摘要:

THE QUARTERLY JOURNAL OF THE CHEMICAL SOCIETY. X.-Pho tochemical Researches. By Professor BTJNSEN and H. E. ROSCOE,B.A. PH.D. PHOTOCHEMICAL determinations which pretend to anything more than a rough approximation are surrounded by difficulties of SO considerable a nature that up to the present time all attempts to gain a knowledge of the laws of the chemical action of light have been fruitless. In a research on this subject which has occupied us for the space of nearly two years we were induced to commence a careful exarnina- tion of the action of light on solutions of chlorine bromine and iodine as well when alone in solution as in the presence of hydro- genous organic sntxtances. Although these our first experiments were not carried on with a view to publication but merely for our own instruction in order to gain a starting-point for the solution of the question which we had proposed to ourselves we nevertheless are obliged to make known these results in consequence of the subsequent publication of a research on the same subject by Dr.Wit t wer .* The experimental and theoretical results found by Dr. Wittwer stand in such complete and inexplicable contradiction to those obtained by us that we have thought it necessary critically to repeat all his experi- ments in order if possible to arrive at the cause of this difference. As however in this respect our endeavours have not been successful we must confine ourselves to a scrupulous communication of our * Pogg. Ann. xciv. 597. VOL.VIIT.-NO. XXXI. 0 PROFESSOR BUNSEN AND DR. H. E. ROSCOE’S experiments from which alone the reader will be able to arrive at any satisfactory conclusion. Dr. With wer undertakes to measure the chemical alterations which chlorine water undergoes when exposed to the action of light. The value of his determination depends therefore chiefly upon the accuracy and reliability of the method by which the amount of free chlorine in the solution is estimated. Dr. Wittwer has used the old determi- nation of chlorine by means of a solution of arsenious acid coloured by indigo. This method which as is well known never gives very exact results especially when the solution of chlorine is very dilute has long since been replaced by much better processes.In all our experiments we have employed the much more accurate and convenient iodonietric method which even with the greatest dilution of the chlorine water gives a degree of accuracy attaiuable by very few analytical processes. The strength of the solution of iodine dissolved in pure iodide of potassium was determined by volumetric analyeis* of a known weight of pure bichromate of potash dried at about 3OO0C.,t and gave the following values :-I. 11. 111. A 0.0808 0-0725 0.1257 n 2 2 3 t 174.0 173.6 173.0 t 58.3 85.0 62.2 Found OL 0.0007138 0.0007077 0.0007043 As mean of these three experiments we obtain ~~=0~0007086 for the amount of iodine contained in one burette division. In order to obtain the value of CY still more exactly the iodine solution was com- pared with another more concentrated normal iodine solution prepared at a different time and from different materials whose mean value was found from the following experiments to be a=0*002416.I. 11. 111. A 0.1755 0-1596 0.2029 n4 3 4 t 61.1 59.2 59-0 t 58.2 7.9 22.1 Found a O*002412 0.002407 0*002428 * For a description of this method and the meaning of the symbols A n t &c. see pp. 219-236 of this volume. f-Ann. Ch. Pharm. Bd. Ixxxvi. 281. In this and in all the following experiments the air contained in the small flask was driven out before the decomposition began by the addition of a few pieces of carbonate of soda to the acid solution. PHOTOCHEMICAL RESEARCHES. To oxidise equal measures of a dilute solution of sulphurous acid 144.0 burette-divisions of the former and 42.1 of th.e latter normal solution were required.Hence the value of the a of the first solution is found to be 0*0007063 the value directly determined being 0.0007086. The mean of these two numbers-0~0007075-is that used in the greater part of the following volumetric anajyses. In like manner we have satisfied ourselves by experiments which we here omit that during the lapse of a whole year the normal iodine solution does not undergo any change which could influence the accuracy of the experiments. The dilution of the sulphurous acid used in these experiments cannot give rise to error because,according to the principle of the method employed by us a slow alteration of this acid liquid has no appreciable influence on the accuracy of the results.* Although the accuracy of the general iodometric method has been proved by very numerous experiments still it does not here appear superfluous to show by a few examples the degree of accuracy in the estimation of chlorine which can in this way be attained.0.2529 grm. pure bichromate of potash was boiled with hydrochloric acid and the liberated chlorine collected without loss in a solution of iodide of potassium. The analysis of this solution gave- n=5 t=62*0 t1=51-5 01=0*002504. This gives 0.18089 grm. of chlorine the amount of chloriue equiva- lent to the salt employed is 0*18091. We cite another experiment on the density of chlorine gas made according to the iodonietric method by Dr.Landolt. A current of pure and dry chlorine was passed through a tube drawn out at either end until all atmospheric air was expelled and then after observation of the barometer and thermometer the tube was closed by pressing two cao1Atchouc joinings at each end and opened under a solution of iodide of potassium in which the liberated iodine was estimated. The experiment gave- Capacity of the tube 31.050 cub. cent.; Temperature of the gas 22O.7 C.; Height of barometer at 25'*4 C. 0.7567". n=2 t=31*9 t1=0.3 01=0-005069. * We consiclei. this peculiarity of our method to be one of its great merita and cannot therefore agree with Mohr (,4nn. Ch. Pharm. Bd. xciii. Heft l) who abandons this improvement and for sake of convenience remodels the process accord- ing to the old volumetric method.Still less to be recommended is his proposal in the same memoir to determine the free chlorine directly without previous addition of iodide of potassium. In this case an entirely inaccurate result is obtained as is generally the case when the separation of the iodine takes place in mixed liquids instead of as the method describes in a solution of iodide of potassium. 1% PROFESSOR BUNSEN AND DR. H. E. ROSCOE'S hence 28.439 cub. cent. of chlorine at 0' and 0.76" pressure weigh 0.08997 grm. The specific gravity of chlorine as calculated from these data is found to be 2.446; that calculated from the atomic weight is 2.449. These experiments together with many others cominunicated in the course of this research prove that the detcrrnination of chlorine by the iodometric method is free from those sources of error to which the old method of Gay-Lussac is known to be subject.Entirely independent of the inaccuracies of a badly chosen method in Dr. Wittwer's experiments a source of much greater error liesin the non-consideration of the disturbing infliiences which the pheno- mena of gas-absorption and diffusion give rise to. Dr. Wittwer imagined that he had entirely eliminated these sources of error by dropping into his solution of arsenious acid a chlorine-water which contained only 1to 4 parts by weight of chlorine to 1000 of water. By the simplest experiments however he might have assured himself that by this method not even approximate results can be obtaiiied for solutions of chlorine of the strength described are influenced by the phenomena of gas-absorption and diffusion in the same way as more concentrated solutions.The amount of chlorine which is liable to be lost from solutions of the above-mentioned strength by mere dropping from one vessel to another may be seen from the following experiments :-EXPERIMENT I.-A small glass of 9,834 cub. cent. capacity fur- nished with a well-closing glass stopper was filled with chlorine- solution which was quickly emptied into a solution of iodide of potassium. The volumetric analysis gave- n =2 t= 107.3 1 =99.6 tc =0.0005952. This is equivalent to 1.94(5grm. chlorine in 1000 grms. of water. The experiment repeated with the difference that the chlorine water was slowly dropped into the solution of iodide according to the plan adopted by Dr.Wittwer in his volumetric analysis gave the follow- ing results :-n = 1 t= 107.2 t,= 1-4 01 =O.OOO5952 or in 1000 grnis. liquid 1.790 chlorine. EXPERIMENT 11.-The same volume of liquid previously employed poured quickly out gave- rh= l t= 107.3 t,= 1.3 a =0*000591i2; PHOTOCHE31ICAL RE SEARCHES. or 1.792 chlorine in 1000 water. When dropped out the amount obtained was- n=l t=107*3 t,=10*8 ct = 0.0005952; or 1.633 chlorine in 1000 parts of water. EXPERIMENT 111.-By quickly ponring out the following values Tvere obtained :-n=l t=148*3 t,=56*9 a= 0*0007075 which is equivalent to 1,838 chlorine per thousand.By dropping the same volume gave- n=1 t-148.3 t,=67-0 c~=0.0007075; or 1.635 chlorine per thousand. EXPERIMENT IV.-Quickly poured out the same volume of solution gave-n-=1 t = 148.2 t,= 62.0 tl =OmO00’i075; or 1.733 chlorine per thousand. Dropped slowly the same volurtie of liquid gave- n= l t = 148.2 t = 68.6 ct = O60Q07O75; or 1.601 chlorine per thousand. The first of the following columns shows the amount of chlorine after quickly mixing; the second after dropping slowly; and the third the loss of chlorine during the dropping expressed in per- cen tap :- I. 11. 111. 1*945 1.789 S.0 1.792 1.633 8.9 1.838 1.635 11.1 1-733 1.601 7.6 The loss of chlorine amounts therefore to a mean of 9 per cent. When vie consider that a loss of chlorine must ensue even in that portion which is quickly poured from the stopped bottle and also that a great part of Dr.TVittwer’s experiments were made with niore concentrated solutions than the above it is clearly seen that the error to which Dr. Wittwer is liable from his method of experi-menting is at least 9 per cent. of the total amount of free chlorine contained in the solution. Let us now examine the relation in which this sGurce of error stands to the accuracy of the experiments given on page 599 of the quoted memoir. In order to make this couiparison more clear we have arranged the PROFESSOR BUNSEN AND DR. H. E. ROSCOE'S following Table in which the first column shows the per-centage loss of chlorine which Dr.Wit t wer found by exposing the chlorine solu- tions to the ligbt ; and the second the loss of chlorine which according to his theory he ~hould have found if his experiments had been free from observatknal errors. The loss of chlorine produced by insolation expressed in per-centage on the amount of chlorine originally contained :-Found. Calculated. I. EXPERIMENT . 28.1 28-2 . 28-0 28-1 11 . 27.4 28.1 1) 11. . 27.3 27'3 71 . 28'1 27.5 >l . 25-3 27.3 11 m. . 41.2 41.2 97 . 42.6 41'2 71 . 40.9 41-2 11 IV. . 10'4 10'4 1) . 11.6 10.4 11 . 10.4 20'4 71 v. . 8.9 8.9 1? . 7.8 8.9 19 Y) . 8.0 8-0 vr. . 33% 33.6 1f . 35.0 33.6 19 . 35.4 33.6 1) VII. . 9.9 9-9 71 .12'4 9.9 It . 20'9 9.9 71 We have just shown that even the error occurring from diffusion I can on an average amount to 9 units of the foregoing numbers and therefore in a few of the experiments is greater than the total loss from which the theory is deduced. If under such circumstances it is difficult to understand how D r .Wit t w er could employ so inaccurate a method it is perfectly unintelligible how using this method he has arrived at results which do not in any instance show an error of more than 3 per cent. We mention another example which shows how little Dr. Wit twer has considered or removed the errors which ensue from the phenomena of the diffusion of gases. At page 608 of the memoir we read ''The action of chlorine on the vapour of water must here be noticed.In order that water be transformed into the vapoury con-dition it is well known that 1 gm. must take up 550 heat-units ; but its constituent atoms on account of this heat are less strongly attracted together; and when chlorine acts upon the vapour in Y1i OTOCHE M ICA L RE8EARCHES. presence of light the action proceeds more rapidly than with liquid water.” We find the following experiments cited as proof of this opinion :-Portions of the same chlorine-solution (of strength 3.720 pa*thou-sand) were poured into three small bottles the first was completely filled the second to one-balf of its volume the third to one quarter of i,ts volume and the three exposed to the action of the light for the same period.The first lost 17.07 the second 32.00 and the third 48.47 per cent. of chlorine. Dr. Wittwer ascribes these differences to a change of affinity arisins from the latent heat of the vapour of water ; and he has not considered that an interchange must take place between thc chlorine in solution and the atmosphere of nitrogen and oxygen which exists above the liquid; and that therefore according to the laws of gas-absorption the loss of dissolvcd chlorine is greater as the relative volume of tlie air to the watcr increases. We have repeated the experiment differing only from D r. Wit t wer’s by the circumstance that we allowed the air and chlorine-water contained in well-stoppered bottles to remain in contact during entire absence of light. After the lapse of even four hours the influence of diffusive absorption has become so visiblc as is wen from the following Table that we must conclude that D r.Wit t wer has detcrniined rather this action than that of the light. TABLEI. Chlorine in Volume. n fl 1000 water. - ljottle completely iillcd . Ilitto half filled . . . 18.13 2G.28 5 6 132.0 112-0 13:;-.2 133.0 4.717 4.341 Ilitto qnnrter filled . . Ditto ditto . . . . 11.42 10.00 2 2 12.5 129.0 3.376 3.650 The bottles were analysed four hours after filling the amount of iodine contained ill one burette-division was ct=0*0005952. The bottle which was half filled lost therefore by standing four hours in the dark 8 per cent. of its amount of chlorine ; the two tilled to a quarter of their volume lost 22.6 and 24.2 per cent.The cause of this con- siderable loss of chlorine niight be ascribed chiefly to the concentra- tion of the solution. We have therefore made a set of similar deter- niinations with dilute solutioiis of chlorine; but in this as in the former case a considerable loss of chloyine was obtained. PROFESSOR BUNSEN AND DW. H. E. I1OSCOE’S TABLE11. The solutions stood in the dark for 4hours after filling ;OL =0.0005952 t Chlorine in Volunie ji~ t t1 1000 parts. Bottle filled full . . . 18.83 1 189.0 18.8 L.303 Ditto half filled . . . 23.80 2 14.0 170.8 M48 Ditto quarter filled . . 10.20 1 180*0 106-0 1.353 i TABLE 111. The solutions stoodinthe dark for 15hours after filling OL =0.0003952. Chlorine in Volume.11 d ‘1 1000 paris. ----_I_ Bottle filled full . . 1.8.83 1 182.0 15.3 1.476 I Ditto half filled . . 29.53 2 182.0 110.3 1.377 Ditto quarter filled . . 10.60 1 181.0 106.0 1-177 Ditto ditto . . . . . 12.15 1 183% 98.0 1.174 The bottles filled to one-half lost therefore 3.66 and 6.64 per cent. of chlorine; those filled to one-quarter lost 9.98 20.2,and 20.4 per cent. respectively. If we now remember that by dropping the chlorine-water into the normal solution Dr. Wittwer must have had a still greater loss of chlorine there can be little doubt concerning the amount of reliance to be placed in the esperimental results which he has obtained. We have in our experiments eliminated these large errors ensuing from gas-absorption by insolating the chlorine-water contained in hermetically sealed tubes in which the volume of the air to that of the liquid employed was inappreciably small.Equal lengths of the same glass tube carefully cleaned and as free as possible from irre-gularities of about 18 millimetres diameter were drawn out to fine long points at each cnd. All these tubes were then dipped into a deep vessel containing a perfectly well-mixed chlorine* solution until the upper end of the tube just appeared above the surface of the liquid. The chlorine water which rises from the bottom of the vessel thus comes in contact with the air of the tube for scarcely a single * The chlorine solutions employed in all these experiments were prepared and after-wards preserved ina room from whkh all daylight was excludecl.P Irl OTOC H E NIC A L RE SEA It CH E S. second and without the slightest agitation. After a small ball of wax had been pressed on the end which rose out of the liquid the whole tube was withdrawn from the solution and by means of the blowpipe hermetically closed at both ends. A small bubble of air remained above the liquid large enough to prevent the tube from bursting by any subsequent alteration of temperature. The tube which was weighed before the experiment was after filling again weighed (by candle-light) together with the ends melted off before the blowpipe and the difference of these two weights gave the amount of chlorine-water contained in the tube. By this mode of filling the titbes the chlorine-water comes in contact for scarcely a second with a perfectly undisturbed colunin of air of only 250 square millimeters sur-face and is then irnrnediately prevented from further contact by being hermetically closed.We are thus perfectly sure that the disturbing influences of diffusion are fully eliminated. In order to avoid the same source of error during the analysis the tube was held vertically and its lower end broken under the iodide of potassium solution and afterwards the upper one also opened so that the chlorine-solution flowed into the iodide without coming in contact with the outer air. The chldrine-solution which remains on the inner surface of the tube is easily collected by washing out with a few drops of iodide-solution. The weight of chlorine (C) equivalent to the amount of liberated iodine is found according to the method described by one of us in the Ann.Chem. u. Pharm. Bd. lxxxvi. 265,* by means of the following formula c1 c= -I a(nt-t,) After these reniarlrs we proceed to a critical examination of Dr. Wittwer’s research. The starting-point and basis of all the conclu- sions contained in the memoir are found in the following sentence (p. 598) :-“By equal amounts of light the quantity of hydrochloric acid formed is proportional to the strength of the chlorine-water.” The supposition of such a proportional action appears even from a theoretical point of view in the highest degree improbable. It would require the further assumption that the chemical attraction which the chlorine exerts on the particles of hydrogen of the water is independent of the chemical attractions of the remaining bodies either already present or formed during the decomposition ; whilst daily occurring examples teach us that affinity must be considered as the resultant not only of the attractions of the combining molecules but * See also page 219 of this volume.PROFESSOR BUNSEN AND DR. H. E. ROSCOE’S 202 also of all those present within the sphere of the chemical action; and that the magnitude of the chemical affinity is changed according to the relative number and material differences of the molecules,- dependent however upon laws which are as yet quite unknown. Nitrogen in the free state is certainly one of the most indifferent bodies known and still the mere presence of this substance is sufli-cient to change the affinity of oxygen to hydrogen to such an extent that in order to induce the combination of the latter gases it is neces-sary to raise their temperature to a very different degree than that required if oxygen and hydrogen be alone present an exactly similar action is found to take place in mixtures of all gases.The numberless phenomena which we class under the term ‘‘ Catalysis,” are merely special cases in which this general action of affinity is rendered more strikingly evident. The consideration of phenomena of this kind makes it at once unlikely that the force with which chlorine decom- poses water should neither be influenced by the volume of the water present nor by the interchange which takes place between the water and the chlorine and oxygen and hydrochloric acid formed during the decomposition.Dr. Wittwer has so little coilsidered the action of these causes on chemical affinity that he states that the presence of hydrochloric acid is indzferent and specially mentions (p. 611) that he has convinced himself by various experiments of this indifference. The following facts will sufficiently show how far this statement is at variance with the truth. The gas obtained by electrolysis of pure concentrated hydrochloric acid evolved from poles of pure carbon consists as one of us has shown of exactly equal volumes of chlorine and hydrogen. When this gas freed from all trace of hydrochloric acid by passing through water is then dried over chloride of calciurn and collected with the necessary precautions t.he afinity of the two gases is such that volunies from 50 to 60 cub.cent. when exposed even on dark days to the diffuse light of a room unite with explosion. The same gas collected over tolerably concentrated hydrochloric acid may be exposed to the direct rays of the sun without any fear of explosion occurring the combination taking place gradually. Here then we have a case in which the diminution of the force of affinity of chlorine owing to the presence of hydrochloric acid is most clearly shown. It is now not difficult to prove that in the dccornposition of water by chlorine the affinity of the latter to hydrogen is altered by the formation of hydrochloric acid.Nearly two years ago we filled a glass tube of 82.3cub. cent. containing about a gramme of water with chemically pure chlorine and closed it hermetically bcforc the blowpipe. This tube PHOTOCHEMICAL RESEARCHES. -. Weig!:t of solution in grammes ..... t ........ 29.037 150.5 29378 135.7 27*.103 133'2 28'GOl 135.7 t n ........ ........ 11.4 1. 95.4 1 24'8 1 22.8 1 Chlorine in 1000 parts . Of 100 chlorine de- 1.017 037 I 0.782 0.782 composed. .... 0.0 73'4 0.0 0.0 was exposed to the direct rays of the sun and to diffused light for the space of more than twenty months without appreciably changing its colour ;and after this period it was opened under a tolerably concen- trated solution of potash. The amount of non-absorbed.gas was found to be only 2.4 per cent. of the chlorine employed. From this experiment it may be coiicluded that the affinity of chlorine to hydro- gen becomes inappreciably small as sooii as a certain amount of hydrochloric acid is formed. The following numerical data show the great retarding influence which hydrochloric acid exerts upon the decomposing force of chlorine on water :-TABLEIV. Time of Insolation 1 hour direct sunlight. Pure Chlorine Water. Chlorine Water with 10 per cent. Hydrochloric Acid. a=O*oOO7~5 Before After Before After insolation. insolation. insolation. insolation. TABLE V. Exposed for 6 hours to direct and diffuse sunlight. Pure Chlorine Water. Chlorine Water xith 10 per cent. HCI. Before After /jBefore After a=0.0007075 1 insolation.insolation. insolation. insoIation. Weight of solution taken .. 29.001 27.832 27.463 .......... 133.3 8.4 133.2 Ifl .......... 115.0 7% 24.6 n .......... 2 1 1 Chlorine in 1000 water .. 1.0338 0-00426 0.7820 Of100 chlorine decomposed . 0.0 99% 0.0 PROFESSOR BWNSEN AND DR. H. E. ROSCOE'S TABLE VI. Insolated 1hour in diffuse light and afterwards 30 minutes in direct -sunlight. Pure Chlorine Water. Chlorine Water with 3 pel. cent. Hydrochloric Acid. a=0.0007075 Before insolation. After insolation. Before insolation. After insolat ion. Weight of solutioii employed t .......... 20.831 108.8 29.48 L 107.1 28.560 108'7 tl .......... 62-0 102.0 92.0 n .......... 3 3 3 Chlorine in 1000 water .. 1.763 1.471 1 -621 01100 chloi.ine decomposed 0.0 16.1 0.0 TABLEVII. Insolated in 1hour diffuse and 30 minutes direct sunlight. Chlorine Water with 3 per Pure Chlorine Water. cent. Hydrochloric Acid. 1 1 Before After Before After a=O'OC07075 insolat.ion. insolation. insolation. insolation. Weight of clilorine water . . 29.531 27.185 31"iGL t..........108.6 108'6 107.0 t .......... 85 4 1.0 87'2 n .......... 2 1 2 Chlorine in 1000 water . . 0'8530 0.5125 0.781)3 Of 100 chlorine decomposed . 0.0 0.0 09 From Table IV. it is seen that a solution of chlorine exposed to direct sunlight during one hour lost 73.4 per cent. of chlorine. The same solution to which 10 per cent. of hydrochloric acid was added was not the least altered by exposure during the same time.According to Table V.,'a solution of chlorine exposed for upwards of six hours to direct and diffuse sunlight lost 99.6 per cent. or nearly the total amount of contained chlorine. By addition of 10 per cent. of hydrochloric acid the action during the same time is reduced to 1-3per cent. In Tables VI. and VII. chlorine water exposed to diffuse light for 1hour and to the sun's direct rays for 30 minutes lost from 16.1to 17.6 per cent. of chlorine; mixed with 3 per cent. of hydrochloric acid and subjected to a similar insolation the amount of chlorine remained unaltered. In order to give astill furthcr confirmation of thc sulJject under PHOTOCHEMICAL RESEARCHES. consideration we mention one other experiment made a year ago which shows that the decomposing force which bromine exerts upon water containing a small quantity of alcohol is considerably altered by the presence of hpdrobroniic acid.TABLEVTII. 11Ditto with ;t-to 9 per cent. Alcoholic Bromine Water. Hydrobromic Acid. II.--I. 11. 111. IT. TT. VI. 1 I Time of insolation ..... -30' -30' 45 60' Weight of solution in pimines 200 200 200 200 200 200 t ...........47.0 46'2 47.0 46.2 46.2 44.4 I,. ..........19.4 32.8 19.4 21-5 24.0 21'7 7~. (a=0'01)22503) ..... 1 1 1 1 13romine iu 1000 water . . I !)cif5 O.!j54 1-SGI 1-75! TAossof bromine per cent. .. 0-0 51.5 0.0 10.5 The lowest horizontal division in the Table shows that the loss of bromine in the liquid free from acid during an exposure of thirty minutes amounted to 51-5 pcr cent.;that the loss during the same period of the solution containing only 1per cent. of hydrobroruic acid was only 10.5 per cent. and during a period twice as long 17.75 per cent. From all these experiments thcx cannot therefore be the slightest doubt that the hydrochloric acid produced by the decompo- sition of water by chlorine exerts a very strong retarding action on the affinity of chlorine for hydrogen. We are unable to conceive what circumstances can have induced Dr. Wittwer* to ignore these plain facts as no single one of his "often repeated" experiments on this subject is given in his memoir. Dr. Wit t wer's fundamental expc:riments are however still more inexplicable.It is difficult to conceive how a mode of experiment which is accompanied by a mean error of 9 per cent. can give results whose inaccuracy scarcely reaches the error incurred by the weighing ; and how these numbers can stand in perfect harmony with a hypo- thesis which as our experiments show has no application to the decomposition of chlorine-water. Dr. W ittwer's theory starts from the supposition that aqueous solutions of chlorine lose by equal insolation an equal fraction of the originally contained chloiine,-with *Dr. Wit t wer actually proposes to employ a solution of chloride of lime decom- posed by hpdroclilo~ic acid as an absolute incnsiire of the chemical rays. PROFESSOR BUNSEN AND DR. H. E. ROSCOE'S the limitation however that the layer of chlorine water does not exmd a certain thickness.To satisfy this condition the following experiments which we have arranged in a tabular form were conducted with hermetically sealed tubes of 20 millimeters diameter and therefore smaller than the stoppered bottle employed by Dr. Wittwer. In spite of this our experiments do not show even approximation to the law founded by Dr. Wittwer. The theory requires that the per-centage decompo- sition remain constant for all concentrations of the chlorine solutions ; the results of the following Tables show that in every case a different per-centage decomposition was obtained. From Table IX. 11.94 and 15.7 per cent. 9 X. 43.0 ,,37*5 , 9 XI. 45.9 , 53.6 ,,and 404per cent. 9 XII.68.6 ,,75.3 , ,,62-8 , , xIIr. 81.8 ,,88.2 , J9 77*7 9 99 XIV. 73.3 ,,58.7 ,, I TABLEIX. Pure Chlorine-water exposed to diffuse light for 69 hours. a=0*0007075 Before After Before After insolation. insolation. insolation. insolat,ion. __I___---Weight of solution .... 32.786 27.879 29.781 28.142 t .......... 144.5 145.5 108.6 149.0 t .......... 9-0 81.0 85.4 40.0 12 .......... 2 2 2 1 Chlorine in 1000 water. .. 1.6884 1.4896 0-8752 0-7378 Of 100 chloriue decomposed . 0.0 11-94 0.0 15.7 TABLE X. Pure Chlorine-water exposed to diffuse light for 168 hours. ~~ a=O*oOo7O75 Before After Before After insolation. insolation. insolation. insolation. -~~ Weight of solution taken . . 27.199 25.686 30.B25 27.570 t .........136.8 135.2 136.2 338.2 i1.......... 25'0 1-3 3.0 GO.0 n.. ........ 2 1 1 1 Chlorine in 1000 water . . 1.8074 1.0309 0.8629 0.5394 Of 100 chlorine decomposed . 0-0 43.0 0.0 37'5 PHOTOCHEMICAL RESEARCHES. TABLEXI. Pure Chlorine-water exposed 1 hour to direct sunlight. I Before After Befom After Before After I 1 1 insolation insolation insolation ,insolation nsolation /insolation I-I-Weight of solution . 24.070 28.3 58 27*020 I 27-156 t ...... 110.0 109.8 tl ...... 5.5 30.0 n ...... 3 2 l1 Chlorine in 1000 water .... 2.669 1-4432 Of 100 chlorine de-composed ... 0.0 45.9 . . ~ TABLE XII. Pure Chlorine-water exposed for 1hour 30 minutes to direct sunlight. a=0*0007075. Before After Before After Before After insolation nsolation nsolation insolation nsolation insolation Weight of chlorine water ...24'070 27.204 27.020 27.889 27.537 28.433 t...... :I 110.0 222.7 109.9 13.4 109.8 13.2 tl...,.. 5.5 7.5 79.6 4.4 27.9 8.2 n. .. ... 3 1 2 3 1 3 ~li~orine in 1000 parts water . . 2.669 0.8574 1.0268 0.253F 0*.5880 0.2184 Of 100 chlorine de- composed ... 0.0 68.6 0.0 7 5.8 0.0 62.8 TABLE XIII. Pure Chlorine-water exposed for 2 hours to direct sunlight. I 4 1 a=0*0007075. Before After Before After Before After insolation insolation insolation insolation insolation insolation Weight of chlorine water .... 24.070 25.716 27-020 25.387 27-53?' 23'110 t....... 110'0 109.5 109.9 13.2 109.8 132 tl ...... 5.5 50.9 79.5 10.9 27.9 11.1 2 1 2 ...3 l2 &Gin; in 1000 parts water . . 2.669 0.45061 1.0268 0.1208 0.5881 0.1309 Of 100 chlorine de- 1 composed ... 0.0 81.8 0.0 88.2 0.0 77.9 PROFESSOR BUNSEN AND. DR. H. E. ROSCOE’S 208 TABLEXIV. Pure Chlorine-water exposed for 2 hours to the direct sunlight. ___-~_____-I I l a=0-0007075. Before After Before Ailer insolation. insolattion. insolation. insolation. -I-Weight of chlorine water . . ~YO~F 29~3 29.300 25.755 t ..........150.5 135.7 135-6 t .......... 11.4 88.4 1084 n .......... I 1 1 1 Chlorine in 1000 prts water. 1.01 66 0.2119 Oi 100 chlorine decomposed . 0.0 73.3 58.7 If we suppose as is most simple that the decomposing force of the light is proportional firstly to the length of exposure and to the intensity of the light and secondly to the mass of decomposing sub- stance present in the unit of volume it is seen from the foregoing Tables that the affinity of the chlorine to the hydrogen of the water first increases by diminution of the amount of contained chlorine then attains a maximum and afterwards again diminishes.Numerous instances of such a mode of action of affinity will occur to every chemist. Although after all these explanations it must appear almost unne- cessary further to examine Dr. Wit t w er’ sexperiments we have repeated the experiment cited in the research at pages 600 and 601. Our only object in continuing this examination was the wish to leave no means untried which by any chance could lead to an explanation of the above contradictions.Here also as might be expccted our attempts were fruitless. In order more fully to establish his sup- position that by equal intensities of light the amount of hydro- chloric acid produced is proportional to the contained chlorine Dr. U’ittwer shows by experiments (which again in spite of the source of error above mentioned agree precisely with the theory to be proved) that the alteration of the chlorine solution is proportional to the product of the amount of light into the strength of the chlorine- water and the time of exposure. In this experiment he determined the loss which a solution of chlorine suffers by exposure for 10 20 30 and 46 minutes each during a constant intensity of light. From S the original strength of the chlorine-water and s the strength after insolation during a time t he finds the intensity I of the light for the whole time during which his experiment lasted; and his numbers agree as far as the third decimal figure.PHOTOCH?CMTCht RESEARCHES. On page 601 of Dr. Wittwer’s memoir we find the following experiment :-t S‘ r 10’ . . . 2.1659 . . 0.11607 20’ . . . 3.9164 . . 0.11923 30’ . . . 1.7279 . . 0,11398 40’ . . . 1.5239 . . 0.11690 50’ . . . 1.3660 . . 0.115411 The first column expresses the time of insolation; the second the amount of chlorine contained in 1000 parts of liquid which before iusolation contained 2.4324chlorine in 1000parts. We have already shown that the mean error which is caused by diffusion during the dropping out of the chlorine-solution amounts to about 9 per cent.Supposing now that this error is twice as large as that actually pre-sent,-that is suppose that the real error amounts to 4.5 per cent.,- the inaccuracy to which Dr. Wittwer is then liable is so large that in his first observation for example he may just as probably have obtained the number 0.16206 instead of 0.11607 as the value of I. In order to avoid a11 disturbing influences in our experiments we conducted them precisely under the outward circumstances mentioned by Dr. W-ittwer we also chose for our insolation the noon of a cloudless day. The probability that the value of I remained constant during-our determination is four times larger than is the case with Dr.Wittwer’s experiment as we conducted the insolation according to a system which required that the light should remain constant for a period only one-fourth so long. The following is a description of the method which we employed :-Suppose that five tubes containing chlorine-water be exposed to the same amount of light during varying lengths of time; for instance the first for 18 minutes the second for twice 18 minutes the third for three times 18 minutes and so on ; all the tubes are exposed at the same moment and after the lapse of every 18 minntes each one of the tubes may be covered. As the first tube was insolated for only 18 minutes the last on the other hand for 90 minutes it is necessary that the amount of light remain constant for 90 minutes.If on the contrary all the tubes be exposed to begin with together but the first insolated for 3 minutes the second for 6 minutes the third for 9 minutes the fourth for lf2 minutes the fifth for 15 minutes and if this regular opening and covering of the tubes be repeated for each 18 minutes the light is only required to remain constant for 18 minutes and gives results as VOL. vIrr.-No. XXXI. P PlIOTOClIEMICAL RESEARCHES. accurate as the other meihod which requires a constant source of light of 90 minutes duration. In the following experiment 5 sealed tubes of chlorine-water of the strength S= 0.2641 per cent. of chlorine wcre insolated according to the preceding system so that the exposure lasted from 18 minutesup to 90 minutes. The required condition for a constant value of I was therefore given when the alteration of the intensity during every 18 minutes is taken as inappreciable ; whereas in Dr.Wittwer's expe- riment a constant intensity for l hour 10 minutes is necessary. TABLE XV. Duration of the experiment 1hour 30 minutes. Pure Chlorine-water u= 0*00059028. Length of insolation. Not 18' in 36' in 64'in 72'in 90' in insolated. sunlight. sunlight. sunlight. sunliglit,. mnlight. --. -Weight of chlorine-water . . . . 24.248 25.208 24.566 23.538 23.448 23.31 1 t . . . . . . . 125.5 125.5 126.0 126.0 126.0 126.0 f . . . . . . . 113.8 57 1 1'0 77.5 27.5 61.4 n . . . . . . . 4 3 2 2 1 1 Chlorine in 1000 parts water . . 2.6409 2.0904 1.6854 1-2214 0 GO297 0.4752 Value ofI.. . . 0.0 0.0130/ 0.01 2 0.0142 0.0186 0.01 95 ___-The lowest line of the preceding Table contains the values of I cal-culated from each experiment ; it is here seen that these numbers are anything but constant varying from 0.013 to 0.019. In reviewing the results of our experiments we find the following conclusions justified :-1. The products formed by the photochemical decomposition qf chlorine-water exert a retarding action on the amount ofth,e original aflnity of the chlorine. '2. The decomposing action of chlorine on water is therefore neither proportional to the length and intensity of the inso- lation nor to the strength of the chlorine-water. As the photochemical action is thus accompanied by a simulta-iieous change in the affinity dependent on laws altogether unknown it lvould be a completely hopcless task to eiidcavour to arrive at the DR.GLADSTONE ON THE COLOUR OF CHLORIDE OF COPPER. 211 laws of the chemical action of light by the insolation of chlorine-water. We have therefore for upwards of a year given up all attempts of this kind and have had recourse to another method by help of which we have succeeded in establishing a series of very simple relations exhibited by the chemical action of light. The simple law which governs these interesting relations we shall conimu- nicate in our next paper on this subject.

ISSN:1743-6893    

DOI:10.1039/QJ8560800193

出版商:RSC    

年代:1856

数据来源: RSC

摘要:

DR. GLADSTONE ON THE COLOUR OF CHLORIDE OF COPPER. 211 XI.-On the Colour of Chloride of Copper in diferent States of Hydration. By J. H. GLADSTONE PH.D. F.R.S. THERE are two theories respecting the aqueous solutions of haloYd salts :-the one maintains that the compound of a metal and a halogen dissolves as such in the water; the other that it becomes a com- pound of the metallic oxide and the hydracid which is also dissolved in the liquid. One of the arguments adduced in support of the latter theory is that certain salts such as the chloride or bromide of copper or the chloride of cobalt change colour on dissolving in water and assume a tint which is supposed to belong to the oxide. It happened that in my recent investigation of circumstances that modify the action of chemical affinity I examined the changes of colour which take place when hydrochloric acid or a soluble chloride is added to a solution of a blue salt of copper.This led to an examination of the chloride itself; and the observations then made have been extended with a view to determine if possible how far the change in colour may really lend support to the theory in question. The following are the facts with which this examination has made me acquainted. Chloride of copper exists in a solid forni in two conditions the one anhydrous the other containing the elements of water. The anhydrous salt.-This is amorphous and of a yellowish brown colour whether produced by the combustion of copper in chlorine or by heating the hydrated compound.Its composition has been deter- mined by Berzelius and J. Davy to be CuCl. The hydrated salt.-This exists either in an amorphous or a crystalline form according to the mode of preparation. If anhydrous chloridc of copper be exposed for a few minutes to 1)R. J. H. GIAADSTONE ON THE COLOUR OF the ordinary atmosphere it begins to change from yellowish-brown to pale bluish-green. This will go on till the whole mass becomes a bluish-greet] powder which is dry to the touch not deliquescent in ordinary states of the atmosphere and devoid of crystalline form even when viewed under the microscope. Professor Graham believes this to be the hydrate CuCl 2130.* An experiment of mine confirmed this view. 0,960 grm. of anhydrous chloride of copper on exposure increased in weight to 1.224*grm.theory requires 1.216 grm. If the oxide or carbonate of copper be dissolved in hydrochloric acid and the solution evaporated nearly to dryness bluish-green crystals separate. Their forin has been determined as that of a right-angled four-sided prism. They are more deliquescent than the amorphous hydrate. No complete analysis of this salt seems to have been published. Its received forniula CuCl+2HO rests on the observation of Professor Graham that the crystals give off 21.53 grm. of water when strongly heated. I. 1grm. of the crystals dried at a temperature somewhat under 100' C. gave off 0.212 grm. of water when heated inore strongly and yielded 0.473 grm. of oxide of copper. 11. 1-22grm.gave 2.003 grms. of chloride of silver. 111. 1grm. of another preparation gave off 0.214 grm. of water when heated and afforded 0.472 grm. of oxide of copper. IV. 05 grm. of the same yielded 0.830grm. of chloride of silver. These red ts give percentage numbers nearly coincident with those deduced from the above formula. Found. Calculated. ..7-.-1st preparation. 2d preparation. Copper. . . 37.84 37-76 37.47 Chlorine . . 41.01 41.06 41.45 Water . . . 21.20 21.40 21*08 100.05 100*22 100~00 It is evident that this green salt may either be Cu C1+2 HO or CuO HC1+ HO. If the latter it might be reasonably expected that some difference would show itself between the two atoms of hydrogen and oxygen; but my observations though specially * Phil.Trans. 1837 p. 71. CIILOltLDE OF COPPER IS DIFFERENT STAPES OF HYDRA'I'ION. 213 directed to the point have failed to remark any. The brown salt appears to assume thc two atoms at once; neither is there auy inter- mediate stage in the dehydration of the green salt. When the crystals are heated to about 90' C. (1 9-4' F.)? they begin slowly to give off water shrink and assume at once the brown colour. If the temperature be raised a little above 100' C. the water is given off rapidly. If strong sulphuric acid be added to the green crystals or to a strong aqueous soluti.;nJ the hown salt is instantly produced. There appears then to be no ground for supposing that the difference of colour betweeu the anhydrous and the hydrated salt depends upon the conversion of the latter into hydrochlorate of the oxide of copper.33fect of solution.-If an equal weight of water be added to the pure green salt it dissolves giving a clear solution of a deep green colour. On the addition of more water a gradual change of colour occurs as indicated in the annexed table :-Composition of Solution. Colour. 1 part crystal. chloride of copper + 1part wdter 1)eep green. 17 JJ ,? 9 3-3 ? Bluish green. 7> ?i ,J >f +3 J Still blue. 99 JJ ,? , + 4 , Nearly pure blue. ,? ?> ?? 99 + 5 > Blue. Oxychloride of Copper.-lt may be as well to remark in this place that on dissolving most specimens of crystallised chloride of copper a white subsalt separates not when the solution is so strong as to appear green but when it passes from green to blue.This deposit was observed in one instance to be as much as -&ths of the whole weight of the salt though iisually it is considerably less than that. When dry it is a pale green powder which remains unaltered though heated up to 215' C. (419' F.)?but when almost at incipient redness it gives off both water and chlorine and is converted into a black mixture of oxide arid dichloride of copper. The following analyses were made :-I. 1 grrn. of the subsalt dried at loooC. and dissolved in dilute nitric acid yielded 0.734 grm. of oxide of copper and 0.812 grm. of chloride of silver. 11. 1 grm. of a different portion gave 0.760 grm. of oxide oi copper and 0829 grin. of chloride of silver. 111. 0.535 grni.of another preparatiou gavc 0.397 grm. of oxide of copper. UR. J. H. GLADSTONE ON THE COLOUR 01" These numbers reckoned to 100 parts represent- I. 11. 111. Copper . . . . 58-72 60.80 59.36 Chlorine . . . . 20.08 20.51 -The proportion of the copper to the chlorine appears thus to be as three atoms to one and though the salt is evidently somewhat irregular in its composition it approaches nearer to the oxychloride CuCl 2Cu0 HO than to any other of the eight or nine that have been described by previous investigators. Copper. . . 61.34 Chlorine . . 22.68 Oxygen and hydrogen . . 15.98 100~00 It isl probably this oxychloride with the admixture of a varying quantity of one containing more of the elements of water. Whether the constitution of this salt be as above written CuC1,2CuO €10 or 3Cu0 HCI there seems nothing to decide.This oxychloride dissolves in a strong solution of pure chloride of copper ;and the crystals derived from such a solution retain the form of the pure salt but are of a yellowish-green instead of a bluish-green tint; when dissolved in water they give an abundant deposit and they contain a deficiency of chlorine,-indeed in a case submitted to analysis only 39.75 per cent. The great disparity of tint observed in different specimens of crystallised chloride of copper seems to arise generally from the varying amount of oxychloride they contain though an excess of acid will also cause the crystals to assume a yellowish colour. Crystals that dissolve without deposit may be obtained from an impure salt by repeated solution filtration and recrystallisation though perhaps the chloride thus obtained is never absolutely free from subsalt.The best method of obtaining pure crystals is to start with a very acid solution. If strong hydrochloric acid not in excess be poured upon the oxychloride a solution results which on dilution deposits the subsalt. Change of coZour.-It has already been observed that the solution from which the oxychloride has separated changes gradually from a deep gifen to a clear blue. The question arises,-Does this change of colour depend npon some action of the water or of the elements of it ; or is it in some way a mere physical result of the solution ? In the hope of determining this inatter the action of other solvents CHLORIDE OF COPPER IN DIFFERENT STATES 01”HYDRATION.215 was tried. It was found that brown anhydrous chloride of copper dissolves in absolute alcohol of a yellowish-green colour and that it does not assume a bluish tint on any amount of dilution with the same solvent. This is the case also when either the bluish-green or yellowish-green crystals are dissolved in absolute alcohol or even in strong spirits of wine,-the alcohol appearing to abstract the water from the hydrated salt. Even the addition of alcohol to a moderately strong aqueous solution heightens the green imparting ayellowish tint to it. If the crystals contain oxychloride alcohol does not cause its separation. The addition of water in considerable quantity to the alcoholic solution causes a production of the blue colour and a deposition of any subsalt that may be present.If a solution of the anhydrous chloride in absolute alcohol be evaporated down it shows little or no tendency to crystallise but becomes an almost black viscid mass which however on standing for some hours becomes filled with tufts of yellowish-brown crystals. Ether in like manner dissolves chloride of copper giving an intense yellowish-green solution which also does not alter in the character of its colour when diluted with any amount of additional ether. The change from green to blue depends then upon the water; but is it because the salt is converted into hydrochlorate of oxide of copper or -because it forms a higher hydrate than exists in the crystals ? The following observations may possibly afford some grounds for forming an opinion.Hydrochloric acid imparts a bright yellowish tint to the green solution of chloride of copper. On dilution with water such a mix-ture also assumes a blue colour but it requires much more water than the neutral salt does. The followiiig table will exhibit the changes of tint produced during the dilution of a mixture of single equivalents of chloride of copper and hydrochloric acid. It would not dissolve completely in an equal weight of water. Coinpositioii of Solution. Colour. 1 part CuCl+ HC1 with 2 parts water Dark green. 5 1) Briglit yellowish green. >? >I 9 1) ,? I> 8 Bluish green. >9 Almost pure blue.>? >? 7 I¶ >> 9) 9) 15 I Blue. During this dilution there is a gradual alteration of the colour; but the change appears to be more rapid at certain points than at others. Yet after careful and repeated examination I caiiie to the belief that the effect of water is regular and that what appears like rather sudden DIL. J. H. GLADSTONE ON THE COLOUR OF transitiuns is due to the difficulty of comparing solutions of different shades of colour. If a solution containing single equivalents of chloride of copper and hydrochloric acid be diluted till it becomes blue the addition of more hydrochloric acid will cause it to resume the green colour and if sufficient be added to become of the bright yellowish tint,-the amount of greenness being regularly proportionate to the amount of hydrochloric acid present.The compound of chloride of copper and hydrochloric acid which niay be supposed to exist in these yellowish-green solutions does not appear to be crystallisable. If a solution of the copper salt in hydro- chloric acid be evaporated crystals separate of a bright green colour. On drying between folds of bibulous paper these part with the adhering strongly acid liquid and at the same time their yellowish tint is greatly reduced. A portion so prepared was dried at SO" C. when it appeared very like the ordinary bluish-green crystalline salt. It weighed 1.240grm. At a higher temperature -it gave off water and a little hydrochloric acid. After being heated at 150" C.it was converted into apparently the anhydrous chloride and weighed 0.969 grm. The same amount of CuCl 2HO would have given by calculation 0.979 grm.,-a quantity scarcely exceeding that actually found so that the hydrochloric acid attached to the crystals must have been a mere trace. Another experiilzeiit gave a similar result. That the brown powder left on heating this was really CuCl was proved by a determination of the copper. 0.531 gni. yielded 0.318 grm. of oxide of copper; which gives the following percentage :- Found. Calculated. Copper . 47.83 47.48 Some other chlorides,-such as chloride of sodium and chloride of ammonium,-produce the same yellowish colour in solutions of chloride of copper as hydrochloric acid does; whilst others such as chloride of calcium do not affect it.Some of these double chlorides have been crystallised and described. The colour of a solution of chloride of copper alters much with the temperature. If it be heated it becomes gradually yellower even if previously diluted to such an extent as to be perfectly blue. Indeed it was found that 2.5 grm. of the crystallised salt when dissolved in three ounces of water so that the blue colour was pale assumed a distinctly green shade when the solution was heated to the boiling point. The same occurs in the presence of hydrochloric acid. 011 CHLORIDE OF COPPER IN DIFFERENT STATES OF HYDRATION. 217 cooling again the yellow tint gradually disappears. This action also is not confined to temperatures above the ordinary a green solution of the chloride placed in a frigorific mixture becomes blue.The remarks here made upon solutions of pure salt in distilled water apply equally to the salt when produced by double decom position :-for instance to a mixture of sulphate of copper and chloride of sodium though of course in such a case the blue colour of the sulphate still unaltered interferes with the result. The addition of sulphuric acid to a somewhat dilute solution of chloride of copper tends to produce the bright green evidently from the liberation of some of the hydrochloric acid though blue sulphate must be produced at the same time. The following are the inferences which I have drawn from these experiments and which I now submit to the consideration of chemists :-Every observation made on this salt is perfectly explicable on the supposition that the proper colour of chloride of copper is brown and that it forms hydrates which are green or blue just as the white sulphate of copper becomes blue when hydrated.Some of the facts too are more easily explained on this view. Thus it is hard to imagine that if green be the colour of CuC1 and blue that of CuO HC.1 the addition of more HC1 to the latter should render it green; while it is readily conceivable that the hydrochloric acid should replace a portion of the water in the blue hydrated chloride of copper and form a green double chloride CuCl IICl. The action of heat is in harmony with what we know of its action on unquestionable cupric hydrates thus the hydrated oxide of copper when heated in the presence of any amount of water loses its combined water and its blue colour.If the change of colour is to be taken as evidence that crystallised chloride of copper hecomes when treated with a considerable amount of water CuO HC1 a parity of reason should lead us to conclude that the bluish-green crystals contain none of the yellowish-brown CuCl; yet if we suppose that these crystals actually contain the oxide we can give no consistent account of the subsequent chanse of colour on solution. Perhaps none of these observations are decisive on the point; yet it appears to me that this examination of the chIoride of copper has golie Far to show that instead of its furnishing an argument in favour of the supposition that haloid salts are decomposed by water it leads towards the opposite conclusion.218 DR. GLADSTONE ON THE COLOUR OF CHLORIDE OF COPPER. There are three incidental remarks which may be appended. Those who hold the binary theory of salts aud contend for the resolution of the chloride into the hydrochlorate must consistently suppose the same when the salt-radical is a compound body thus-If NaCl in water becomes NaO HCl 9, then NaNC , NaO HNC, 99 and NaSO , Na0,HS04. Even where different salts of a base have the same colour the same amount of the base does not give the same intensity of colour. Thus if equal portions of oxide of copper be dissolved respectively in acetic hydrochloric nitric and sulphuric acids and equally diluted the acetate will be found to be far deeper in colour than the nitrate this somewhat deeper than the sulphate and this again far deeper than the chloride.On being converted into ammoniacal salts these four approximate more nearly but are still far from identical in colour. Whatever theory be preferred for explaining the changes of colour that take place during the solution of chloride of copper the influence of mass is very apparent. It is almost self-evident that different compounds co-exist in the solution in proportions varying with the amount of water present or of free hydrochloric acid and that the final state of combination is the resultant of.severz1 affinities of dif-ferent degrees of strength acting on the same particles.

ISSN:1743-6893    

DOI:10.1039/QJ8560800211

出版商:RSC    

年代:1856

数据来源: RSC

摘要:

NOTICES OF PAPERS CONTAINED IN OTHER JOURNALS. BY HENRY B.A. F.C.S. WATTS C)n a Method of Volumetric Analysis of very general Application." By R. Bunsen. THISmethod which is applicable to a great number of analyses de-pending upon oxidation and reduction is founded on the principle of liberating a quantity of iodine equivalent to the substance which is to be determined and estimating this iodine by means of a standard solu-tion of sulphurous acid. The use of sulphurous acid for the estimation of iodine which was originally proposed by D up asquier gives exact results provided always that the solution of sulphurous is sufficiently dilute. Sulphurous acid and iodine in presence of water form hydriodic and sulphuric acids; but on the other hand sulphuric and hydriodic acids may react upon each other in such a manner as to yield sulphurous acid water and iodine This latter reaction takes place to a greater extent as the liquids are more concentrated.Kence when iodine is treated with sulphurous acid this acid will not be completely osidised unless the liquid is sufficiently dilute. Hence the necessity of using in this process solutions not containing more than 0.04to 0.05 per cent. of anhydrous sulphurous acid. The method about to be described requires three test-liquids a solution of iodine a solution of sulphurous acid and a solution of iodide of potassium. To prepare the first a quantity of iodine as pure as can be obtained is dried at ordinary temperatures over chloride of calcium g gramrnes of it then weighed out between watch-glasses and dissolved in a 1itre.measure by a concentrated solution of iodide of potassium which solution must not exhibit any brown colour either by itself or on the additioii of hydrochloric acid.If one' degree of the burette contains as usual 0.5 cubic centirnetres the resulting * Ann. Ch. Pharm. Ixxxvi. 265 ; Aun. Ch. Phys. [3] xli. 339 220 BUNSEN OX A solution must be diluted with a quantity of water sufficient to bring the volume to -cubic metres. Each degree of the burette will 0.005 then contain 0.0025 grm. of the iodine used. But as commercial iodine even the purest contains traces of chlorine it is necessary in determining the strength of the solution to take account of this impurity.For this purpose a weighed quantity of dried iodine is dissolved in cold sulphurous acid the solution precipitated with nitrate of silver and the precipitate digested with nitric acid before filtration to remove any sulphite of silver that may be thrown down at the same time. Jf the quantity of impure iodine used be called A the quantities of pure iodine and chlorine contained in it by x and y and the precipitated chloride and iodide of silver by R;then x-+y=A Ag+I Ag+C1 y=B and -x+-c1 I If we denote the ratio of the equivalents of iodide of silver arid iodine namely -AgI4-I by a,and the ratio of the equivalents of chloride of Ag + C1 silver and chlorine namely -Cl by /3 we have- From this value of 9 we may readily calculate the quantity of pure iodine which is equivalent to a unit of weight of the impure substance.For the quantityof chlorine 9,exerts the same oxidising action as the I quantity of iodine -9. Hence the chlorinated iodine A exerts the C1 same oxidising action as the .quantity of pure iodine denoted by I A-y +-yc1 ;and therefore the quantity of pure iodine a’ which corresponds to the quantity a of the impure iodine contained in a degree of the burette is given by the equation- a’=u+-.a H-UA A p-a (A-1) Of the iodine used in most of the following experiments 1.4379 grm. gave in one experiment 2.7498 grms. iodide and chloride of silver ; in another 1.7456 grm. iodine gave 3.3251 grms. iodide and chloride of silver. Substituting these values together with a =0.0025 in the last equation we find for the quantity of pure iodine in a degree of the burette from thc first cxperiment 0.0026246grrn.and from thc second 0*00253,E8; riican (I’ =0.00:?6387. GENERAL METHOD OF VOLUMETRIC ANALYSIS. A simpler and better method of finding the value in pure iodine of a degree of the burette when the iodine used is impure will be given with the volumetric analysis of chromate of potash. If the standard iodine-solution be used at a temperature different from that at which it was prepared an error will be committed in consequence of the change of volume of the liquid which is measured. As however this variation for 10"C. of temperature does not amount to more than Tgmof the quantity of iodine to be determined (which is at most 0.2or 0.3 grm.) it mag be safely neglected with any variation of temperature that may actually occur and the more so as the atomic weights of the substance to be determined are gene-rally small in comparison with that of iodine.The measurement of this iodine-solution which is perfectly stable is best performed in a burette the degrees of which correspond to 0.5 cubic centirnetre of liquid. To avoid any error in reading arising horn parallax the instrument is loosely held between the thumb and forefinger and allowed to hang down and the level of the liquid is read off at the lfwer surface of the fluid meniscus as soon as that surface coincides with a horizontal line fixed at some distance. In this manner the reading may be performed with certainty to &th of a degree especially if the observer waits till the liquid adhering to the sides of the burette has run down sufficiently to make the level constant .Of the second test-liquid the dilute sulphurous acid it is best to prepare 20 or 30 litres at a time so that the alteration in the amount of acid produced by the action of the air during the course of an experiment may be imperceptibly small. In such a fluid mixture the decrease of sulphurous acid in a bottle half full of air amount8 in 24 hours to about 1or 2 burette degrees so that the diminution which occurs during the three or four minutes occupied in an experi- ment does not exceed -+m of a burette degree or 0*0002milligramme of iodine a quantity altogether inappreciable.To give the acid the proper degree of dilution 20 or 30 litres of water are mixed with a small measure-glass-full of concentrated sulphurous acid ; the liquid shaken; 200 burette degrees of it measured off; and this portion tested after addition of starch with the standard solution of iodine. If r degrees of this solution are required to decompose the acid and if the quantity of iodine a contained in a burette degree amounts to about 0.002 to 0.003 grm. then in order to obtain the required degree of concentration viz. about 0.03 sulphurous acid to 100 water it is merely necessary to add to the entire liquid ($ -1) of con-centrated sulphurous from the small measuring bottle. T:If -1) becomes negative we may know that the assigned 222 BUXSEh’ ON 21 measure has already been exceeded by the first addition of acid.The experiment must therefore be repeated with a smaller measure or with less concentrated acid. As sulphurous acid oxidises by exposure to the air the solution niust be renewed every three or four days which may be done without any trouble as the quantity of sulphurous acid to be added to the water is known from the previous preparation. The solution should also be shaken up before being used. The third test-liquid used in the determinations is a solution of iodide of potassium containing aboiit 1grm. of the iodide to 10 cubic centimetres of water. With a little practice however this solution may be dispensed with a small piece of solid iodide of potassium being added in each experiment.1. Determination of Iodine.-The weighed sample of iodine is dissolved in the solution of iodide of potassium contained in a capa- cious beaker glass about 4 or 5 cubic centimetres of the solution being taken to 0.1 grm. of iodine. To the resulting brown solution as many measures of the standard soluticn of sulphurous acid (measured in a stoppered cylinder) are added as are required to destroy the brown colour completely the acid which adheres to the sides of the cylinder being each time rinsed into the beaker with distilled water and the measuring vessel subsequently washed with the iiormal sul- phurous acid solution The next step is to determine the quantity of iodine x,by which the sulphurous acid has been partially decomposed.For this purpose it is necessary to determine the quantity of iodine required to decompose the sulphurous acid still present in excess. This is effected by adding 3 or 4 cubic centimetres of clear and very dilute starch solution and then dropping in the standard solution of iodine till a blue colour begim to appear. If the quantity of iodine- solution required to produce this effect is measured by t’ degrees of the burette and the quantity of iodine in one degree is x,theri the quantity required to decompose the n tneasures of sulphurous acid added will be x+at’. Further if we determine by means of the burette the quantity of iodine at required to decompose 1measure of sulphurous acid we shall obtain the equation x+at‘ =nut whence a=a(nt-t’).If the weight of the sample of iodine be A the quan- tityof iodine expressed as a percentage will be 100n and if -=1 that is if the quantify weished out be exactly 100 a, A the equation becomes simply x=nl-i!’ that is to say the difference of the two rrieasureinents nt-t’ gives at once the percentnge of iodine in the saiiiple. GENERAL METHOD OF VOLUMETRIC ANALYSIS. 0.7979 grin. of chemically pure iodine mixed with 1.0400 grm. iodide of potassium and tested in this manner gave- n-5; t='73*2; t'=52-0; n=0.0025387 Iodine . . 43.41 Quantities use d. 43.37 Vol. anal'ysis. Iodide of potassium . 56.59 56.63 1oo'oo 1oo*oo 2. Determination of Chlorine.-Chlorine decomposes a solution of iodide of potassium instantly and completely even in the cold setting free an equivalent quantity of iodine.If this quantity be volume- trically determined iii the manner just described the quantity of chlorine will be given in the equation- c1 x = -I a (nt-t') or in pcrcentages if the quantity used in the experiment was A 100 c1 x = -n (nt-t'). A-1 100 c1 If again A= -a 1 the difference of the two measurements nt-t' will give at once the quantity of chlorine in 100 parts: To give an idea of the great aecuracy of this method we may adduce an example of the determination of the density of chlorine. A stream of chlorine gas evolved from hydrochloric acid and peroxide of man-ganese washed with water and dried by passing over chloride of calcium was made to pass through a glass tube of the capacity of 91.005 cubic centimetres drawn out at both ends and connected with the gas- generating apparatus by means of a tube of vulcanised caoutchouc As soon as the tube had assumed the constant temperature 2.1' C.and the air had been completely expelled by the chlorine the tube was tightly closed on the side next the generator by pressing the caoutchouc tube with the finger close to the aperture; and the other extremity which remained open dipped into a solution of iodide of potassium. Rapid absorption took place the tube becoming com- pletely filled with the liquid which was at the same time decomposed with scparation of iodine. This liquid gave by the volumetric method above described n=9; t=44*7; t'=5*0; a=0.0025387. From these elements it was found that thc tube which contained 91.005 cubic centimetres of water at 4' C.containcd 0.28191 grm. of chlorine at 0.7467 met. bar. and 2.3 C. ; mid this givcs for the sp. gr. of' .. . chlorine-Found. Calculated. 2 4.4182 2* 42 489 224 BUNSEN ON A 3. Determination of Bromine.-A solution of bromine may be readily estimated in the same manner as chlorine the result being calculated by the formula- p = -looBy a (nt-t’). A1 As commercial bromine always contains a little chlorine which is very difficult to separate the bromine used for testing the method was prepared from pure bromide of potassium. For this purpose 0.2869 grin. pure bichromate of potash was mixed with 2 or 3 grm. bromide of potassium and distilled with concentrated hydrochloric acid from a small glass flask and the bromine which passed over was received in a solution of iodide of potassium containing 0.9030 grm.of the iodide. As 1at. K Cr liberates exactly 3 at. bromine the bromine distilled off from the above mixture should weigh 0.4629 grm. The volumetric analysis gave the following results- n=6 ; t=55.4 ; t’=44*4; A= 1.3659 ; a= 0.0025387 ; whence Used. Found. Iodide of potassium . 66.11 66-20 Bromine . . 33-89 33.80 100~00 100*00 4. Determination of Chlorine and Iodine tqyether. -When a mixture or compound of x chlorine and y iodine is to be determined it is best to measure out two equal volumes of the liquid which con- tains them. One of these measures is mixed with sulphurous acid till it loses its colour and then precipitated with nitrate of silver.Let the weight of the precipitate of bromide and iodide of silver collected on a filter after digestion for some time with dilute nitric acid be A. The quantity of iodine a (nt-t’) equivalent to the chlorine and iodine together in the second measure is then deterniined by the method above given for bromine. These experiments give the fol- lowing equations of condition- I mx + y = a (nt-t’) whence A-*g+I I a (nt-t’) GENERAL METHOD OF VOl.UM%TRIC ANALYSTS. This method becomes inapplicable when the liquid contains hydro-chloric acid and other compoiinds of chlorine. But as this condition is rarely fulfilled in practice it is Senerdly better to dctermine the iodine in one portion of the liquid as iodide of palladium.If the weight of the palladium obtained by igniting the precipitated iodide of palladium be 7,the first of the two equations of condition takes the form -a=y; whence Ycl z = -C1 d (nt-t’) -c1 I. I’d T’ An analysis of a sample of protochloride of iodine prepared with aqua-regia gave- n=0.1156; t=241*6 t’=131-4; n=l; n=0*0050. Calculated. Found. Iodine . . 21.85 21-86 Chlorine . . 78-15 78.15 100*00 100.00 5. Determination of Chlorine and Bromine together.-To estimate the quantity of chlorine contained in a sample of bromine a quantity A of the bromine thoroughly dried is dissolved in soliltion of iodide of potassium and the quantity of iodine u (nt-t’) thercby sepa-rated determined as above.Thc cquations of condition which form the basis of thc calculation and in which chlorine is denoted by y and bromine by x,are-x+y = A -I x + I g = a (nt-t’) Br wticnce we find a (nt-t’) -IA Rr Y T 1 a-Br To test this method 0.1148 grm. of bromine free froin iodine and dried on chloride of calcium was wcighed in a glass bulb converted by sulphurous acid into hydrobromic acid and precipitated by nitrate of silver. The resulting chloride and bromide of silver weighed 0.2826 grm. Putting 0*114H=A’ and 0.2826=B’,the quantity of chlorine in the sample examined is found froin the eqwdtions-VOL. VII1.-NO. XXXI. 8 226 BUNSEN ON A xi-y = A’. Ag + C1 ?J Ag + Br x + 7= B’. therefore Ag+ Br A/-X 13r 0.09448 grm.of the same bromine dissolved in iodide of potassium gave by volumetric analysis- A = 0.0948; n= 1 ; t= 80.5; t’ = 17.3; a = 0.002578. Weighed niialgsis. Vol. analysis. Bromine . . 93.42 93.34 Chlorine . . 6-58 6.66 100~00 1oo*oo 6. Determination of Chlorites and Hypoch1orites.-A solutioii of the salt is mixed with solution of iodide of potassium and hydro- chloric acid added till a slight acid reaction is produced. By rneans of the quantity of iodine a (nt-t’) separated in the solution and detemined by the volumetric method the weight of chlorous acid x or of hypochlorous acid XI is found from the following equations in which A denotes the weight of the salt or mixture of salts employed 100 c1 x = 41A a (nt-t’) 100 Cl XI = -a (nt-t’) RIA The method was tested upon a mixture of caustic potnsh’ancI hypochlorite of potash.To obtain a perfetly definite quantity of thc latter 0.3256grammes of pure bichromate of potash was boiled with fuming hydrochloric acid and the chlorine which passed over with the vapours of hydrochloric acid conducted into a solutim of 44grammes of caustic potash. Now since 2 at. K Cr eliminate under these cir- cumstances exactly 3 at. C1 the potash-solution must absorb 0.1427 grammes of that substance. The volumetric analysis gavc n=4; t = 83.6; t’=8 ; u =0*002578,which corresponds with th!\ following composition QENERAL METHOD OF VOLUMETRIC ANALYSIS. 227 Used. Vol. analysis. Aqueouspotash .. . . 96-55 96.52 Hypochlorite of potash . . 3-46 3.4-8 100*00 100~00 This method is peculiarly well adapted to the technical estimation of chloride of lime. If we take a solution of that substance con- taining =a of dry chloride of lime the difference of the two I measurements (nt-t') gives directly the bleaching power of the product in per centages of chlorine. 7. Determination of Sulphurous Acid und Sulphuretted Hydrogen. -It has already been observed (p. 219) that sulphurous acid (and we may add sulphuretted hydrogen) cannot be exactly estimated by means of iodine if the quantity of it contained in an aqueous solution exceeds 0.04per cent. If therefore a more concentrated acid is to be examined it must be diluted with boiled water till the total volume P has attained the required concentration.From this solution p cubic centirnetres are then measured off starch added and the quan- tity of iodine at determined which is required for the complete de- composition of the sulphurous acid. The quantity of anhydrous sul- phurous acid contained in the volume P of the liquid is then given by the following equation-.. The estimation of sulphuretted hydroFen is made in' exactly the same manner by means of the corresponding formula- PH sf = -at. PI But the great facility with which sulphuretted .hydrogen decom- poses often renders this latter estimation very inexact. A determination of the density of. sulphuroris acid gas made in a manner similar to that described for chlorine (p.Z&Y),-excepting that the tube containing the gas dipped into boiled water instead of a solution of iodide of potassium,-gave the following results :-Volume of sulphurous acid gas at 1.1' C. and 0.7507 met. bar.= 90.699 cub. cent. P=lOOO; p=1940; t=76*95; a=0-0025387. These numbers give for the density of the gas 2.190; the calculated density is 2.211. 8. Estimation of Chromates.-When a chromate e. y. bichromate 298 BUNSEN ON A 4f potash is boiled with excess of funling hydrochloric acid every 2 at. chromic acid eliminate 3 at. chlorine. The decomposition is rapid arid complete. The 3 at. chlorine passed into a soliltion of iodide of potassium set free an equal nuinbcr of atonis of iodine. If therefore we determine the quantity of a (nt-t') obtaiucd by using a known weight.A of bichromate of potash the quantity of chromic acid x contained in a pantit)? A of salt is found from the equation- x=- 2 Cr 31 a (nt-t') or in 100 parts ... 200 cr If again A = -31 a,-i.e. if the sample taken weighs exactly this quantity then the difference of the two measurcments (at-t') gives directly the percentage of chroniic acid. Similarly for A = 100 Cr )aJ this difference would give the per-centagc of (1' :i $b +Cr neutral chromatc of potash and for A = 200 ( 31 )u the per-centage of pure chromate of lead in these respective salts. The annlysis is made by introducing a weighed quantity of the chromate inbo a small flask of the capacity of 36 to 40 cubic centi- metres filled about two-thirds with fuming hydrochloric acid and having a gas-delivery tube sdapted to the neck by means of a tube of vulcaniscd caoutchouc.Into the open extremity of this tube is inserted a small glass bulb with a narrow neck which serves as a valve and the tube is inserted into the neck of an inverted retort of the capacity of 160 cubic centimetres and containing a solution of iodide of potassium. The middle of the neck of the retort is blown out into a bulb to receive any liquid that may be thrown up by the disengagement of gas. Instead of the glass bulb above mentioned an excellent valve may be made by tying a piece of vulcanised caoutchouc tightly ovcr the open end of the tube and cutting a small slit in it with a sharp wet penknife. This slit opens when pi-cmed from within but closes tightly when pressed in the opposite direction.Thc liquid in the flask is now boiled for three or four minutes by which time the whole of the chlorine is expelled and liberates ar! equiident quantity of iodine which is estimated in the ordinary way. 0.7116 grm. piire hichromate of potash heated to the melting point gave off O*OOLG grm. water; and 1.0230 grm. reduced wit!) GENERAL RlETHOD OF VOLUMETRIC ANALYSIS. hydrochloric acid and precipitated by continued digestion with am-monia yielded 0.5327 grm. of ignited sesquioxide of chro~niutn. The volumetric analysis gave-A=0.2379; n=3; t=5; t’=81g6; a=0.0025387; and in another experiment- A=0.2943; ?2=3; t=103*7; t’=16.0; a=0.0025387. This gives- Weighed analysis.Volumetric analysis. /-. 11. I. Chromic acid . . 68.18 68-32 67-95 Potash . . . . 31-60 31.47 31.83 Water . . . . 0.22 0.22 0.22 1oo*oo 100-00 100~00 Another sample composed of 0,4632 grm. chromate of potash dried at l5O0 C. and 1.27 grni. sulphate of potash gave- A=1-7332; t=101-7; t’=38*2; n=5; a=0*0025387. Taken. Vol. analysis. Chromate of potash . 26-72 26.91 Sulphate of potash . . 73.28 73.09 7--100~00 1GO*OO The volumetric analysis of pure bichromate of potash gives as above observed (p. 221) the simplest method of determining the value of a or the quantity of pure iodine corresponding to the weight of impure iodine contained in a degree of the burette. ‘l’his value is obtained from the equation- 3 IA a= (K+iZCr) (nt-t’) The action of concentrated hydrochloric acid on chromates often gives rise to the formation of traces of volatile chromate of terchloridc of chromium CrCl 2Cr0,.This however does not affect the result of the analysis inasmuch as the quantities of chlorine chromic acid and terchloride of chromium obtained from a given weight of a chromate eliminate the same quantity of iodine. 9. Estiinntioiz qf Chlorutes. -The action of hot concentrated hydrochloric acid on clilorates is well known to be attended with a rcductiun of the chluric acid. The reaction which is not attended 230 BUNSEN ON A With any evolution of oxygen may be expressed by one of the following forrnub-2c10 ClO c10 C10 3C10 c105 2Cl HO HCf [clos 2HC1 2H0 3HC3 I3HO.ClO 6C1 5HC1 )5HO It is impossible to determine by theory which of these reactions actually takes place or which of them may occur simultaneously. But this uncertainty is of no importance for whatever may be the reaction which takes place when the products are brought in contact with the iodide of potassium 6 at. iodine are set free for each atom of hydrochloric acid. Consequently x parts of a chlorate R C1’decom-61 posed by hydrochloric acid liberate -x. This iodine a (nt-t’) w c1 estimated by the volumetric method gives for the value of x-R C1 x = -a (nt-t’) 61 Similarly the per-centage of chloric acid contained iu a quantity A of a chlorate is determined by the equation- and if A be taken = -looc1 a the difference a (at-t’) gives 61 immediately the per-centage of chloric acid.An experiment with pure chlorate of potash gave- A=0.0889; n=3; t=74*1; t’=7*2; a=0*002578. Calculated. Found. Chloric acid . . 61-57 61.83 Potash . . 38.43 38.17 10000 1oo*oo 10. Estimation of the Peroxides of Lead Manganese Nickel Cobalt &.-The percentage of oxygen in peroxide of lead is given by the formula- x = 100 AT ’’ a(nt-tt’) GENERAL METHOD OF VOLUMETRIC ANALYSIS. A sarnple of the peroxide which was prepared by boiling red lead with acetic acid and yielded by ignition in a stream of dry air O*OMgrm. water and 0.043 grm. oxygen gave by volumetric analysis on 0.7402 grru. n = 5 ; t = 58.8 ; t’= 9.8 ; a= 0.002578. Hence-CaIculated.Weighed analysis. Vol. analysis. Lead . . 86.12 87.23 86.95 Oxygen . 13.31 12n20 12.48 IVater . 0.57 0.57 0.57 _.--100~00 1 oo*oo 100~00 The per-centage of peroxide of manganese in a sample of conimcrvial black oxide d is given by the formula- x=-100’’’ a (nt-t’) A-I 0.4839 grm manganaso-manganic oxide obtained by igniting pure carbonate of manganese gave- A= 0.4839; n = 3 ; t = 78.3; t’ = 16.4; a = 0-0025387. A second analysis of the sarnc product gave- A= 0,3725 ; n = 3 ; t = 75.7 ; t’= 59.4 ; a = 0*0025387. Calculated. Volumetric analysis. I. ,-. 11. 1 at. MnO 2 at. MnO . . . . 37.98 62.02 39.37 60.63 39.25 60.75 100*00 100~00 100~00 It would appear from these two experiments that the degree of oxi-dation which manganese acquires by the ignition of its oxides does not agree exactly with the formula usually assigned to it.If this is the case the error thence arising in estimations of manganese may be easily corrected by a voluiiietric analysis of the ignited precipitate. A pyrolusite from Bohemia which according to a weighed analysis contained 0.32 per cent. silica 0.08 per cent. ferric oxide and 0.5 per cent. water gave- A=0-3128; n=5; t=79.3 ; t’=4S.O; a=0.0026387. Peroxide of manganese . . 98.25 Sesquioxide of iron . . 0.08 Silica . . 0.32 Water . 0.50 -09.15 232 BUNSEN ON A In presence of lime magnesia oxide of zinc and siniiIar strong bases the oxides of manganese yield by ignition in the air not BlriO . Mn203 but when lime or magnesia is present :$ ) Rln20J or if mag-nesia is in excess MgO Nin20,.If therefore we wish to determine not merely the quantity of separable oxygen in the peroxides of man-ganese but likewise the quantity of metallic manganese this circum- stance must be taken into consideration. 11. Esiimation of lodic Vunodic Selenic $Iun.qanic Ferric Acid Ozorte &c.-As all these and many other volumetric determi- nations may be made by one and the same method arid the corre-sponding equation of condition is easily deduced frorn the principles above explaiiied it will be sufficient to give a single example viz. that of the determination of iodic acid. When iodic acid either free or combined with a base is distilled with excess of fuminq hydrochloric acid each atom of iodic acid elimi- nates 4 atonis of chlorine while 1 atom of protochloride of iodine remains in the liquid.The percentage of iodic acid in a mixture of salts whose weight is A is therefore determined according to the pro- cess described for the estimation of chlorine by means of‘ the equations-. ..... A mixture of‘ 0.5321 chloride of calcium with 0.2755 iodate of baryta gave- n=3; t=85*5; t’=31.4; a=0*002578. Used. Vol. analysis. Chloride of calcium . 65.53 65.89 Iodate of baryta . . 34-47 34-11 100~00 100~00 12. Volumetric Separation of Cerium and Lanthanum.-These metals are precipitated together as oxides the precipitate dissolved in strong sulphuric acid and the solution precipitated by potash. The precipitate consisting of the hydrated protoxides of the two metals is suspended in a strong solution of potash a stream of chlorine passed through the liquid and the precipitate carefully washed with cold water.The precipitate corisistiiig of ceroso-ceric oxide is treated while still moist with fuming hydrochloric acid (in the flask above described p. 228) in which it dissolves with brown colour On heating the mixture cech ntoin of ceroso-ceric oxide eliniiiiatcs 1 atom ehlorine which separates 1 atom iudiiie froiii the iodide of yotassiuiu GENEKAL METHO9 OF VOLUMETICTC ANALYSIS. iu the retort. If this quantity of iodine is a (nt-f) then the quan- tity of the ceroso-ceric oxide contained in the precipitate is- 3 Cef40 x= I a (nt-t’j or expressed as cerous oxide- x’= =a (nt-tt’) I A mixture of cerous and lanthinous oxides carefully purified from all other metals was treated seven times with potash and chlorine as above and the yellow precipitate dried up to a nioist jelly.An inde-finite quantity of this precipitate gave by volumetric analysis-n=2 ; 1’=20.1; t=106*9; a=0.0025387. Thc solution of cerous oxide remaining in the flask gave by preci-pitation with oxalate of ammonia after neutralisation 1.2127 grm. oxalate of cerium 0.5273 gym. of this precipitate bui’ned with oxide of copper gave 0.2073 grm. carbonic acid and 0 0460 water. Assuming that the salt is neutral the quantity of oxygen in the cerous oxide must be one-third of that in the oxalic acid and therefore the com- psitioil of cerous oxide must be-Cerium .. 87.918 Oxygen . . 12.082 100-000 Heuce the atomic weight of cerium must be 727.7 (O= 100) or 58.22 (H=1). Assuming this to be correct we obtairi-Calculation. Analysis. 1at. cerous oxide . . 59.4 59.13 1at. osalic acid . . 32.47 32-15 1at. water . . 8.08 8.72 100~00 100~00 According to these numbers the cerous oxide in the entire quantity of oxalate 1.2137 must contain 0.0866 oxygen. Before the reduc-tion with hydrochloric acid the cerium was associated with another portion of oxygen which by means of the above formula and volu- metric data is found to be 0.0296. Now 0.0866 :0.0296 ::3 :1. Thus Found. Calculated. Oxygen in cerous oxide . 0.0866 0.0872 Excess of oxygeii in ceroso-ceric oxide 0.0296 0.0291 234 BUNSEN ON A Hence we may conclude that hydrated cerous oxide when treated with chlorine in a solution of caustic potash is converted into a higher oxide of the form CeO .Ce,O, and that the behaviour of this lat,ter oxide when heated with hydrochloric acid may he applied to the volu- metric estimation of cerium even in presenceof lanthanum.It retilains however to be determined whether cerous oxide in presence of lan- thanous oxide may not be converted by hypochlorous acid into La0 -Ce,O,. Besides the preceding and a great number of other bodies which give rise to a separation of free chlorine t,he volumetric method above described may likewise be applied to the estimation of those substances which are easily and completely raised by chlorine to a higher degree of oxidation.These substances are heated with fuming hydrochloric acid and a weighed quantity of pure bichromate of potash the evolved chlorine passed into a solution of iodide of potassium and the sepa- rated iodine estimated as above. The quantity thus separated viz. p-31 a (~it=t’)is equal to the quantity of iodine - equivalent to K Cr the chromate of potash used minus the quantity i equivalent to the protoxide employed. The latter is therefore-i= p.31 -u (nt-i’) K +acr Hence the weight of the substance itself may be easily calculated as in the following examples. 13. Estimation of Ferrous Oxide alone and in conjunction with Ferric Oxide.-The quantity of ferrous oxide b in a sample of iron ore &c.may be found from the following considerations i denotes the quantity of iodine which the ferrous oxide subjected to volumetric ex- amination requires in order to convert it into ferric oxide. Now this quantity of iodine is to the ferrous oxide present as I :2Pe. Hence substituting for i its value above given we find for the quantity of ferrous oxide in the compound cxaw ined- 6 Fe 2 Fe (1) e = Y -u (nt-t‘) ; I K+2Cr thc corresponding quantity of iron is- (2) e’ = 6 Fe p -.-2 1 Pe u (?it t’j K+2Cr GENERAL METHOD OF VOLUMETRIC ANALYSIS. 235 and the equivalent quantity of ferric oxide- 3s s.3 (3) e” = P-I a (nt-t’). K+2Cr The formula (1) is true only so long as the equation of indication I <. is satisfied.This is the case when one or more 2Fe 1i+2Cr parts by weight of bichromate of potash are used for every 1 part by weight of the iron-compouud. The equations (2) and (3) are of course subject to corresponding limitations. To estimate ferrous oxide either by itself or in conjunction with ferric oxide the flask (p. 228) is two-thirds filled with fuming hydro- chloric acid and the air in the upper part expelled by carbonic acid evolved by throwing a few grains of carbonate of soda into the acid. When all the air has thus bcen expelled the chromate of potashy and the substance A weighed in a small open glass tube are thrown into the acid the gas-delivery tube put on and the process conducted as for the estimation of chromates. Magnetic iron ore from the Tyrol crystallised in beautiful octohe- drons gave by this method after thorough drying- A=0.2869; p=0.4206; n=6; t=71.3; t’=65*6; a=0.0025387.Calculation. Analysis 1at. Pe,O . .68.97 68-96 1at. FeO . .31.03 -31.04 100~00 1oo*oo To determine metallic iron or ferric oxide the substance is dissolved in hydrochloric acid and the sesquioxide of iron completely reduced to protoxide by boiling with sulphurous acid or better with chemically pure zinc. The ferrous solution is then treated with hydrochloric acid and bichromate of potash as above. 0.5603 grm. of fine bright harpsichord-wire was disolved in aqua regia :the silica removed by evaporation and re-solution in acid and the ferric oxide precipitated by ammonia ;it weighed after ignition 0.7977 grm.0.2087 grm. of the same wire gave by the volumetric methocl- A=0.2087; n=l ;t=68.4; t’=11.0; a=0*0025387. 236 BUNSEN ON A GENERAL METROD OF VOLUMETRIC ANALYSIS. Quantitie0 used. Volumetric analysis Iron . . 99.66 99.62 Carbon and silicum . 0.34 0.38 1oo*oo 100.00 14. Estimation of Arsenious Acid and its Salts.-If A be the weight of the substance containing the arsenious acid and p the quantity of bichromate of potash acid the percentage of arsenious acid is given by the equatim- ... 100 3 As t’>1. x=-As a(Izt -A [2(K+2Cr) P-T The quantity of iodine consumed by the arsenious acid x in the 21 substance A is -x,and the iodine set free byp is 21 Y-As K+2& The weight of the arsenical substance must therefore be so propor-tioned to the bichromate of potash that the equation of condition 21 -x< I p may be satisfied that is to say that there ...As K+PCr may always be more than 0.998 parts of bichromate of potash to I part of the arsenical substance. 0.2615 grm. of pure arsenious acid mixed with 0.5274 grm. gyp-sum and treated as above with 0.4334 grm. bichromate of potash gave-A=0*7889; p=04334; n=3; t=79.8; 2’=66*4; a =000025387. Quantities used. Volumetric analysis. Arsenious acid . . 33.15 33.14 Gypsum . . 66.85 66.86 II_-100*00 100.00 237 HOUZEAU ON OXYGEN IN THE NASCENT STATE. Researches on Oxygen in the Nascent State. ny A. Houzeau. WHENperoxide of barium is acted upon at ordinary temperatures by inonohydrated sulphuric acid the oxygen evolved possesses very active oxidisins properties.A simple apparatus for the purpose consists of a tubulated flask to the narrower neck of which is adapted a tube to convey the gas into a jar standing over water. The sulphuric acid being first poured into the flask the peroxide of barium is added to it in small fragments and the neck quickly closed with a cork. The disengagement of gas soon begins and is more rapid as the acid mixture becomes more strongly heated. It is therefore sometimes necessary to accelerate the action by immersing the flask in a water- bath;-at other times on the contrary to moderate it by the use of cold water. Nascent oxygen is a colourless gas having a powerful odour; it must be respired with caution for if introduced into the system in large quantity it gives rise to nausea which may be followed by vomiting.Its odour also which at first is by no means unpleasant becomes insupportable after smelling it frequently its taste resembles that of the lobster. IVhen heated to 75' C. (168' F.) or exposed to the sun's rays it loses all its active properties. In presence of water and at ordinary temperatures it oxidiaes most of the metals,-evcn silver,-pcrosidises metallic protoxides and immediately transforrris arsenious into arsenic acid &c. The alkalies (potash soda lime baryta) and the stronger acids (sulphuric phosphoric nitric) act powerfully on it. Ammonia in contact with nascent oxygen undergoes a true coni-bustion the product of which is a nitrous compound on pluriging a glass rod dipped in ammonia into a jar of the odoriferous oxygen the vessel is immediately filled with white fumes of nitrate of ammonia.Phosphuretted hydrogen of the non-spontaneously influmrriable variety which is not acted upon at 20' C. (58O P.) by ordinary oxygen burns with emission of lifiht in the odoriferous gas. Lastly hydrochloric acid dissolved in water is completely decom- posed by nascent oxygen; the hydrogen is burned and the liberated chlcrine dissolves gold-leaf inmierserl in the modified acid. Nascent oxygen is therefore a chlorinisin,p agent in the same manner as chlorine is an oxidising agent it is in fzct to this reinarkable powcr of combustio!i in nascent osygcn that the metallic peroxides owe their faculty of e1inlii:ating chlorine under tlic iiiflr:eilcc of hydrochbric acid.* Compt. rcnd. xl. 947. 238 HOUZEAU ON OXYGEN IN THE NASCENT STATE. Thc odoriferous gas acts still more rapidly on iodide of potassium liberating the iodine ; it decolourises spontaneously the tinctures of litmus cochineal campeachy wood sulphate of iiidigo &c. exhibiting a bleaching power equal to that of chlorine itself. Porous bodies absorb nascent oxygen and modify it in a remarkable manner ; for when the gas is slowly passed through a glass tube filled with asbestos platinum-black lint carded cotton shreds of flannel &c. its odour and oxidising properties are completely destroyed. The following table gives a summary of the differences between ordinary and nascent oxygen :-Properties of ordinary oxygen in the free Propdies qf nascent oxygen in the free stiite nitd at the temperahire of 15' C.stde and at the temperature of 15" C. (SO"F.) (SOo F.) Colourless gas inodorous and tastelees. Colourless gas liming a very poweiful odour and the taste of lobsters Has no action on blue litmus. Rapidly decolourises blue litmus. Does not oxidise silver. Oxidises silver. Haa no action on ammonia. Burns ammonia spontaneously and trane- forms it into nitrate. Has no action on phosphuretted hydrogen. Instantly burns phosphuretted hydrogen with emission of light. Does not decompose iodide of potassium. Acts rapidly on iodide of potassium set- ting the iodine free.Has no action on hydrochloric acid. Decomposes hydrochloric acid setting the chlorine free. Has a feeble oxidising action. Is a powerful oxidising and chlorinising agent. Very stable at albtemperaturea. Stable at 15" C. but destroyed towards PO r5. Peroxide of barium is not the only body which is capable of yielding active oxygen. Oxygen in the combined state possesses indeed the intensified power which distinguishes free oxygen in the nascent state and which it ceases to exhibit when completely isolated because the temperature at which it is usually evolved from its combinations is equal or superior to that at which active oxygen passes into the ordinary state. [It appears from the experiments of Dr. Rndrews lately com- municated to the Royal Society,* that ozone evolved by the electro- lysis of water and stated by Uaumertt and others to be a peroxide of hydrogen is nothing but active oxygen.Andrews attributes the results obtained by these chemists to the presence of a small quantity of carbonic acid which always accompanies electrolytic oxygen and Proc. Roy. SOC. vii. 475. + Chem. SOC. Qu. J. vi. 169. f DEVlLLE ON ALUMINIUM. is difficult to remove. He also confirms the statement of Frdmy and Becquerel that ozone is formed by the action of the electric spark on perfectly pure and dry oxygen ; and shows that ozone how- ever prepared has always the same properties and is not a compound body but oxygen in an altered or allotiropic condition.-Eo.] On Aluminium." By H.Ste.-Claire Deville. ALUMINIUM was discovered in 1827 by \VohIer,t who obtained it by reducing the chloride with potassium in the form of a grey powder ; and afterwards showedf that by the same method the metal may be obtained in fused globules. He described it as a tin-white .perfectly malleable metal which does not tarnish by exposure to the air; melts in the blowpipe flame; has a density of 2.5,increasing by hammer- ing to 2.67;not decomposing water at ordinary temperatures but evolving hydrogen from it slowly at 100"C. Deville has lately obtained the metal in much larger quantities and has studied its properties more minutely. He prepares it by two methods:-1 by reducing the chloride of aluminium with sodium ; 2 by redacing the double chloride of aluminium and sodium by electrolysis.To prepare the chloride of aluminium Deville mixes ignited alumina with charcoal and oil to the consistence of a paste; heats the mixture in a crucible ; introduces the pulverised inass into a tubulated earthen retort having a short neck to which a bell-shaped receiver is adapted; heats the retort to dull redness; and tlien passes chlorine gas into it chloride of aluminium then passes over after a short time. To decompose the chloride of aluminium with sodium,§ 200or 300 grarnmes of the chloride are placed in a wide glass tube between two plugs of asbestos; pure dry hydrogen passed through the tube; and the chloride of aluminium heated (the stream of hydrogen being continued) to drive out hydrochloric acid chloride of sulphur and chloride of siliciuni which are formed at the same time.A number of porcelain boats each containing a few grammes of sodium dried bctween bibulous paper are then introduced into the tube; and the * Ann. Ch. Phys. [3] xliii. 5. f-Pogg. Ann. xi. 146. X Ann. Ch Pharm. liii. 422. 9 For the preparation of sodium Deville recoiiiinencls a mixture of' 717 parts dry caiabonate of soda '175 charcoal and 108 chalk,-the lat,tcr for tlic purpose of keeping the mixture during the heating in a pasty condition and tv condense tlie sodium in a small receiver a% recommended by Maresca nud Donny (Ann. CIi. Phge. [33 xxxv. 147). DEVILLE ON ALUMINIUM. tube is heated till the sodium melts and the choride of aluminium volatilises in the atmosphere of hydrogen and coming in contact with the sodium is thereby decomposed.As soon as all the sodium has +appeared and the resulting chloride of sodium has taken up chloride of aluminium to saturation the porcelain boats are with- drawn from the glass tube and introduced into a wide porcclsin tube in which they are heated in a stream of pure hydrogen till the double chloride of sodium and aluminium volatiliscs and condenses in the receiver. The aluminium which remains behind aspyqated in one or two masses is washed out with a little water to remove small quantities of the double salt and of brown silicium (produced by the action of sodium and aluminium on the silica in the porcelain). To unite. the separate globules of aluminium into one a quantity of chloride of aluminium and soclium is then fused in a porcelain crucible; the alurninium added to it as soon as the evolution of hydro-chloric acid (proceeding froni adhering moisture) ceases ; the heat increased till the aluminium fuscs together; the excess of the double chloride poured off after the nietal has solidified by cooling; and the aluminium kept in a state of fusion in a cowed porcelain crticible till the adhering double chloride is completely volatilised.A globule of very pure aluminium is then found at the bottotn of the crucible coated with a thin pellicle of alumina proceeding from the partial decomposition of the flux. Allminiurn may also be reduced from the chloride by means of vapour of sodium.For this purpose the sodium disengaged by heating a iiiixture of carbonate of' soh charcoal and chalk is made to pass into a large earthen crucib!c by mems of an iron tube passing from the bottle cmtaining the rnixturc through a hole in tlic side of the crucible. The oxide of carbon which first passes into the crucible burns at the bottom heats and dries it; afterwards the vapour of sodium passes over; and as xw:i ;is the flame of that iiietal becomes visible chloride of aliiiiiiniurii is thrown into the crucible in small pieces from time to time aiid is there reduced. At the end of the operation the cracible is broken and the saliiie mass composed of chloride of sodium small globules of aluminium and charcoal impregnated with soda is digested in water if acid in dilute nitric acid if alkaline to dissolve out the saline rnatters.The several globules of aluminiiim are thvn fused into one in the manner already described. The autlior has not yet perfected this lstter method ; but it appears to prot:iisc wry good results yielding ;1 consiclerdble quantity of verg pure ;I!uminiuni cven from very impurc chloride.* * From a paper rccefitly published by R. Rose (Pcggv. Ann. xcri. 152) it appears tliat nlumiuium rnq be much more advantageoilsly ohtalncd by the action of sodium on Cryo/iIv which is ;Inative flooride of al111i1i~li:lrn9ntl sotliuni. DEViLLE ON ALUMINIUM. 241 sodium prepared by fusing in a porcelain crucible at 200' C. a mixture of 2 parts chloride of aluminium and 1 part dry and pulverised chloride of sodium is introduced into a heated porcelain crucible in the cover of which are two apertures,-one near the edge of the crucible to admit a broad platilium plate which forms the negative pole of tht battery ; and the other in the middle to admit a porous cylindrical cell likewise tilled with the fused double chloride in which IS immersed a piece of dense charcoal serving as the positive pole.On passing the current of a few galvanic elements through this arrangement the aluminium separates together with chloride of sodium on the platinum plate which must be taken out from time to time quickly freed wheu cold from the deposit which has formed upon it and again iuimersed pieces of dry chloride of sodium must be dropped into the porous cell from time to time to compensate for the quantity which passes to the negative pole.When the several deposits removed from the platiiiuni plate are collected together and fused in a crucible and the fusecl mass treated with water chloride of sodium dissolves and a grey metallic powder reriiains which by repeated fusion with the chloride of aluminium and sodium may be united iuto bright metallic masses.* Properties of Aluiiii/tiunc.-Pure aluminium is white with a faint bluish iridescence when recently fused it is soft like pure sil\er and has a density of 2-56; but after hauirnering or rolling it is as hard as iron and has a density of 2-67 It condiicts electricity eight times as well as iron and is slightly magnetic. Its melting point is between that of zinc and that of silver ; when solidified from fusion and also when reduced by electrolysis it exhibits crystalline fornis (apparently regular octohedrons).It does not oxidise in the air even at a strong red heat neither does it decompose water excepting at the stronpt red heat,-and even then but slowly. It does not dissolve in nitric acid either dilute or concentrated at ordinary temperatures and but very slowlj in boiling nitric acid; dilute sulphuric acid scarcely attacks it at ordinary temperatures even after a long time; hydro- chloric acid of any degree of concentration dissolves it readily even at low temperatures with evolution of hydrogen. Sulphuretted hydrogen has no action upon it; neither is it attacked by the fused hydrates of the alkalies.It does not combine with mercury; and when fused with lead takes up only traces of that metal. With copper it unites in various proportions forming light very hard atid white alloys ;and conibiues also with silver and iron. The aluminiiitii obtained by Deville in the niaiiiier above described differs iii 242 DEBHAY ON some respects from W ohler’s aluminium,-chiefly in being less fusible and in not decomposing water Deville attributes the inferior fusibility of Wohler’s aluminium to the presence of platinum (proceeding from the platinum tube which Wohler used to effect the decomposition); and its power of decomposing water to the presence of potassium or of undecomposed chloride of aluminium. Devil1 e did not succeed in reducing aluminium by electrolysi~ from an aqueous solution of any of its compounds; but according to G.Gore,* this metal may be reduced on copper by the galvanic current from a solution of hydrochlorate or acetate of alumina or more slowly from a solution of alum ;it then forms a lead-coloured deposit which acquires the colonr of platinum by polishing.New Form of Silicium-The first portions of aluminium obtained by D eville’s electrolytic process contain silicium and other impurities derived from the chloride of aluminium used :one sample was found to contain 10.3 per cent. silicium and 89.7 aluminium with a trace of iron. On treating this impure and highly crystalline aluminium with hydrochIoric acid hydrogen gas having a very offensive odonr is evolved and silicium remains behind in the form of shining metallic laminae which may be heated to whiteness in a stream of oxygen without alteration are not dissolved by any acid excepting a mixture of hydrofluoric and nitric acids and are but very slowly oxidised by fused potash even at a red heat.This modification of silicium which appears to be related to the previously known forms of that substance in the same manner as graphite to charcoal is a conductor of elec-tricity (Uev ill e). On Glucinum and its Compound8.t By H.Debray. GLUCINAwas discovered by Vauquelin in 1797 in the emerald of Limoges and has since been found in cymophane chrysoberyl phenakite the gadolinites ieucophane and helvine ;but on account of the great difficulty of preparing it its properties and the consti- tution of ~ts compounds have not hitherto beem satisfactorily studied.Berzelius from the similarity of its behaviour in solution with that of alumina and from its insolubility in acids after calcination was *Phil. Mag. [4] vii. 227. t hn. Ch. Phgs. [3] xliv. 5. GLUClNUW AND ITS COMPOUNDS. led to regard it as a sesquioxide Gl,O,,-a view which was further confirmed by the discovery of H. ICose that chloride of glucinum may be prepared in the same manner as chloride of aluminum; and by the similarity of the metal (isolated by Wohler in 1827) to metallic aluminum. But in 1843 Awdejew,* after having vainly endeavoured to obtain a sulphate of glucina and potash analogous to common alum prepared one in which the potash and the glucina were combined with equal quantities of sulphuric acid,-agreeing in fact with the formula KO,SO +GlO,SO3 +2H0 ; and likewise a double fluoride of similar constitution KF1+ GlFl.This view of the constitution of glucina was further confirmed by the examination of several minerals containiog that earth,-particularly of the cymophanes from the Ural and from Ceylon in which the relative quantities of glucina and alumina were found to be as constant as in the emerald,-contrary to the generally-received opinion that glucina and alumina are capable of replacing one another as bodies of similar constitution. Regardipg glucina as a protoxide G10 the formula of cymophane is GlO,AI,O, and that of the emerald GlOSiO,+ A1,0,,3Si03.The formulae of all these compounds on the hypothesis of Berzelius are much more complicated. Prom the analysis of the sulphate of glucina regarded as G10 A w dejew deduced for the metal the atomic weight 4-65 (H=l) which is less than that of any of the other elements except hydrogen. This circumstance was regarded by Berzelius as a capital objection to Awdejew’s theory ; and he accordingly (admitting the correctness of Awdejew’s analysis) fixed the atomic weight of glucinum at 15 77 regarding glucina as Gl,O,. It appears also from Ebelmen’s researches on the artificial formation of minerals that glucina crystallises in the same form as alumina. This circumstance cannot however be regarded as of much importance with reference to the formula of glucina inasmuch as oxide of zinc which is universally regarded as a protoxide likewise crystallises in the same form as alumina.The following researches were made with the view of supplying additional materials for the decision of this question and contributiug further to the knowledge of glucinum and its compounds. The metal Glucinum is obtained from the chloride by reduction with sodium in a manner similar to that adopted by Devi 1le for the preparation of aluminium (page 239). It is a white metal whose density is 2.1. It may be forged and rolled into sheets in the cold; its melting point is below that of silver. It may be melted in the outer blowpipc flame without exhibiting the phenomenon of ignition presented by zinc and iron under the same circumstances ; it cannot even be set on fire in an atmosphere of pure oxygen but in both experiments becomes covered with a thin coat of oxide which seema * Ann.Ch. Yhjs. [3] rii. 155. 2 4.4 DEBRAY ON to protect it from further oxidation. It is not attacked by sulphur even when melted in the vapour of that substance; and as Fremy did not succeed in obtaining a sulphide of glucinum by heating glueina with charcoal and sulphide of carbon it seems probable that glocinum does not form a sulphide. Chlorine acts upon glucinum with the aid of a gentle heat but without vivid incandescence the metal merely becoming red-hot when exposed to a rapid current of chlorine. Iodine combines readily with glucinum at a dull red heat ; at lower temperatures part of the iodine remains in excess and forms with the iodide of glucinum a reddish mass which becomes liquid and blackish under the influence of a larger quantity of iodine.Silicium unites readily with glucinum forming a hard brittle sub- stance susceptible of a high polish this alloy is always obtained wheu glucinum is reduced in porcelain vessels. Glucinum does not decompose water at a boiling heat or even when heated to whiteness. Gaseous hydrochloric acid attacks the metal at the temperature pro- duced by a small spirit-lamp the action being attended with evolution of heat. Aqueous hydrochloric acid even when dilute attacks it readily with evolution of hydrogen ;if the metal contains silicium that substance remains behind in the graphite-like form first observed by Deville (page 242).Sulphuric acid either dilute or concentrated acts like hydrochloric acid. Nitric acid even when concentrated does not act upon glucinum at ordinary temperatures and dissolves it but slowly even at a boiling heat. Glucinum is not attacked by ammonia but dissolves readily in solution of potash. The above- mentioned properties differ considerably from those of the metal which Wohler obtained by igniting chloride of glucinum with potassium in a platinum crucible the metal thus obtained being a grey powder very refractory in the fire but combining with oxygen sulphur and chlorine much more energetically than De bray’s metal. The differences iiowever appear to be due partly to the difference of aggregation and partly to the contamination of Wohler’s metal with platinum and potassium.Qlzicina G10 = 4-54 -+ 8 = 12*54..-Debray prepares this earth from the emerald of Limoges by the following process :-The mineral finely pounded is fused with half its weight of quicklime in an air furnace and the glass thus obtained is treated first with dilute and then with strong nitric acid till it is reduced to a homogeneous jelly. The product is then evaporated to dryness and heated sufficiently to decompose the nitrates of alumina glucina and iron and a small portion of the nitrate of lime; and the residue consisting of silica alumina glucina sesquioxide of iron nitrate of lime and a strdl quantity of free lime is boiled with water containing sal-ammoniac which diss:)lves the nitrate of lime immediately and the free lime after a whilc with evolution of anirnonia (if no ammonia is evolved OLUCINUM AND ITS COMPOUNDS.245 the calcination has iiot been carrid far enough and must be re- peated). The liquid is then decanted ; the precipitate after thorough wauhiug treated with boiling nitric acid ; and the resulting solution of alumina Flucina and iron poured into a solution of carbonate of ammonia mixed with free ammonia. The earths are thereby pre-cipitated without evolution of carbonic acid and the glucina re-dissolves after seven or eight days in the excess of carbonate of' ammonia. As the carbonate of ammonia may also dissolve a small quantity of iron it should be mixed with a small quantity of sulphide of ammonium to precipitate the iron completely.Lastly the carbonate of arniuouia is distilled off and the carbonate of glucina which remains yields pure glucina by calcination. Glucina is a .white loosely-coherent powder without taste or smell. It is infusible even in a blowpipe flaine fed with ether-vapour and oxygen but volatilises at that temperature like magnesia and oxide of einc. It is not hardened by heat like alumina but merely rendered less soluble in acids. E belmen has obtained it in hexagonal prisms by exposing a solution of glucina in fused boracic acid to a powerful and long-continued heat. It may be more easily obtained in micro- scopic crystals apparently of the same form by decomposing the sulphate of glucina at a.high temperature in presence of sulphate of potash; also by calcining the double carbonate of glucina and ammonia. The hydrate of glucina resembles the hydrate of alumina but when dried in the air absorbs a considerable quantity of carbonic acid Hydrate of glucina dissolves in potash but is precipitated by boiling when the solution is diluted with water to a certain exteat. It is likewise soluble in carbonate of potash or soda sulphurous acid and bisulphate of ammonia. When precipitated by ammonia it is completely redissolved by prolonged ebullition especially when precipitated from the oxalate or acetate. Sulphate of GZucina.-This salt has according to Awdejew the formula G10,S03+4H0. Debray has verified this formula by calcining one portion of the salt in powder to determine the glucina; evaporating another portion in aqueous solution together with a known quantity of pure lime and calcining the residue.If the lime is in sufficient excess nothing but water is driven off. The increase of weight of the lime minus the quantity of glucina gives the quantity of sulphuric acid and the water is determined by difference. This method may be applied to the analysis of a great number of sul- phates; lime is more convenient for the calcination than the oxide of lead generally used because the latter is apt to oxidise and deoxidise during the calcination thereby rendering the weight uncertain ; moreover the heating with lime may be safely performed in vessels of platinum. A solution of sulphate of glucina disso1vt.s ziuc n-itk e\olution of 246 DEBRAY ON hydrogen which burns with a peciiliar bluish flame.If the solution is dilute a compound of sulphate of zinc with bibasic sulphate of glucina is formed ; but in concentrated solutions a more basic sulphate of glucina decornposible by water may be formed by prolonged ebullition. A solution of sulphate of alumina under the same cir- cumstauces gives off hydrogen and is converted into sulphate of zinc and insoluble suhsulphate of alumina very dense and easy to wash. These reactions afford a method of separating glucina from alumina. The mixture of the two earths is dissolved in dilute sulphuric acid and ammonia added till the precipitate just begins to become permanent after which the liquid is boiled with zinc and the water renewed as it evaporates.The alumina is then precipitated as subsulphate while the zinc remains in solution. Nearly all the alumina is precipitated after a few hours’ boiling; but to remove the last traces the solution must be left in contact with the zinc for twenty-four hours. The zinc may be precipitated from the filtered solution by sulpliuretted hydrogen with addition of acetate of soda and the remaining sulphate of glucina purified by cry stallisation. This method is very useful for preparing a pure salt of glucina but it will not do for quantitative analysis because with chemically pure zinc which it would be necessary to use for that purpose the pre-cipitation of the alumina is extremely slow not being complete for several days.The subhate of glucina and potash has according to Awdejew’s analysis the composition KO SO,+ G10 SO +2Aq. According to Berzelius’s formula of glucina this formula would become 3 KO SO +G120 3 SO +6 Aq. which does not agree with that of the alums. has obtained this salt in the form of a Debj a ding sulphuric acid to a concentrated mix- crystalline powder b:ai ture of the two sulphates. Carbonate of G1ucin.u.-D e bra y gives for this salt (without having analysed it) the formula 3 G10 CO +5 Aq. ;but according to the analysisof Schaffgotsch,* the formula is 5GlO CO,+5Aq. Acdording to Weer en,? however this salt differs in composition according as it is separated from solution in carbonate of ammonia by boiling or precipitated from a salt of glucina by carbonate of ammonia.The carbonate obtained by the latter method appears to be a mixture of that obtained by the former with hydrate of glucina; but even the former appears to be of variable composition. Weeren is of opinion that it is decomposed by boiling water with separation of carbonic acid and fixation of water. It does not give off carbonic acid when heated to 100°-llOo C. in a current of dry air. *; Pogg. Ann. hi. 101 ; also Gmelin’s Handbook Tr. iii. 296. t Ibid. xcii. 91. GLUCINUM AND JTS COMPOUNDS. Carbonate of Glucina and Amm.onia is obtained by boiling a solution of glucina in carbonate of ammonia and stopping the ebullition at the moinent when it begins to show turbidity.The filtered liquid mixed with alcohol till turbidity appears deposits the double carbonate after a while in transparent colourless crystals which are very soluble in cold water but are easily decomposed by hot water with evolution of carbonate of ammonia The salt is much less soluble in dilute alcohol and nearly insoluble in absolute alcohol. It is quickly decomposed by heat leaving glucina in the form of a crystalline powder. It does not exhale any sensible odour of ammonia at ordinary temperatures but nevertheless decomposes after a while and loses its lustre. The composition of the salt is as follows :-CalCUlatiOll. Analysis. 4 (310......... 60.4 3 NH,O ...... 78'0 HO ......... 9.0 6 CO ......... 132-0 18.8 28.7 3.5 49.0 19'3 28.2 3.3 47.7 19.0 28'8 1.8 48-7 3 (NH,O .CO,) +4(310.3CO +Aq 269.4 100.0 100.0 100.0 Carbonate of Gkcinu and Potash.-Whcn glucina in excess is digested for some time in a solution of carbonate of potash a liquid is obtained which when mixed with alcohol till it begins to show turbidity deposits after a while small crystals of the double salt.This salt dissolves very readily in cold water but is decomposed at a boiling heat the liquid depositing ordinary carbonate of glucina. It quickly absorbs moisture from the air and is therefore very difficult to dry. It is decomposed by heat into carbonate of potash glucina carbonic acid and water. It is dficult to prepare this salt in the state of purity; moreover it is obtained only in small quan- tities and not distinctly crystallised.Hence the analysis could not be made in tt very satisfactory manner ;but the results agreed pretty well with the formula 3(K0,C02) +4G10,3cl2 +Aq which is aimilar to that of the ammoniacal carbonate. Oxalate of GZucina.-Oxalic acid dissolves glucina with facility but without forming crystabed compounds ; but the oxalate of glucina unites with the oxalatev of potash and ammonia forming crystalline compounds of definite form and very simple constitution. Oxalate of Glucina and Potash.-Obtained by dissolving car-bonate of glucina in binoxalate of potash. The reaction takes place in the cold and is complete as soon as the evolution of carbonic acid ceases. At. higher temperatures a large quantity of glucina dissolves but the resulting salt is basic and uncrystallisable.The salt is white and sparingly soluble in cold water. When heated it first decrepi- 2448 DER R .4 Y ON tates with violence and then decomposes on exposure to the air yielding glucina and carbonatc of potash no water is formed by the decomposition. Calculation. Analysis. -. KO ..... .. 47.2 35.7 35.7 GlO ......... 12.6 9.5 9.8 2 C,O ......... 72.0 54 6 545 KO .C,O,+ GI0 .C,O or C,KGlO 131.6 100.0 100.0 Oxalate qf Glucina and 9mmonia.-Prepared by treating car-bonate of glucina with binoxalate of ammonia. Forms colourlesa crystals belonging to the right rhomboidal prismatic system. It is sometimes obtained in tabular crystals the faces of which are rounded and do not admit of precise measurement.It is sparingly soluble in cold much more in hot water. Decrepitates with violence when heated arid then decomposes. The quantity of glucina in the salt was determined by boiling with nitric acid till all the oxalic acid was destroyed evaporating the resulting nitrates to dryness and calcining. The glucina thus obtained amounted to 11.4 per cent. (mean of three experiments). The salt burnt with oxide of copper gave 33 per cent. HO and 79.45 CO,. These results agree with the formula NH,O .CO,+G10 .0,or C,(NH,)GlO, which requires 114 per cent. GIO 32.5 HO and 79.5 CO,. The result of this analysis may also be used to determine the atomic weight of' glucina (admitting the formula) ;for as the atomic weight of carbonic acid is known to be 22 and the 2 at.C 0 would give 4 at. CO, the atomic weight of glucina will be determined by the proportion-79'45 :88 =11.4 :x which gives x= 12*61,-a result approaching very near to that found by Awdejew riz. 12.64. General ConcZu~ions.-From these researches it follows-1. That the metal glucinum should be placed side by side with aluminium. These bodies intermediate between the precious and the ordinary metals such as iron are distinguished by the following properties:-They are permanent in the air at high as well as at ordinary temperatures; do not decompose water even at a white heat; are not attacked by sulphur sulphuretted hydrogen or the alkaline sulphides; are not attacked by strong nitric acid at ordinary temperatures and but slowly even with the aid of heat ;but dissolve readily in dilute sulphiiric and hydrochloric acid.2. Glucina cannot be classed with alumina. It has been already observed (page 242) that the reasons which induced Berzelius to regard glucina as a sesquioside were derived from the resemblance of GLUCISUM .\ND ITS CO\lPOCK DS. glucina and alumina in the hydrated state from the volatility of the chlorides and from the interchangeability of the oxides in minerals. This last point has been completely settled by Awdejew whose analyses as well a3 those of D a iii our show that cyniophane from various localities has always the same composition. The analyses of the emerald likewise show that no such substitution takes $ace in that mineral.With regard to the hydrates it is true that alumilia and glucina are precipitated under the same circumstances and with the same aspect; but there the reseniblance ends. Glucina when dried in the air absorbs carbonic acid with which it forms a carbonate. The existence of a definitely crystallised double carbonate of ammonia aud glucina constitutes another important difference between that earth and alnniina. The identity of form between gliicina and alumina in the crystallised state is merely an isolated fact which would bc important if the two oxides possessed similar cheriiical properties but not otherwise. Now thcse oxides differ both in their behaviour when heated and in their reactions with more basic oxides. Glucina volatilisee like magnesia without me1 ting whereas alumina fuses under the same circumstances.Glucina cannot be fused with lime like alumina to enable the fusion to take place the presence of another body is required to play the part of an acid,- such as silica or alumina. In this respect again glucina resembles magnesia. Chloride of gluciiium exhibits at first sight coiisiderable resemblance to chloride of aluminium but a closer examiliation shows that the resemblance does not go far. Chloride of glucinum is less vdatile than chloride of aluminium thus when a mixture of finely-pounded emerald and charcoal made into a paste with oil is calcined in a crucible then powdered and heated in a porcelain tube through which chlorine gas is passed chloride of glucinum and chloride of aluminiuui are formed together ; but the chloride of glucinum passes over first and may be separately condensed.Chloride of glucinum in fact approaches in volatility more nearly to proto- chloride of iron than to chloride of aluminium it is about as volatile as chloride of zinc. Chloride of aluminium unites with the alkaline chlorides forming compounds which may be called spinelles and are represented by the general formula-MCl+ AI,CI (Deville) ;but chloride of glucinum does not form any similar compounds. Another argument in favour of the formula GI0 is derived from the greater simplicity of the formulae which it gives for the salts of glucina thus if glucina were regarded as G1203 the formula of car-bonate of glucina and potash would be 3(KO .CO,) +Gl,O * 3C0 ; and that of the oxalate of glucina and ammonia- 9(NH,O * C20,) + (4Gl2O3 * 9c,03)+ 3HO.It must however be remembered that glucina does not exhibit any 250 HAUER ON very close analogy to the class of protoxides. It is not isomorphous with lime or magnesia. Cymophane may be represented by the general formula of the spinelles-G10,Al,03~; but the dissimilarity of its crystalline form prevents it from being included in that class of minerals. The emerald also differs completely in crystalline form from the generality of silicates of the same composition whose general formula is-MO SiO + M',0,,3Si03. Neither is there any greater analogy between the double sulphates carbonates and oxalates of glucina and those of lime or magnesia.On the whole glucina appears to be intermediate in its properties between the protoxides and sesquioxides. On some Salts of Cadmium." By Carl von Raner. 1. Subhate of Cadmium CdO SO + H0.-When cadmium or oxide of cadmium is dissolved in an excess of dilute sulphuric acid and the solution is concentrated by boiling a salt is obtained which separates in verrucose crystals. The salt crystallises immediately on the cooling of the solution and corresponds in its constitution with the sulphate of cadmium with 1atom of water obtained by Kiihn. As the solution of the metallic cadmium in sulphuric acid only takes place slowly even with the aid of heat it is advisable to add a little nitric acid occasionally in order to facilitate the oxidation.This salt is also obtained when concentrated sulphuric acid is added to a boilin'g saturated solution of sulphate of cadmium ; it is imme- diately thrown down in the form of a Gne crystalline powder and may be almost entirely freed from the adhering sulphuric acid by pressure between blotting-paper. The salt prepared in three different man- ners gave the following results on analysis :-Calculated. Found. .----.-CdO . . . 64 66-63 56.63 56-70 56-56 SO . . . 40 35-39 35.39 35.45 35.54 HO. .. 9 7-98 7.98 7-85 7-90 _I-110 100~00 100~00 100*00 100~00 The salt does not effloresce in the air. At 100OC. the loss was 7.85 and 7.90 per cent. in two experiments so that the salt loses the whole of its water of crystallisation at this temperature and leaves dry sul- * Wien.Ahad. Ber. xv. 23. SOME SALTS OF CADMIUM. 25 1 phate of cadmium. At a red heat it gives off sulphuric acid and leaves sesquisulphate of cadmium. 2. Sulphate of Cadmium 3(Cd0 SO,) +8HO was obtained by the spontaneous evaporation of a saturated solution. The crystals were determined by Rammelsberg who found that their form was exactly that of Stromeyer’s salt Cd0,S03+4H0. This salt is perfectly stable in the air. At 100’ C. it loses 11.78 to 11-84! per cent. or nearly 3 atoms of water ; it is then perfectly opaque. At a slight red heat the remainder of the water is driven off without any loss of sulphuric acid; at a stronger red heat half the sulphuric acid is expelled and there remains sevquisulphate of cadmium.By long-continued calcination a portion of the remaining sulphuric acid is driven off; the mass is partially fused and appears brown from the production of free oxide. ‘l’he saturated watery solution of sulphate of cadmium boils at 102’ C. At 23* 1 part of water dissolves O-SS part of anhydrous sulphate of cadmium. Its solubility in hot water is not much greater. The autbor’s analysis led to the above formula :-Calculated. Found. w-3Cd0 . . 192 50.00 49.75 49*68 49.20 3S0 . . 120 31-25 31.35 31.27 31.94 8H0 . . 72 18.75 18.90 19.05 18.86 384! 100*00 100.00 100.00 100*00 Sulphate of cadmium dissolves in large quantity in concentrated ammonia with evolution of heat. When the solution is diluted with water a partial precipitation of hydrated oxide of cadmium takes place.The solution of sulphate of cadmium in ammonia is not im- mediately precipitated by carbonate of ammonia but precipitation takes place on the application of heat. If the solution in caustic ammonia be evaporated it becomes covered with a film and an uncrystallisable mass is deposited which dissolves but sparingly in water. This takes place during the spontaneous evaporation of the fluid but then requires a long time. A cold saturated solution of sulphate of cadmium is not precipitated by alcohol. A thick oily fluid settles to the bottom of the vessel and the supernatant fluid is at first a little turbid but soon becomes clear ; after a time some rather large crystals are formed at the bottom of the vessel which appeared both from mea-surement and analysis to be the salt 3(CdO S03),+8H0.3. Nitrate of Cadmium CdO N05+4H0 is obtained by dis-solving carbonate of cadmium in dilute nitric acid evaporating the solution and leaving it to cool. As the salt is very soluble crystal- hsation only takes place when the fluid is much concentrated. It crystallises as stated by Stromeyer in acicular and columnar crys-tals united in a radiate form. It deliquesces in the air as stated by 252 HAUCR ON Meissner. At 212' F. it nielts in its water of crystallisation. The analysis of the air-dried salt gave- CdO . . . 64 Calculated. 41-56 S trom eyer.42-15 Ha ue r. 40.78 NO . . . 4H0 . . . 54 36 35-07 23-37 35.78 22.07 34.41 24-81 A- 154 100*00 100~00 1oo*oo 4.Amrnonio-chloride of Cadmium.-According to Croft dry chloride of cadmium absorbs 3 atoms of ammonia. Fhe compound thus formed which has the formula 3H3N CdCl gives off ammonia in the air until it becomes inodorous. The loss of ammonia amounts to 2 atoms so that therc remains a coinpoiind of the forwiila R,N+ CdCl. A compound similar to this and also containing only 1 atom of ammonia may be obtained according to Croft by dissolving chloride of cadmium in heated liquid ammonia and leaving the solu- tion to cool when the compound is deposited in crystalline grains. The loss of weight on heating was 16.63per cent. H3N. By the addition of hydrochloric acid to a solution of chloride of cad-mium in ammonia Schiiler obtained a fine crystalline powder the constitution of which he found to be SH3N CdCl he states that this is the same salt that is obtained by the spontaneous evaporation of a solution of chloride of cadmium in ammonia.By this process the author has obtained a salt with only 1 atom of ammonia which is consequently the same as that described by Croft,-a proof that this compound loses 2 atoms of ammonia just as quickly as that which is produced by passing amrnoniacal gas over chloride of calcium. This loss of ammonia must take place during drying. For analysis the salt was dried between blotting-paper. It gave-Calculated. Found. H,N. . . 17 15-68 16.15 Cd . . . 56 51-66 51.64 c1 . . . 35-4 32.65 32.21 108.4 100~00 100~00 If hot liquid ammonia be used in the preparation of this com- pound a little precipitated hydrated oxide mixes with it during cool- ing; it is therefore better to mix ammonia with a cold aqueous solu- tion of chloride of cadmium until the precipitate which is formed at first is again dissolved leaving the solution to evaporate spontaneously when crystalline crusts are deposited.It is nearly insoluble in water. When carbonate of cadmium or the anhydrous or hydrated oxide is treated with an aqueous solution of sal-ammonia it dissolves in con- siderable quantity with evolution of ammonia. The filtered soliltion SOME SALTS OF CADMIUM. yields crystalline crusts on evaporation ; but these differ very con- siderably in the proportion of chloride of cadmium and chloride of ammonium according to the length of the reaction.But if one of the above compounds be boiled for a long time with sal-ammoniac then filtered and left to cool anhydrous crystallised cbloride of cadmium and ammonium is deposited having the composition 2H,NC1+ CdCl. 5. Chloride of Cadmium and Ammonium.-C roft has prepared two salts of chloride of cadmium and ammonium which according to the author have the following formulze :-a. NH,C1 ZCdCl+HO. b. ZNH,Cl CdCl. 6. Chloride of Cadmium and Potassium forms two salts of exactly similar composition to the two preceding :-a. KC1 + 2CdClf- H0.-This salt is produced when equivalents of the two constituents are dissolved together and left to spontaneous evaporation; it forms silky needles united in tufts.The salt is very soluble; when dried over sulphiiric acid it partially loses its water of crystallisation and this water is entirely driven off at 1000 C. ; in either case the salt becomes opaque. It undergoes no change at the ordinary temperature of a room. When strongly heated it melts readily but loses a part of its chlorine and is then no longer soluble in water. When dissolved in water it crystallises again unchanged from the solution. Its analysis gave- Calculated. Found. K... 39.2 14-71 13.93 2Cd . . . 112 442.04 4255 3C1 . . . 106-2 39.86 49.24 HO. . . 9 3.37 4.58 266.4 100~00 100~00 b. 2KC1 CdC1.-When the saIt u has been removed from its mother-liquor the latter furnishes on further spontaneous evapora-I tion large limpid crystals siriiilar to those of nitrate of soda and constituted according to the forniula 2KCl CdCl.This salt is remarkable for its great facility of crystallisation whilst the corres- ponding amnioniacal double salt is generally obtained in scalariforni groups of dull crystals the potash-salt shoots out readily on all sides into perfectly formed transparent crystals with brilliantly shining faces. This salt can be obtained directly only by mixing aqueous solutions of at least 3 atoms of chloride of potassium with 1atoiii of chloride of cadmium and leaving the mixture to crystallise. This salt is rather less soluble in water than the preceding. If the aqueous solution be left to spontaneous evaporation the salt a first of all crptallises again froni it.It melts when strongly heated 254 HAUEK ON and then behaves like the precediug potassium-salt. It undergoes no change in the air. The two salts 2H,NCl+ CdCl and 2KC1 +CdCl are iuomorphous. The analysis of the potassium-salt gave- 2K.. . 78.4 Calculated. 32.58 Found 32.72 Cd. . . 56 23-28 23.66 3C1 . . . 106-2 44.14 43-62 -I Y- 240.6 100*00 100~00 7. Chloride of Cadmium and Sodium NaCl CdC1+3HO (air- dried).-A solution containing equivalents of chloride of cadmium and chloride of sodium concentrated by heat soon deposits this double salt ; it consists of small dull verrucose crystals which are constituted according to the above formula as stated by Croft. When dried at 100°C.itloses 12.30 per cent. = 2 atomswater; the third atom is only expelled between 150' and 160' C. From this it would appear that the salt has 2 atoms of water of crystallisation and 1 atom of constitution-water the latter being more obstinately retained. The salt niay consequently be regarded as a hydrated com- pound of chloride of sodium with hydrochlorate of cadmicoxid the formula of which would be (NaCl + CdO HCl) +2HO ; and the salt dried at 212' F. after losing its water of crystallisation would have the formula NaCl+ CdO HCI. When heated it melts and behaves like the potassium-salts. It undergoes no change in the air. 8. Chloride of Cadmium and Barium BaCl CdCl+4HO.-If aqueous solutions of chloride of barium and chloride of cadmium be mixed and left to evaporate spontaneously a salt is pro-duced when the chloride of barium is in excess which forms small crystals is difficult of solution in water and appears to contain an indeterminate proportion of chloride of cadmium.When this has been removed the mother-liquor furnishes large well-formed crystals which are sometimes transparent when small but lose their trans- parency as they grow larger although their faces exhibit a brilliant lustre. By placing these crystals in recently saturated liquor they may be obtained in the course of a few weeks more than an inch in length. When solutions of equivalents of the two salts are mixed the salt is obtained directly. It is produced in the same way by spontaneous evaporation and by heat. . Analysis :-Calculated.Found. Ba . . . 68.6 29-64 29-62 Cd . . . 56 24.20 24-17 C1 . . . 70.8 30.39 30.56 HO. . . 36 15.5ti 15.65 231.4 200.00 100~00 SOME SALTS OF CADMIUM. 255 The salt is perfectly stable in the air dissolves readily in water and crystallises unchanged from the solution. The above analysis is of the air-dried salt. At 100' C. it loses 8.82 per cent.. or 2 atoms of water ; the other 2 atoms are only expelled at 160° C. ;it has then a porcelain-like appearance. Judging from this behaviour of the water the constitution of the salt might be more exactly expressed by the formula (BaO HC1+HO) +(CdO HC1+ HO) as it indicates more distinctly the part which the water plays in it; it is a simple com-pound of hydrated hydrochlorate of baryta and hydrated hydrochlorate of cadmic oxide.The composition of the salt dried at 100"C. at which temperature it loses its water of crystallisation is consequently (BaO HCl) +(CdO HC1) ;and when dried at 160"F. when its con- stitutional water is expelled BaCl +CdC1. When heated to redness it fuses after loss of water forming a clear colourless fluid which on cooling is not crystalline and has an enamel-like appearance. The fused mass is no longer perfectly soluble in water; it has therefore probably lost a part of its chlorine. 9. Bromide of Cadmium and Bromide of Potassium form the same salts as chloride of ammonium and chloride of cadmium namely- a. KBr * 2CdBr+HO ; and 6. preceding. 2(KBr) CdBr which is deposited from the mother-liquor of the They are isomorphoils with the above-described chlorides.The bromide of cadmium employed in the preparation of these two salts was obtained by bringing metallic cadmium in contact with bro- mine and water. In the distillation of oxide of cadmium with char- coal for the preparation of the metal the latter is obtained not only in large globules but also in a finely divided state of a greyish colour very similar to platinum-black. In this form the metal is best fitted for combining with bromine :the combination is effected in a short time aud with a considerable evolution of heat. As by this means even when a large quantity of water is present a considerable quantity of the bromine is expelled in the form of vapour it is advisable to bring the two substances in contact in a closed flask and to put this into cold water if the heat be too great.The solution which is at first red soon becomes perfectly cdourless as the combination goes on very rapidly. 10. Sulphate oj Cadmium and Ammoniuin.-!Chis salt which was first prepared by Mitscherlich is readily obtained in large well- formed crystals by the spontaneous evaporation of a solution con-taining the two salts in equivalent propprtions. The crystals undergo no change in the air and possess a peculiar fatty lustre and are fatty to the touch; they are only transparent when small larger crystals being always opaque. The compositiou of the salt agrees with the general formula of' the numerous salts belonging to this series,- NH,O * SO +CdO * SO + 6HO ; H.AUEH ON SOME SALTS OF CADMIUM.but to obtain this quantity of water the drying must be wry carefully conducted. If large crystals are analysed without drying theiii in a pounded state .a quantity of water is obtained much greater than that which is required by the above formula even though the crystals may have been long in drying ; for they always contain water mechanically arid retain it very obstinately. Analysis :- Calculated. Fouud. NH . . . 17 7-59 7.66 CdO . . . 64 28.57 28-50 ZSO 7130 . . . . . . 80 63 35.71 28-12 35.85 27-99 - 224 100~00 100~00 The salt cannot be dried over srilphurie acid as it effloresces. When dried at 212O it loses 26.60 per cent. or 6 atonis of water ; the last atom which is united with the ammonia is only driven off by a higher temperature simultaneously with sul'phate of ammonia.If the salt be directly exposed to a high temperature it swells up and melts par- tially in the water of crystallisation and the sulphate of aninioiiia is completely driven off together with the water; sulphuric acid is after.. wards expelled and the residue csnsists of sesquisulphate of cadmium The salt may be recrystallised without alteration by dissolving it in a small quantity of water. 11. Sul'hate of Cudmiurnand Potassium KO SO 4-CdO . SO, + 6HO.-This salt is obtained with difficulty as the sulphate of potash which is less soluble has a greater tendency to crystdlise. It is best prepared by saturating a solution of bisulphate of potash with carbonate of cadmium adding a little sulphuric acid and leaving the solution to spontaneous evaporation.It could riot be obtaiued pure by con- centrating the solution by heat and leaving it to cool. Even the formed crystals are decomposed when the temperature of the mother- liquor changes a little. It is scarcely possible to obtain large crystals in a state of purity as they are generally covered with small crystals of sulphate of potash. 113 its crystalline forin and constitution the salt resembles the preceding. When the crystals are taken out of the mother-liquor they exhi bit beautifully shining faces but soon become dull; the efflorescence goes on so rapidly that it is difficult to get the salt for analysis with its whole 6 atoms of water unless it is employed with the mother-liquor adhering to it.Analysis :-Calculated. Found. KO . . . 47-42 19.25 20.23 CdO. . . 64 26.10 26.54 2S0 . . . 80 32-62 33-73 6HO. . . 54 19.50 19-50 245.2 1oo*oo 100*00 SCHNEIDER ON THE SULPHOCHLORIDE OF MERCURY. 257 If the salt has been kept for a few hours in a heated room only 4 or 5 atoms or even less water will be found. 1%.Sulyhate of Cadmium and Sodium is obtained by mixing the two salt! in equivalent proportions. The crystallisation takes place with difficulty and only when the solution is much concentrated. The salt forms small verrucose crystals like those of siilphate of cadmium with 1 atom of water. In the air-dried state it contains 2 atoms of water and is consequently composed according to the formula NaO SO + CdO SO,+ZHO.Analysis :- Calculated. Found. NaO . . . 31 16.06 16.37 CdO . . . 64 33.16 32.71 2s0 2H0 . . . . . . 80 18 41-4,5 9.32 41.57 9.35 - 103 100~00 100~00 This salt appears to be obtained with less difficulty when a slight excess of acid is present. On the Preparatien of the Sulphochloride of Mercury in the DryWay.* By R. Schnelder. H. ROSEhas long since shown that the white precipitate formed during the first period of decomposition by passing sulphuretted hydrogen gas into a solution of mercuric chloride is a compound of chloride and sulphide of mercury in such proportions as to be ex-pressed by the formula HgC1 * 2HgS. According to H.Rose the same compound may be obtained by boiling moist black sulphide of mercury with an excess of a solution of mercuric chloride.When prepared by either of these methods it has the appearance of a white amorphous powder which is insoluble in boiling water and simple acids but is readily decomposed by nitrohydrochloric acid or potash in the latter case leaving a residue of black oxysulphide of mercury. This compound may also be obtained with ease and certainty in the dry way by enclosing sulphide of mercury (either black or red) with an excess of mercuric chloride in closed glass tubes when on the application of heat the sulphide of mercury dissolves in the fusing chloride forming a yellowish-brown fluid which on cooling solidifies into a pearl-grey enamel-like mass a mixture of mercuric chloride * Pogg.Ann. xcv. 167. VOL. VII1.-NO. XXXI. S 258 llUCHNER ON PURIPYINO SULYHURJC ACID FROM ARSENIC. and sulphochloride. The operation is best performed by means of a Berzelius lamp at about 662' to 752' F. ;and if the tubes are formed of strong hard glass and well closed at the ends it generally goes on without any disturbance. The mercuric chloride must be employed in considerable excess if the sulphide is to be completely dissolved; the quantity should be about 8 to 10 parts of the chloride to 1 of sulphide (cinnabar) ;if less of the former be used the cinnabar is certainly converted into sulphochloride but a portion of the latter remains undissolved as a white powder. The excess of mercuric chloride may be completely extracted from the solid mass by treat- ment with boiling water; the sulphochloride then remains in the form of a diugy white distinctly crystalline powder.Its analysis gave- Found. Calculated. Hg ......81-26 s ....... - 8152 8.57 C1 ...... 9.68 9.91 In its properties and chemical behaviour the compound prepared in the dry way nearly agrees with that obtained in the humid way. It is however essentially distinguished from it by its crystalline form and also by the circumstance that when agitated in water it rapidly sinks to the bottom and may be very easily washed upon the filter whilst that which is prepared in the humid way remains long sus- pended in the fluid and causes difficulties in filtration from producing turbidity in the filtrate.On an easy Method of Purifying Sulphuric Acid from Arsenic." By A. IBuchner. ARSENIOUS ACID as is well known is easily changed by the action of hydrochloric acid into the much more volatile chloride of arsenic. If arsenious acid be dissolved in hydrochloric acid or if a liquid containing arsenious acid be mixed with hydrochloric acid and then a sufficient quantity of concentrated sulphuric acid be added chloride of arsenic as Liebig has shown will separate out in oily drops and as such may be distilled off. Chloride of arsenic boils at 132O C. and volatilises with hydrochloric acid vapour much under its boiling point while concentrated sulphuric acid boils at 325' to 327' C. I am not aware whether these facts have been made available for puri- fying sulphuric acid from arsenious acid,? but experiments have shown *Ann.Ch. Pharm. xciv. 241. f-J. Lijwe recommended for the purification of siilphuric acid from arsenious acid the addition of finely-pow.dered chloride of sodium to the hot acid (Chem. Gaz. xii. 464). LIEBIG ON THE MELLONIDES. me that they form the basis for sucha method of purification. In fact if sulphuric acid containing arsenic be mixed with a little hydrochloric acid and warmed,-or better if a moderate stream of hydrochloric acid gas be passed through the heated sulphuric acid,-all the arsenic is rapidly removed as chloride of arsenic. I have purposely dissolved a large quantity of arsenious acid in sulphuric acid and then treated it in this manner.Soon the arsenic was so perfectly removed that Marsh’s apparatus gave no trace of arsenic even after some time. After passing the hydrochloric acid through the liquid the heat may be continued for a little time in order to drive off evpry trace of hydrochloric acid if necessary. I consider this process the only possible one for preparing sulphuric acid pure for chemico-legal investigations. It is known that sulphuric acid cannot be freed from arsenious acid by rectification because their boiling points are too near and because the sulphuric acid is the more yolatile of the two; and the precipitation of the arsenious acid out of sulphuric acid by sulphuretted hydrogen is too unpleasant and takes too much time. This process offers also the advantage that any nitrous acid which may be present is removed in the form of chloride of nitric oxide.On the Mellonides.* By J. Liebig. AN examination of the mellonides has led me to an incontestable proof that the radical of those compounds contains no trace of hydrogen. The composition of hydromellonic acid is expressed by the formula C18N13H3. This compound should be a tribasic acid capable of forming with potassium three distinct compounds the constitution of which may be expressed by the formula+- K Clf3N13 { H The composition of the mellonide of silver would be expressed by C,,N13Ag3. If hydromellonic acid be compared with some compounds of the same group it may be considered as constituted in the following manner :-c1*Nl +NHP * Comyt.rend. XI. 1077. 260 L~WIGON The following products might then be connected with this compound; namely-Melam . . . Cl N8,+3NH3 Melamine . . . . . c6 N4+2NH3 Amnieline . . . . . C6N,+%”,+2H0 Ammelide . . . . . 2(C6N,)+NH3+6H0 Cyameluric acid . . . Cl,N70,+3H0. If an excess of potash is made to act upon mellonide of potassium with the aid of heat this compound is decomposed by the inter- vention of 18 molecules of water forming ammonia ammelide and cyameluric acid as shown in the following equation :-2(C18N13K3)-+ 18HO = C12NgH906+ 2(C12N703,3KO) + 3NH.3. 1 Mellonide of Ammelide. Cyamelurate of potash. potassium. By continuing the action of the potash the ammelide fixes the elements of 2 molecules of water and loses 1 molecule of ammonia becoming converted into the compound the formation of which by the action of a proper degree of heat upon urea has already been signalised by Wo hl er and myself.Thus-The latter compound is finally converted into cyanuric acid by the proloiiged action of the potash. Thus-C12N8H,0 + 4H0 = 2(C6N30 * 3HO) + 2NH3. On some Compounds of Stibethylinm.* B)r R. LOWlg. Iodide of Stibethylium SbAe4Z+ 3HO.-This body is formed when stibethyl and iodide of ethyl are allowed to act upon each other. The two fluids mix together but only act upon each other slowly. When enclosed by fusion in a glass tube and heated to 100’ C. the combination takes place very rapidly and much heat is suddenly set free. The best mode of obtaining it is by mixing equal parts of stibethyl and iodide of ethyl putting the mixture into a retort filled with carbonic acid nearly filling this with water and closing it by fusion.The retort is then laid in boiling water where- upon the combination takes place in two or three hours. The solution * J. pr. Chem. Ixiv. 416. SOME COMPOUNDS OF STIBETHYLIUM. is allowed to cool and evaporate on the water-bath during which pro- cess it acquires a somewhat yellow colour which however may be removed by the addition of a few drops of ammonia. Properties.-Iodide of stibethylium crystallises in beautiful hexa- gonal prisms often an inch in length or in small pointed crystals which acquire a yellowish colour in the air. It has a very bitter taste.19.02 parts of it dissolve in 100 parts of water at 20' C. ; it dissolves more easily in absolute alcohol but in &her with more difficulty than in water. The analyses (a) are of the hydrated and (b) of the anhydrous salts :-Calculated. Fonnd. Calculated. Found. Sb 129 32-33 7-(4 (4- 34-33 w-.. (6) (6)- 16C 96 24-06 24.25 24-03 25.80 25.75 25.84 23H 23 5.77 6.28 5.95 5-47 5-68 5-58 1 30 127 24 - 31.83 6.01 32.24- 31-88 - 34-40 34.38 34-17 399 100~00 100~00 During the crystallisation of iodide of stibethylium especially when it separates from warm solutions another salt is often formed with a different amount of water 2 (SbAe,I) +3HO. Iodide of Stibethylium and Mercury 3HgI + (SbAeJ1.-When a solution of mercuric chloride is added to a solution of iodide of stibethylium a white precipitate is produced which melts into an oily fluid even at a gentle heat.This salt is insoluble in water and ether and dissolves with diffi- culty in boiling alcohol. It crystallises from this solution in columnar crystals. If the precipitate be allowed to melt under water of 70' C. it solidifies to a white mass and only exhibits single red spots but becomes entirely red after some time. If the mass which has become red be dissolved in boiling alcohol the white salt separates again in hexagonal prisms. Both forms of the salt have the same composition but the red crystals appear to belong to the regular system. This salt gave on analysis-Calculated. Found. 7-. SbAe . . . 245 23.27 -3Hg . . .. 300 28.49 29.30 28.40 41 . . . . . 508 48.24 49.00 48.60 1053 100.00 A similur compound 3HgI + 2(SbAe,I) is obtained by adding iodide of mercury to a hot solution of iodide of stibethylium until It 262 LOWIG ON no longer loses its red colour. The conversion of the excess of iodide of mercury is then effected by a fresh addition of iodide of stibethylium. None of the latter remains in the fluid ;'the precipi- tate melts when heated forming a yellow oil. Analysis :--Calculated. Found. 2SbAe . . . 490 34.38 -3Hg . . . . 300 21.06 20.86 21.80 51 . . . . . 635 44.32 4456 44.52 1425 100*00 Chloride of Stibethylium (SbAe,)Cl+ 3H0 is obtained by satu- rating oxide of stibethylium with hydrochloric acid or by decom- posing 4 atoms of iodide of stibethylium with 3 atoms of mercuric chloride by which means 3 atoms of chloride of stibethyliurn are obtained.In the latter case the solution contains neither iodine nor mercury. The salt crystallises and deliquesces more readily even than chloride of calcium. It loses its water of crystallisation on the water-bath. It has a strongly bitter taste. The analysis of the dry salt gave- Cdculated. Found. - I Sb . . 129 56-03 -16C . . . 96 34-29 33.29 33.21 20H. . 20 7-01 7.76 7.63 C1. . . 35.9 12.67 11.13 12.50 7-280.5 100.00 Chloride oj' Stibethylium and Mercury.-Compounds exactly similar to those of iodide of mercury with iodide of stibethylium are obtained by bringing in contact chloride of mercury and iodide or chloride of stibethylium.1 atom of iodide of stibethylium with 3 atoms of chloride of mercury furnish the iodine compound which melts under water whilst the water takes up the corresponding chloride 3HgClf (SbAe,)Cl. If concentrated sblutions of chloride of stibethylium and mercuric chloride be mixed a compound of the formula 3HgC1+ 2(SbAe4)C1 is obtained. The former salt is soluble in alcohol and water; the latter forms a white powder which is difficult of solution in water. Chloride of Stibethylium and Plaatinum 3PtC1 + 2SbAe4Cl.-This salt is produced by mixing a somewhat dilute alcoholic solution of chloride of stibaethylium with a similar sollition of chloride of platinum and evaporating the mixture. It is a fine yellow com-pound tolerably soluble in water and alcohol which yields 68.6 SOME COMPOUNDS OF STIBKl'IIYLIURI.67.2,and 69.2per cent. of platinochloride of platinum. (Calculation 68.53 per cent.) Bromide of XtibethyZiuna (StAeJBr was obtained by saturating oxide of stibethylammoniuni Gth hydrobromic acid. It crystal- lises in dazzling white acicular crystals which dissolve very readily in water and alcohol and do not deliquesce in the air. Analyses gave 24-39and 24.37 of bromine. With oxide of stibethylium bromine appears to form bromide and bromate of stibethylium. Hydrated Oxide of Stibetltylium StAe,O,HO is obtained by decomposing iodide of stibethylium with oxide of silver. Traces of dissolved oxide of silver are renioved by the careful addition of hydrochloric acid.The fluid is evaporated in vacuo when the hydrate is obtained in the form of a thick colourless oily fluid of a strongly alkaline and intensely bitter taste which quickly renders litmus- paper blue. It dissolves in water and alcohol in all proportions but is insoluble in ether. It sets ammonia free from its compounds and precipitates the oxides of the heavy metals. Oxide of tin and alumina are again dissolved by the excess of the alkali. The salts of the alkaline earths are not decomposed by the base. The salts are produced by bringing the base in contact with the acids or by double decomposition. They have a strong bitter taste. The sulphate (SbAeJO SO, crystallisee. The nitrate (SbAeJO -NO, crystallises. The carboilate (SbAeJO CO, is a tough deliquescent niass.The formiate (SbAe,)O FoO, forms acicular crystals difficult of solution. The acetate (SbAe,)O AcO, forms more soluble acicular crystals. The succinate (SbAeJO SuO, does not crystallise. l!he oxalate (SbAe,) 0 C,O, crystallises. The tartrate (SbAeJO C4H205,forms large deliquescent crystals. The racemate (SbAe,) OC,H,O, forms large deliquescent crystals. Subhide of Stibethylium (SbAe,)S is obtained by treating oxide of stibethylium with sulphuretted hydrogen. It is evaporated without access of air and forms a yellowish oily fluid which does not crystallise; it dissolves readily in water and alcohol and behaves towards the salts of the metals like sulphide of potassium. 264 WUR'FZ ON On Butylic Alcohol." By A.Wurtz. THJS alcohol is obtained from the fusel-oil which remains after the rectification of the alcohol obtained from beet-molasses. Different samples of this fuse1 oil however contain veiy different quantities of the alcohol and many none at all. To separate the butylic alcohol W u rt z collects apart the portions which distil over between 80' and 105' 105' and 115' 115' and 125' C. The first portion is washed with water the oily layer which separates repeatedly rectified the portion which passes over above 104' being each time collected apart. The latter is united with the portion which passed over between 105' and 115O and with so much of the last portion (which passed over between 115' and 125') as in repeated rectifications of the latter passes over below 115'.A11 the liquid which has distilled over between 105' and 115' is then boiled for forty-eight hours with a strong solution of caustic potash in such a manner that the volatilised portion may condense and flow back again ; th% impure butylic alcohol is then distilled over separated from the water which passes over at the same time more completely dehydrated by leaving it for twenty- four hours in contact with half its weight of caustic potash and then distilled. The distillate is repeatedly rectified and the portion which goes over bttween 108' and 110' collected apart if the boiling point remains constant between these limits during the whole of the distillation the butylic alcohol is very nearly pnre.The process of purification may be shortened by causing the vapour to pass from the distilling flask through an upright tube having two bulbs blown on it and fitted with a theimometer which is immersed in the vapour at the top before it reaches the condensing apparatus. The less volatile portion then condenses in the tube and runs back into the flask and the separation of the more and less volatile portions is thereby greatly facilitated. Butylic alcohol purified as above and boiling at llOo gave results nearly agreeing with the formula C,H,,O ; v 1z .- Analysis. Calculated. /--I. 11. 111. Carbon 64.86 64.55 64-49 64.94 fiydrogen 13.51 13.90 13.53 13.65 For complete purification Wurt z converted the butylic alcohol into iodide of bntyl which boils at 121' C.and is easily separated by fractional distillation from iodide of ethyl which boils at 73O and iodide of amyl boiling at 146' transformed the iodide of butyl into * Ann. (211. Phjs. L3] xlii. 129; Ann. Ch. Phann. xciii. 107. HUTYLIC ALCOHOL. acetate by means of acetate of silver ; and decomposed the latter by continuous boiling with concentrated solution of potash the volatilised portion being condensed and made to run back; the butylic alcohol was then poured off and rectified over caustic baryta. Butylic alcohol thus purified is a colourless liquid more mobile than amylic alcohol and having an odour similar to that of the latter but less pungent and more vinous it rotates the plane of polarisation of a ray of liFht; exhibits the composition marked III.in the above table; and boils at 109' C. Sp. gr. = 0.8032 at 18'*5 C. Vapour density = 2.589. The formula C,H,,O gives 2.565 for a condensa- tion to 4 volumes. Butylic alcohol readily takes fire on the approach of a burning body and burns with a bright flame It dissolves in 104 times its weight of water at IS' and is precipitated from that solution by chloride of calcium chloride of sodium or other soluble salt in the form of an oily layer. It dissolves chloride of calcium and forms a crystalline com- pound therewith. Potassium converts it with evolution of hydrogen '8 3] into 0,. When the alcohol is dropped upon soda-lime heated to 250° hydrogen gas is evolved and a salt of butyric acid formed.Sulphuric acid acts violently on butylic alcohol the mixture becoming heated and coloured. When the alcohol is mixed with sulphuric acid sulphurous acid is evolved and an oily layer sepa- rates consisting chiefly of hydrocarbons polymeric with butylene. When butylic alcohol is quickly mixed with excessof sulphuric acid a small quantity of gas is evolved with great rise of temperature by the application of a gcntle heat the gas niay be obtained in larger quan- tity ; it consists chiefly of butylene together with carbonic and sulphurous acid. When the alcohol is gradually mixed with an equal volume of sulphuric acid and the mixture kept cool sulphobutylic acid is produced. The formation of butylic alcohol from grape-sugar alone or simul- taneously with vinic and amylic alcohols is expressed by the following equations :-C,,H,,O, = 2C8H,,02 + 8C02 + 4H0 2C,,H2,O2 = 2C,,H1202 + C,H1,O + C4H602 + 16C0 + 8H0.Wurtz searched in vain for propylic alcohol in the fusel-oil from beet-molasses. Some samples of this fusel-oil yielded by distillation a small quantity of a liquid which distilled over at 160' and upwards this however was not an alcohol but a mixture of certain compound ethers of the arnyl series. Action of Chloride of Zinc on Butylic Alcohol.-Butylic alcohol dissolves receutly fused chloride of zinc at ordinary temperatures forming with it a syrupy liquid. Heated with excess of chloride of zinc it is dccomposcd giving off first butylene gas C,€I, afterwards 266 WURTZ ON a mixture of that gas with hydride of butyl CEHlo.On passing the (in which certain hydro- 0' evolved gases through a tube cooled to carbons are condensed) and thcn through a tube surrounded with a freezing mixture a colourless liquid condenses in the latter wbich when taken out of the freezing mixture is suddenly converted into a mixture of about equal volumes of butylene and hydride of butyl the boiling point then rising to about 8'. The less volatile hydrocarbons which boil from 100" to 300° exhibited a composition expressed by C,,H, or C4,H,, The butylene is produced from the butylic alcohol C,H,,02 by separation of 2HO ; the hydride of butyl and the less volatile hydrocarbons from the butylene possibly as represented by thc equations- = + C24H'22 6 CSH *= CBH1 + C40H33 Butyl CEHg,the radical of butylic alcohol is obtained by heating iodide of butyl with potassium in sealed tubes for several days at the temperature of the water-bath.The potassium is gradually converted into iodide on opening the tubes butylene gas escapes; and on applying a gentle heat the vapour of hydride of butyl C,H, (which niay be condensed by a freezing mixture) the boiling point then rising rapidly to 100'. From 105O upwards butyl C,H or CI6Hl8 passes over; it is a colourless oily liquid having a faint odour and specifically lighter than water.* Found. Calculated. 84.21 Carbon . . 84-26 C Hydrogen . 16.15 H . 15.79 -I-i00-41 1oo*oo Chloride of Butyl is formed by the action of pentachloride of phosphorus on butylic alcohol ;the action is violent and attendcd with considerable evolution of heat.The yentachloride is gradually added to the butylic alcohol in a flask having a long neck which must be kept very cool. The pentachloride is then converted into oxychloride (or the oxychloride may be used in the first instance in which case the action is less violent). After twenty-four hours the contents of the flask are distilled off; the portion which distils over below 100' is washed with water dehydrated with chloride of calcium and rectified ; the poi6on which goes over below 70' is chloride of butyl. This liquid is lighter than water and has an ethereal odour recalling also that of chlorine. It is rapidly decomposed by potassium with rise of temperature and evolution of gas.Its composition is C,H9CI. BUTYLIC ALCOHOL. 267 Found. Calculated. ,-. Carbon . 51-21 51-86 C 51.88 Hydrogen 9-69 9-99 H 9.70 Chlorine . -C1 58.40 100~00 Chloride of butyl is also formed by the action of hydrochloric acid on butylic alcohol. When the alcohol is saturated with hydrochloric acid gas and the liquid enclosed in a sealed glass tube and heated in the water-bath a large quantity of chloride of butyl is formed which may be obtained in the separate state by washing the product with water rectifying it and collecting apart the portion which distils over between 70' and 75'. Bromide of Butyl is obtained by adding a few drops of bromine to butylic alcohol introducing a small quantity of phosphorus after the liquid has cooled to a certain point and repeating the addition of bromine and the decoloration of the liquid by phosphorus till vapours of hydrobromic acid are given off in abundance and a quantity of bromine has been added at least equal to the butylic alcohol.The liquid is then distilled at a gentle heat not exceeding loo' whereupon the vapours of hydrobromic acid dissolve in the water while the bro- mide of butyl collects at the bottom. This product is washed with water dried over chloride of calcium and rectified. Pure bromide of butyl boils at 89' and smells like chloride of butyl. Its specific gravity at 16' is 1.274. Vapour-density by experiment 4.720,while the formula C,H,Br gives for a condensation to 4 vols.the number 4.749. Found. Calculated. 7-y Carbon . 34.58 34.97 C 35.03 Hydrogen 6*79 6.67 H 6-56 Bromine . -57.91 Br 58.41 99.55 100.00 Bromide of butyl is decomposed by potassium very slowly in the cold but with violence when heated. When the substances were heated together in a sealed tube the action took place immediately after the fusion of the potassium. Large quantities of gas were evolved probably butylene and hydride of butyl ; and the tube exploded with violence. Ammonia acts but slowly on bromide of butyl at ordinary temperatures probably with formation of butylamine. Iodide of Butyl.-Obtained by adding 1-5 pt. iodine to 1pt. of bntylic alcohol which must be kept cold ;yadually introducing about (1-i 5 phosphorus ; and subsequently heating the mixture (at last to 268 WURTZ ON ebullition) the colour of which beconies lighter and brownish-yellow while hydriodic acid volatilises together with a little iodide of butyl.These vapours are received in cold water; the residue when cold washed with this liquid and afterwards with pure water ; then dehy- drated by chloride of calcium ; and freed from a small quantity of un- altered butylic alcohol by treating it while warm with pulverised iodide of phosphorus* till that conipound crystallises out. The liquid then distilled and the distillate washed with water dehydrated with chloride of calcium and rectified the portion which distils over at 118' to 122' being collected apart. Iodide of butyl recently prepared is a colourless strongly refracting liquid which however soon turns brown when exposed to light.It boils at 121'; but when a mixture of water and iodide of butyl is distilled the thermometer at the commencement of the process when iodide of butyl chiefly distils over shows a tempe- rature of only 88' to 89'. The specific gravity of iodide of butyl is 1.604 at 19O. Vapour-density by experiment = 6.217 the formula C,H,I gives 6.343 for a condensation to 4 volumes. Found. Calculated. ,-<-Carbon . 26-04 26.59 26.26 26.41 -c8 26.22 Hydrogen 5-00 5.13 5.04 4-92 -H 4-91 Iodine . --68.68 I 6887 Iodide of butyl burns with difficulty and only in contact with an inflamed body and gives off vapours of iodine. It is but slowly attacked by aqueous solution of potash even after long boiling ; alco-holic potash decomposes it with formation of iodide of potassium and butylic alcohol.It is readily decomposed by silver-salts. With an alcoholic solution of nitrate of silver it immediately forms iodide of silver ; it likewise acts on dry silver-salts and this reaction gives rise to the formation of several other ethers from the iodide of butyl. Butylic Ether C,HgO or C8Hg 1 O, is formed by the action of C8H9 ',:9butyl on the compound ofiodide f 0, produced by the action of potassium on butylic alcohol but could not be separated by fractional distillation from the excess of butylic alcohol which boils nearly at the same point. On attempting to remove the excess of butylic alcohol by saturating the liquid with potassium ultimately with the aid of heat and treating the still hot liquid with iodide of butyl a violent * Wurtz prepares this compound by adding 8 or 10 pts.of iodine to 1 pt. phos- phorus in a glass vessel which admits of being closed ; violent action takes place and the resulting compound fuses. The heat is continued for a short time till the film which adheres to the aidea of the vessel becomes dark red and t.ranslucent and the liquid coniyound separated from the solid phosphorus (which has become amorphous) the compound solidifies in the crystalline state. BUTYLIC ALCOHOL. action takes place attended with formation not of butylic ether but of butylic alcohol and butylene C,H,I +C,H,KO =C,H1,02 +C,H +KI. Iodide of butyl is completely decomposed by dry oxide of silver,-with formation of butylic ether and iodide of silver,-the former being however associated with small quantities of butylene- gas water reproduced butylic alcohol and carbonate of butyl.The formation of the water and carbonic acid is attributed by Wurtz to the oxidising action of the excess of silver-oxide :the formation of butylic alcohol he regards as taking place in the manner represented by one of the equations C,HgI +Ago +HO =C,H,,O +AgI. f2C,H91 +2Ag0 =C,HI,O 4-C,H +2AgI. Vinobutylic Ether C1,HI4O3=c4H5 ]O, is prepared by the '8 H9 action of iodide of ethyl on the compound C8H9K02 at ordinary tem- peratures. After the mixture had been left to stand for a day it was distilled the excess of iodide of ethyl passing over first then vino- butylic ether and lastly (above 95O) the excess of butylic alcohol.The last portion of the distillate was again treated with potassium then the first portion to form a new portion of vinobutylic ether; and lastly the entire liquid rectified the portion which distilled over between 78" and 80' being collected apart. This which was a colour- less liquid having an agreeable odour exhibited a density of 0-7507 and the composition C1,H1402. Found. Calculated. Carbon .70.15 C, 70.58 Hydrogen ..14.04 H, 13-72 Oxygen ..-0 16.170 100.00 Carbonate aJ' Butyl was prepared by enclosing equal parts of car-bonate of silver and iodide of butyl in a sealed glass flask and heating the mixture in the water-bath for two days.On opening the flask after cooling a small quantity of carbonic acid escaped together with a gas (butylene) which burned with a smoky flame. The liquid remaining in the flask was then distilled in the oil-bath and the portion which passed over above 180' again rectified. Carbonate of butyl thus obtained is a colourless liquid specificaIIy lighter than water having an agreeable odour like that of carbonate of ethyl and boiling at 190'. Its composition answers to the formula- 270 WURTZ OM Found. Calculated. Carbon . 62.14 c, 62.09 Hydrogen . . 10.49 H, 10.34 Oxygen . -O6 27-67 100*00 Aqueous ammonia converts it into butylic alcohol and butylic urethane . Nitrate of Butyl.-Prepared by mixing previously fused nitrate of silver with a small quantity of urea likewise fused and adding a quantity of iodide of butyl not quite sufficient to decompose the silver- salt ;action immediately takes place and the nitrate of butyl is dis- tilled over partly by the heat evolved in the reaction and the rest between 140"and 150'.The distillate after being washed with water and dehydrated by chloride of calcium is a colourless liquid heavier than water and tasting sweet at first but afterwards pungent and aromatic. It boils at 130'; burns with a pale flame; its vapour does not detonate. Its composition corresponds with the formula Calculated. Carbon . 40.55 c 40.33 Hydrogen . . 7-31 H 7.56 Nitrogen . -N 11-76 Oxygen . -0 40.35 100*00 With alcoholic potash it yields butylic alcohol and nitrate of potash Sulphuretted hydrogen has no action upon it.Sulphate of Butyl is formed by the action of iodide of butyl on sulphate of silver at ordinary temperatures. The heat evolved in this reaction is sufficient to exert a decomposing action on the resulting sulphate of butyl ; the mixture blackens in separate places; and on opening the vessel in which the action has taken place the odour of sulphurous acid becomes perceptible. The action may be moderated by cooling the vessel; but the sulphate of butyl is so unstable that it decomposes from one day to another yielding sulphurous acid a coloured viscid hydrocarbon and a peculiar conjugated acid which may be extracted.by treating the residue with water; and forms with baryta a soluble salt which dries up to a gummy mass in vacuo.BUTYLIC ALCOHOL. Acetate of Butyl is prepared by decomposing the iodide with nitrate of silver. The latter salt is mixed in a small flask with a nearly equivalent quantity of iodide of butyl the neck of the flask sealed and the flask heated for several hours in the water-bath. Iodide of silver is then formed together with acetate of butyl which may be separated by distillation. The distillate is washed with water containing a little carbonate of soda in solution then dried with chloride of cal-cium and rectified. Pure acetate of butyl is an ethereal perfectly colourless liquid having a very agreeable odour boiling at 114' and having a density of 0.8845 at 16'. Vapour-density by experiment =4.073; by calculation from 'the formula C12H,204 4.017 for a condensabion to 4 volumes.Found. Calculated. Carbon . . 61.94 C12 62.06 Hydrogen . . 10-42 H, 10.34 Oxygen . -O4 27-60 100~00 When boiled with solution of caustic potash it is decomposed with formation of acetic acid and butylic alcohol. Acetate of butyl may also be obtained by distilling equivalent quan- tities of sulphobutylate of potash and recently fused acetate of potash In a similar manner Formiate of Butyl may be prepared it is a liquid having an agreeable odour and boiling at about 100". Su@hobutyZic Acid may be separated from its baryta-salt by sul- phuric acid but has not yet been minutely examined. The baryta-salt is obtained by gradually adding strong sulphuric acid to an equal volume of butylic alcohol diluting the mixture after twenty-four hours with ten times its volume of water saturating with carbonate of baryta and evaporating the filtrate.The baryta-salt crystallises in large white rhombic laminae which are unctuous to the touch. Their com-position is- Found. Calculated. - Carbon . . 20.18 -C8 20.01 Hydrogen . 4-63 -H, 4-58 Oxygen . . -0 10.00 Siilphuiic acid -ZSO 33-39 Baryta . . 31.75- 32.73 BsO 32-02 272 WURTZ ON The ciystals dissolve readily in water at 100' or in vamo they give off 2 eq water. The potash-salt of sulphobuiylic acid was prepared by diluting the mixtureof sulphuric acid and butylic alcohol with twice its brilk of water mixing it with solid carbonate of potash evaporating in the water-bath and exhaustiug the residue with boiling alcohol.The potash-salt crystallised from the filtrate in broad nacreous laminz. It dissolves readily in water with tolerable facility in boiling alcohol sparingly in cold alcohol. The concentrated aqueous solution is pre- cipitated by alcohol. Its composition is s ~ 2 91 0,. Found. Calculated Carbon . . Hydrogen . Oxygen . Sulphuric acid Potash . . 24-82 4.94 -241.1 24.81 --24.53 C,g92s0,KO 24.97 6-68 -24.55 The aqueous solution of this salt distilled with caustic potash yields butylic alcohol and sulphate of potash. Sulphobutylate of lime was prepared like the preceding salts By evaporating the aqueous solution it was obtained in small nacreous crystals which under the microscope presented the appearance of six-sided laminze.They are anhydrous dissolve readily in water (the solution is highly efflorescent) and have the composition S f '&:9 ] 0 ; analysis gave 16.41 per cent. lime while the for- mula requires 16.18 per cent. ButyZamine.-This base like all the bases of the series N f CnHn+lj H, may be obtained by the action of potash on cyanate and cyanurate of butyl. A mixture of these two ethers is obtained by distilling 2 parts of sulphobutylate of potash with 1part of perfectly dry and recently prepared cyanate of potash. The pasty distillate is dissolved in alco- hol and the solution boiled with addition of fragments of caustic potash. CRrbonate of potash is then formed and butylamine evolved which is condensed in a small quantity of cold water acidulated with hydrochloric acid.The boiling is continued till the residue is quite fused and no longer gives off alkaline vapours. The resulting solution of hydrochlorate of butylamine is evaporated to dryness and the salt after being freed from residual water by fusion is pulverised when cold and quickly mixed with an equal weight of quicklime. This mixture is introduced into a tube of hard glass which must be filled with it to four-fifths. The remaining portion of the tube is filled with BUTYLIC ALCOHOL. 273 fragments of caustic baryta; a gas-delivery tube bent at right angles attached to this tube and made to dip into a small flask surrounded with ice; and the tube carefully heated in a combustion-furnace beginning at the closed end.The butylamine which escapes is com-pletely dehydrated by caustic baryta and condenses in the flask. It boils at 69' to 70"; smells strongly ammoniacal and somewhat aro- matic ; is inflammable and burns with a luminous flame. In contact with hydrochloric acid it forms dense fumes. It dissolves in all proportions in water or alcohol. The aqueous solution smells like the pure base and is very caustic ; when concentrated it is somewhat viscid. Most metallic solutions are precipitated by butylaniine in the same manner as by ammonia the precipitates formed in solutions of zinc cadmium and copper dissolve in excess of the precipitant gelatinous alumina likewise dissolves in excess of butylamine.The oxides of nickel cadmium and chromium do not redissolve in excess of the precipitant. Nitrate of silver forms with butylamine a tawny yellow precipitate easily soluble in excess. Gelatinous silica dissolves very perceptibly in butylamine and remains in the pulverulent and arnor- phous state when the solution is evaporated. The composition of butylamine is expressed by the formula- Found. Calculated. Carbon . ,-65.58 65.87 c8 65.75 HydrogenNitrogen 14.99 - 15.26 - Hi N 15-06 19-19 100*00 Hydrochlorate of butylamine C,H,,N.HCl crystallisee in deliques-cent needles melts above loo",emits thick white' fumes in the air and volatilises without residue. It gave by analysis 43.83 per cent. C and 11.05 H the formula requiring 43-83and 10.95.The platinum-salt of butylamine does not separate out immediately on mixing hydrochlorate of butylamine and bichloride of platinum even in concentrated solutions but crystallises after evaporation in beautiful orange-yellow laminae which are soluble in water and alco-hol and have the composition C8Hi1N H C1-I-PtCl,. Analysis gave 17.18 per cent. C 4.52 H and 35.02 Pt the formula requiring 17.19 C 4.29 H and 35-32Pt. VOL. VII1.-NO. XXXI. T 274 HUMANN ON Hydrochlorate of butylamine and terchioride of gold may be mixed without separation of a double salt; but on evaporating the mixture the double salt crystallises in yellow rectangular tables which when heated above loo' melt to an orange-yellow liquid. The analysis of these crystals gave 18.79 per cent.C 4.84 H and 37-50Au the formula Z(C,H,,N,Hcl) + AuCI requiring 18.30 C 457 H and 37-94Au. On ButylBc Mereuptan aml Butylic Urethane.* By E. Humann. Butylic Mercaptan C,H&.-This compound is easily obtained by distilling at the heat of the water-bath a mixture of solution of sulph-hydrate of potassium and a concentrated solution of pure sulphobutykteof potash taking care to receive the product in a well-cooled flask. The oily liquid which condenses is decanted placed in contact with chloride of calcium and then distilled with the thermo- meter the pwtion which distils over between 85' and 95' C. being collected apart. The reaction which gives rise to the formation of butylic mercaptan is expressed by the following equation :- SO,).C,H90}2~~,+ HK)sz = cg9)s + 2(KO KO -Sulphobutylate Butylic of potash. mercaptan. Butylic mercaptan thus obtained is a colourless very mobile liquid lighter than water and having the peculiar disagreeable odour which characterises the mercaptans. Sp. gr. 0.848at 11'-5 C. Vapour-density by experiment 3.10. CaIculation from the formula C,Hl0S2 gives 3-11for a condensation to 4 volumes. Boils at 88' C. Very inflammable and burns with a very bright blue flame. Very sparingly soluble in water. Mixes in all proportions in alcohol and ether. Has no action on vegetable colours. Dissolves sulphur and iodine. -' * Ann. Ch. Phya. 133 xliv. 337. BUTYLJC MERCAPTAN AND BUTYLIC URETHANE. The analysis of this body gave the following results :-Experiment.Calculated. -. Carbon . 53.52 53-16 c 53-33 Hydrogen 11-71 11-32 H, 11.11 Sulphur . -S 35.56 I 100~00 Dilute nitric acid acts very strongly on butylic mercaptan; the liquid becomes red from forination of a certain quantity of nitric oxide which dissolves in it; but the colour disappears on heating and an oily liquid is then found on the surface. Butylic mercaptan like its homologues forms compounds in which its basic hydrogen is replaced by a metal. Thus when it is heated with potassium hydrogen is evolved and a white granular substance formed which is soluble in alcohol and consists of butylosukhopotassic alcohol "$91 S,. On pouring an alcoholic solution of butylic mercaptan into acetate of lead a yellow crystalline precipitate is formed containing S .When an alcoholic solution of butylic mercaptan is poured upon red oxide of mercury ampid action takes place attended with con-siderable elevation of temperature and a white substance is formed consisting of butylomercaptide of mercury or butyZosulphomercuric alcohol On dissolving the product in boiling alcohol and leaving the solution to cool the compound is deposited in white nacreous scales very fusible and unctuous to the touch. Their composition is as follows :-Expt. (mean). Theory. Carbon . . . 25.78 C 25.39 Hydrogen . . 5.01 H 4-76 Mercury . . . 52.55 Hg 52-91 Sulphur . . . -S 16.94 100-00 This compound is decomposed by sulphuretted hydrogen yielding sulphide of mercury and butylic alcohol.216 HUMANN ON BUTYLIC MERCAPTAN AND URETHANE. Butylic mercaptan acts in a similar manner on other metallic oxides thus it forms white precipitates with acetate of copper and ter-chloride of gold. Butylic Urethanp,C,,H ,NO,.-Obtained by the action of gaseous or liquid chloride of cyanogen on butylic alcohol,-its formation being however accompanied by that of carbonate of butyl. 2C,H,,02 + C2NC1 = C,,H,,NO + C,H,Cl and 2C,H1,02 + C2NC1 + 2H0 = fL(C,H,O. CO,) + NH,Cl. -c a- Carbonate of buty 1. The best niride of preparing butylic urethane is to pour liquid chloride of cyanogen into butylic alcohol. The reaction takes place quickly with the aid of heat more slowly at ordinary temperatures.It is generally indicated by the formation of a mass of crystals within the liqiiid,in case the butylic alcohol contains a little water. It is complete when the odour of chloride of cyanogen has completely dis- appeared. The best mode of' accelerating it is to heat the mixture in a sealed tube placed in the water-bath. After cooling the crystals must be well pressed the liquid introduced into a retort and distilled When nearly tNo-thirds of the liquid has passed over the receiver is to be changed and the portion which distils over above 220' C. collected apart. This product is an oily liquid which solidifies on cooling and partly collects in the neck of the retort in a shining crystalline niass which is unctuous to the touch this is butylic urethane.It must be carefully collected and pressed between folds of blotting-paper. It is finally purified by crystallisation from boiling alcohol. Butylic urethane thus prepared form beautiful nacreous scales which are very brilliant unctuous to the touch insoluble in water soluble in alcohol and ether; they melt at a very gentle heat and distil without alteration. The analysis of these crystals gave 51.09 per cent. C and 9-18H ; corresponding with the formula- which requires 51.28 C and 9-40 If. YilSTEUll ON -4MYLIC ALCOHOL. The first portion of the distillate obtained hy the action of chloride of' cyanogen on butylic alcohol consists of Carbon& of Butyl. On redistilling this liquid and collecting that which passed over between 180" and 190' C.a colourless very mobile liquid was obtained lighter than water having a very agreeable odour and yielding by analysis 61.53 per cent. C and 10.65 H. The formula C,H,O,CO, or c20,{ 2:: 1 requires 62-09C and 10.34 11. Wurtz had previously obtained the carbonate of ethyl by the action of chloride of cyanogen on common alcohol. On dmylic Alcohol.* By L. Pasteur. THEfusel-oil of commerce consists chiefly of a mixture of two kinds of amylic alcohol,-one active and the other inactive with regard to polarised light. These two varieties are exactly similar in their chemical properties differ but slightly in density and boiling point and give rise under similar circumstances to products which resemble each other in all respects excepting in their relation to polarised light those which are derived from the active alcohol being themselves active and those which result from the inactive alcohol being themselves also inactive.The proportion of the active and inactive alcohols in fusel-oil varies according to its origin thus the fusel-oil obtained by fermen- tation of the juice of mangold-wurzel contains about one-third of active and two-thirds of inactive arnylic alcohol whereas that which is produced by fermentation of the molasses contains about equal parts of the two alcohols. The two alcohols cannot be separated by fractional distillation but only by fractional cry stallisation of the active and inactive sulphaniylates of baryta. For this purpose it is necessary to prepare a large quantity of sulphaniylate of baryta from crude arnylic alcohol rectified by a single distillation in order to free it from water and vinic alcohol.The amylic alcohol thus far purified is mixed as usual with an equal weight of sulphuric acid the mixture treated with carbonate of baryta then filtered and left to crystallise. The crystals have all the same aspect lustre form and angles ; and as in the case of a perfectly constant and homogeneous substance the salt may be crystallised either wholly or partially any * Conipt. rend. di. 296. PASTEUR ON AMYLIC ALCOHOL. number of times without the slightest change in the aspect of the crystals. Nevertheless the mass is really composed of two kinds of crystals differing in solubility and in t,heir action on polarised light,- one being indeed active and the other inactive.They are very diffi- cult to separate in consequence of their complete isomorphism. Nevertheless the active salt is 2& times more soluble than the inac- tive ; and if the fir& crystals which separate be recrystallised about 20 times a product will at length be obtained which has no action on polarised light ; and by repeatedly crystallising the mother-liquor a solution will ultimately be left containing nothing but the active salt. Lastly on extracting from these two varieties of the sulphamylate the amylic alcohol of which they contain the elements it is found that the more soluble salt yields an amylic alcohol which rotates the plane of polarisation to the left and to the amount of 20' in a tube 50 centi-metres long while the less soluble salt yields an amylic alcohol which has no perceptible action on polarised light.The comparative study of these two alcohols exhibits many points of interest. Every reaction that can be performed with the one may likewise be produced with the other under the same circumstances and the resemblance of the resulting products often approaches nearly to identity without ever actually attaining it. Moreover the active alcohol always gives active products and the inactive alcohol inactive products provided we do not go as far as the radical CIOHII, in which reside the dissymmetry of the molecules and the action on polarised light. One of the most remarkable differences exhibited by the two alcohols is in their densities.The active alcohol is heavier than the other and the difference amounts to nearly &. Consequently equal volumes of the two alcohols do not contain equal numbers of molecules those of the active alcohol being more crowded than those of the other ; and the difference is considerable for a phenomenon of such a nature. The active alcohol boils at 127' to 128' C. under the ordinary pressure and the inactive alcohol at 129'. The mixture of the two boils at intermediate temperatures and not at 132' as is commonly stated. ~OSSMANNAND SCHEVEN ON HYPOG~EICACID. 2 79 On Hypogselc Add a new fatty acid obtained froln Earthnut-oil." BY A. Qossmann and H. Scheven. THEearthnut (Arachishypogaa L.) is a small low-growing legumi- nous plant which grows wild in South America and on the south coasts of Africa and Asia and is cultivated in Italy Spain and the South of France.The seeds which ripen only when the-pods are covered up with earth produce a large quantity of a nearly colourless oil having an agreeable taste. This oil burns with a bright flame forms an excellent soap with alkalies and mixes very readily with essential oils. At +3OC. it yields a solid fat resembling stearine becomes viscid at -3' or -4' and solidifies completely at 7'.- This oil contains two fatty acids viz. drachinic acid belonging to the series C,H,O, and Hypogeic acid belonging to the oleic acid series C,H,-,Oh. Arachinic acid was discovered by Gijssmann,t who obtained it by saponifying the oil with very strong caustic soda decomposing the resulting fat with hydrochloric acid and separating themore solid portion of the fatty acid thus obtained by rep-ated cry stallisation from alcohol and by pressure.After four crystallisa- tions a solid fatty acid was obtained exhibiting a constant melting point. It was procured in larger quantity by subjecting the mixed fatty acids to Heintz's method of fractional crystallisation of the lead-salts. Aracliinic acid crystallises in very beautiful shiny laminae ; acquires a nacreous lustre by pressure ; melts at 75' ; solidifies with radiating structure at 73*5O and becomes white and like porcelain by keeping. When pure it dissolves but very sparingly iu cold alcohol of ordinary strength sparingly also in cold absolute alcohol readily in hot absolute alcohol and very readily in ether.Its analysis gave the following results :-Calculated. Found. 40C 240 76.92 76.84 76.84 76.82 -40 H 40 12.82 12.96 12.93 12-82 12.82 40 32 10-26 C4,H4,04 312 100.00 The formula was confirmed by the analysis of arachinic ether- { c,zr] C40 0 prepared in the usual manner by passing hydro- chloric acid gas into an alcoholic solution of the acid. # Ann. Ch. Pharm. xciv. 230. t Ibid. lxxxix. 1. 2 80 G~SSMAKNAND SCHEVEN ON Hypog~icacid C32N3004,more recently discovered by Gos s m ann and Scheven is obtained as follows :-After the earthnut oil had been saponified with caustic soda and the separated acids purified by re- peated fusion in water they were diasolved in alcohol precipitated with acetate of magnesia and ammonia and the liquid filtered.The filtrate was then mixed with an excess of alcoholic solution of acetate of lead and excess of ammonia and left at rest for several days. As soon as the precipitate ceased to increase it was collected dried as quickly as possible by pressure and thoroughly exhausted with ether in a well-closed cylindrical vessel. The ethereal solution of the lead- salt was then mixed with a slight excess of dilute hydrochloric acid access of air being as far as possible prevented; the chloride of lead filtered off; and the filtrate several times shaken up with water freed from air by boiling. As soon as the ethereal solution of the oleic acid had become clear it was taken off and set aside in a well-closed stoppered cylinder till the temperature became favourable for the examination of the acids.The greater part of the ether was then carefully distilledoff in the water-bath. As the liquid cooled an acid crystallised out which had a slight yellowish colour ; but by gentle pressure and recryatallisation from alcohol it was obtained quite white and in needle-shaped masses. In solution there remained a yellowish acid which was probably altered by oxidising influences. At a lower temperature this also crystallised completely in a mass of yellowish stellate needle-shaped crystals which by recrystallisation from alcohol were likewise obtained colourless. The several crops of crystals thus pursed constitute the new acid-hypogeic acid-which is charac-terised by the following properties.It consists of colourless acicular aggregates ;melts at 34' to 35' C. ; dissolves readily in alcohol and ether ; saponifies pretty easily even in the cold ; becomes yellowish red on exposure to the air acquiring at the same time an extremely rancid odour and an acid reaction. The acid when thus altered crystallises with great difficulty even at a very low temperature. In this respect it bears some resemblance to ordi- nary oleic acid. For analysis the acid was brought to a constant weight at 100' C. with as little access of air as possible. Cdculal,ed. Found. 32 C . .192 75.59 7G&XZ-G-l 30 H . . 30 11-81 11-70 11.81 11.79 40 . . 32 12-60 __..-> C~,,H,,O 254 100.00 HYPOGIEIC ACID.Copper-salt C32H2gCu404.-Prepared by passing an excess of dry ammonia'cal gas into an alcoholic solution of the purified acid and adding an alcoholic solution of acetate of copper. The solution remained clear at first but when cooled to a low temperature depo- sited a fine light blue granular crystallised compound which when quickly and carefully dried remained unaltered contained no am-monia and dissolved with tolerable facility in alcohol forming a clear solution. At 75' C. it baked together becoming translucent and waxy. Dried at looo it yielded 67.27 per cent. carbon and 10.40 hydrogen the formula requiring 67.36 and 10.17. Baryta-salt C,,H,9Ba0,.-Obtained like the copper-salt in the form of a white granular precipitate which dissolved when heated leaving only a small quantity of a very basic salt.The solution on cooling yielded a granular crystalline salt containing 24.08per cent. BaO ;the formula requires 23-81. Hypoyaic ether C32 "29 f O,.-This compound was prepared C4H5 by passing dry hydrochloric-acid gas into a solution of the purified acid in 95 per cent. alcohol as long as it continued to be absorbed; then heating the liquid leaving it to stand for 24 hours and repeating the whole process with the layer of ether*thus obtained. The product after being freed from hydrochloric acid by shaking up with water and from free hypoFaic acid by treating it with small quantities of alcohol was dried in a retort at 100 to 120' in a stream of carbonic acid gas and analysed.Calculated. Found. 36 C . . 216 76.59 76.56 76.91 76.72 34 H . .,34 1295 12.01 11-92 11.93 4 0 . .32 11-36 282 100-00 Hypogzeic ether has a yellowish colour probably arising from slight impurity; it is not volatile heavier than alcohol (at the bottom of which it collects),.lighter than water. It is insoluble in water and dissolves very sparingly in alcohol whence the latter is well adapted to free it from unetherieed acid. The authors endeavoured also to ascertain whether the earthnut-oil contains any other acid of the olcic series besides hypogaeic acid. For this purpose the entire quantity of ncid separated from the ethereal 2a2 ANDERSON ON PAPAVERINE. solution of the lead-salt obtained from a certain portion of the oil was converted into ether and the ether analysed.This ether gave quantities of carbon and hydrogen agreeing exactly with the above ; hence as the lead-salts of all the acids of the oleic series are soluble in ether it may be concluded that no other acid of that series is con-tained in the oil. en Payaverhe.* By T. Anderson. .IN the mother-liquors obtained in the purification of narcotine by repeated crystallisation from boiling alcohol A n derson has found besides narcotine the more soluble alkaloid papaverine. This body is obtained free from narcotine by finely pulverising the last crystale obtained from the mother-liquors and digesting the powder with a small quantity of acetic acid which then combines only with the papaverine.As soon hs the liquid becomes neutral it is decanted the residue again treated with a sniall quantity of acetic acid and this treatment repeated as long as the acetic acid is completely neutralised by contact with the residue. From the liquid filtered from the nn-dissolved narcotine the papaverine was precipitated by ammonia and recrystallised from boiling alcohol. Papaverine was obtained in con-siderable quantity from the mother-liquor remaining after the first crystallisation of the crude narcotine by precipitating that liquid with subacetate of lead ; boiling the finely pulverised precipitate with alcohol ;driving off the alcohol from the dark alcoholic decoction ; treating the residue with dilute hydrochloric acid ;concentrating the hydrochloric acid solution of narcotine and papaverine filtered from the black resinous matter ; removing from the liquid the crystals of the sparingly soluble hydrochlorate of papaverine which separate in a few days ;purifyizlg them by repeated recrystallisation ;separating out the base by means of ammonia; and purifying it by recrystalllsation from boiling alcohol.The analysis of the product thus obtained exhibited the composition found by Merck,t vis. C,,H,,NO,. * Ed. Phil. Trans. xxi. Pt. 1 ; Ann.Ch. Pharm. xciv. 235. t Ann. Ch. Pharm lxxiii. 50. ANDERSON ON PAPAVERINE. Found. Calculated. Carbon . 70.71 70.60 70.58 C40 70.79 Hydrogen Nitrogen* Oxygen . 6.29 4.40 18.60 ' 6-46 3.96 18.96 6-46 - H, 6.20 N 4.14 0 18.78 The platinum-salt gave 17.82 per cent.platinum the calculated quantity being 18.10. Action of Nitric Acid-Papaverine dissolves in dilute nitric acid without decomposition; but on mixing the solution with an excess especially of strong nitric acid and heating the liquid a vivid action takes place; red fumes are evolved ; the liquid assumes a deep red colour ; and orange-coloured crystals separate out from it consisting of the nitrate of a new base Nilropapaverine. This base separates from a solution of the salt in boiling water or in excess of nitric acid on addition of ammonia in the form of a light yellow flocculent precipitate and after recrystallisation from boiling alcohol is obtained in needles. It is insoluble in water soluble in alcohol and ether blues reddened litmus paper dissolves in acids and neutralises them completely forming salts which are all of a pale reddish yellow colout and insoluble in water.It fuses when heated and burns away quickly at a higher temperature. When boiled with strong solution of potash it gives off traces of a volatile base. It does not like papaverine give a purple colouration with sulphuric acid. Its com-posit ion is C4,HZ0(N0,)N0,. Calculated. Found. 40 C . . . 240 62.50 62.31 20H . . . 20 5-20 5.21 2N.. . 28 7.29 120 . . . 96 25-01 -384 100*00 The crystals which separate from the alcoholic solution retain 1eq. of water (2.29 per cent.) The nitrate of nitropapaverine prepared as above forms four-sided * Anderson observe3 that papaverine precipitated by ammonia appeara to carry sonic of tho ammonia down with it which makes the nitrogcn deterinination come out too high.Tlie second of the above determinations of nitrogen ww made with papaverine which had been precipitated by 1)otash. ANDERSON ON PAPAVERINE. tables generally of an orange colour but yellow when quite pure. The crystals are anhydrous. It is nearly insoluble in cold somewhat more soluble in boiling water and dissolves abundantly in water mixed with nitric or hydrochloric acid ; dissolves also in alcohol and ether. When heated it melts and burns quickly away leaving a black sub- Rtance which also burus conipletelg away at a stronger heat. Its composition is C,,H,,(NO,)NO .HO .NO,. Found.Calculated. Carbon . 53-68 C . . 53.69 Hydrogen . 4.95 H, . . 4.69 Nitrogen . . -N . 9.38 Oxygen . . -O, . . 32.24 100~00 Sulp hate of nitropapaverine dissolves sparingly in water and crys- tallises in small prisms. Hydrochlorate of nitropapaverine likewise dissolves but sparingly in water but readily in excess of hydrochloric acid and in alcohol; it crystallises in pale yellow needlea. Bichloride of platinum added t ts solution throws down the platinum-salt C,,H,,(NO,)NO,HCl .PtCI in the form of a pale yellow precipitate. Found. Calculated. Carbon . . 40.47 C . . 40.66 Hydrogen . 3.80 H, . . 3.55 Nitrogen . . -N . 4-72 Oxygen . . -O, . . 16.26 Chlorine . . -C1 . . 1809 Platinum. . 16.56 Pt . . 16.72 100*00 Action of Bromine.-When bromine-water is added by drops to a solution of hydrochlorate of papaverine a precipitate is formed which redissolves at first but afterwards remains permanent ; this precipitate is the hydrobromate of Bromopapaverine.From this salt the base itself is readily obtained by digestion with ammonia and recrystallisa- tion from boiling alcohol; as the solution cools the baee separates in small white needles which are insoluble in water but readily soluble in alcohol and ether. The crystallised base is anhydrous and its con1 posit ion C,,H,,Br N 0,. ANDERSON ON PAPAVERJNE. 285 Fomd. Calculated. Carbon . . 57-23 C, . . 57-41 Hydrogen . 5-02 H, . . 4.78 Nitrogen . . -N . . . 3-36 I Oxygen . . 0 . . 15.34 Bromine . . 19-46 13r .. 19.13 I oo*oo The hydrobromate is obtained as above mentioned from the concen- trated liquid as a yellowish but from a more dilute solution as a white precipitate; from the solution in boiling alcohol it separates in the form of a crystalline powder ; it is insoluble in water. When heated it melts and decomposes. Its composition is C2,H20BrN0,. HBr. Found. Calculrrted. Carbon . . 48.36 C, . . 48.09 Hydrogen . 4-35 H, . . 4.20 Nitrogen. . -N . . . 2-80 Oxygen . . -0 . . 12.85 Bromine . . 3.2.48 Br . . 32.06 100.00 Hydrochlorate of bromopapnverine dissolves though sparingly in water. Action of ChZorine.-When chlorine gas is passed into a solution of h ytlrochlorate of papaverine the liquid beconies brown and after a while deposits a dingy grey precipitate which is insoluble in water but dissolves in boiling alcohcl and separates from that solution in the form of a resin.Ammonia withdraws hydrochloric acid front it, and leaves undissolved a pulverulent substance which is a basic chlorinated substitution-product. Action of Iodine.-An alcoholic solution of papaverine mixed with tincture of iodine yields after a while small crystals which when recrystallised from boiling alcohol form rectangular prisms having a purple-red colonr by reflected and dark red by transmitted light. They are insoluble in water are not attacked by dilute acids but are quickly decomposed by ammonia and potash d When the liquid apaverine then re-maining. Their composition is C,,H,,NO,+ separated from these crystals is evaporated another compound sepa- rates out which after recrystallisation from alcohol forms thin needles exhibiting an orange-colour by transmitted light but leaving 2m HERMANN ON THE VOLATILE COMPOUND a reddish surface.This comyonnd remains unaltered at looo but gives off iodine at a higher temperature. Its composition is c,,H,,No;+ 5 r. C,H,,NO + 3 I. CaH2,1N08+ 5 I. Fou11d. Caloulated. Found. Calculated. Carbon . 33-0.2 33-47 24-78 24-76 Hydrogen. . 3.21 2.92 2.59 2-16 Nitrogen . . -1-95 -1-44 Oxygen . . -8.95 -6.63 Iochne . . . 52.90 52-71 G4.60 65-01 100~00 1oo*oo Action of Soda-Zime.-When papaverine is heated with four times its weight of soda-lime a volatile base is evolved the platinum salt of which contains 36.21 per cent.of platinum a result intermediate between the quantities of platinum in the corresponding salts of propylamine and ethylamine. Anderson thinks it probable that both these bases were present. On the Volatile Bromine-compound obtailred in the Technical Preparation of Bromine.* By 1.Hermann. IN the preparation of bromine from the last portions of the mother- liquor obtained from the Schonebeck salt-spring,? there distils over together with the free bromine an oily liquid which being less vola- tiie than bromine itself remains in the first of the series of receivers used to condense the products. This substance was formerly regarded by Hermann as a definite compound CZHBr2 the variations in its boiling point being attributed to the facility with which it decom- poses ; but later experiments performed with a larger quantity of material have showii that this view is incorrect and moreover that the liquid canriot be brought to a definite state by fractional distil- lation even in an atmosphere of carbonic acid.By subjecting the * Ann. Cli. Pharm. XCV. 211. -f J. pr. Chem. 1x. 5. OBTAINED IN THE PREPARATION OF BROMINE. liquid however to the following treatment a definite compound is obtained from it. The oily liquid cooled to -20' C. by a mixture of ice and salt soli- difies for the most part in white shining crystalline laminz. To purify these the mother-liquor is carefully decanted the crystals melted again crystallised and separated from the mother-liquor and these operations several times repeated.The solidified mass after being freed as completely a8 possible from the mother-liquor is then introduced into a capacious funnel in the apex of which is placed a small perforated filter. At first the principal part of the mother- liquor runs off and the rest is displaced by the liquid proceeding from the gradually melting crystals. The product which last drips from the melting crystals may be regarded as perfectly pure. If the mother-liquor obtained a8 above be again treated in the same manner a product is ultimately obtained which no longer crystallises at -20° c. Themelting point of the crystals is -9'C. :if they have previously been completely dehydrated by remaining some time over dry chlo-ride of calcium they form in the melted state a colourless very mobile liquid having a saccharine taste with a very persistent burning aftertaste.When exposed to the air they decompose to a certain extent assuming a red colour from the presence of free bro- mine. When distilled even in a stream of carbonic acid they are decomposed in the same manner as the crude liquid a small quantity of the above-mentioned bromide of carbon being ultimately formed. When exposed to the action of chlorine in sunshine the liquid is gradually but completely converted into solid chloride of carbon. The analysis of the crystals gave the following results :-2c. . 12 Calculation. 4-74 Expt. (mean).4-80 H. . 1 0.40 0.43 3Br. . 240 94-86 94-77- - C,HEr 253 100.00 100*00 The substance appears therefore to be Bromoform ;in fact it agreed perfectly in composition and properties with a sample of that compound prepared in the ordinary way.Its formation is due to the action of the free bromine on the highly carboniferous organic matters contained in the mother-liquor of the salt-spring. It is generally supposed that bromoform like chloroform is con- verted by caustic potash into bromide of potassium and formiate of potash. This however is not the case. Not a trace of formic acid HERMANN ON BR0;MOFORM. is produced and the reaction is different according as the hydrate of potash is used in the free state or dissolved in alcohol. When hydrate of potash is brought in contact with bromoform no action takes place at first but after a while the mass becomes so strongly heated that the broniofornz begins to distil over and at the same time a gas is evolved which when freed by agitation with water from a small quantity of diffused bromoform exhibits the characters and composition of pure carbonic oxide.The deconiposition is expressed by the following equation :-C,HBr + 3K0 = ZCO + HO + 3KBr and is analogous to that which the corresponding oxygen-compound viz. formic acid undergoes under the influence of sulphuric acid. With an alcoholic solution of potash on the other hand the evolved gas is a mixture of carbonic oxide and olefiant gas the latter pro-ceeding from the alcohol which under these circumstances is resolved into olefiant gas and water its decomposition being induced by that of the bromoform.The relative quantities of carbonic acid and ole- fiant gas thus produced vary with the degree of concentration of the alcoholic solution of potash; but it is especially remarkable that the simultaneous decompositions of the bromoform and alcohol though not connected by any mutual action nevertheless take place in simple atomic proportions so that for example 1atom alcohol is decom-posed for every 3atoms bromoform ;or with a differently concentrated solution 5 atoms bromoform to 3 atoms alcohol; thus affording an example of the remarkable law discovered by Bunsen relating to the coefficients of affinity. The non-crystallisable portion of the original liquid appears to contain protobromide of carbon C,Br,.

ISSN:1743-6893    

DOI:10.1039/QJ8560800219

出版商:RSC    

年代:1856

数据来源: RSC