摘要:

THE QUAETERLY JOURNAL OF THE CHENIGAL SOCIETY IX.-Om certain sources sf loss of Precious Hetal in some operations of Assaying. BY G. H. MAKINS. INthe assay of specimens of alloyed gold the degree of heat used in the first operation viz. cupellation (when this is carefully performed) is usually somew hat varied according to presupposed proportions in the alloy,-for example a much lower temperature being suBicient where the gold is only associated with silver than where it is also mixed with oxidisable metals which latter have to be separated entirely by this first operation About five years since I chanced to have before me some 20 assays of gold wherein the silver also had to be estimated and in which for other reasons an extraordinary degree of heat was required to be employed ; and as I made simultaneously with these several synthetieal prods I was milch struck by the great extent of loss of gold and silvep; and satisfied that it could riot be eutirely due to what is known amongst assayers as cupel absorption I determined upon examinirrg scme af the contents of an iron flue of a onpel furnace which passed from its hood into a chimney iu order to see if gold had been volatilized along with other metals and if so to what extent.VOL. XIIX. H WAKTNS ON PRECIOUS METALS IN ASSAYING. A quantity of apparently carbonacernxs matter mas therefore taken out of it; and aq this flue mas at the time recently ptit up afresh I had the means of knowing that it had been used for the cupeliation of gold assays only.Upon examiiration of tliis material by the microscope under an inch power it exlitbited very distrzlctly portions of oxide of lead in yellow masses little nodules of suboxide of copper minute grains of silt er together u ith portion8 resembling silver reduced from chloride,-the whole mixed with a quantity of' carbonized matter containing small grains of unburnt fuel From pressure of bnsiness at tEe time this material was laid aside (after cursory examination sufficient to prove the presence of the metals) until it cotild be completely examined. This mas not done horn ever until after the appearance of some collateral matter comniunicated to the Society by my late pupil Mr. Kapier. On further examination the metallic matters present mere found to consist of oxide of lead mixed with small portions of gold silver and oxide of copper; arid as my object was only to estimate the gold and silver present I took separate portions viz.two of 50 and two of 100 grains each. They were each treated with 400 grains of pure lead that is to say with eight times the weight of the former two and four times the latter each having also its own weight of borax added. The mixtures were then scorified and the operation carried to its full extent so as to diminish as much as possible the quantity of lead tor the subsequent cupel process. The process completed the specimens were poured in a god fluid conditiou; the slag (which was quite free from metallic beads) separated ; and the resulting mehi next subjected to cupel-lation.The little buttons 80 obtrtined consistiog of pure silver and gold were then weighed. Ti'r~~n the first two assays (the material operated upon being 3 00 grains) the resulting buttons weighed (after compensating for silver contained in &he lead employed) just .089 grain. From the second two upon 900 grains the buttons weighed *166. If pie average these ahich are very nearly alike and calm-late the quantity for 10 grains we should have a result of -850 grain. They were next all parted for gold and the result gas -026; equal to *087in every 1000grains MAKINS OX PRECIOUS METALS IX ASSAYING. Deducting then the weight of this gold from the weight of the compound metal we fiud the quantity of the precious metals in 1000 grains to be Gold ..-087 SJver . . -763 Of coiirse I do not attempt to establish any ratio between these quantities arid an individual assay; for although the flue whence this material wa3 taken had only been reriewed a few months yet during that time the fumes of many thousand assays had passed through it. But on the other haud I would rerriark that considering that this flue is removed daily when the furnace is at work the proportion which the precious metals bear to the whole is very large indeed. I will now call attention to a second cause of loss of gold occurring in parting operations and possibly also in refining upon the large scale viz. the solution of a portion of gold iu the nitric acid used although the latter is pure and quite free from hydro- chloric acid Berselius in speaking of this fact says <‘Itmust not be forgotten that if nitric acid contains hydrochloric or nitrous acid it will dissolve gold; in truth the quantity dissolved is incon- siderable in the latter case but sufficient to lead to an incorrect result.” NOW,in parting gold by nitric acid we are generating during the operation quantities of nitrous acid and consequently have the conditions present for this loss to take place.Some time since Mr Field (the Queen’s Assay Master) had in his office a pear-shaped bottle irrto which nitric acid was con- stantly being potired after parting operations it was thickly coated with gold. He showed this to Sir J. Herschell vho was then Master of the Mint otsserting that it was deposited from an actual solution of the gold.The latter gentleman supposed rather that it was a deposit from mechanically suspended particles; but this cpuld have hardly been the case as. the bottle was a large pear-shaped one a4d the gold coated the upper part as thickly as the lower and yery uniformly which certainly could not have been the case had it been simply a deposit of mechanically SUE. pended particles. It was no doubt as Mr. Field observed a good example of deposit from an actual solution. I tried the following experiment in order to arrive at gome idea of $he quantity so taken up in ordiaary assaying operations H2 100 MAKINS ON PREIOUS METALS IN ASSAYING. Four assay-quantities of pure gold were accurately weighed then added to the usual proportion of fine silver aud of lead and cupelled.The buttons then rolled and coiled were parted with nitric acid. For the hoilings acids mere prepared of specific gravity 1.25 and 1.35 respectively. KO.1 assay was then boiled 20 minutes in the weaker and aftervrards for 13 minutes in the stronger acid between which operations the cornet was washed with hot distilled water. No. 2 assay was boiled once in the first and twice in the second acid. No. 3. Once in the first and three times in the second. And No. 4. Once in the first and four times in the second; the boilings as I have said being continued for 20minutes in the weak and for 13 miniites in the second acid.The several cornets were then washed off with hot distilled water annealed and weighed and the following is the result :-Calling the weighi:tgs before the operations 1000 the first cornet weighed 999.6 the second 992 the third 998.7 and the fourth 997.9; the loss thus increasing in proportion as we multiply the number of boilings. Now the qucstion occurs as to whence the loss arises. I may first say that it has been suggested that it is due to silver being more completely separated by the repeated boilings. But inreply to this I can state that I have examined these cornets over and over again; and that after the first boiling as above described the amount of silver left in them is very uniformly 1.16 in the I000 parts. But the difference between 999.6 the weight of the first cornet and 997.9 that of the fourth is 1.70 ; here then supposing the latter to be entirely free from silver (which is not really the case) we have 0.54 abstracted a quantity just equal to 3 graius in the troy pound which loss can only be traced to the removal of gold.Next it has been urged that; the appearance of gold in the used pasting acid is due to mechanical causes dependent upon the friction of an exceedingly soft and spongy body by its being thrown violently about in a dense acid fluid and by the rapid evolution of bubbles of acid or acid vapour rushing from its surface all this being of course increased as the density of the acid is increased by evaporation. I believe that this is not the case and that in the fluid medium no such abrasion takes place but that it is a true case of solution MAKINS ON PRECIOUS BlETALS IN ASSAYING.101 and by the agency of the nitrous acid evolved. In proof of this I have taken a portion of this acid which had been so used and after dilution separated the silver then evaporated arid obtained small quantities of gold which were nest redissolved in nitro-hydrochloric acid and proved to be such by the usual tests. Again I do not think that the deposit upon Mr. Field’s store bottles (to which I have alluded) could have taken place in so regular a manner upon their upper portions without actual solution; for had it been mere mechanical suspension the metal upon the lower part would of course have been much in excess.Now as to the evolution of this nitrous acid. At the first boiling when the silver is present in such large quantity nitrous acid is given off most copiously; but probably its solvent action upon the gold is then controlled and checked by electrical action that is by the gold becoming the negative and the silver the positive element in a voltaic circuit; but when the silver is wholly (or nearly) removed this check no longer exists and the solution of the gold progresses more rapidly. Then with respect to the cause of the evolution of nitrous acid,-of course as I have already said as long as there is any silver to oxidise it will be generated; and when the silver is nearly abstracted the method of boiling adopted by many assayers induces its continuance; for it is scarcely possible to boil an assay in strong acid without some means of disengaging the vapour formed if some help be not afforded the.acid will “bump” so much as almost if not quite to throw it out of the flask. Hence it is the custom with some to introduce a small portion of char-cod which from its porosity tends to the steady evolution of this vapour. Now if the charcoal be entirely carbonized it does not materially affect the acid; but if it coritairi much woody matter not thoroughly carbonized it is then sure to decompose it and set nitrous acid free. Indeed I have for some years ceased to use this body from its injurious effects upon the acid. I am aware that the matters mentioned in this paper are some- what trivial in a scientific point of view; but their commercial importance will be at once admitted when we remember the enormous values dealt with in this country and consider more-over that they are at times turned over and over again and that 10.2 PERHIN AND DUPPA ON BIBROMOSUCCINIC ACID the question of profit and loss in such commercial operations are much if not entirely in the hands of the assayer.Lastly this publication may serve to account for some of the discrepancies which are sometimes found between assayers.

ISSN:1743-6893    

DOI:10.1039/QJ8611300097

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

10.2 PERHIN AND DUPPA ON BIBROMOSUCCINIC ACID X.-On Bibromosuccinic Acid and the Artijkial Production of Tartaric Acid. BY TV. H. PERKIN,F.C.S. AND B. F. DUPPA,ESQ. INApril of last year we published a paper on the action of penta-chloride of phosphorus on malic acid,* in which we stated that there seemed reasons for believing that there existed a close relation between succinic malic and tartaric acids similar to that which exists between acetic glycollic and glyoxylic acids; and for the purpose of verifying that supposition we proposed endeavouring to obtain mono -and bibromo-succinic acids thinking that by hyclrat- ing them by means of hydrate of silver or by decomposing their silver-salts in the presrnce of water we might obtain malic and tartaric acids.Since that time we have obtained both of these bromo-acids but up to the present haveonly studied the bibromo- succinic acid. Bibromosuccinic Acid. We endeavoured to produce this snbstance by the direct action of bromine on succinic acid but did not obtain any satisfactory results. The process by which we have succeeded in obtaining this acid is as follows Equal volumes of bromine and chloridc of succinpl are heated in a strong sealed tube to a temperatureof 120 or 130%. for three or four holm. The tube after having cooled mixst be very care- fully opened so that the hydrobromic acid which has formed may slowly issue fwth ; if the tube be opeqed too rapidly its contents will be projected and lost. The product thus obtained is an oily liquid consisting of impure chloride of bibromosuccinyl.This is * Phil. Mag. April 1859. PERKIN AND DUPPA ON BIBBOMOSUCCINIC ACID 103 decomposed by being well agitated for an hour or two with two or three times its volume of water afier which the liquid will contain considerable quantities of the new acid in the form of a crystalline precipitate; this is purified by being well washed on a filter to separate hydrochloric acid and also another extremely soluble acid which has been formed. It is then dissolved in a moderately strong solution of carbonate of sodium and filtered for the purpose of removing a small quantity of an oily substance. The resulting sodium salt is then decomposed by nitric acid which causes the new product to separate as a crystalline precipitate which when thoroughly washed ona filter with cold water and then dried con- stitutes pure bibrornosuccinic acid.Carbon hydrogen and bromine determinations of specimens dried in vacuo over sulphuric acid gave the following numbers :-I. *4150of substance gave *2643of carbonic acid and *0600of water. 11. *2950of substance ga1.e -4035 of bromide of silver. Percentage composition :-I. n. Carbon . 17’36 -Hydrogen . 1.60 -Bromine. 58.2 I which agree with the formula as may he seen from the following table :-Theory. Experiment. -Carbon 8 equiv. . . 48 17.39 17-36 Hydrogen 4 , . .4 1.44 1-60 Bromine 2 , . 160 57-97 58.20 Oxygen 8 , . -64 23.20 -276 100*00 Bibromosuccinic acid is difficultly soluble in cold but tolerably so in hot water from which it crystdises on cooling in opaque 104 PERKIN AND DUPPA ON BIBROMOSUCCINIC ACID prisms; it is very soluble in alcohol and extremely so in ether.We have found the latter solvent very useful in separating small quantities of this acid from its aqueous solutions. Crystals of bibromacetic acid decrepitate when gently heated but when subjected to a high temperature decompose with formation of hydrobromic acid. It has a strong acid taste and reddens litmus rapidly. We have but cursorilg examined the salts of this acid. Bibromosuccinate of sodium is very soluble and appears to contain water of crystallisation. Acid bibromosuccinate of potassium is a white crystalline salt sparingly soluble.Bibromosuccinate of silver is obtained by adding a solution of nitrate of silver to either of the above salts. It is a white salt nearly insoluble in water The following determinations were made of a specimen dried over sulphuric acid in vacuo :-I ,5316 of substance gave 01879of carbonic acid and *0288of water. 11. 04163of substance gave -2418of chloride of silver and 03195of bromide. These results agree with the theoretical numbers as may be seen by the following table :- - Theory. Experiment. Carbon 8 eyuiv. . 48 9-79 9.63 Hydrogen 2 , b 2 *40 060 Bromine 2 , 160 4&08 43.71 Silver Oxygen 2 8 , Jj . b . 216 64- 32.65 33.08 - 32.64- 490 100~00 On boiling a quantity of bibromosuccinate of silver with water it graduall? decomposes with evolution of carbonic acid and forma- tion of bromide ot silver; the ebullition must be continued until no more cnrkonic gas is evolved.The resulting mixture is then thrown on a filter; the less soluble portion which consists chiefly of bromide of silver is well washed with water; and to the filtrate PERIC'IN AND DUPPA ON BIBROMOSCCCINLC ACID 105 which contains a small quantity of silver in solution a few drops of hydrochloric acid are added. The liquid is then separated from the chloride of silver by means of a filter and evaporated on a water bath until of a syrupy consistence. After remaining at rest for four and twenty hours under a bell-jar over sulphuric acid it is found to contain a considerable quantity of large crystals which are then separated from the residual syrupy acid by washing rapidly with cold alcohol; the product thus obtained is tartaric acid.A portion of this acid was dissolved in water and divided into two equal quantities. One of these was neutralized with carbonate of potassium and then the other added to it which caused the well-known precipitate of the acid tartrate of potassium to form whereof we made the following carbon hydrogen and potassium determinations :-I. 0202p. of substance gave *18875grm. of carbonic acid and *0540of water. 11. -205grm. of substance gave *19200grm. of carbonic acid and 10500 of water. 111. 01545grm. of substance gave 00590of chloride of potassium. Percentage composition :-I.11 In. b Carbon . 25.49 25.5 -Hydrogeii . 2.9 2.7 -Potassium -7 20a These numbers agree very closely with the theoretical as may be seen by the subjoined table :-Theory Experiment. Carbon 8 equiv. . 48 25.60 25-49 4 5 2*65 2.80 Hydrogen 5 , Potassium 1 , . . 39.2 20.00 zo*o 96 51.75 -Oxygen 12 , -188.2 100*00 HADOW ON THE This intepesting formation of tartaric acid may be thus explained ('SHZBr )' 0 + H!2°2 = (C8H'204K{ 0 + 2AgBr; 2ig) Bibroniosuccinate of Silver. Tartaric Acid. evidently showing that it is derived from four molecules of water. We have alluded to a syrupy acid which is formed at the same time astartaric acid and from which it had to be separated by means of cold alcohol. This we have not investigated as its nature shows that it would be very difficult to obtain pure and consequeritly would require considerable quaD tities which coupled with the expense and labour of obtaining only a few grammes of bibrumosuccinic acid has induced us to lay this part of the investigation aside for the present.It seems however probable that it is pyruvic acid which it will be remembered is formed from tartaric acid by the loss of carbonic acid and water; arid mag it not be possible that part of the tartitric acid at the moment of formation splits up into carbonic acid water arid pyruvic acid ? We are now investigating monobromosuccinic acid from which we expect to obtain some interesting results.

ISSN:1743-6893    

DOI:10.1039/QJ8611300102

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

HADOW ON THE XI.-On the Composition of the Ptatinidcyanides. BY EDWARD ESQ, A. HADOW As the platinidcyanides are derived from the platinocyanides it will be well briefly to mention in the first place the rnde of forma-tion aiid properties of the latter. The platiiiocyanides are a remark-able set of salts belonging to the stable class of double cyanides exceeding the ferrocyanides in the force with which they retain the electro-negative metal and disguise it to ordinary tests. Coucen-tratecl and boiling nitric or hydrochloric-acids alone or mixed extract no platiuum from them; they are unaffected by digestion with peroxide of mercury -and coacentrated boiling sulphuric acid liberates cyanide of platinum with difficulty only. They have COMPOYlTlON OF THE PLATZNIDCYANIDES.107 the general formula MCy.PtCy or MPtCy2 the platinum in them existing in the state corresponding to protochloride of platinum so that before preparing these salts from a solution of bichloride of platinurn it must be reduced to the condition of protochloride either by sulphurous acid or by evaporation to dryness and expul- sion of half the chlorine by heat. The product in either case is treated with excess of cyanide of potassium until a clear solution is obtained which if previously warm and sufficiently concen- trated will deposit on cooling long prisms of the potassium-salt from which the other piatinocyanides may easily be derived by precipitating its solution with that of a salt of copper washing the precipitate suspending it in water and decomposiGg it by a current of sulphuretted hydrogen ;the solution which contains hydroplatinocyanic acid and after filtration from the sulphide of copper may be saturated with any required base.A more couve- nient way I find in many cases is to treat the protochloride of platinum directly with the required base and sufficient hydro- cyariic acid to form the double cyanide; the combination takes place easily if assisted by a gentle heat and it is only uecessary to crystallise a few times to get rid of the chloride present in the solution. These salts are remarkable for the great beauty and variety of the colours their crystals exhibit while their solutions are trans- parent and colourless. The platinocyanide of magnesium is perhaps the most beautiful of these salts; it forms by slow evspo- ration large and regular prisms of a deep red by transmitted light but viewed by reflected light the sides of the prisms exhibit a brilliant beetle-green and the extremities a deep blue or purple colour.The red salt gently warmed even under water becomes bright yellow wliich is also the colour of crystals deposited from a solution at a temperature of 160 OF.; heated to 212O F. the salt becomes quite white and again at a higher temperature bright yellow. These changes of colour correspond to successive losses of water the ordinary red salt contaiuing 7 equiv.; the yellow according to Wesclsky 6 equiv. At 212" F. the salt still retains 2 equiv. which are only expelled by a heat of between 300" and 400",when it becomes anhydrous and again yellow.If a portion of this yellow anhydrous salt be laid on the red salt in powder it will soon abstract water (from the latter) and a white layer will be formed between two yellow borders one of these yellow compouuds being anhydrous and the other contriining 6 equiv. of water. In 108 HADOW ON THE endeavouring to prepare this salt I on one occasion made use of a method given by Quadrat which consists in evaporating to dryness mixed solutions of sulphate of magnesia and platino-cyanide of potassium and digesting the dried mass in a mixture of alcohol aid ether; instead of which however I used only alcohol and that somewhat weak and by so doing obtained a solution which gave in addition to the ordinary dark red salt another set of crystals of a paler red and exhibiting a steel-blue lustre by reflected light instead of the usual emerald-green of the ordinayy salt.Analysis proved it to be a double platinocyanide of magnesium and potassium having the formula MgPtCy2.KPtCy + 2H0 + 5aq = 416.5. Calculated. Found. 2Pt = 47-54! 47.2 -4'7.1 4Cy = 24.97 - MgK = = 3-00 9.36 3.02 9.41 2HO = 5H0 = 4.32 10.81 4.40 expelled above 212' F. 10.97 expelled at 212. In this as in many other platinocyanides a portion of water is retained at 212'. This sdt csnnot be recrystallised except from a considerable excess of platiiiocyanide of magnesium and even when this is present sudden cooling or agitation of the saturated solution causes the separation of the potassium salt free from magnesium.These platinocyanides represented by the general formula MPtCy, may be transformed into thi salts termed platinidcya- nidep by the action of chlorine bromine nitric acid &c.-a set of compounds characterised in the crystalline form by a peculiar coppery lustre and to which the general formula M,Pt,Cy has hitherto been assigned. They are thus represented a3 differing from the platinocyanides by the addition of an atom of cyariogen to every two atoms of the latter salts. Mg,Pt,Cy = 2(MgPtCy2) .Cy. This somewhat improbable formula seemed yet to be strongly confirmed by the following facts. Gerhardt at first doubted it COMPOSITION OF THE PLATINJDCYANXDES.109 but afterwards confirmed it by an analysis of the potassium-salt. A determination of the platinum and potassium made by myself agreed so closely with the requirements of the formula as also strongly to confirm it. These salts act like the ferridcyanides in presence of a free alkali,-exerting a powerful bleaching action on cochineal ; they also liberate iodine from iodide of potassium corifirming the analogy between the two sets of salts. They evolve cyanogen when heated sufficiently leaving a residue of platinocyanide. They arc produced equally by the action of bromine ziitric acid and other oxidizing agents on the platiuo- cyanides showirig that no single one of these is ebsentially neces- sary for their formation. But then cn the other hand the following difficulties pre- sented themselves The platinum and basic metal remain in the same proportion to each other in the platinidcyanides as in the platitlocyanides from which they are derived the difference being merely an excess of cyanogen in the latter over that in the former.Whence is this cyanogen derived? In the case of the ferrid- cyanides the proportion between the iron and the basic metal in the ferrocyauide has been altered by the chlorine which abstracts a portion of the basic metal leaving the cyanogen behind to explain the excess found in the ferridcyanide But to account for that in the platinidcyanides it is necessary to assume the simultaneous removal by the action of chlorine on the platinocyanides of equal proportions of platinum and basic metal an explanation which appears very improbable to any one who has observed the great stability of the platinocyarzides and the remarkable ease with which the transformation by chlorine occurs.These salts it is true have an oxidizing effect in presence of potash in consequence of which by the addition of an oxidizable body they are reduced to platinocyanides; but then it ought to occur with simultaneous formation of free cyanide of potassium but no free cyanide can be detected as a product of such a reaction in any case. Moreover there exists another salt t4e HADOW ON THE ultimate product of the action of chlorine on the platinidcyanide of potassium (the salt chiefly examined) usually rcpreseiited by the formula PtCy,.KCl the formation of which from the plati- nidcyvanicle is equally difficult of explanation with that of the latter from the platinocyanide; and further still is it difficult to represent the mode of the reduction of the chlorinated salt to the state of platinidcyanide which however actually occtirs very readily under the action of reducing agents The determination of the proportions between the cpanogen and the platinum at once served to clear up most of these difficulties.The proportion mas found to be identically the same in the platinidcyanides as in the platinocyanides ; and the difference between the two sets of salts i4 composition was found to consist in the addition of a certain amount of the chlorine bromine or other elementary or compound salt-radical used for their forma- tion,-so that there exist not one set but many sets of platinid- cyanides requiring the prefix of cl'doro bromo &c, to distinguish them.Such being the case it appeared most probable that Knop's and Gerhardtjs salts had been true cgano-platinocyenides as the above formula indicates formed under some peculiar condi- tions perhaps in presence of excess of cyanide of potassium so that cyanagen instead of chlorine had really been supertdded to the original platinocyanide and that the salt under examination differed from theirs only in containing chlorine in place of cyanogen I was therefore nat a little surprised to find instead of 1 atom of chlorine to 2 atoms of platinum which a chlorine-compound analogous to this cyanogen- compound should contain not above a third of that quantity; accordingly even if the chlorine ever were truly replaced by cyanogen-which after several attempts I failed to effect-the formula M,Pt,Cp never could represent the composition of the cyano -platinocyanides the super- added cyanogen being too large in amount by two-thirds Considerable difficulty was found in determining the amount of chlorine in the salts on account of their high atomic weight.Repeated corn bustions of the chloro-platinocyanide of potassium with nitrate of potash and carbonate of soda gave a proportion of 1 equiv. of chloi-ine to between 6 and 7 equiv. of platinum. This analytical method proving unsatisfactory from not giving a probable formula a spthetical method was tried with better success; it was found that a solution of pltltina-cyanide acidulated with hydrochloric acid rapidly and perfectly COXPOSITIOX OF THE PLATISIDCYARIDES.decolorises a solution of permanganate of potash until the platino- cyanide has taken up the rnaxiinum amount of chlorine and become converted into the salt PtCy,KC1 tthich has been before mentioned as the ultimate product of the action of chlorine on the cldoro-platinocyanides and which might be termed the percliloro-platinocganide of potassium. As no method could be devised to indicate when the firat stage of the change namely from platinocyanitie into chloro-platinocyanide is complete it was not possible to determine the amoirtit of chlorine necessary for its foi-mation in this direct way; but starting from the chloro-platinocyanide it was easy to determine by means of permanganate of potash how much additiond chlorine was necessary to convert it into the percliloro-platinocyanide the true composition of which had been determined and found to have been correctly represented in its elementary proportions by the formula hitherto given.It was thus found that while 6 equiv. of the platinocyanide containing 6 equiv. of platinum required 6 of chlorine for the formation of the perchloro-platinocyanide,a quantity of the chloro-platinocyanide contaiiiing the same amount of platinurn required only 5 equiv. of chlorine to convert it into the same salt proving that 1 equiv. already existed in this quantity of the salt arid therefore that its true composition in the anhydrous state is 6(KPtCy,) C1.This composition explains its oxidizing power in alkaline solutions and why no free cyanide can be detected when its force has been spent on an oxidisable body an alkaline chloride and not a cyanide being formed The evolution of cyanogen and its reduction to platinocyanide when heated is due to the chlorine partly entering the salt and dis-placing cyanogen; (a certain arnoiint of chloride of ammonium is however likewise formed at the time when moisture is present) fj(KPtCy,)Cl = 5(KPtCy,) + KC1 + PtCy + Cy. The salt after this gives a sornevhat turbid solution from PtCy which has been set free. The formation of the salt from the platinocyanide arid its ready conversion into the perchloro-platinacyarlide and the reduction of the latter into the chloro- platinocymide and platinocyanide successively by reducing I12 HADOW ON THE agents is due to the successive additions of chlorine in one case and successive abstractions of it in the other without any forma- tion or separation of cyanide of platinum or of chloride of potassium in either case- The chloro-platii~ocyanide of potassium as ordinarily dried in a hot-water oven loses the percentage of water given by Gerhardt in his analysis but still retailis 3 equiv.which tQgether with the chlorine overlooked correspond pretty nearly in weight with the excess of cyanogen supposed to exist in the salt and which thus appears to have been determined by difference only.The compo-sition of the crystallised salt is The direct determinations of chlorine as before stated were unsatisfactory inasmuch as they showed on the average a deficiency of about 0.20 per cent. The salt has a slight tendency to lose water of crystallisation in dry weatter. The water was therefore determined in two samples one dried spontaneously in the air the other by strong pressure in bibulous paper immediately after removal from its solution as the two extremes to furuish a oorrect mean. Air-dried. Dried by Aver-Calculated Pressure. age. for 18HO 18H0 Loss per cent at 212" = 11.34 20.9 12-34 11.53 11-87 3H0 1) 400' = 1.94 1-97 -1'96 1.98 Composition of salt dried at 212' :-6Pt = 49.27 Found.50.07 48-7 Average 49*34 Ca+lculated. 49.39 6K 12Cy = = 19.68 25.83 - 19.92 L 19*8Q 25.83 19.47 25.95 C1 = 2-76 2.82 2.79 2.79 2.95 3HO = 2.19 2.23 _I 2.21 2.24 99-97 100~00 The quantities of the salt taken for the various determinations varied from 7 to 13 grs. The platinum and potassium were COIMPOSITION OF TRE PLATINIDCYANXDES. 113 obtained by evaporation with pure concentrated sulphuric acid followed by gentle ignition. The cyanogen was determined by combustion of 10.6 grs. with soda-lime. The above formula represents the empirical composition of the chloro-plstinocy anide of potassium. Its true ration a1 cornposi tioil was cliscovcrecl on precipitating its solution with a solution of zinc when it was found to have resolved itself into a platinocyanide which mas precipitated in combination with zinc and a percliloro- platinocy anide which remained in solution ; and accordingly on mixing a solutioii of the perchloro-platinocyanide a salt which forms large colourless crystals with another of the nearly colour- less platinocyanide the mixture if sufficiently concerritrated will deposit immediately an abundant crop of copper-coloured crystals of chloro-platinocyanide + KPtc*v2c1 It appears in fact to be a double salt of the two.The solution accordingly of the so-called platinidcyanides exhibits the reactions of a mixture of its component salts and it is thus impossible by any direct tests to ascertain whether either is in excess or not; this p0in.t can only be determined by careful crystallisation.By this latter method the formula of the chloro- platinocyanides was further confirmed ;the two component salts were mixed in various proportions and the compound salt was crys- tallised out when one or other of its components would be found in excess unless the right proportions had been taken. The results obtained in this way were not absolutely satisfactory in conse- quence of partial decomposition during repeated crystallisation ; but they served to counterbalance the determinations of chlorine by analysis the errors in the numbers obtained being in the opposite direction and indiccting tho proportion of 1 equiv. of chlorine to between 5 and 6 equiv. of platinum. It was found that from whatever solution the chloro-platinocyanide was crystal-lisecl it always contained the sanie amount of chlorine so that there appears to be no double salt intermediate between tbe chloro-platinocyanide and perchloro-platiriocyanide; and accord- ingly if a pixrely cyanogen-platinocyanide existed it may be concluded from analogy that it mould have the composition 5(PtR@y,) + PtBCy and not (PtKCy2 -+ PtKCy,) -vvhich the hitherto accepted formula requires.The bromo- and VOL. XIII. 1 114 HADOW ON THE COMP9SITION OF THE PLATINIDCYANIDES. nitro-platinidcyanides so closely resemble the corresponding chlorinated salts as hitherto to have been confourided with them under the general term of platinidcpanides and as their appearance and facility of formation are so much alike there is every reason to conclude that they have an analogous composition being in fact double salts of a platitlocyanide and a corresponding perbronio- and pernitro-platinidcyanide which like the highest chlorine com- pounds are colourless.In the caqe of nitric acid NO must represent the chlorine and bromine of the corresponding salts. There appear to be no analogous iodine coinponnds sirice any one of these salts treated with iodide of potassium immediately liberates iodine. But there are analogous compounds containing the salt radical SO in place of chlorine bromine &c. and doubtless similar compounds with the salt-radicals of other acids; the existence of the sulphizric compouncl was inferred in the first instance from finding that a solution of a platinocyanide acidulated with sulphuric acid rapidly decolorises a perrnan-ganate.The crystallised oxysulpho-platinocyanideof potassium is readily obtained by adding a little peroxide of lead to a saturated solution of platinocyanide of potassium acidulated with sulphuric acid ;-each particle of peroxide dropped in becomes iiistantly enveloped in a moss-like growing mass of the copper-coloured salt. From a few experiments recently made it would appear that these remarkable cornpounds may also be regarded as salts in which the platinocyanide MPtCy plays the part of a metal since in the sulphuric compoundt the sulphuric acid readily admits of replacement by another acid by doizble decomposition with a baryta salt; aud accordirigly it Eeems to be not unlikely that there are oxygen-compounds capable of acting the part of bases and combining directly with acids to form the per-compounds which by combination with the platinocyanides form the platinid- cpdnides.It is on account of the feeble affinity that exists between the platinocyanide (as a compound metal) and the salt- radicai thTt reducing agents so readily decompose them into the platinocyanide and the corresponding acid just as they would the corresponding salts of gold the gold being supposed to represent the platinocyanide in its feebly electro-positive character. If sulphurctted hydrogen be passed into their solutions which are neutral they immediately become stronglyv acid. BUCHTON ON THE STIBETHYLS AXD STIBXETHYLS.115 The most distinctive reactions between the platinocyanides and perchloro-platinocyanides are that the former give au abundant small-blue precipitate with nitrate of suboxideof rrmcury and a $f~occuZent blue precipitate with sdts of copper. The latter give a white with nitrate of suboxide of mercury and a fine sandy blue with salts of copper ;they liberate iodine from iodides ; aitd if dropped in the solid form into a concentrated sdution of platiuocpanide of potassium they are immediately coated with copper-coloured needles The platinidcyanides in solution exhibit both sets of reactions aid accordingly cannot be distinguished until crystallised ont when their dark coppery lustre at once characterizes them. The neatest way of forming the chlorine and bromine salts at once in a state of purity is to take a concentrated solution of a platino-cyanide measure off a sixth-part and cotivert it 5y an excess of chlorine or bromine into the perchloro- or perbromo-platinocgznide expelling the excess of the cklorine and bromine subsequently by a gentle heat and then adding the remaining five-sixths of platinocyanide; in a very short time the double salt will form abundautly in a state of perfect purity.

ISSN:1743-6893    

DOI:10.1039/QJ8611300106

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

BUCHTON ON THE STIBETHYLS AXD STIBXETHYLS. 115 XII.-On the Stibethyls and Stibmethyls. BY G. B. BUCKTON, Esa. F.R.S. CHEMISTSare already aware through the researches of Dr. Hofmann that zinc-ethyl reacts on terchloride of antimony in a manner similar to that shown by terchloride of phosphorus;-in the former case triethplstibine is formed in the latter case tri- ethplphosphine. The same successful labourer in this field of chemical inquiry in his profouiid and complete history of am-monia lately communicated to the Chemical Society groups these bodies as primary triamines or amrnonias in wliicli antimony and phosphorus severally play the parts of nitrogen and three equiva- lents of ethyl those af hydrogen. The following experiments were undertaken with the intention of testing how far the compounds of antimony with methyl and ethyl were limited to the ammonia-type and more particularly to determine whether by assimilating more than three in olecules of methyl &c.bodies might arise referable to the types of anti-monious and antimouic acids. 12 I16 BUCHTON ON THE Triethylstibine is known to combine with two equivalents of chlorine or iodine to form its haloYd salts. If substitution could be effected through zinc-ethyl in these substances a pentethylated radical mould arise showing the antimony in a complete condition of saturation. Coarsely powdered antimony attacks iodide of ethyl readily when sealed in tubes and exposed to a temperature of about 140" C. An oily liquid is formed composed of biniodide of triethylstibine with probably a little teriodide of antimony.This biniodide Sb(C,H,),I, produces considerable heat when mixed with zinc-ethyl a pasty mass being formed upon the surface of which a yellowish liquid floats. Distillation is attended by an abundant evolution of inflammable gas which is charged with the vapour of triethylstibine. To remove as far as possible the inconvenience of these dense white antimonial fumes the first distillation is best performed in a quilled receiver the tube of which is plunged into water. The yellowish heavy liquid obtained as above mas rectified in an atmosphere of coal gas. The first portion contained a little ether which ras separated after which the temperature rose to 150° between which and 170' C.all the liquid products passed over. The fraction boiling below 160' C. had the properties of triethylstibine but gave numbers slightly higher than those re- quired by theory Theory. Experiment. h -Sb '129 59.73' -Cl 72 33.33 33.51 33.97 Hl 15 6-94! 7.17 7.39 216 100.00 Triethylstibine when pure is a colourless and limpid fluid having a faint odour which can scarcely be styled alliaceous. An unpleasant and very persistent taste is left in the mouth when a small portion only of its vapour has been inhaled. It is spon-taneously inflammable in air but may be kept unchanged under a layer of water. It mixes with bromine under water without disengaging any noticeable quantity of gas and the oily bibromide of triethylstibine is formed.With hydrochloric acid hydrogen gas is liherated acd the corresponding non-fuming bichloride is produced. Triethylstibine is a very stable body and distils withont STIBETHYLS AND STIBNETHYLS. 117 change. Here it differs from Stanethyl which as Dr. Frank-land has shown deposits when heated half its quantity of tin and passes into stannic diethgl. Lowig and Sch weitz er found the boiling point of triethylstibine to be 159' C. 'A combustion of the samples boiling between 160' and 170' C. showed a considerable increase in the percentage of both carbon and hydrogen. Although the numbers obtained approach more nearly the com- position of tetrethylstibine than that of pentethylstibine it is thought more probable that the latter rubstance is really con-tained in the mixture.The percentage of carbon and hydrogen. was not increased by another rectification of the sample and it soon became evident that the body was broken up by heat. This observation furnishes an explanation of the copious liberation of gas noticed during the distillation of biniodide of triethylstibine with zinc-ethyl. Tetrethylstibine. Sample 1. Sample 2. Sb 129 52.65 -1- _. C, 96 39.19 37.51 37.44 35.96 35*4<4 €I2(-) 20 8-16 7.90 8.01 7.43 7.39 245 lOO.80 The decomposition of such a body by heat is analogous to that of pentachloride of antimony ~hich is thus known to yield chlorine gas and the terchloride In the same manner The existence of a stibium compound containing more than three molecules of ethyl was confirmed by the deportment of the sample under examination towards bromine.A portion of the fuming liquid was thrown up into the head of an eudiometer tube standing over mercury and small quantities of bromine were introduced from time to time. The mixture was attended with a violent action and a bulk of permanent gas was formed. As the neutral point was approached all visible action ceased but when the bromine was in slight excess a partial absorption of gas was noticed. As triethylstibine unites with bromine to form the bibromide without liberation of gas the appearance of ethylene and hydride of ethyl can only be explained by the presence of a more complex ethylated radical than triethylstibine 118 BUCKTON ON THE The absorption of gas also would thus be easily explained.Sb(C,H,) + 4Br = Sb(C4HJ3Br2 + C,H,Br + C,H,H. Triethylstibine passes into the non-fuming bichloride also more readily with concentrated hydrochloric acid than the substance here described which loses its character of spontaneous inflam- mability only after long boiling. It is remarkable that zinc-ethyl is not attacked by bichloride of triethylstibine even when the mixture is raised to its boiling point. The most characteristic salt of triethylstibine is the bisulphide which is easily formed by heating the radical with alcohol and sulphur. It crystallises in long silky needles which are readily soluble in water. This salt is rapidly decomposed by boiling in excess of aqueous cyanide of potassium.The cyanide is in this manner converted into sulphocyanide of potassium aud triethyl- stibine is liberated in white fumes. If the mixture containing the higher stibium-radical be boiled with alcohol and sulphur there is formed together with bisulpliide of triethylstibirie a corisiderahle quantity of bisulphide of ethyl. This substance becomes immediately evident by its powerful and repulsive odour. Although triethylstibine is remarkably persistent in itself its salts are in general easily reduced. The most convenient method of obtaining the radical triethpl- stibine is by distilling its salts with granulated ziiic. As the biniodide is easily formedj it is well suited for such an operation. The action is set up with some euergy ad the products are most corivcriiertly received under water.7 have failed in forming substitution-products by bringing to- gether trietliplstibirie and bisulpliide of carbon. The satrie failure also has happened in my attempts to cause a reaction between triethjlbtibine and t,ibromide of ethylene. AK~ interesting body from trictii ylpliosphine hornologous to sulphocar barnate of ammonium has been obtairied by Hofmann (C2S2)’’E,P 2PE3 + C2S4 = Witti triethylstibine the tubes invariably burst at a temperature of 240”C. and below this point no change appeared iu the materials. STIBETHYLS AND STIRMETHYLS Having some quantity of triethylstibine at my disposal a few experiments in confirmatiou of those of N.Lijwig were made.On the Salts of Tetrethylstibine. Triethylstibine was mixed with a slight excess of iodide of ethyl. In the course of it few hours a mass of fine crystals of iodide of tetrethylstibine was obtained. Iodide of tetrethylstibine when mixed with zinc-ethyl and distilled yields the same results as if biniodide of triethylstibine had been employed. Iodide of zinc fixed gases and a mixture of two radicals incapable of separation by heat were obtained. Oxide of Tetrethytstibine is very soluble in water and is un- crystallizable. When heated ahove 100' C. it undergoes decom- position with liberation of white fumes of triethylstibine. Sulphate and nitrate of tetrethylstibine are crystallirie salts. Chloride of Tetrethy lstibine is also crystalline.When dissolved in water and mixed with bichloride of platinum it yielded a fine yellow crystalline salt which was but little soluble in alcohol. When ignited and separated from the antimony the following analytical result was obtained. 0.7856 grm. of salt gave 0-1752 grm. of platinum which accords most nearly to the formula Sb(C!,H,),Cl.PtCl Theory requires. Found. Sb . 129.0 28.63 7 C16 H,,c1 ' . . . . 96.0 20.0 106.5 21-30 4.44 23.65 -- Pt . . 99.0 21-98 22.31 450.5 100.00 Lawig obtained a salt much richer in platinum to which he assigns the composition 3I?tCl, 2(Sb(C H5)*C1). Action of Zinc-methyl on Biniodide of Trimethystibine. As the methyl-molecule is simpler in structure than that of ethyl it was thought that a penta-methylated body might possibly resist decomposition during distillation.The biniodide of tri-methylstibine may be obtained in beautiful crystals by acting on BUCICTOX ON TIIE metallic antimony with iodide of methyl at a temperature of 140"C. As these crystals were found to decompose zinc-methyl energetically an appeal TF as again made to experiment. The materials were mixed slowly in a retort and after the first action had subsided the mass mas submitted to a temperature of 100' in a water-bath which removed the excess of zinc-methyl and ether. Subsequently the distillation of the solid mass was com- pleted over the sand bath. In this way a heavy pale-coloured liquid was obtained which after agitation with water and weak acid was rectified in an atmosphere of coal gas heat being applied by a water-bath.Fractions were tzken between 8Oo-86O 86'-96' 96°-1000 C. All these samples had the following properties They were oily bodies with faint oclours hca-vier than water with which they did not mix. When exposed to the air they were not spontaneously inflammable neither did they at ordinary temperatures give off white fumes. When dropped on a warm surface however they ignited and burnt with a luminous flame accompanied by a dense mtimonid cloud. The following numbers were obtained by analysis of these samples :-86"-96' -.-80"-86" 96"-IOO0 -31.64 -, 21-99 Carbon . . 21.20 26-90 30.18 Hydrogen . 5.08 5.23 5.92 6.83 6.98 Fw comparison the numbers required by theory for antimony with three four and five equivalents of methyl are appended.-7- Sb Me Sb Me4 Sb Me Sb 74-25 Sb 68.37 Sb 63-19 C 20.69 C 25.39 C, 29.46 H9 5*1G €Il2 6.34 H, 7.35 100.00 100.00 100.00 Notwithstanding the circumstance that the above samples are not spontaneously inflammable (a cham cter pre-eminently shewn by trimethylstibine) the composition of No. 1 seems to indicate its identity with that body. Before being confident with reference to the composition Qf Nos. 2 and 3 some weight must be given to an observation here made viz. that in the decomposition of zinc- methyl by a high temperature instcad of gases being eliminated as is known to be the case with zinc-ethyl hydro-carbons are pro- STIBETHYLS AMD STIBNETRYLS.duced which burn with a smoky flame. These substances I have not yet been able to examine but it would appear that the methyl- molecules undergo dupiication and thus give rise to bodies pos-sessing high boiling points. It is therefore possible that pentamethylstibine may be resolved by heat into trimethylstibine and such a hydrocarbon. This would account also for tlie excess in the carbon and hydrogen given by analysis of sample No. 3. In conclusion it is thought that a reviewal of these experiments in both the ethyl and methyl series will justify the conclusion that the higher stibium organo-radicals exist. A better method for their isolation however is still a desideratum. Apparatus for general fractional Distillation in Carbonic Acid Gas.A. Inverted bell glass with open neck. B. Stand with thick vulcanized indian rubber collar E. C. Circular table with sockets for holding bottles 1 2 3 &c. D. Thick glass rod sliding air-tight through col- lar and stand by which the table and bottles may be raised lowered or rotated at pleasure. P. Quilled re-ceiver and retort. I.and K. Tubes for entrance and exit of c'arbonic acid or other gas. C. Clamp with forked arm to secure the bell to the stand and permit the table to rotate eccentrically if required. The tube of the receiver may thus be introduced into any one of the bottles. H. Slate cover which may be ground to fit the lip of the bell or simply luted to it with linseed.

ISSN:1743-6893    

DOI:10.1039/QJ8611300115

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

122 XIIL-On Crystallized Sodium and Potassium. BY CHARLESEDWARD LONG. INendeavouring to prepare perfectly bright specimens of sodium and potassium I have succeeded in obtaining large crystals of both metals. I will briefly describe the method now employed. A piece of the best combustion tube about 2+ feet in length and 2-inch in bore is sealed up at one end and contracted before the blow- pipe at about one-third of its length horn the sealed end (fig. 1). A glass funnel with a wide rim (fig. 2) is then prepared so as to fit into the tube as represeuted care being taken that the funnel fits at the rim alone. Into the filter is introduced a piece of wire gauze in which a small hole has been cut at a (fig 2). The sodium (or potassium) is now intro-duced into the upper part of the tube in fragments \\hich have been freed from all adhering oxide and especially from rock-oil by cutting the metal clean with a knife.Before introducing the metal the tube is filled with coal-gas which has been dried and partly purified by passing through sil of vitriol. For this purpose the delivery tube is passed through the tube b which is fitted with a cork into the larger tube. After the introduction of the metal the gas is still passed into the tube; the delivery tube is then drawn out and the tube b is lightly corked The large tube is now drawn out and sealed before the blowpipe at c care being taken to avoid melting the metal lest it should attack the glass and render it brittle.The metal is next fused in the upper part of the tube and partially LONG ON CRYSTALLIZED SODIUM AND POTASSIUM. 123 poured off from the oxide so as to present a bright surface for the absorption of any oxygen there may be in the tube. The whole is then allowed to stand for several days after which the metal is again melted poured through the filter into the lower portion of the tube and allowed to solidify. The tube is now cautiously heated at d so as to detach the rim of the filter which will then readily fall back to the top of the tube on reversing its position leaving a perfectly clean surface of tube oi about 3 inches. The lower tube may now be drawn out and sealed at e. In this manner either metal may be obtained without the slightest tarnish or oxidation.In order to crystallise the metal it is fused over a Bunsen's lamp and allowed to cool; as soon as the solid points of crystals appear on the surface the liquid portion is poured off by suddenly inclining the tube. Specimens prepared in this manner 18 months ago still retain their lustre unimpaired. Sodium-Sodium presenting a perfectly clean metallic surface is not silver-white but is of a most beautiful rose colour. The colour is best seen when a ray of light falling upon a surface of the metal is reflected back from a second surface of sodium and again reflected from the first so that more of the light of the primitive ray is decomposed than by direct reflection since the great number of undecomposed reflected rays entirely masks the small number of pink rays as is the case with silver which is really yellow and not white.The pink colour of sodium is brought out more strongly by contrasting the metal with bright potassium which has a greenish-blue tinge. Sodium is obtained in large octahedra by crystallisation It does not crystallise in the regular sptem but most probably in tt-e quadratic system. As it is impossible to meastire the crystals by reflection o~ing partly to their being enclosed in a glass tube but chiefly to the irregularity of the faces which are always striated in a direction at right angles to the major axis I was only able to measure the facial angles by using a narrow tube provided with an arc and across which a fine hair was stretched.Ilrifortunately I have not obtained any crystals with the base-angles well defined. The following are measurements of the angle of the apex :-Angle of apex. I 1 2 3 Crystal I. face a . . 49O.8 5OO.O 50O.5 faceb . . 50"-5 50"*0 49O.5 Crystal 11. . . 49" 5 50"-0 49"*5 WANKLYN ON ZINC-BIETHYL. -Potassium-Has a greenish or greenish blue tint. The beauti- ful green colour of the vapour may be observed by volatilizing a small portion of the metal in a sealed tube contaiiiing no oxygen. It is much more crystalline metal than sodium but is more difficult to obtain in good crystals since it passes almost imme- diately from the liquid to a pasty state. The crystals present an almost smooth metallic appearance for a few moments after the liquid metal has been pourd off.Suddenly they assume the appearance of frosted silver a network of minute lines darting out in every direction. For this reason they disperse light much more than sodium crystals whereby the real colour of the metal is effec tuallp rnasked. Potassium crystallises in obtuse octahedra belonging to the quadratic system. Tlre following are the measurements of the three facial angles of one of the crystals. In crystal 11 I was only able to measure one of the angles of the base :-1 2 3 Crystal I. Angles of base 5.2'*0 52'9 52O.O !$ 52O.O 52"*0 52O.O Angle of apex y 75O.5 75O.8 76O.O 1 2 3 4 Crystal 11. Angle of base 52'-0 51'5 51"*8 51O-8

ISSN:1743-6893    

DOI:10.1039/QJ8611300122

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

WANKLYN ON ZINC-METHYL. XN.-On Zinc-methyl.* BY J. A. WANKLYN, F.R.S.E. DEMONSTaATOR OF CHEMISTRY IN THE UEIVERSITY OF EDINBURGH. ZINC-METHYL was discovered rather more than ten years ago by Frankland. It was then obtained nearly pure but in quantity so small that many of its leadiug physical properties including its vapour-density specific gravity and boiling point were not determined. Xore recently the subject has again been taken up by the same chemist who this time operated upon several pouuds of materials and under conditions widely differing from those of his former experiments. * An abstract of this paper waa read before the Royal Society of Edinburgh April Znd 1860. WANKLYN ON ZINC-METHYL. The latter investigstion has however not been so successfult as the former inasmuch as it has given no piire zinc-methyl having instead disclosed peculiar and unlooked-for difficulties in the preparation of th3t compound.When zinc and iodide of methyl are heated together in closed tubes the following reactions take place :-(1) . Zn + C2H$ = ZnI.ZnC,H (2) . Zn + ZC2H,T= 2ZnI + C,H,.C,H,. At moderate temperatures the former rcaction predominates ; at higher temperatures the latter. When only iodide of methyl and zinc are employed and no ether is used it is imporsible to obtain complete decomposition of the iodide without at the same time obtaining much gas. This circumstance renders it imprac-ticable to prepare much zinc-methyl by this method as the high pressure of the generated gas necessitates the employment of very small tubes.The copper digester which Frank land emplop for the manufacture of this class of siibstances cannot be made to replace the small glass tubes. Frankland has found that when the materials are heated in the copper digester no pure zinc-methyl can be obtained. A mixtiire of ether with iodide of methyl is easily converted into iodide of zinc and ethereal solution of zinc-methyl. Here however a fresh difficulty arises. Fractional distillation does not avail to separate ether from zinc-methyl. And so pertinaciously do these two liquids cling to oiie another that it is even a matter of doubt whether a chemical compound does not exist between them. To this point our knowledge was advanced by the publication of Frankland's paper" last year.My attention was drawn to this subject in the course of my investigation of the compounds formed by methyl with the alkali-metals. These compounds are prepared by acting upon zinc-methyl with the alliali-metals. At first I employed the solution of zinc-methyl in ether but I found the ether to be a very troublesome complication and therefore was led to enquire whether it were really impossible to obtain zinc-methyl in a state of purity and at the same time in considerable quantity. 'Ann. Ch. Pharm. cxi. 62; also Bakerian Lecture 1859. 126 WANKLYN ON ZISC-3lETHYL. During my experiments I observed the fact that a strong ethereal solution of zinc-methyl equally with ether renders the decomposition of iodide of methyl by zinc easy and comparatively unaccompanied by the cirolution of free methyl.Thereupon I tried a stronger solution of zinc-methyl and found it also effectual. A still stronger solution was also successful and it seemed that even pure zinc-methyl itself possesved the same property. Here then was an available method of making pure zinc-methyl. Strong ethereal solution of that compound was first prepared. The strong ethereal solution was next mixed with iodide of methyl and sealed up with zinc; then after digestion in the water-bath distilled. In this manner a stronger solution of ziiic-methyl was prepared. By repeating the process a sufficient number of times the amount of ether originally taken was made to bear a very trifling ratio to the ultimate product; and indeed could be made to vanish altogether.In evidence of the practicability of the plan just proposed I may mention that the product from a single tube which had undergone four successive digestions amounted to about half an ounce and proved to be zinc-methyl as pure as the gramme or two obtained by Frankland ten years ago. Before giving the analysis of this sample I will just men-tion it few particulars cennected with its preparation which may be interesting to any one who may desire to prepare the compound. The digestions were ail made in the water-bath the substance being always contained in glass tubes. In order that an ounce or two of iodide of methyl might be with safety heated in a single tube the precaution mas taken of opening the tube several times in the course of the digestion.By this means a dangerous accumulation of hydro-carbon gas was avoided. The distillation of the zinc-methyl was made over the naked flame. Finally previously to the last distillation a digestion with metallic-zinc without any fresh iodide of methyl was made. I map aiso mention that iodide of zinc forms with zinc-methyl a crpstalline compound of great beauty and very different in appearance from the crystalline compound between iodide of zinc and zinc-ethyl. This compound containing probably one equivalent of zinc-methyl corn bined with one equivalent of iodide of zinc I regard as the repiesentative of the so-called iodide of mercury-methyl obtained by Fran kl an d.WANKLYN ON ZINC-METHYL. Double zinc compound. Double mercury compound Passing on to the properties of the half-oiince of zinc-methyl whose preparatiori I have just described :-It mas highly inflam- mable and acted upon water with explosive violence agreeing with Franliland's description of that compound. In one particular however our observations do not accord with one another. The poisonous nature of the fumes their action upon the nervous system which Frankland mentions," I have not been able to verify. I have distilled zinc-methyl more than a dozen times and been much exposed to its fumes and still have not been able to mark any particular effect upon myself. In addition to the properties detailed by Frankland I have to record that sinc-methyl in a state of purity is very per- manent.If carefully excluded from the atmosphere it will bear without decomposition a temperature of at least 200"C. r At about 270" C. it begins to be reduced to metallic zinc and hydro-carbon gases. I have made an analysis of the sample of zinc-methyl with the following results :-I. 01134 grm. of the liquid were passed up into a graduated tube standing in the pneumatic trough and filled with water. Hydride of methyl was evolved measuring 48*77 cubic-centimeters (dry) at 760 m.113 pressure and O'C. This equals 0034898grm. by weight :-Hydride of methyl per cent. =30*77 11. -1172 grm. similarly treated gave -0361 grm. of hydride of methyl or 30.83 per cent. The theoretical percentage of hydride of methyl which pure zinc-methyl should give on treatment with water equals 33.51.These results do not depart from the theoretical quantity firther than that which Frankland published ten years ago. His percentage of hydride of methyl was 29.91. In estimating the value of these determinations it should be borne in mind that the quantity of hydride of methyl obtained represents its equivalent of unoxidized zinc-methyl. The slightest oxidation tells enormously upon the analysis; for not only does * -4nn. Ch. Pharm. lxxi. page 214. WANKLYN ON ZINC-METILYL. the oxygen lower the percentage of methyl by its presence but by combining with a certain amount of zinc-methyl it still further lowers the percentage of methyl which can clecoinpose water.The great violence of the reaction between zinc-methyl and water is also a source of loss especially %hen water and not mercury is the confining fluid as was the case in both Frankland's analysis and my own. A determination of' the vapour-density by Gay Lussac's method was also made. 01163 grm. of zinc-methyl were employed. The temperature to which the vapour was exposed was 100"C ; the boil- ing point of the compound lying between 50" C and 60' C. The ex- periment gave 3.291 as the vapour density of zinc-methyl. If as seems likely the condensation of this compound is analogous to that of its ethyl representative the theoretical vapour-density is 3.299 a number which is nearly identical with that found by experiment.The accurate determination of its boiling point and also of the specific gravity in the liquid state I hope shortly to have an opportunity of making as I expect at no very distant period to be in possession of several ounces of pure zinc-methyl. I cannot conclude this paper without calling attention to the very remarkable state of condensation disclosed by examination of the vapour-densities of zinc-ethyl zinc-methyl mercury-ethyl mercury-methyl and indeed of all the so-called organo-metallic bodies so far as has yet been investigated. It has been said the metals are the strict representatives of hydrogen; and yet in not a single compound of a metal with a hydro-carbon radical Tias the metal been found in the state of condensation of hydrogen.If we write the formuh of equal volumes of several of these bodies we arrive at the following expressions :-Zinc-methyl. Zinc-ethyl. Mercury-methyl Mercury-ethyl Distann-methyl. Distann-e thy1 . Writing also the formuh of equal volumes of the fiydrogen alld oxygen terms for comparison with the former :- GGTHRIE ON SOME DERIVATIVES FRON TBE OLEFINES 129 Hydride of methyl. Hydride of ethyl. Methyl-ether. Ethyl-ether. Inspection of the above shows that considered as to the state of condensation in their hydro-carbon compounds the metals do not represent hydrogen mercury and zinc represent oxygen. Nor is this peculiarity confined to the organic case. Deville and others have recently taken the vapour-density of various metallic chlorides and have found that these likewise are present in a more condensed form than their hydrogen representative. Whereas the formula of hydrochloric acid is ,the formula of an equal volume of metallic chlqride is

ISSN:1743-6893    

DOI:10.1039/QJ8611300124

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

GGTHRIE ON SOME DERIVATIVES FRON TOE OLEFINES 129 XV.-On some derivatives from the OZeJines. BY FREDERICK GUTHRIE. 1x1. THEintroduction of nitroxine* into organic bodies and the forma-tion of the so-called nitro-compounds has been hitherto effected with apparently a single exceptiont by the action of iiitric acid either alone or in presence of sulphuric acid The reason of this is obvious :-such introduction has in every case .consisted in the replacement of hydrogen by nitroxine. The nitric acid offers its fifth atom of oxygen to the hydrogen being replaced while the nitiwxine replaces it. Such replacement is of course double recomposition expresssed generally by the equation and is quite parallcl to the reaction attending the formation of *It will be found conrenient to call NO nitrozine a compact term recalling the analogy which this molecule bears to chlorine iodine etc.Accordingly the nitrites MONO, will be nitroxides MNO as has been sometimes proposed. Further regarding the nomenclature as with the chlorides C H&12is bichlor-ethy!ene C,H,CI bichloride of ethylene etc.:-So with the nitroxides C,,H7N0 Nitroxinapthaline loH,,2N0, Binitroxide of Amylene etc. 'k See below ;nitroxinapthaline. VOIJ. XZlI. H GUTHRIE ON SOXE DERIVATIVES the chlorine substitution derivatives obtained by the action of chlorine C,. ...H + p(C1 Cl) = C,. *..H,-,Cl + pHCl and probably also to that which occurs when chlorine is introduced by means of hypochlorous acid. The formation of binitroxide of amylene C,,H1,.2N0, by the action of nitric acid upon amylene * immediately suggested the question:-May the olefines whose privilege it is to combine directly with two atoms of the halogens without elimination of hydracids behave in a similar manner towards nitroxine ? If nitroxine prepared by heating anhydrous nitrate of lead be passed through an empty bottle and then into a flask containing amylene the gas is instantly absorbed and the amylene gradually becomes converted into a pasty mass of minute crystals.To avoid loss the flask containing the amylene should be surrounded by a freezing mixture. The product is thrown upon a filter washed with cold alcohol in order to remove an oily liquid which accompanies the crystals then recrystallised from boiling ether and dried in vacuo over sulphuric acid.I. 0.2682 grm. gave 0.3664grm. carbonic acid and 0.1572water. 11. 0.2290grm. gave 32.3 cc. of nitrogen at 760 mm. and 0" C which gives Calculated Found I. 11. c, . 37.09 37.26 ti 'I 'I JY H, 6.18 6.51 N* . 17~28 Ji 17.66 0 ' Yi >Y 3 This substance is therefore the binitroxide of amylene CloHlo. 2N0 and is identical with the crystalline body obtained by the action of nitric acid upon amylene (see 11). It is curious as being the only known nitroxine-isotype of Dutch liquid but more remarkable in this latter manner of its formation as furnishing the only instance in organic chemistry of the behaviour of free nitroxine as a halogen without the elimination of hydrogen.Bintroxide of amylene is but slightly soluble in cold but readily in boiling alcohol ;it dissolves in ether and in bisulphide of carbon *See 11. FROX THE OLEFINES. but is perfectly insoluble in water. It crystallises in small square and rectangular colourless transparent plates. Heated by itself in a dry tube binitroxide of amylene decom- poses exactly at 95OC. giving rise to a gas and to a liquid heavier than water. The decomposition of a portion having been effected in a very strang sealed tube by heating to loo* C. the tube on opening gave off much gas which reddened moist litmus paper. Another portion was treated in the same way in presence of' water. After opening the tube neutralizing the acid water with ammonia filtering and evaporating to dryness on a water bath a residue was obtained which gave off nitrogen on being heated.Accordingly the gas evolved from the binitroxide of amylene was nitrous acid NO, or nitroxhydric acid HNO,. The next point was to determine the nature of the liquid product the supplementary factor to binitroxide of amylene which appears in the preparation of that body. The filtrate and alcoholic washings from binitroxide of amylene after evaporation for some hours on a water bath washing with water and drying yielded an amber-coloured transparent liquid heavier than water and immiscible with it. Neither this liquid nor the binitroxide of amylene underwent any change on being kept for several days in an atmosphere of nitroxine.On analysing the liquid 0.2586 grm. gave 0.3882 grm. of carbonic acid and 0.1717 water. The substance whose composition corresponds most closely with these numbers is a mixture of equivalent quantities of bini-troxide of' amylene with nitrate of amyl. Found. 10H10*2N04 C,,H,,O*NO!, C . . 40.67 40.94 H.. 7.12 7.37 Although the presence of amyl would point to the disintegration of anather molecule of amylene the above given composition of this mixture is rendered probable on the following grounds :-On heating to 95' C.,* it undergoes decomposition whereupon the temperature rises spontaneously to 170" C. and the greater * Identical nith that at which C,,K,,.2NO4 is decomposed K2 132 GUTHRIE ON SOME DERIVATIVES quantity of the liquid passes over.On rectifying a portion was obtained which boiled almost constantly at 160' C. Of this 0.2263 grm. gave 03850 grm. carbonic acid and 0-1712grm. Found. C,OH,,ONOB C . . 4511 46-40 H.. 8.27 8.40 On boiling a portion of this distillate with an alcoholic solution of caustic potash nitrate of potash was formed. The original liquid also gave rise to nitrate of potash under the same circumstances. Nitrate of amyl also appears among the liquid products formed when binitroxide of amplene is heated by itself. Heated with quick lime binitroxide of amylene gives rise to an aromatic body differing from valeral and probable amylenic ether C,OH,,O,* The actions of sulphide of ammonium nascent hydrogen and other reducers upon binitroxide of amylene will be well worthy of study.As yet my attempts to combine nitroxine with ethylene have not been successful. Neither protoxide nor binoxide of nitrogen has any action upon amylene. The affinity of amylene for nitroxine is so great that by means of this hydrocarbon a very small trace of nitroxine may be detected in the above named nitrogen-oxides. Thus if amylene be added through a funnel tube to a flask containing copper and nitric acid which is kept quite cold and from which the evolved gas has expelled the air crystals of binitroxide of amylene are continuously though slowly formed; but if the binoxide of nitrogen be first absorbed by protosulphate of iron and then expelled thence by heat* and made to pass through amylene in an apparatus from which a current of carbonic acid has expelled the air no change occurs.Nitroxinapthalin. (Witronapthalin.) The laborious reseaches of Laurentt and others have long since established the claim of napthalin to be an olefine. It combines directly with chlorine to form bichloricie of napthalin C,H,Cl, 8nd although it may unite with four atoms of halogen as in the * Bunsen's Gas~m?~fy.Engl. Ed.p. 51. -t. Ann. Ch. Phys. '8'9 lix. FROM THE OLEFINES. quadrichloride C,H,Cl, in the tercliloro bromide C,oH,C1,Br and in their numerous idiotypes C,,H6Cl,C1 quadrictiloride af bichlornapthalin. C2,HGBr2C1 quadrichloride of bibronapthalin etc. etc. yet as we have already seen in examining the behaviour of ethylene and amylene towards chloride of sulphur ad as we shall abundantly see in the sequel this assumption of four haloid atoms is quite consistent with the nature of the olefines isotypic with ethylene.Like ethylene napthalin combines with anhydrous as well as with hydrated sulphuric acid and finally in napthalamim C,,H,HN me find it still preserving the biatomic character of an olefine taking the place of two atoms of hydrogen. Laureiit’s exaiuiuation of the action of nitric acid on napthaline resulted principally in the discovery of three nitroxine-replacemeut derivatives idiotypic not with the bichloride of napthalin but with napthalin itself. Nitroxinapthalin . . C20H,(N04) Bini t roxinap thalin . C,OHG(NO,) Triuitroxinapthalin .%OH (NO,) Bearing in mind on the one hand the analogy which these bodies have to the chlorine-idiotypes of ethylene and on the other the above described direct union of mnylene with nitroxine we might h priori expect to obtain nitroside of napthalin or binitroxide of napthalin by the action of nitroxine on napthalin. So that although Laurent gives this reaction as a method of preparing nitroxinapthalin yet as no analysis appears to have been made of the body so produced I thought it worth while to comfirm Laurent’s experiment. If napthalin be thrown into a ffask containing aa excess of nitroxine considerable heat is developed scanty white fumes are formed which quickly subside and an oily liquid resdts whioh solidifies on cooling.To ensure complete reaction the flask is corked with an excess of nitroxine and the product is repeated13 shaken and melted. After re-fusion under water drying and recrystallisa- tion from ether a product was obtained which gave on analysis 0.4202 grm gave 1.0707 grm. CO and 0.1590 grm water. C,,H (N 0,) Found. C . . 69-36 69.49 H . . 4.05 4.20 134 GUTHRIE ON SOME DERIVATIVES FROM OLEFINES. The substance formed is therefore undouhtedly nitroxinapthalin. We accordingly find that nitroxine in its behaviour towards napthalin more closely resembles bromine than chlorine ; for while the former gives bromonapthalin the latter gives bichloride of napthalin c20€€, + 2c1 = C2,€€,Cl2 C2,Hs + 2Br = C,,H,Br -/-HBr CmH8 + 2NO,= C,,H,NO + HNO, BisdphoclzkmYe of Ethylene.Although as before shown,* ethylene and bisulphide of chlorine are without appreciable action on one another under ordinary circumstances of temperature etc. and although a temperature of 139"C. effects a disintegration of the ethylene-moleculet. I have again sought to unite the two directly because the result- ing body if it resemble its amylene-isotype would give rise to a highly important series of derivatives. $ If bichloride of sulphur be exposed in a stoppered bottle in an atmosphere of dry ethylene to direct sunlight the two unite slowly but almost completely hydrochloric acid however being liberated. If a few grammes of bisulphide of chlorine be placed in a well-stoppered bottle which is then filled by displacement with ethylene the waxed stopper inserted and covered with sheet-caoutchouc and the whole be completely immersed for twenty hours in boiling water very complete absorption is found to have taken place on opening the bottle while only a trace of hydrochloric acid is formed.The bottle may be then refilled with ethylene and the same operation repeated three or four times. The resulting product is then shaken up with warm water dried digested with ether filtered evaporated in vacao till the ether is expelled dissolved again in a minimum of ether filtered and evaporated in vacao. gm. grm. m. 1. 0.3058 gave 0.2908 carbonic-acid and 0.1184 water. 11. 0.2197 , 0.2356 water. 111. 0.1798 , 0.2638chloride of silver. IV. 0.2829 , 0.6934 sulphate of baryta.* Niernann. Ann. Ch. Pharm. cxiii. 3; F. Gnthrie ibzd. +Chem. Yoc. Qu. J. March 1860. $ See Memoir iv. HOWARD ON THE HISTORY OF CINNAMIC ACID. 135 Found. C4H,S,C1 I. 11 111. IV. C = 25.13 25.93 1 J> >J H= 419 4.30 (4.33) 9) ?J S = 33-51 I JJ >Y 33-47 C1= 37.17 JY >> 36.29 92 100*00 100~01 This substance is according to the previously adopted nomenclature the bisulphochloride of ethylene C4H4.S,Cl. Bisulphochloride of ethylene has a not unpleasant but indescribable smell ; its taste is intensely sweet and pungent. Like the bichlorosulphide of ethylene its annoying effect upon the eyelids is very enduring ;* Its colour is a pale yellow ; specific gravity 1.846at 19 C.* Like the previously described chlor-sulphur compounds of the olefines it is decomposed by heat and gives off an insupportable smell. In the next communication I shall describe the action of anhydrous and hydrated oxides upon this substance and the behaviour of it and its isotype bisulphochloride of amylene upon some of the metal-radicles.

ISSN:1743-6893    

DOI:10.1039/QJ8611300129

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

HOWARD ON THE HISTORY OF CINNAMIC ACID. 135 XVI.-Contribution towards the history of Cinnamic Acid. BY DAVIDHOWARD. NOTWITHSTANDING the experiments of Gerhardt and Cahours and the subsequent researches of Blyth and Hofmann the history of cinnamol and its derivatives is far from being complete. To fill up some of the gaps still existing I engaged in some experi- ments upon this interesting group of substances. In the prosecu-tion of my enquiry I had an opportunity of observing some facts which I beg to lay before the Chemical Society. Liquid storax treated in the usual way afforded the crude * A drop placed beneath the tongue destroys the epidermia and causes a soreness which lasts many days. ROWARD ON THE cinnamic acid for the experiments.For the purpose of purify-ing it I adopted the plan recommended by some chemists of submitting the crude product to careful distillation. To my surprise a large portion of the distillate came over in the form of a permanent liquid. The smaller portion which so!idifieci on cooling was purified by crystallisation and converted into a silver salt. The silver determination gam the following result *2090grm. of the silver-salt left on ignition *Q9850grm. = 47.13 per cent of metallic silver. The percentage of silver in benzoate of silver being 47.16 it was obvious that the solid distillate consisted of benzoic instead of cinnaniic acid. To find whether this benzoic acid was present in the original crude acid or whether it had been formed by the destruction of cinnamic acid a portion of the crude acid was recrystallized and converted into a silver-salt.05735 grm. of this salt left on ignition *2500grm. of metallic silver = 43.59 per cent. 42-37being the percentage of silver in cinnamate of silver it could not be doubted that the crude acid employed contained an appreciable admixture of benzoic acid. It was therefore further purified by solution in alcohol and crystallisation by epontaneoris evaporation of the solvent when large regular crystals were obtained which on analysis of a new silver-salt proved to be purc cinnamic acid. *ti170grm left .It190 = 42.36 per cent. of silver *SO85grm. left ,2150 = 42.28per cent. of silver. These numbers coincide with the theoretical percentage of cinnamate of silver.A careful distillati611 of this pnye acid afforded together with a large portion of an oily product a small quantity of an acid mliich solidified in the neck of the retort. This acid was converted into a silver-salt and in this form submitted to analysis :--2255 grm. left on ignition -0955 = 42-35 per cent. of silver -2165 grm. left on ignition 9915 = 42-27per cent. of silver. The distilled acid was therefore undecomposed cinnamic acid. In other experiments in which the acid was submitted to a still slower distillation the whole of it was entirely decomposed and converted into liquid products of decomposition. RISTORY OF CINNAMIC ACID. 13'7 Thus it would appear that cinnamic acid contrary to the state- ments of most Manuals is decomposed when kept at a boiling heat and that it can only be distilled even partially unchanged when very rapidly heated care being taken to carry over the vapour as quickly as possible by keeping the upper part of the retort at a very high temperature.In order to find whether cinnamic acid would decompose when maintained for a long period at a somewhat lower temperature a portion of the acid was sealed up in a glass ttibe and heated for several hours to 200"C. in a paraffin bath ; no change however took place. Another portion was similarly heated in presence of water. It remained likewise unchanged the silver-salt yielding the following percent age :-*4805grm. gave -2040 =I 42.45per cent of silver. The fluid which is formed by the action of' heat upon cinnamic acid proved on investigation to be almost pure cinnamol; the boiling point remained constant at 145" C.till the greater part of the liquid had passed over when the temperature rose rapidly leaving in the retort a resinoid mass of metacinnamo2. By treat- ing the liquid with bromine the characteristic crystalline dibromide of cinnamol was obtained; and by exposing a portion sealed up in a tube to 200° it was entirely converted into a glassy mass of metacinnamol which when submitted to a still higher temperature was reconverted into cinnamol. These properties identify the oily product of decomposition of cinnamic acid with cinnamol or what is the same thing with styrol although it appears that the tendency to pass into the solid condition is perhaps leas marked in this liquid than in styrol a fact noticed by other observers in cinnamol foymed by the usual process.When very carefully heated cinnamol obtained by the destructive distillation of cinnam'lic acid may be almost entirely distilled without the production of the solid modification. The preceding experiments prove that at a temperature very near its boiling point cinnamic acid is decomposed into cinnamol and carbonic acid according to the equation a decomposition similar to the transformation into benxol and carbonic acid which benzoic acid undergoes when its vapour is passed through a red hot tube. HOWARD ON THX The cinnamol thus obtained from cinnamic acid amounts to from a fourth to a third of the acid employed so that this reaction furnishes a method of preparing cinnamol much more easily and much more copiously than it could be hitherto obtained.Cinnarnol obtained in this manner is perfectly free from benzol. It is well known that the liquid obtained by the usual process viz. distillation of cinnamic acid with lime and even baryta consists of a mixture of hydrocarbons in which so large a proportion of benzol is present that some chemical Manuals state the boiling point of cinnamol at 89" C. proving that the proportion of cinnamol in these mixtures is excessively small. The dry distillation of pure cinnamate of lime likewise furnishes cinnamol qiiite free from benzol thus affording a remarkable contrast to the behaviour of a mixture of cinnamic acid and excess of lime.The crude cinnamol obtained from either cinnamic acid or cinnamate of lime contains a small quantity of a crystalline substance which may be separated from the more volatile cinnamol by distillation with water ;the formation of metacinnamol is thus in a great measure prevented arid the substance in qiiestion may be extracted from what is left in the retort by alcohol from which it crystallises. When purified by several crystallisations from boiling alcohol which dissolves it freely while cold alcohol retains a comparatively small portion the crystallirie substance presents itself in the form of brilliant pearly scales which on analysis gave the following results :-I. '1563 grm. gave *5341carbonic acid and *0992water.11. -2500 grm. gave -8605 carbonic acid and ,1545water. These numbers represent a hydrocarbon C,,H6 or a multiple of it Theory Experiment c,* I. 11. 84 93.33 93-19 93.76 6. 6.67 7*05 6.86 H6 -. -90 100~00 The crystalline substance when gently heated with bromine gives rise to the formation of a bromine-compound which is only slightly soluble even in boiling alcohol. The hot solution deposits on cooling minute scales exhibiting a slightly reddish tint. On analysis the following results were obtained :- HISTORY OF CINNAMIC ACID I. -2780grm. gave *5060carbonic acid 0.985water 11. *1915grm gave 02120bromide of silver 111. *2020grm. gave 02255bromide of silver. The formula C,,H6Br requires the following values which 1 place in juxtaposition with the experimental numbers :-Theory Experiment 7 I 11.111. 84 49.41 4964 .-c1* . 6 3.53 3.68 -H6 Br . . 80 47.06 -47.10 47.50 -7-170 100.00 The formation and composition of the bromine-compounds could leave but little doubt that the crystalline hydrocarbon must be represented by the formula C2*H12. A hydrocarbon of precisely the same composition and exhibiting also the general characters of the substance derived from cinnamic acid was described some years ago by Laurent. He obtained the body which he calls cCstilbene,” together with another crystalline body ‘‘thionessal,” in the destructive distillation of hydride of sulphobenzoil thus Eydride of Sulphobenzoll Stilbene Thionesml 8C14H6S2= 2c,s4 4-6HS 4-2C,,HI2 3-C,2H,,S2* In order to establish the identity of the two substances I have prepared a quantity of stilbene according to Laurent’s process In repeating the experiments of Laurent I observed all the phenomena described by that chemist.On comparing the stilbene procured in this manner with the crystalline substance obtained from cinnamic acid it was impos-sible to doubt their absolute identity. I have nothing to add to Laurent’s description except that stilbene prepared by the dry distillation of either hydride of sulphobenzdil or of cinnarnic acid fuses at 125”C. The transformation of cinnamic acid into stilbene is obviously the result of a destructive process which does not admit of simple representation in formulae. The experiments which I have described were performed in Dr. Hofm a n n ’s laboratory.

ISSN:1743-6893    

DOI:10.1039/QJ8611300135

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

140 XVTI.-Action of Sodzum upon Iodide of Methyl mixed with Ether. F.R.S.E. AND IF. BUGHEISEN, BYJ. A WANKLYN PH.D. PUREmethyl has not yet been obtained. Kolbe's method viz. electrolysis of an acetate yields methyl always contaminated by some foreign body probably oxide of methyl which cannot be conipletely removed. Frankland's method viz. decomposition of iodide of methyl by zinc also gives a mixture which in this case consists of bydride of methyl and free methyl. This hydride of methyl Frankland regards as a secondary product foymed after the gas has left the production tube and due to decomposition of moisture by some zinc-methyl with which the gas as it issues forth is invariably accompanied. Bearing this circ\Jlmstance in mind we determined to try the action of sodium upon iodide of methyl Since sodium-methyl cannot be prepared by such a process we expected to obtain pure methyl.Our expectation mas not realized as will appear in the course of the paper. The iodide of methyl used in our experiments boiled constantly at 43" C. We enclosed in a glass tube some sodium along with a few grammes of iodide of methyl and ether. In order to insure the absence of moisture we next made a short preliminary digestion in the water-bath. Then we let out the first portion of gas which was no doubt contaminated with products due to traces of water adhering to the materials employed in the experiment. After-wards we resealed the tube heated again to 100"C. and collected the gas over boiling water.After having stood in contact with water during a night the gas was analysed according to the method employed by Bunsen. We give the particulars of the analyses :-The gas was divided into two portions one of which was placed in the combustion eudiometer and the other in the absorption tube. WANKLYN AND BUCKEISEN ON IODIDE OF METHYL. 141 I.-h the Eudiometer. I 1 I Volume re- meter ----26*9"C. 0'15085 --Volume of gas taken . . . . . . 72'00 --19.8876 Volume after addition of oxygen . . 180.96 27.1" 0,25844 42.547 ---_ ------Volume after addition of air.. . . 340 90 26.2" 0.41561 159.28 .--.-,---c_-___I_ --308.54 26 '7" 0 38336 1075'4 Volume after explosion . . . . --_II-____.----Volume after absorption of CO ,.276.42 25 5" 0.378 95-221 ----..--L______----Volume after addition of Hydrogen.. 375'0 26.7" 0.4717 161'13 --l__l_-_--Volume after explosion ,. . . 253.98 273" 0 3575 82.23 I 1 &-.In the absorption tube. Volume re- Volume Tempe-Pressure duced to 0°C. sature and 1 meter pressure -___I--meter Volume of gas taken . . . . . . 93-70 26.9" 0.65305 559'06 I Volume after the action of potash 90.63 26.6" 0.6781 55.591 and pyrogallic acid.. . . Volume after the absorption of oleflnes Some gas after the removal of Cd2 oxygen and olefines was transferred from the absorption tube to the eudiometer Its analysis gave the numbers following :- 142 WANRLYN AND BUCKEISEN ON THE ACTION OF SODIUX 1x1.-In ti%e Eudiorneter.26*?"C. 0'16676 12.809 Volume taken ........ -84-32 --- ---.---_I ---.I-26.70 171.12 177-12 Volume after the addition of oxygen . . 399.36 26.7" 0.48686 - ---I-----_I--_ Volume after explosion .... 364.95 27.8" 0.45242 150.11 ---__I_-----__I_-Volume after the absorption of car-} 330.25 car-2S*lo 0.4463 134.99 bonia acid ...... Another analysis of the same gas yielded 2-IV.-Tiz the Eudiornete r. Corrected at 0" C. and one meter pressure Volume taken ................ 10-365 1Volume after the addition of oxygen .......... 260.75 1Volume after explosion .............. 138.40 Volume after absorption of CO ............125.60 I A third analysis of the same gas gave :-V.-.h the Eudiomejeer Corrected at 0' C.and one meter pressure I 1Volume taken ................18.037 IVolume after the addition of oxygen .......... 85.611 I Volume after the addition of air ............198'04 Volume after explosion and absorption of CO ........ 137'05 ---__.--___.---Volume after addition of hydrogen ..........258.61 -----.----Volume after explosion ..............114.73 UPON IODIDE OP METHYL MIXED WITH ETHER 143 Analysis 11. shows that the gas was free from carbonic acid and oxygen. It also shows that 55.706 volumes of the gas contained 5.155 vol. of olefines. In percentage C,H . 9.3 b Gas freed from C,H . . 90.7 _I_ 100.0 Analysis I. shows that 9.8876 vols. of gas contain 0.368 pol. of nitrogen. In percentage nitrogen = 3.7.Analysis V. of the gas free from C,H shows that 18.037 vols. contain 0.21 vol. of nitrogen or 90.7 vols. contain 1.05 vols. of nitrogen. But 100 vols. of the original gas contain 90.7 vols. of gas free from C,H,. Therefore 100 vols. of the original gas contain 1.05 vols. of nitrogen. The determination of nitrogen at the end of a hydro-carbon gas analysis is subject to a little irregularity inasmuch as the small quantities of air introduced in the course of the analysis tell in the aggregate upon the final nitrogen determination. Adopting the mean of our two results we have 2.4 for the per- centage of nitrogen. From Analysis I. we obtain :-In percentage. Original gas . 9.8876 10o'o Nitrogen . . . 0.237 2.4 Combustible gas .. 9.6506 97.6 Oxygen consumed . . 24*4084 246.9 Carbonic acid formed . 12.519 126.6 Analyses III. IV, and V. all of the residual gas after removal of C,H give :-III. Iv. V. Mean. Combustible gas . 12.507 10.091 17.560 88.3 Oxygenburnt . 29.623 25.059 43.430 215.7 Carbonic acid formed 15.120 12.80 __. 109.1 To arrive at the condensation of the olefines we make use of the following data :-100 vols of the original gas are composed of 9.3 vols. of C,H,. 2.4vols. of nitrogen. 88-3vols. of residual hydro-carbon. 144 WANKLYN AND BUCKEISEN ON THE ACTION OF $ODIUM And on combustion furnish 246.9 voh oxygen consumed. 126.6 vols. carbonic acid. 88.3 vols. of the residual hydro-carbon gas furnish 215.7 vols. oxygen consumed.109.1 vols. carbonic acid. Hence the 9.3 vols. of C,H furnish 31.2 vols. oxygen consumed. 17.5 vo1s. carbonic acid. The C,H, therefore has the condensation of ethylene which requires Vol. taken . . 1.0 Oxygen burnt . 3.0 Carbonic acid . 2.0 With so low a percentage of CnHn as is present in the gas under examination great accuracy in the determination of its con-densation is not to be expected; the very indirect manner of arriving at the result having the effect of concentrating the errors of the whole analysis upon the small percentage of olefine. The 88.3 vols. of hydro-carbon must consist for the most part of marsh gas. Some other more complex hydro-carbon is also present ;but what other cannot be revealed by a mere combustion analysis.If the hydro-carbon be very complex then the percent- age of marsh gas must be high ; if less complex then the percent- age of marsh gas falls. Assuming that the accompanying hydro-carbon is methyl in which case the proportion of marsh gas reaches its lowest we have for the composition of the gas C** ' 9-8 0 Nitrogen . . 2.4 Hydride of methyl 65.0 Methyl * . 23.3 1oo*o As ie well known a combustion cannot distinguish marsh gas from a mixture in equivalent quantities of methyl and hydrogen. UPON IODIDE OF' METHYL MIXED WITH ETHER 145 That our marsh gas was such a mixture was highly improbable. Direct proof we have rieverttrieless sought in another experiment We made a fresh quantity of gas collected it over strong alcohol (previously boiled) and shook it up therewith.Since methyl is very tnuch more soluble in alcohol than is hydrogen the gas discharged from this alcohol by boilinr should have been very rich in methyl. After washing with water however it yielded 011 combustion numbers agreeing with the composition of hydride of methyl viz. :-Contraction Carbonic A cid. 10.31 5-27 Wydride of methyl requires contraction to carbonic acid in the ratio of 2 :1. This gas also contained hardly my olefine viz. only 2.7 per cent. We have thus established the fallowing conclusions :-At 100°C. sodium decomposes iodide of methyl in presence of dry ether yielding a large quantity of hydride of methyl. The equation expressing the production of the hydride is neither of the following :-Na + Z(C,H,I) = 2NaI + C,H 4-C,H Na + 4(C,H,I) = 4NaI + C,H + 2(C,H,) because the amount of C,H is too small for the hydride of methyl.What the product complementary to the hydride of methyl really consists of we have not yet been able to determine. In conclusion we have to add that we have repeated the experi- ment and obtained similar resiilts to those which we have described in the paper With potassium likewise the same peculiarity has bceri observed as with sodium. The further ivvestigation 9f the subject viill be made by one of us. 14,L.XIIL.

ISSN:1743-6893    

DOI:10.1039/QJ8611300140

出版商:RSC    

年代:1861

数据来源: RSC

摘要:

146 ROSCOE ON THE COMPOSITION OF AQUEOUS XVIII.-On the Composition of the Aqueous Acids of constant Boiling Poini. BY HENRYENFIELD ROSCOE. IT is still a very generally received opinion that a liquid which boils unchanged at a fixed temperature must be regarded as a chemically homogeneous body. This supposition is not how- ever borne out either by theoretical considerations or by practical experience The proportions in which the constituents of a mixed liquid pass on boiling into the state of vapour depend upon the propor- tions in which the constituents are contained in the liquid and upon the separate tensions of the vapours of these constituents at the temperature of ebullition. Although the laws which regulate the vaporization of mixed liquids are as yet far from being under- stood it is easy to see that the relations between the several tensions and the proportions by weight of the two or more con- stituents may be such that at a given temperature of ebullition the composition of the vapour is identical with that of the liquid.As soon as this point is reached the mixed liquid boils at a constant temperature without undergoing any change of com-position arid in this respect does not diRer from ft uniform chemical combination Such mixed liquids possess however other proper- ties by means of which they can be easily distinguished from definite chemica lcombinations. The characteristics by which a chemical compound is recognized are generally considered to be (l),that the components of such a combination are united in quantities represented by some simple atomic relation ; and (it) that this relation rernaihs unaltered under a certain change of physical conditions Prom the experiments of Dalton Mitscherlich Millon Bineftu and others it has been hitherto supposed that most of the aqneous aci&+and especially hydrocl~loric hydrobromic hydriodic hydro-fltioric nitric and sulphuric acids of very various degrees of strength not only attain a fixed composition when boiled under the ordinary atmospheric pressure but that the liquids thus pre- pared are definite chemical compounds of acid and water.In the present communication my aim xt7ill be to show that this latter supposition is incorrect ; that a1though liquids possessing constant ACIDS OF COISBTANT BOILIKG POINTI composition are obtained by boiling the above-mentioned acids under the ordinary atmospheric pressure these bodies cannot be regarded as definite hydrates but that the phenomenon of constant composition and fixed boiling-point is to be ascribed to the establishment of that particular relation between the weights and tensions of the constituents by virtue of which acid and ivater are contained in the vapour in the same proportions in which they are present in the liquid.I shall show in the first place that the compositioh of the acids obtained by ebullition under the ordinary atmospheric pressure does not in the case of any of the acids examined with one exception agree with that of a simple hydpate; and secondly that in every case when these constant acids are brought under other physical conditions such as when boiled under different pressures or when a current of dry air is passed through them at different temperatures they are decom-posed and attain a different but constant composition so that a mixture of acid and water may be made which on vaporization at a given temperature does not undergo any alteration in composition I.Nitric Acid. Dalton was the first clearly to point out that mixtures of nitric! acid and water when boiled undergo such a change that the weak mixtures lose \later and the strong mixtures lose acid until the residual liquid attains a specific gravity of 1-42,and boils under the ordinary atmospheik pressure steadily at 120" C.This observatiun has since been corifirmed by the experiments of Mitscherlich B ineau Millon and Smith. The residual acid obtained by boiling either a weaker or a stronger acid was found by these chemists to possess an almost constant composition the analyses giving an amount of nitric acid (HNO,) varying from 66 to 70 per cent. on the liquid. From his own experimeuts Mitscherlich concluded that this acid of constant boiling point contains 4 atoms of water to 1 atom of NKO, mhilst Bineau and others supposed that this acid consists of 3 atoms of water and 1 of nitric acid (HNO,) corresponding to the well-known series of magnesian nitrates of the formula RNO,+ 3H0. Owing to the discrepancy in these statements it appeared of interest to determine as accurately as possible in the first place whether the acid obtained by distillation under the ordinary L2 148 ROSCOE ON THE COMPOSTTTON OF AQUEOUS atmospheric pressure has a constant composition ; and secondly whether the relation between acid and water is one capable of expression in simple numbers.For this purpose a quantity of strorig acid was prepared by the usual processes,* and freed completely from lower oxides of nitrogen by passing a current of dry carbonic acid through the warm liquid. ‘l’he acid thus prepared was perfectly colourless and free from every trace of chlorine and sulphuric acid. The method of determination adopted consisted either in volumetric analysis with a standard solution of caustic soda of exactly known strength or in neutralizing the acid with a weighed quantity of pure fused carbonate of sodium boiling the solution and adding a small quantity of test acid or alkali to reach the exact point of neutrality which was supposed to be attained when the litmus becsme blue.The quantity of acid employed for each deter- mination was such that the maximum analytical error the amount of which was determined by control experiments never attained 0.2 per cent. on the liquid. In order to check the two methods employed an acid which with test alkali was found to contain 68-00 per cent. of HNO, and with pure carbonate of sodium gave 68.02 per cent. of HNO, was neutralized with freshly precipitated carbonate of barium the barium in solution being estimated as siilphate; 1.3368 grms.of the nitric acid yielded 1.6815 grms. of sulphate of barium corresponding to 67.95 per cent of HNO,. The composition which aqueous nitric acid of various degrees of strength attains when boiled under the ordinary atmospheric pressure was determined by diluting portions of the pure can- centrated acid to a given extent with water and after analysis distilling them in a small retort the strength of the residual liquid being then accurately estimated. The experimental results are contained in the following Table in which Column I gives the volume of acid employed ; Column 11 the percentage quantity of real acid (HNO,) contained in the liquid before distillation ; Column 111 the volume of liquid remaining in the retort; and Column IV the percentage quantity of real acid (HNO,) con-tained in the residual liquid after distillation.* Mil Ion’s statement respecting the difficulty of scparating from the distillate the sulphuric acid used for concentrating the nitric acid aas nut confirmed. Strong nitric acid was easily obtaiued free from every trace of either sulphuric or hydro- chloric acid. ACIDS OF CONSTANT BOILING POINT. 149 TABLE1. NO. 1 i 99.8 5 cbc. 95.8 95.2 5 J? 84.8 84.7 5 ?Y 71.8 77.8 20 y> 69.1 74.7 Jf 68.1 70-5 20 y 68.6 '10.5 15 y 68.6 65.1 30 , 68.0 68.3 ! I NO. I. IT. 111. IV. --_I_-- (1) 20 cbc. '70.2 5 cbc. 68 1 (2) 20 7f 68*3 J> 68 -0 (3) 20 >I 68-3 5 ?> 67 -9 (4) 20 Y 66.9 5 J? 68 *O (5) 20 1) 66.2 5 YI 68 *O (6) 20 3) 66 -2 5 Y) 68 *O Mean 68-00 150 ROSCOE ON THE COi!vZPOSITKON OF AQUEOUS Hence we may conclude :-(1.) That the residual liquid obtained by boiling aqueous nitric mid of various degrees of concentration under the ordinary atmospheric pressure possesses a constant composition.(2.) That the liquid thus obtained contairis 68.0 per cent. of real acid arid that therefore the proportion between acid and water cannot he represeiited by any simple atomic relation the formula HNO +3H0 reqiiiring 70.0 per cent. of FINO,.* The boilitig-point of the acid containing 68.0 per cent. mas fourid to be 120°*5C. under a barometric pressure of 0"'*735;its specific gravity at l5O-5 C. was showir to be 1.414 as a mean of two deterin inations.Distilled at other temperatures the relation of real acid to water will if the phsnomenon of constant boiliug-point depends alto- gether on physical causes he found to be a different one. In the following experiments aqueous nitric acid of various degree8 of strength was distilled under diniinivhed atmospheric pressure effected by placing the acid in 8 retort the neck of which drawn out and bent at an acizte angle passed through a solid caoutchouc stopper into a large bolt-head of 20 litres capacity furnished with a divided manometer-tube and cammunicating with the cylinder of a large air-pump. By this means the acid could be distilled under any wished-for pressure less than that of the atmosphere; by cooling the bolt-head agid by having a large absorbent surface of caustic soda in the interior of the flask it was easy to keep the mercury in the manometer tube to within 5 millimetres of the required height during the whole coiirse of the distillation.Table 3 contains the results of a series of such experiments; Column I gives the prcsswe in millimetres of mercury under which the distillation took place (i. e. the barometric pressure,-the height of the mercurial column in the manometer-tube) ; Column 11 the volumes of liquid employed; Column 111 the percentage of real acid contained in this liquid; Column IV the volume remainiug after distillation ; Column V the percentage of real acid contained in the residual liquid. * Calculated percentage composition of the hypothetical hydrates of nitric acid :-(1st) (2nd) (3rd) H.NO .. 87 5 77 8 70 -0 HO . . 12.5 22 .2 30 .O 100-0 100'0 100.0 ACIDS OF CONSTANT BOILING POINT. TABLE3. Y. - 69 $9 66-7 68 *3 67 *2 66 *9 66 *7 66 *5 66 *S 66.2 66 -5 65 -1 66 *7 66 -9 67 '6 1-1'i obtained whilst under a pressure of 150 millimetres the equilibrium occurs when the percentage of acid reaches 67.6. The distillation of nitric acid under pressures greater than that of the atmo-sphere is accompanied by considerable experimental difliculties owing to the impossibility of bringing the acid into contact with mercury. These difficulties were overcome by employ-[====Ifl A ing the following arrangement :-The bulb-retort (a) Fig.1 152 ROSCOE ON THE COMPOSITION OF AQUEOUS containing the acid was connected by means of a solid caoutchouc stopper with a strong bottle (b) of one litre capacity containing Eome dilute nitric acid ; through the stopper passes a second tube communicating with another similar bottle (c)containing mercury (m)and a strong solution of caustic soda (s) ; a divided manometer tube (d) dipped into the mercury and a third tube (e) passing through the stopper of the battle (c) could be placed to any required depth into a reservoir of mercury. The bottle (6)being immersed in cold water the increase of pressure was attained by pushing the glass bucket (91 filled with pieces of marble into the dilute acid by means of the stiff iron wire (f) working perfectly air-tight through the caoutchouc stopper.As soon as the mercury in the manometer tube had attained the wished-for height and the gas issued from the extremity of the tube (e) under the mercury a portion of the acid in the retort was distilled over and the residue afterwards analyzed. By withdrawing the marble from the acid and again immersing it vhen required the pressure was kept tolerably constant during the whole course of the experiment. The numbers in the following Table show that distilled under a mean pressure of 1,220 millimetres of mercury beyond which it was found inconvenient to operate the composition of the residual liquid reached 68-6per cent. of real acid being a deviation from the acid distilled under ordinary pressures of 0.6 per cent.TABLE 4. NO. I. 11. v. (1) 1260 mn. 20 cbc. '10.5 5 68.8 (2) 1210 ) 20 , 68.3 5 68.7 (3) 1190 Yf 20 JY 68 0 5 68-4 Mean 68.6 The numbers in the columns have the same signification as those in Table 3 except in the first in which the sum of the heights of the barometric column and the column of mercury in the manometer tube is given. As it has thus heen shown that aqueous nitric acid is a liquid wtiich does not give rise on distillation to bodies possessing a simple atomic constitution but that for each temperature a liquid ACIDS OF CONSTANT BOILING POIST. 153 having a constant composition is obtained it appeared of interest to determine for lower temperatures the composition of the acid unalterable by vaporization.For this purpose air completely dried over sulphuric acid and phosphoric anhydride was passed through the nitric Fig. 2. acid contained in the burette-shaped vessel Fig. 2 until no further change in composition was observed. The requisite temperature was obtained by immers-ing the burette in a large water-bath the heat of which was kept constant a weighed U-tube con- i taining phosphoric anhydride being placed bet ween the burette and the drying apparatus to ensure all absence of moisture. Experiments thus conducted for every temperature show that a point is reached at which the composition of the aqueous acid undergoes no further change by vaporization. In Table 5 Column I gives the percentage of real acid in the liquid before the experiment; Column 11 the per- centage after the experiment; Column III?the fraction of the original volume of acid remaining after the experiment; Column IVY the duration of the experiment in hours.TABLE5. NO. 3;. ---111. --IT. 7-1 I (11 68.0 66.2 2 hrs. (2) 64.9 66.1 -4 z 1 I:, 1 (3) 64.9 66.3 1 + 3 >? Passage of dry air through acid at 60"C. 68.0 66.9 66-9 65.7 65.7 65.2 65-22 64.9 64.9 68.8 64.9 64.8 6443 64.5 64.5 64.4 64.0 64-5 64.5 64.5 154 ROSCOE ON THE COMPOSITION OF AQUEOUS It is thus seen-(1,) That weak or strong aqueous nitric acid through which dry air is passed at looo attains a constant com-position of 66.2 per cent.of real acid. (2.) That when air is passed through the same acid at 60*,the composition becomes constant at 64%per cent.; and (3.) That at the ordinary atmospheric tempera- tures-ip mean 13"-the equilibrium is reached when the liquid wntains 64.0 per cent. of real acid. The ease with which strong nitric acid is decomposed even at temperatures below its boiling point is well known. It seems to he impossible to prepare the real acid HNO by employing the usual method of distillation rectification over sulphuric acid and volatilization of the oxides of nitrogen by means of a current of dry air or carbonic acid. None of the chemists who have worked upon this subject appear to have had the real acid and I have also failed to obtain it although every care to ensure absence of moisture was taken; one colourless acid contained 99%per cent.of real acid another 99-47 per cent The former nearly anhy- drous acid not only suffered decomposition on boiling as is seen by refererice to Table I but underwent alteration when a current of air perfectly dried over a large quantity of phosphoric anhy- dride was passed through the liquid at 15". In seven hours after which time three-fourths of the acid had been volatilized the per- centage of real acid had sunk to 98.77. This shows that nitric acid ("0,) undergoes decomposition not only when vaporized at the boiling point but also at the ordinary atmospheric temperatures. n.-&h@huric Acid. Ve owe to Marignac the interesting and important observa- tion that real sulphuric acid (HSO,) cannot be obtained by the 155 ACIDS OF CONSFANT BOILING POINT.distillation either of a weaker aqueous acid or of a stronger fuming acid. The real acid can only be prepared by crystdlisa- tion and on boiling is decomposed into anhydride which is seen in the receiver and a weaker acid remaining in the retort. Marignac showed that this weaker residual acid boils at 338"C without undergoing ohange; and he further proved that aqueous sulphuric acid of every degree of concentration whether containing more or less water than the real acid (HSO,) attains this constant composition on boiling. From four separate deter- minations Xarign ac found that this residual liquid oontained 98.70 per cent. of real acid.The followipig determinations have confirmed in every par-ticular M ar i gn ac' s conclusions. The analyses were made by weighing out the requisite quantities of pure fused carbonate of sodium the exact point of neutrality being estimated by addition of small volumes of standard alkali and acid of well-established strengths. (1.) Pure strong sulphiiric acid eontaining 93.4 per cent. a€ real acid was distilled in a retort until two-thirds of tlie liquid had been volatilized The liquid remainizlg in the retort con-tained 98.7 per cent. of real acid. (2.) An acid containing 98.37 per cent. of HSO was distilled in a small retort until one-fifth of the original volume remained. The residue contained 98-32per cent. of HSO,. (3.)An acid containing 98-37 per cent.of ffS0 was boiled down in a porcelain capsule to one-third of its original volume. The residual liquid contained 9845 per cent. of real acid. (4,) An acid containing 100.33 per cent. of HSO, and fuming in contact; with the air at ordinary temperatures was boiled down to one-eighth of its orignal volume. The residual liquid con-tained 98%per cent of real acid. (5.) Another portion of the same fuming acid which a second analysis showed to contain 100.34 per cent. IISO, was boiled to one-fourth of its original volume. The residual liquid contained 98-40per cent. of' real acid. It thus appears not only that aqueous sulphuric like aqueous nitric acid attains an unalterable cornposition not correspoiiding to any definite hydrate on distillation under the ordinary atmo-spheric pressure ; but we also notice what is very remarkable that both the real acids HNO and HSO, bodies which passess in other respects the characteristics of well-defined chemical corn- 156 ROSCOE ON THE COMPOSITION OF AQUEOUS pounds are decomposed on boiling yielding that aqueous acid which remains unchanged at the temperature of ebullition.III.-Hydrochloric Acid. Bineau found that aqueous hydrochloric acid boiled under the ordinary atmospheric pressure attained a composition of 20.2 p.c. of HC1 corresponding exactly to the formula HC1+16RO and this liquid he conceiwd to he a definite hydrate. In a research upon the absorption of hydrochloric acid and ammonia in water published in vol. XI page 1.28 of the Journal of the Chemical Society which I made in conjunction with Mr.Dittmar this result of Bineau's was to a certain extent confirmed inas- much as the acid of constant composition obtained by ebullition under the ordiuary atmospheric pressure was found to contain f20*24 per cer,t. of HCl; but it was at the same time shown that distilled under other pressures or vaporized at other temperatures this acid was decomposed other liquids of constant composition being then produced and the conclusion was there-fore drawn that this hydrate has no red existence. The following Table 6 extracted from the above-mentioned memoir gives the relation between the pressure under which the acid is distilled and the cornposition of the constant liquid.The Column F shows the pressure in metres of mercury under which aqueous hydro-chloric acid must be distilled to attain the constant composition given in the next column. TABLE6. -PercentagePm* i ofHC1. Pm. Percentageof HC1. pm. Percentageof HC1. Pm. Percentageof HCl. --._. -I_ 0.05 23*2 0-6 20.7 2-0 18.5 0.1 22-9 0.7 20.4 2.1 15.4 0.2 22'3 0 76 20.24 23 18-3 0-3 21.8 0.8 20.2 2.4 18.1 0'4 21.4 0.9 19.9 25 18 0 0.5 21'1 1-0 19.7 1-1 19.5 1-2 19.4 ACIDS OF CONSTANT BOILING POINT. Hence it is evident :-(1.) That there exists for each pressure a corresponding aqueous hydrochloric acid which undergoes no change in composition when distilled under this pressure and therefore has a constant boiling point. (2.) That the com-position of these aqueous acids is different for each pressure a gradual change in pressure being accompanied by a gradual zlteration in the percentage of hydrochloric acid.When aqueous hydrochloric acid is vaporized by passing a current of dry air through the liquid at a given tempemture a similar point is reached beyond which no decomposition occurs. Table 7 contains the interpolated values obtained from the expe- rimental results given in the original paper. The first column gives the temperatures ; the second column gives the percentage of HCl contained in the acid unalterable at the corresponding temperature. TABLE-7. -TO. Percentage TO. Percentage TO. Percentage TO. 'ercentage of HCL. of HCl. of HCI. of HCI. -- -_I 0" 25.0 30" 24.3.60" 23-0 goo 21.4 5" 24.9 35" 23'9 65" 22.8 95" 21'1 loo 24.7 40" 23.8 '70" 22.6 100" 20-7 15O 24.6 45" 23.6 7 5" 22.3 20° 24.4 50" 23 4 80" 22.0 25" 24.3 55"- 23.2 85" - 21-7 - IV. Hydrobromic Acid. Lowig first observed that water saturated at the ordinary atmospheric temperature with hydrobromic acid gas loses acid when boiled and that water containing but little gas in solution loses water under similar circumstances. Bineau showed that the composition of the acid obtained by boiling mas constant and his experiments proving that such acid contained from 46.1 to 47.4 per cent. of HBr he concluded that 017 distillation the hpdrate containing 10 atoms of water is formed. According to theory this hydrate should contain 47*38per cent.of HBr when the equivalent of bromine is taken as 80. On exposing aqueous acid of the above strength in a closed vessel over dried potash or on passing a currerit of dry air through the acid Bineau found that the residual liquid contained from 48.7 to 51.7 per cent. of 158 ROSCOE ON THE CONPOSITION OF AQUEOUS hydrobromic acid; this he assumes to be a hydrate containing 9 atoms of water composed theoretically of equal weights of water and real acid (HBr.) For the purpose of determining the exact relation of the composition of aqueous hydrobrornic acid to the temperature of ebullition the acid was prepared by shaking together pure bromine water and phosphorus added in small pieces from time to time until the liquid became colourless the strong fuming solution being freed by distillation from phosphorus and phospharic acid.The pure and colourless acid thus prepared was diluted to it given extent with water; and as soon as the percentage of real acid (HBr) which the diluted liquid contained had been estimated by accurate volumetric ahalysis with silver it was boiled in a bulb- tube retort under the ordinary atmospheric pressure until a certain pc;rtion of the acid had distilled over when the composition of the residue was determined by exact analysis with silver. In Table 8 are seen the results of eight such distillations with aqueous hydrobromic acids of various degrees of concen-tration Column I gives the barometric pressure under which the acid boiled; Column If the volume in cubic centimetres of acid employed Column 111 the perccntage of HBr contained in the original liquid ; Column IV the volume in cubic centimetres of acid remaining in the rctort after the distillation; and Column V the perceBtage of HBr contained in the residual liquid being the mean of two aiialy~es which generally differed orily in the second decimal place.TABLE8. BO. I. 11. 111. IV. v. rn 0.752 25 cbc. 45-54 8cbc. 47.28 0 752 j 45.68 47.39 0.753 47.30 47 78 0 -762 I 47 *65 47 86 0 T53 47 .'18 47 61 0 T62 47-87 47 -73 0 752 49 -00 47 -71 0 962 49.51 47 *84 ACIDS OF CONSTANT BOILIXG POINT. If the distillations are conducted under the same conditions the compositions of the residual acids are identical (see Nos.4 and 8); if the physical conditions (barometric pressure and volume of liquid employed) are different the acid may vary in composition about 0.1 or 0.2 per cent. as is seen in one or two of the numbers. From the foregoing experiments we see that aqueous hydrobromic acid when boiled under the ordinary atmospheric pressuw of 0.76 of mercury attains a fixed composition of 4'7% per cent. of real acid or contains 0.5 per cent. more acid than Bineau's hypo-thetical hydrate. Under these circumstances it was found to boil constantly at 126OC. That the point of constant composition which aqueous hydrobromic acid attains on vaporization is not solely dependent upon chemical attractions but is mainly influ- enced by physical circumstances is still more distinctly seen on examining the change which the aqueous acid undergoes when a current of dry air is passed through the liquid at a constant temperature.Through a liquid containing 4'7.65 per cent. of real acid dry air was passed at the temperature of 16' for 50 hours; after the lapse of this time the strength of the acid reached 51.8 per cent. and after the air had passed for 30 hours longer the liquid contained 51-65per cent. of real acid as a mean of two analyses and had therefore attained the point of constant compo- sition. Hence it is clear that neither of the supposed hydrates of hpdrobromic acid has a real existence. In order to determine the point of equilibrium for other temperatures perfectly dry air was passed through the acid at 100' contained in the burette Fig.2 and the alteration which the liquid underwent was deter- mined. The following results were obtained :-Dry air passed through aqueous acid at 100OC. P.C.reai acid. (1) 1 vol. acid containing 48 0 p. c. when reduced to Q vol cohtained 49 *59 (2) JI 7) 48-05 17 2? 8 79 49 07 (3) ?> f> 49.10 79 1s 4 7f Y? 49 35 ?7 (4) 73 3t 50 *lo 4 7) 7$ 49 35 ?7 17 The aqueous acid was also distilled under a greatly increased pressure by help of the arrangement represented in Fig. 3. (a) Fig. 3 is a small bulb blorPn before the lamp to which is fused the glass tube (b) communicating ,by a solid caoutchouc stopper with 100 ROSCOE ON THE COJIPOSITION OF AQEEOVS Fig. 3. the divided manometer tube (c) containing mercury.After the tube (c) had been filled with mercury to the requisite height the acid was placcd in the bulb u and then the drawn-out end closed before the blow- pipe. The distillation was now commenced and con- tinued until the acid had diminished to a given volume when the pressure was read off' from the ditTereiice of height of the columns of mercury in the two tubes. For the purpose of obtaining the boiling point of the acid under these circumstances a thermometer was inserted into the bulb-tube and the apparatus made air-tight by a joint of caoutchouc and lead-foil carefully wrapped with copper-wire. Uiider a total pressure of 5 1.952 metres of rnercury the acid boiled at 153"C; analysis of the residual acid gave the following results :-(1) Acid containing 48.0 per cent.left after distil- lation a residual liquid containing 46.30 per cent. of real acid (HBr). (2) Acid containing 46.07 per cent. left after distil- lation a liquid containing 46-36 per cent of real acid. v. Hydriodic Acid. Bineau concluded that the liquid of constant boiling point obtained by distilling a diluted or a saturated aqueous solution of hydriodic acid was composed of I1 atoms of water to one of real acid (HI). The residual pcid contained according to Elis experi-ments from 56.3 to 57.2 per cent. of hydriodic acid whilst according to calculation the 11-atom hydrate requires 56.39 per cent. of real acid. Aqueous hydriodic acid was prepared by leading into distilled water the gas evolved by heating a mixture of 20 parts of pure iodine 14 parts of iodide of potassium and 14 parts of phosphorus mixed with a little water.The acid thus obtained of any reqtiisite degree of coiiceii tratiori was perfectly oolourless when preserved out of contact with air and although the acid was always distilled in a current of hydrogen it still became slightly ACIDS OF CONSTANT BOILING Pomr. lei coloured but was not decomposed to such an extent as to affect the results of the analysis. The composition of the acid before and after the distillation mas determined by volumetric analysis with silver; the results of these determinations as is seen by reference to the following numbers are closely concordant ; care however must always be taken to have excess of silver present at the commencement of the analysis otherwise some iodine is liberated by the free nitric acid.TABLE9. Distillation of aqueous hydriodic acid under the ordinary atmospheric pressure. Volume of liquid employed in each experiment 25 cbc. > , remaining after each distillation 13 cbc. Percentage of real acid taken. Percentage of real acid in the residue. (1) 56.50 .. .. ". 5 7.03 56-93 (3) 56.70 .. .. .. 56-94 56.90 (3) 57524 f. .. .. 57.03 (57.16 (4) 57.17 .. 1. .. Hence it is seen that the acid of constant composition which is obtained when aqueous hydriodic acid is boiled under the ordi- nary atmospheric pressure contains 57.00 per cent. of real acid and cannot therefore be considered to be a definite hydrate of hydriodic acid.The boiling point of this acid was found to be 127O C. under a barometric pressure of 0.774 metre. In order to ascertain the point of equilibrium for other temperatures aqueous hydriodic acid was vaporized in a current of dry hydrogen gas at the temperatures of 16' and 100". Table 10 gives the results of such experiments. VOL. XIII. M 162 ROSCOE ON THE COMPOSTTFON OF AQUEOUS TABLE10. Vaporization of aqueous hydriodic acid in a current of dry hydrogen at ordinary atmospheric temperature. Temp. Duration of the experiment. Percentage of real acid taken. Percentage of real acid in residue. (1) 15O .. 32 hours .. 57.0 .. 59.44 (2) 15" .. 41 , .+ 59.44 . (60.36160.33 (3) 17" ..15 , . . 60.03 . . 60.27 (4) 17" .. 15 , . . 60.27' . {60,3960.42 (5) 19O *. 10 , .. 60.21 .. 60.68 (6) 19' . 6 7 . 60*68 .. Vaporization of aqueous hydriodic acid in a ciirrent of dry hydrogen at looo until half the liquid was volatilized. Percentage of real acid taken. Percentage of real acid in residue. (1) (2) 56.98 59-78 .. .. .. .. *. .* 58-49 58-26 (3) 58-21 .. .. ' f58-24 158.20 VI. HydroJluoric Acid. Aqueous hydrofluoric acid when boiled under the ordinary atmospheric pressure attains according to Bineau a constant composition corresponding to the formula €IF1 + 4 HO and containing 35.9 per cent. of anhydroiis acid. In order to verify this assertion pure aqueous hydrofluoric acid was prepared by leading the gas evolved from a strong acid heated in a platinum retort into water also contained in a platinum vhssel; the acid thus obtained being then boiled under the atmospheric pressure and the quantity of acid contained in the residual liquid determined by throwing the acid weighed in ACIDS OF CONSTANT BOILING POINT.a platinum capsule into a vessel containing an excess of standard soda solution. The quantity of free soda was estimated by adding a slight excess of test acid and the point of neutrality was considered to be reached when the litmus again became coloured blue on adding soda solution drop by drop in the cold. The results of a series of experiments thus conducted are seen in Table 11 in which Column I gives the volume of' acid before boiling; Column I1 the percentage of €IF1contained in the liquid before boiling; Column 111the volume of HF1 after boiling ; and Column IV the percentage of HF1 contained in the liquid after boiling.TABLE11 11. IY. I. 11. 111. 1 -2 '*a 12 cbc 36 *9 6 6 -2 11 -8 38 *1 12 16 -5 38 -1 6 32 .O 38 9 12 35 *4 39 .o 20 r 36 -4 136 8 41 -6' 40 26 -5 From these experiments it is evident that wlien aqueous hydro-fluoric acid is boiled in platinum vessels under the ordinary atmo- spheric pressure it attains a composition varying from 36 to 38 per cent. of HFI. The great differences observed arising from the impossibility of keeping the physical conditions constant under which the ebullition takes place.We may take the mean 37.0 per cent. as representing pretty closely the composition of the acid unalterable by bailing in the air. If a true chemical compound between acid and water were thus produced such large 3% 2 164 ROSCOE ON COMPOSITION OF AQUEOUS ACIDS ETC. variations in the composition of the residual acid could not have been found. Vaporized at other temperatures this constant hydro- ffuoric acid containing 37.0 per cent. of PEFl undergow change. A portion of acid of the above strength obtained by ebullition was placed in a platinum crucible over quick lime inside a leaden exsiccator closed 'iFith a lid having a sulphuric acid joint. After standing at a temperature of 15°C. for 4 days the acid was found to contain in two analyses 36.4 an6 36.6 per cent.of HF1; after remaining 4 days longer at the sRme temperature the liquid contained 33.5 per cent. of acid; and when the acid had been standing for 2 more days at the same temperature over quick lime it was found to contain 32.5 and 32.7 per cent. of acid. A weaker acid was next vaporized under like conditions ;an acid containing 31.6 per cent. of HFI placed over quick lime at 15" attained after 2 days a composition of 32.1 per cent. and after a further exposure in the exsiccator for 4 days two analyses showed that it contained 32*4and 32.3 per cent. of WF1. I beg to thank my assistant Mr. Schorlemmer for the able help which he haa given me in carrying out the foregoing experi- ments

ISSN:1743-6893    

DOI:10.1039/QJ8611300146

出版商:RSC    

年代:1861

数据来源: RSC