. -amylophosphate of 137. -insolinate of 212. -on the action of heat on the oxy- chloride of by F. Fi e 1 d 140. Cyanogen action of on menaphthala-mine.12. D. Dandelion-root analysis of the ash of 46. Datiscu ewnuabiiia 226 239. Datiscetine action of chromic acid on ?33. -and datiacinc analyses of 230. -action of nitric acid on 282. -_-action of potash on 233. Datiscetine preparation and properties of 229. Datiecine action of sulphuric acid on 228. -preparation and properties of 227. Decamalee gum of Scinde 238. D e ssai g n e a V.,on methyluramine and its derivatives 286. Dicymenaphthalamine 13. Dinitrobenzole action of nascent hydro-gen on 1. Dinitronaphthaline on some new colour- ing matters derivatives of 1. Disulphanilate of barium 260. -of silver 261. Disulphetholates 251 252. Disulphobenzolate of barium 255. Disulphometholates 245 246.Disulphometholate of ammonia exami- nation of the mother-liquor of 247. E. Ethyl binitrobenzoate of 270. Ethylonaphthalamine 264. F. Ferricyanide of potassium new method of making by L. P1 a y fai r 128. Field F. analysis of a meteoric stone from the Desert of Atacama 143. -on the action of heat on the oxy-chloride of copper (atacamite) 140. G. Gardenine 239. Gurdmiiu lucida gum of 238. G 1 ad 8 ton A J. H. on circumstances modifying the action of chemical affi-nity 54. --some experiments illustrative of the reciprocal decomposition of salts 144. Gossmann A. and E. Atkinson on lophine 220. Graham T. J. Stenhouse and D. Ca m p b e 11 chemical report on the mode of detecthg vegetahle substances mixed with coffee for the purposes of adulteratiou 33.Gum of the Gaydenia Zucidu (the Deca- malle gum of Scinde) 238. G u t h r i e F. on the sulphovinates and on amylophosphorie acid and the amy- lophosphatas 131. 376 INDEX. H. Heat action of on menaphthoximide 15. -action of on oxychloride of copper 140. H o f m a nn A. W. on insolinic acid 2 10. -and G. B. Buck t on researches on the action of sulphuric acid upon the amides and nitriles together with remarks upon the conjugate sulpho- acids 241. Hydride of benaoyl on a new mode of formation of by H. Kolbe 266. Hydriodate of lophine 223. Hydrobromate,hydrochloroplatinate and hydriodate of menaphthalamine 11. Hydrocarbon and stearopten of ptychotis ajovan 235.Hydrochlorate of biamidobenzoic acid 272. -of lophine 223. -of menaphthalamine 10. I. India examination of vegetable pro-ducts from by J. Stenhouse 226. Insolinates 210-215. Iodide of stibethyl action of ammonia upon 278. -of stibethy1,action of stibethyl upon 278. -of stibtriamyl 284. -of stibtriethyl 281. Iodine action of chloride of upon opianyl 276. Iodopianyl 276. -estimation of sulphur in crude 20. -on the composition of some varieties of foreign by I?. A. Abel 202. J. Johnston F. W. obituary notice of, 157. K. K o 1 b e H. on a new mode of formation of hydride of benzoyl 266. L. Lead action of sulphuric acid and per- oxide of upon opianyl 276. __ and cadmium reciprocal preuipita- tion of 293.Lead and copper reciprocal precipitation of 292. -and tin reciprocal precipitation of 292. -amylophosphate of 135. -disulphetholate of 251. -disulphometholate of 246. Lime amidobenzoate of 270. L imp r i c h t N. chemical notices 184 264. Lophine and nitrate of silver 225. -on by A. Gossmann and E. At-kinson 220. Lupins analysis of the mh of 46. Magnesia amidobenzoate of 270. Maize analy8is of the ash of 46. Meconine identity of with opianyl 274. -preparation of 2’73. Menaphthalamine combinations of 10. -metamorphoses of 12. -_ preparation of 8. -properties of 10. Menaphthoximide action of heat on 14 15. Merck W. on the compounds of stibe-thyl 278. Metals on the reciprocal precipitation of by W.Odling 289. Meteoric stone analysis of a from the Desert of Atacama by F. Fie Id 143. Metbyluramine on and its derivatives by V. Dessaignes 286. Naphthalamine action of chloride of cyanogen on by W. H. Perkin 8. -preparation of 8. Nitrate of biamidobenzoic acid 272. -of lophine 224. -of menaphthalamine 11. -of stibtriamyl 284. -of stibtriethyl 281. -of silver compound of with lophine 225. Nitre contributions to the hist.ory of nitric acid with especial reference to the evaluation of by F. A. Abel and C. L. Bloxam 97. Vitriles and amides ou the action of sulphuric acid on the by G. B. B u c k-ton and A. W. Hofmann 241. Wrosonaphthyline composition of 7. -properties of 6. Qitropianyl,274. Qitrosophenyline composition of 4.-properties of 2. INDEX. 377 No:L~,H. M. mttc on the solubility of siilphate of baryta in hydrochloric acid 15. 0. Obituary notice of Professor Bowman,l59. --of Professor Johnston 157. 0d 1i 11 g W. on the reciprocal precipita- tion of the metals 289. (Ennnthol 185. Opianyl action of bromine upon 276. ~ action of chloride of iodine upon 276. -action of chlorine upon 275. -action of nitric acid upon 274. -action of sulphuric acid and yer- oxide of lead upon 276. -identity of with meconine 274. Opium on some constituents of by T. Anderson 273. Oxalate of biamidobenzoic acid 272. -of menapht,halamine 11. Oxide of stibtriamyl 283. Oxychloride of copper (atacamite) on the action of heat on the by F.Field 140. Oxide of stibtriethyl 279. Ozone on the composition and properties of by T. Andrews 168. P. Paracyanogen-compound on a by L. PlayPair 129. Parsnips analysis of the ash of 46. Perkin W. H. on the action of chloride of cyanogen on naphthalamine 8. -W. H. and A. H. Church on some new colouring matters deriva-tives of dinitrobenzole dinitronaph- thaline &c. 1. Peroxide of lead action of sulphuric acid and upon opianyl 276. Phosphate of menaphthalamine 11. Playfair L. on a new method of making ferricyanide of potassium and a paracyanogen compound 128. Platinum-salt of lophine 224. Potassium disulphometholate of 246. -insolinate of 213. -and sodium insolinate of 214. -+ new method of making ferricyanide of by L.Playfair 128. Proceedings at the Meetings of the Che- mical Society 28 163. Potash action of on datiscine and datiri- cetine 233. Propionitrile preparation of 249. Propylaldehy de 18 8. Ptychotis Ajowam 234 239. R. Seciprocal decomposition of salts some experiments illustrative of by J. H. Gladstone 144. Report of the Council of the Chemical Society 157. Roots quantity of augar in various sweet 42. S. gaits Nome experiments illustrative of the reciprocal decomposition of by J. H. Gladstone 144. leeds,.quantity of sugar in various 42. lilica in roasted coffee 43. Jilver amylophosphate of 136. -and copper reciprocal precipita- tion of 290. -and mercury reciprocal precipita- tion of 289.-anisoate of. 187. -compound of nitrate of with lophine 225. -disulphanilate of 261. -sulphanilate of 260. -disulphetholate of 252. -disulphometholate of 245. -insolinate of 211. soda amidobenzoate of 269. anisoate of 186. Sodium and potassium insolinate of 214. specific gravity of various vegetable in- fusions 39. Stearoptem of Ptychotis Ajowmt 235. S t e n h o use J. examination of select vegetable products from India 226 -J. T. Graham andD. Campbell chemical report on the mode of detect- ing vegetable snbstances mixed with coffee for the purposes of adulteration 33, Stibamyls on the by F. Be r 16 282. Stibbiamyl 284. Stibethyl action of iipon iodide of stibe-thyl 278. -on the compounds of by W.Merck 278. Stibtriamyl 282. Stibtriethyl compounds of 279-281. Strontia amidobenzoate of 269. Siigar quantity of in chicory and other sweet roots 42. -quantity of in coffee 41. -quantity of in various seeds 42. Sulphacetates of ammonium and barium 247. Sulphanilates 260. Sulphate of baryta note on the solubility of in hydrochloric acid by H. M, Noad 15. 378 I ?\’I)I<S. Sulphate of biamidobenzoic acid 272. -of lophine 223. -of menaphthalamine 11. -of stibtriamyl 284. -of stibtriethyl 281. Sulphide of stibtriethyl 279. Sulpho-acidls remarks on the conjugate by a. B. Buckton and A. W.Hof-mann 256. Sulphobenzoate of barium 255. Sulphocyanide of benzoyl 264. Sulphopropionate of barium 253.Sulphovinates on the by F. Guthrie 131. Sulphur estimation of in crude iron 20. T. Tin and cadmium reciprocal precipita- tion of 293. -and copper reciprocal precipitation of 291. -and lead reciprocal precipitation of 292. END OF v. Valeraldehgde 189. Vegetable products from India examina- tion of by J. Stenhouse 226. Voit C. on some compounds of ben-zoyl 268. Voltaic battery on a coal-gas carbon and nitric acid by J. L. and L. Wheeler 198. Wanklyn J. on cadmium-ethyl 193. Washing bottle description of a self-acting by W. J. Clark 200. Water on the source of the of the deep wells in the chalk under London by D. Campbell 21. Wheeler J. L. and L. on a coal-gae carbon and nitric acid voltaic battery 198. Z. Zinc disulphometholate of 246. VOL. IX. PRINTED BY HARRISON AND SOh’B. ST. MARTIN’S I.AN!:. w c.

ISSN:1743-6893    

DOI:10.1039/QJ8570900373

出版商:RSC    

年代:1857

数据来源: RSC