摘要:

Thc Favnday Socicty is tiot vesportsiblc for ofiinioizs e.t$vcssed befrrc i t b y Azithors or Speakers. OF FOUNDED 1903. TO PROMOTE THE STUDY OF LLECTROCHEM18TRY, LLECTROMLTALLURQY, CHEMICAL PHYSICS, METALLOQRAPHY, AND KINDRED 8UBdROTS. VOL. 111. MARCH, IPS. PART 3. ON THE ELECTROLYSIS OF SALT SOLUTIONS IN LIQUEFIED SULPHUR DIOXIDE AT LOW TEM- PERATURES. BY BERTRAM D. STEELE, D.Sc.* DISCUSSION. Dr. T. M. Lowry was sceptical as to the existence of the sulphur cathions postulated by Dr. Steele. A few years ago Walden had made a similar assumption in reference to bromine, which was supposed to act both as anion and cathion when dissolved in sulphur dioxide. In that case the conductivity was doubtless due, not to the electrolysis of the element, but to that of hydrogen bromide and sulphuric acid formed by the interaction of the bromine with the solvent sulphur dioxide in presence of moisture. To attribute electrolytic properties to a compound of two elements so similar to one another as sulphur and oxygen was only one degree less fanciful than in the case of an element. The formation of sulphur as a secondary product of cathodic reduction would, however, be perfectly normal, since this reduction actually took place in the electrolysis of sulphuric acid, which at high con- centratioiis yielded both sulphur and hydrogen sulphide at the cathode. issued in October, 1907. * This Paper was published in the volume o f Trnnsaciiotis (vol. iii. part 2, p. 164)

ISSN:0014-7672    

DOI:10.1039/TF9080300169

出版商:RSC    

年代:1908

数据来源: RSC

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NOTE ON THE ACTION OF ALUMINIUM POWDER ON SILICA AND BORIC ANHYDRIDE. BY FRANK E. WESTON, B.Sc., AND H. RUSSELL ELLIS, B.Sc. ( A Paper read before the Faraday Society, Tuesday, October 29, 1907, Mr. N. T. M. WILSMORE, M.Sc., in the Chair.) The statement of Goldschmidt that boric anhydride and silica are reduced by aluminium to boron and silicon respectively has been called in question by other workers.::: Having observed that silica in the form of kieselguhr and titanium dioxide in the form of rutile are readily reduced by aluminium, and as we required quantities of boron trichloride, it was thought worth while to examine Goldschmidt's reaction with respect to boric anhydride and silica respectively. ACTION OF ALUMINIUM POWDER ON BORIC ANHYDRIDE. Aluminium powder, the finest obtainable from the British Aluminium Company, was found to react with boric anhydride more or less vigorously, according to the conditions :- (I) Using B,O, which had passed through a sieve of 14,400 meshes to the square inch- (a) The reaction took place instantly in the cold, using a fuse of BaO, and Mg ribbon, spreading throughout the whole mass, and throwing off incandescent particles, when the mixture was made in the pro- portion of the molecular weights Al, and B,O,.(b) The reaction only took place on heating the mixture, which was contained in a Hessian crucible, in a muffle furnace to dull redness, when the mixture was in the ratio of Al, and 2 B203. (2) Using B,O, that had passed through a sieve of 3,600 meshes to the square inch, it was found that the reaction would only take place after the mixture had been heated- (a) Using molecular quantities and heating to about 300' C., the reaction started when a magnesium fuse was used and proceeded through- out the mass.(b) Using quantities represented by Al, and 2 B20,, the action started and proceeded throughout the mass when heated for some time to dull redness in the muffle furnace. The products of the reaction are difficult to isolate owing to the in- solubility of the Also3 produced in the reaction and also to the presence of one or more borides of aluminium. However, it was shown that free boron is produced in the reaction in which excess of B,03 is used, with more or less borides of aluminium ; whilst in the reaction between molecular quantities the borides of aluminium probably predominate.The authors would not recommend this reaction either as a method of See Proceedings of Farnday Society, vol. iii. parts 5 and 6. 170NOTE ON THE ACTION OF ALUMINIUM POWDER 171 obtaining boron, owing to the difficulties of separating it from the other products of the reaction, or for the preparation in quantity of BCl,, since the G1,0, reacts on the BCl, formed with the production of AlCl, and B,O,, and hence the yield of BC1, is far from the amount of RCl, actually first produced. Experimental. Experimertfs, Set 1.-35 grams of B,O, (finest used) and 27 grams of Al-ie., in proportions of Al, and B,O,-were intimately mixed and placed in a Hessian crucible ; the reaction was started in the cold with a fuse of Mg ribbon and '2 gram BaO,, and spread rapidly throughout the mass, throwing off incan- descent particles.When cold, the crucible contained a black porous mass, easily removable from crucible and homogeneous in composition, and easily powdered in an iron mortar ; this powder was finally ground in an agate mortar until it passed through the 14,400 mesh sieve-a residue which did not pass through the sieve scratched the agate mortar. The whole of the powder was extracted with boiling dilute HC1-hydrogen was evolved to a small extent at first ; it was filtered, and the filtrate on evaporation to dryness gave a residue of AlCl,, FeCI, (traces), and H,BO, ; the insoluble residue was again extracted with hot concentrated HCl until filtrate gave no H,BO, and only a trace of AlCl, and FeC1,.This insoluble residue still left gave the alcohol and sulphuric acid reaction for boron, It is probable that the AlCI, came from a little unused Al, the borides of aluminium and the A1,0, which is only very slowly attacked by HC1. The iron came originally from the Al, which Contained a little iron and paraffin wax, or stearin. Exantiriafiorz of' Residue Insoluble in HCI (A).-In order to obtain some idea of the amount of boron or aluniiniuni borides it was decided to convert the same into BC1, by the action of chlorine. The residue was dried, placed in a piece of dry combustion tube, fitted on the one hand to a cylinder of liquid C1 and on the other hand to a tube placed in a freezing mixture 0 of ice and salt which registered a temperature of -19.C. throughout all the experiments.On heating the residue and passing a slow current of chlorine, the mass became red hot, but did not appear to burn rapidly. AlCl, with traces of FeCI, condensed in the cool part of the tube and BCl, condensed (I) On removing from freezing mixture it was seen to be slightly yellow in colour, and immediately commenced to boil ; keeping tube in freezing mixture, a few drops of dry Hg were run in and the tube shaken ; the liquid became colourless and on connecting to another tube placed in a freezing mixture, it was distilled into the same by simply withdrawing the first tube from its freezing mixture. (2) It reacted with water violently, producing H,BO,. (3) It reacted with anhydrous alcohol-free ether, producing a white crystallised solid with considerable evolution of heat (cf. SnCl,, TiCl,, CCl,, and SiClJ ; this reaction is being further investigated. (4) It reacted energetically with Grignard's reagent C,H,MgI, evolving great heat ; this reaction is also being further investigated.( 5 ) Its B.P. was found by Siwoloboffs' method to be 17' C. Hence liquid was BCl,.173 NOTE ON THE ACTION OF ALUMINIUM POWDER EXAMINATION OF RESIDUE LEFT IN TUBE AFTER HEATING I N C1. The residue was black, but contained more white particles than original powder. It was extracted with boiling water, filtered, and filtrate evaporated to dryness, leaving a residue containing AlCl, (with trace of FeC1,) and H,BO,. The part insoluble in water gave no reaction for boron by the alcohol and sulphuric acid test, showing that all the boron or boride present in original had been attacked.The presence of H,BO, in the soluble part is accounted for by the fact that BCl, reacts on heated A1,0,, producing B,O, and AlCl, ; thus AlCl, condensed in cool part of tube comes from the ALO, as well as the borides of aluminium present in the original. ATTEMPTS TO REMOVE A1,0, FROM RESIDUE A. Mefhod I.-the residue A was digested with commercial HF in a platinum dish for one hour, filtered and washed ; the filtrate, on evaporating to dryness, left a residue of AlF, (traces of FeF,) but no boron, the boron or boride if attacked having escaped as HF,. The insoluble residue was extracted eight times with HF, when the filtrate on evaporation left an extremely small residue. On drying this residue and treating with C1 as before combination took place with incandescence and the action was over very quickly.BC1, was produced atid AlCl, (with traces of FeCl,) condensed in the tube as before, but quantity was relatively smaller than before. Method 2.-The residue A was fused in a platinum dish with twenty times its weight of fused borax in a muHe furnace, the top of the crucible being tightly covered with asbestos wool. The heating was continued for 13 hours at a temperature of about goo°C. The melt was allowed to cool and then extracted with water and dilute HCl. The resulting inass was quite black, and had decreased in weight from 8.4 grams to 3.3 grams. On treating this mass with C1 as before, it took fire, and the incandescence rapidly passed throughout the mass, thc products being the same as before.N.B.-In both cases the residue left after passing C1 was quite white and contained B,O,, which on removing with boiling water left a perfectly white residue of A120,. Hence both of these treatments removed the greater part of the A1,0,, and from the colour of the residue after treatment it appears that borides of aluminium were present. The yields of BC1, and AlCl, from residue A were compared before and after treatment. I. Before Treatwent- Residue A taken Amount of residue A attacked = I*@ ,, Weight of BC1, obtained = 3.9 ,, = 13-8 gins. J 9 A1C13 9 , = 8.3 1 , I.c., for I grain attacked z grams BC1, are produced and 4'23 grams AlCl,. 2. After Treatmeizf wifh Borax- Amount of substance taken Weight of BC1, produced = 1-44 ,, 1, MC1, ,, = 1.25 ,, I.e., for I gram attacked are produced 2-99 grams BC1, and 2.55 grams AlC1,.Experiment, Set 2.-Reaction between Al, and z B,O,. 16 grains B,O, and 6-2 gram A1 were mixed, and as reaction did not take place in the cold even = 1,485 gm. 7, ,, attacked =0'485 ,,ON SILICA AND BORIC ANHYDRIDE 173 with a fuse of Mg and BaO,, the mixture was heated in a muffle furnace. The contents of the crucible on cooling presented a hollow appearance, and on extracting with water repeatedly gave a large deposit of HaB03. The mass was distinctly brown in colour. On drying carefully at a gentle heat white fumes were seen to be evolved, and on again extracting with water, H,BO, was obtained, showing that the free boron was undergoing slow combustion. The residue after well washing again with water was dried in ~ C I I O over sulphuric acid.On treating I portion with fused borax in the molten state it immediately took fire, and so the borax was allowed to partially cool beforc adding the impure 13, well covered with asbestos wool, and treated as in previous ex per im e n t . The crude boron now obtained burnt vigorously in C1, producing the same products as before, but the BCI, now greatly predominated, viz.- Amount of substance taken =0*5j gm. ,) substance attacked = 0.06 ,, ,, BCl, produced =0-49 ,, - -0.158 ,, 9 ) Ale13 ,) I.c., I gram of substance attacked produces 8.12 grams BC1, and 2.6 granis AlCl,. From the foregoing experiments it will be seen that the action of A1 on B,O, produces : (I) in molecular quantities Al,O, and B with excess of borides : ( 2 ) in quantities of 2B,O, to A1,0,, boron is the chief product.Exferinzenf, Sei 3.-An attempt was made to see if the amount of boron formed in the second reaction could be estimated. It has already been pointed out that some of the AlCI, produced in the action of C1 on the crude B was formed by the action of the BCl, first formed on the Al,O, in the mixture. 2BC1, + A1,0, = 2AlC1, + B,O,, it is seen that if the amount of BZO, formed in this action, and which is found in the residue after passing the C1, can be estimated, it is possible to calculate (a) the amount of BCI, used up in its formation and ( b ) the amount of AlC1, formed at the same time. The B,O, was therefore estimated in the residue by ascertaining the weight of residue after passing CI, extracting the B,O, with boiling water, and again weighing the dry residue, and hence calculating the B,O, by difference. The apparatus used was as in previous experiments, the crude boron being weighed in a porcelain boat, which could be withdrawn after the passage of the C1 and again weighed.Plugs of glass wool were inserted in the combustion tube, which was about 30 cms. long ; the chlorine was dried by passing through strong sulphuric acid, A fresh quantity of crude boron was made, but was not treated with fused borax as in experiment, Set 2 . 32 gms, B,O, and 12-3 gms. A1 were mixed in a Hessian crucible, covered with asbestos wool and well dried MgO ; the crucible was placed in the hottest part of the muffle and heated to redness for I hour; it was then cooled, the MgO removed from the top by blowing, and the contents of the crucible taken out.The mass came out whole, and on breaking brown streaks were seen interspersed with black and white specks. The mass, after powdering, was treated with water and dilute HCl, practically no effer- vescence taking place, showing that all the A1 was used up ; the aqueous HC1 extract consisted of H,BO, solution ; after thoroughly washing with hot Now, taking the action to he-174 NOTE ON THE ACTION OF ALUMINIUM POWDER water, it was washed with alcohol and dried in a current of dry CO;* at as low a temperature as possible. Action of Heat oiz this Residue.-A small quantity of the substance heated in a crucible lid in the open air rapidly changed colour to a grayish white ; on extracting this with water and evaporating filtrate to dryness H,BO, was obtained, whilst the insoluble portion was still brownish in appearance, showing that the boron had superficially oxidised.The following quantitative operation was carried out :- Weight of substance = 2,991 gins. ,, B,O, found= ~2829 ,, ,, BCl, = 1.88 ,, 9 ) AIC1, = 1'2 ,, But 35 gms. B,O, = t117-5 gms. HC1,. Therefore '2829 ,, = t I 17 x 2829 = -9s gms. BCl,. Also 35 grams. ,, = t 133.5 gms. AlC1,. Therefore ,2829 ,, = f 133-5 x 2829 = 1-08 gm. AlCI,. 35 35 Therefore total weight of BCI, produced by primary reaction = 1-88 + -95 = 2-83 gms, and weight of AlCl, produced by primary reaction = 1.2 - 1.08 = '12 gins. Hence the boron is chiefly present in the form of free boron. The only borides of aluminium that have been described are AlB, and AlB,, (Hampe).Now the ratio of the weight of BCI, to the weight of AlCl, produced by action of C1 on AIB, is as 235 : 133.5, i.e., less than 2 : I ; similarly for AlB,, the ratio is as 1410 : 133.3, i.e., nearly 11 : I . Hence if in above experiment the BC1, had been produced entirely from these borides, the ratio of weights of BC1, and ACl, could not have been greater than I I : I , whilst i n the actual experiment the ratio is as 283 : 12, i.e., nearly 24 : I ; hence the boron greatly predominates over the borides. ACTION OF ALUMINIUM ON SILICA. Vigouroux states that crystalline silicon can be obtained by heating finely powdered quartz with A1 in excess in the electric furnace (R.and S., p. 876, vol. I ) ; Minet (" Production of A1 and its Industrial Use," p. 208) states that if two molecules of silica and four molecules of A1 are thoroughly mixed and carefully heated to 800' C. the reduction from silica to silicon takes place. In our experiments three kinds of silica were used, e.g., kieselguhr, pre- cipitated silica, and silver sand. The aluminium powdcr was the same as used in the experiments with B,O,. It was found that when mixtures of aluminium and silica were made in proportions given by +I1 and 3SiO, the reaction could not be started in the cold by means of a fuse of BaO, and Mg; but on heating to dull redness the reaction commenced and spread throughout the whole mass more or less quickly. Using quantities in the proportions given by 8A1 + 3SiO,, and using a fuse of BaO, and Mg ribbon, the reaction started at once in the cold with kiesel- guhr and precipitated SiO,, but only on heating in the muffle to red heat in the case of the sand.* It was observed that when CO, was passed over the partially dried substance at a temperature of from IOOO to I ~ o O , a small, white sublimate was formed which proved to be ammonium carbonate. This was probably formed by the action of steam on boron nitride (HCl having removed any aluminium boride), viz. :- zBN + 3H,O=B,O, + zNH, and 2NH, + CO, + H,O= (NH,) 2C0,.ON SILICA AND BORIC ANHYDRIDE 175 Silicon was produced in all cases, this being proved by conversion into SiCl, on passing C1 over the products of reduction. No attempt was made to ascertain the quantity of silicon produced, but tests were carried out to ascertain the yield of SiCl, obtained in each case.AlCl, was also formed, owing to the action of SiC1, on the Also,, but the quantities of AICl, were relatively smaller than in the experiments with boron. EXPERIMENTAL. Aluminium Powder and Kieselguhr. I. I n Projorlion of 4 AZ fo 3 Si0,.-1o grams kieselguhr and 6 grams A1 powder were intimately mixed and placed in a Hessian crucible and attempts made to ignite by means of a fuse of BaO, and Mg. No reaction resulted. On placing in a muffle and heating to dull redness the action started and proceeded steadily throughout the mass, and at the surface the Si produced took fire. The mass, on cooling, was extracted with HCl (I -I), when a slow evolution of H took place, but much less than is produced with the product from Mg and SiO,.The residue contained brown masses, and on thoroughly drying the well powdered mass was a dark grey colour. The action of C1 on the residue was carried out in a similar apparatus to that used for Cl and B. Weight of substance taken = 2.72 gms. Loss of weight of substance= -36 ,, Weight of SiCl, produced = -62 ,, Small quantities of AlC1, and FeC1, produced. C1 passed slowly for one hour. 2. In Proportion of 8 A1 and 3 SiO,.-15*64 grams kieselguhr and 19.57 grams A1 were intimately mixed and a portion placed in a Hessian crucible and ignited whilst cold by means of a fuse of BaO, and hlg'; the reaction took place at once and spread rapidly throughout the mass.The other portion, in a Hessian crucible, was placed in a hot muffle, and the reaction commenced in a few minutes and spread throughout the mass. On cooling, both lots were powdered, extracted with HC1 (I - I), filtered, washed, and dried, The action of C1 gave- Weight of substance taken = xo'oo gms. LOSS of weight of substance = '95 ,, Weight of SiCl, produced = 2-47 ,, AlC1, and FeCl, (small quantity). C1 passed steadily for one hour. Aluminium Powder and Amorphous Silicon. I . In Proportion of 4 A1 and 3 SiO,.-s.8 grams A1 and 9.7 grams SO,. This mixture would not react in cold with fuse of BaO, and Mg, but on heating with a blower burner the fuse started the action, which proceeded quietly through the mass. On heating residue as before and passing C1, the following result was obtained :- Weight of substance taken = ro'6 gms.'7 ,9 Weight of SiCl, = 2.72 ,, - Loss in weight - C1 passed slowly for one hour,176 NOTE ON THE ACTION OF ALUMINIUM POWDER 2. 111 Proportion of 8 A1 and 3 SiO,.-3 grams SiO, and 9'7 grams Al. This Residue mixture reacted rapidly in the cold with a fuse of BaO, and Mg. treated as in previous experiments. Weight of substance Weight of SiCl, - '20 ,, = 2'00 gms. Loss in weight of substance = '12 ,, - ,, AlCl, and FeC1, = '20 ,, (about). C1 passed for ten minutes. Alunzinirrvi Powder nud Sand. The sand was extracted with aqua regia till no further action took place, well washed, dried, and sifted through a sieve (3,600 meshes to square inch). I . In Proportion 4 A1 and 3 SiO,.-9-7 grams SiO, and 5-8 grams sand.This mixture would not react with a fuse, cold or hot ; reaction took place on heating to redness in a muffle. The resulting mass was treated as before. A greater evolution of hydrogen took place on heating with HC1 than in case of kieselguhr and amorphous silicon. Weight of substance = 3-00 gms. - ,, SiCl, '20 ), ,, AlC1, = '20 ,,(about). Cl passed for thirty minutes. 2. I n Proportion of' 8 A1 and 3 SiO,.-9.7 grams SiO, and 11.6 grams Al. This mixture also would not react with a fuse, but reaction took place on heating in a muffle to dull redness. On grinding in a mortar the gritty nature of the sand had disappeared. Violent evolution of H was obtained on treating with HCl. Weight of substance = 1-00 gms. - ,, SiCl, - '20 ,, - ,, A1C1, - very small. C1 passed for fifteen minutes. N.B.-The aluminium powder used in all these experiments had been treated for some time at a temperature of 13o0-~5o0 in order to free it partially from the adherent paraffin wax. All the forms of silica were previously heated to redness in a muffle. Tlz ermock emical Data. The Heat of Formation of Al,O, = 390,000 calories ,, ,, 9 , B,O,=317,ooo 9 , 7 9 > I ,, SiO,=219,000 ,, Hcnce 2Al+ H,O? = A1,0, + 2B + ( ~ ~ o , o o o - ~ i ~ , o o o ) calories Also + (qA1 + 3SiO,) = + (2A1,0, + 6Si) + 3 (~8o,ooo-6~~,ooo) calories That is, according to the principle of greatest heat development, B,O, and SiO, should be decomposed by Al, and B,O, should be decomposed more readily than A1,0,. This was found to be the case experimentally when the conditions of esperimenting were the same in each case. = A1,0, + 2B + 73,000 calories. = 3 (2A1,0, + 6Si) + 61,500 calories. CHEMICAL LABORATORY, THE POLTTECHS IC, REGENT STREET, W,

ISSN:0014-7672    

DOI:10.1039/TF9080300170

出版商:RSC    

年代:1908

数据来源: RSC

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ON SILICA AND BORIC ANHYDRIDE I77 DISC USS ION. Dr. R. Seligman : I am inucli interested in the experiments which Messrs. Weston and Ellis have brought before us, and should like to draw attention to one or two points, I was, unfortunately, not present when Dr. Perkin read his paper comparing the activities of calcium and aluminium, but I understand that my colleague, Mr. 147. Murray-Morrison, suggested that the apparent inactivity of aluminium in reducing silica was due to the coarseness of the ingredients used. The proof of the accuracy of this statement is contaiiied in the present paper, if such proof were needed. I say “if such proof were needed” because a method of controlling the rate of reaction of thermite mixtures by varying the grain size of the ingredients has actually been patented by Beuk.The effect of temperature on the rate of the reaction is neatly brought out in the authors’ paper. The retardation due to the excess of the oxide is also interesting. The case is, of course, not isolated, the same phenomenon being observed, for instance, with tungstic acid, where a considerable excess of aluminium is required in order to make the reaction take placc. That it should be SO marked in the case of boric anhydride is a little surprising, and would lead to the supposition that in the case where A1 and B,03 are mixed in theoretical proportions, the combination of aluminium with air may be responsible for the generation of some of the heat required to keep the reaction going. The authors assume that the boron produced burned again in air, and cite the production of an ammonia-yielding body as evidence of the formation of boron nitride.This evidence is not conclusive, because when aluminium is burned in air aluminium nitride is produced. I think, therefore, that the authors’ observation confirms my view. The fact that the aluminium nitride is not at once decomposed by the acids used by the authors is probably due to its being surrounded by fused alumina. Perhaps I may be allowed a slight digression at this point. I think it is not generally known that at one stage in the preparation of pure aluminium thermitic temperatures (if I may coin the word) are obtained. These tem- peratures are produced solely by the combustion of aluminium in the air, and the results of this combustion on a large scale are rather peculiar.Thus, for instance, we frequently get large masses of fused, or partly fused, alumina which, cooling slowly, often contain nests of acicular crystals, which show the most delicate shades of blue or red according to their content of foreign matter. I had hoped to be able to show you some of these to-night, but have been disappointed in my efforts to get them up from the works in time. There is only one other point which I want to raise, and which is of general interest in connection with all thermitic processes ; I mean the fused alumina which caused the authors so much trouble in the present case. Perhaps you know that a use for this material has now been found, and that several patents have been taken out for preparing fire- and acid-resisting ware from it for which great claims are made.I am able to show you a piece of this material. The rest of thc vessel of which it formed a portion is being tested in Staffordshire. I think that any one who has had to deal with high temperatures, whether on a large or small scale, must view the advent of :i new fire-resisting medium with the greatest interest. Dr. F. M. Perkin said he had tried the kieselguhr reaction, but had used molecular proportions and not varying proportions as the authors had done. Under the conditions he had employed the reaction worked very badly.178 NOTE ON THE ACTION OF ALUMINIUM POWDER The great difficulty in employing this I‘ thermitic ” reaction on a laboratory scale was to get rid of the oxide, because, generally speaking, when carried out on a small scale it did not fuse or form a slag.The careful work done by the authors in getting rid of the oxides chemically after the reaction was complete was very interesting, but one could not say that the problem was solved until pure silicon and pure boron had been obtained. Upon a small scale either with aluminium or calcium this had not been done. It was doubtful even whether absolutely pure boron had ever been produced. Mr. F. E. Weston in reply, said that with regard to the question of the burning of the aluminium which had been raised, molecular mixtures could be made which would not start with a fuse. Possibly in such cases some preliminary burning of aluminium gave the temperature required to start the reaction. However, in many experiments they had made, the air had been excluded entirely from the mixture, which, when treated in a muffle, reacted quite as well as if open to the air. He thought that once the action had started, the air entered no further into the matter. The question of the necessity for the slag fusing before the metals could be reduced in reguline form had been raised. The authors had made metallic nuggets of iron, chromium, and manganese on a small scale, but had not succeeded in preparing boron, silicon, titanium, and tungsten, excepting in the form of powder.

ISSN:0014-7672    

DOI:10.1039/TF9080300177

出版商:RSC    

年代:1908

数据来源: RSC

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REDUCING ACTION OF METALLIC CALCIUM AND CAL- CIUM HYDRTDE UPON METALLIC OXIDES, SUL- PHIDES, AND HALOGEN SALTS. BY F. MOLLWO PERKIN AND LIONEL PRATT. ( A Pa#r read before the Fur-u(lay Society, Tuesday, October 29, 1907, RIr. N. T. M. WILSMORE, MSc., in the Chair.) In a previous paper read before this Society (this vol., p. 115) one of us has shown that metallic calcium is a particularly energetic reducing agent when mixed with metallic oxides or sulphides, the reaction being started either by heating in the furnace or by means of a fuse consisting of a mixture of calcium and barium or sodium peroxide. This work has been continued, and we have also tried the action of calcium hydride as a reducing agent in place of the metallic calcium. Although calcium hydride may be used successfully in certain cases, it is not so energetic a reducing agent as metallic calcium itself.This, of course, is to be expected, because the formation of calcium hydride by the action of hydrogen upon molten calcium is an " exothermic " reaction, considerable heat being evolved. In fact, if hydrogen gas is passed sufficiently rapidly into molten calcium, the reaction once commenced will continue without further addition of heat until the whole of the metal has been converted into the hydride (German Patent 188,570). Consequently, when calcium hydride is mixed with a metallic oxide and the mixture heated, before reaction can take place a certain amount of heat is required to decompose the hydride. Now, although in many cases the reaction once started will go on-and is thercfore exothermic-until the whole of the oxide is reduced, the temperature of reaction can never be so high as when metallic calcium alone is employed, because a portion of the heat of reaction will .be required to decompose the hydride as the reaction proceeds.Beside trying calcium hydride as a reducing agent, further experiments have been carried out with metallic calcium. We find in the latter case that tungstic oxide is readily reduced, and the tungsten can be obtained as a molten mass. With titanic oxide the reaction is less vigorous and the heat is not sufficient to melt the metal produced. We have also found that the hydroxides of the alkali metals are readily reduced by means of calcium, and also barium and strontium hydroxides. The heats of formation of the hydroxides are as follows- Ca, 0, H,O .. . . . . . . . . . . . . . 160,540 cals. Sr, 0, H,O . . . . . . . . . . . . . . . . . . 146,r40 .. Ba, 0, H,O . . . . . . . . . . . . . . . -- Na,, 0, H,O . . . . . . . . . . . . . . . 135,380 ,, I<*, 0, H,O . . . . . . . . . . . . . . . . . . 137,980 ,, Consequently, the reactions with metallic calcium should be exothermic, and once they are started should go on to conclusion. In carrying out these reactions the metallic calcium, in the form of turnings, was placed on the I79180 REDUCING ACTION OF METALLIC CALCIUM AND bottom of an iron crucible and covered with the broken alkali hydroxide ; the reason for proceeding in this manlier was because of the difficulty experienced in powdering the deliquescent hydroxide. The flame of a blowpipe was then played against the upper part of the crucible in order to melt the hydroxide and to cause it to run down upon the calcium. The reaction once started in this manner then went on until the whole of the material had been reacted upon.In the case of sodium, lithium, potassium, rubidium, and czesium the metals were vapourised and burnt round the edge of the crucible lid. With strontium and barium hydroxide the substances were ground up and intimately mixed with the metallic calcium, Of course, too much reliance cannot be placed upon the reactions between the hydroxides. The temperature of the reaction is, for example, certain to be lowered by the amount of heat required to vapourise the water, because finally not Ca(OH), hut CaO is produced. The reactions, however, are exothermic, because when anhydrous strontium or barium hydroxides are mixed with an equivalent of metallic calcium- Sr(OH), + Ca = Sr + CaO + H,O, the mixture is readily fircd by means of a fuse, and the reaction oncc started goes 011 until the whole of the mixture has reacted. Strange to say, however, we have not managed to obtain a metallic regulus from the hydroxides ; the explanation of this is given later.The heats of formation of the oxides are as follows (we have taken the numbers given by Professor J. W. Richards, Electrochemical nrtd Metallurgical Industq, 6, 8, except for calcium, where we have employed the value given by Moissan by actual ineasurcmeiitl- Ca, 0 ... Mg, 0 ... +ill2, 0, ... Sr, 0 ...Naa, 0 ... Ba, 0 t ... +Si, 0, ... Zn, 0 ... +Sn, 0, ... A-Fe,, 0, ... Pb, 0 ... Ca, S ... Mn, S ... Nan, S ... Zn, S ... Pb, S ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Su If hides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... ... ... ... ... ... ... ... ... ... ... ... ... .*. ... ... ... 145,000':' . * * 143,400 ... 130,870 ... 128,440 ... 98,000 ... 84,000 ... 70,650 ... 65,200 ... 50,800 ... lO0,goO ... 104,000 ? ... 94,300 45,600 ... 89,300 ... 43,- ... 20,200 With the sulphides calciuin reacts vigorously ; the heats of formation given above show that this should bc the case.But there is a tendency for the calcium to react with the sulphide to form a thio-compound, such as Ca,(SbS,), ; alihough we have not analysed the slag produced, this seems the most probable explanation of the small amount of metal produced in these reactions. On the other hand, it may be that sub-sulphides are produced see p. 184). * Richards 131,500. t The number for BaO is certainly too low ; in the determinations the barium used was always obtained from the amalgam and contained traces of mercury.CALCIUM HYDRIDE UPON METALLIC OXIDES, ETC. 181 Experiments were also tried with the chlorides, the heats of formation of which are as follows- Ca, C1, Sr, C1, Ba, C1, K,, C1, Na2, c1, Liz, C1, $ -AI2, C1, Pb, C1, . .. . . . . . . . . . . . . . . . 183,890 cals. . . . . . . . . . . . . . . . . . . 184,560 .. . . . . . . . . . . . . . . . . . . 195,380 .. . . . . . . . . . . . . . . . . . . I 87,620 .. . . . . . . . . . . . . . . . . . . 82,770 .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211,220 ,y . . . . . . . . . . . . . . . . . . 107,320 ,, From the heats of formation it follows that the reactions between metallic calcium and potassium, strontium, sodium, and lithium are endothermic, and therefore for the reactions to take place completely it will be necessary to add heat from an external source. A5 a matter of fact, these reactions cannot be started by means of a fuse. But they can be made to take place by playing the blow-pipe flame on to an iron crucible in which the mixtures are contained.Another method by which the reaction can be caused to take place is to mix a certain quantity of iron oxide and calciuni with the alkali chloride and calcium, thus- Fe,O, + 3 Ca = 2 Fe + 3 CaO + 240,000 cals. The great amount of heat generated by this reaction is sufficient to cause the reaction- Ca + z NaCl = CaC1, + 2 Na - I 1,490 cals. to go on to completion. On the other hand, the reactions between aluminium chloride and calcium and lead chloride are exothermic and take place with great readiness. In fact, it is difficult to control them, a large portion of the contents of the crucible frequently being ejected. It has not been found possible to obtain pure strontium or pure barium by reacting with metallic calcium and the respective chlorides, the metal regulus produced being always contaminated with more or less calcium.When the theoretical proportions of the materials are mixed and reaction caused to take place by the addition of an external source of heat very little metal is obtained, probably owing to the formation of a sub-chloride, thus- BaCl, + Ca = ClBa-CaC1. But when two atoms of calcium are employed the reaction is very much more vigorous, and a metallic regulus is obtained ; it is, however, an alloy of calcium and barium or calcium and strontium, as the case may be. Theoreti- cally one might expect to obtain the sub-chloride- BaC1, + 2 Ca = Ba + CoCl,, but only a portion of the calcium reacts with the CaCl, first produced, the remainder alloying with the alkaline metal as it is formed.EXPERIMENTAL. (Calcium Hydrid e. ) Coppev Oxide.-When molecular proportions of copper oxide and calcium hydride, according to the following equation, are intimately mixed together- 2 CuO + CaH, = 2 Cu + CaO + H,O,182 REDUCING ACTION OF METALLIC CALCIUM AND and fired by a fuse, or even by means of a taper, a very vigorous reaction ensues and volumes of steam are given off, showing that both the calcium and the hydrogen enter into the reaction. The cooled product, which was black on the surface, owing to superficial oxidation, was treated with dilute hydrochloric acid, until on filtering and washing a test for calcium was no longer given. I t was then washed with water and alcohol and dried in the steam oven.The copper so obtained was in the form of a fine powder, only a portion of it having been fused into small metallic globules. It is evident, therefore, that the heat of reaction is only ;L little above the melting-point of copper. The temperature would not, therefore, rise much above I,IOO', at any rate on a small scale. Manganese Peroxide (Pyrolusite).-In this case it was not found possible to start the reaction by means of a fuse. The crucible was therefore placed in a crucible furnace and strongly heated. After about five minutes volumes of black smoke and steam canie from the furnace, showing that reaction was taking place, probably according to the forinula- MnO, + CaH, = Mn + CaO + H,O. As the heat of reaction was not sufficient to cause the manganese to fuse, it was obtained in the form of a powder intimately mixed with calcium oxide, therefore it was not attempted to separate them. Ferric Oxide (Ha?matite).-The crucible containing the mixture was placed in the crucible furnace and heated to bright redness for about an hour.At the end of the time the product was cooled and the dark mass powdered. The iron had not fused, but particles were attracted by a magnet, showiiig that reaction had taken place. Lead Monoxide (Litharge).-The mixture was heated to bright redness in the furnace, and on cooling a regulus of molten lead was found at the bottom of the crucible, This experiment was repeated several times, and it was found that the lead did not always rim together, but remained as globules interspersed through the calcium oxide.But by stirring with an iron rod the bulk of the lead could be caused to run together at the bottom of the crucible. Stanizic Oxide.-Reaction in this case is very slow, and it was necessary to heat to bright redness. On cooling the mass had a dark grey colour, but no specks of tin were noticed. The experiment was repeated, heating for a longer time-about two hours-to a bright red heat, and towards the end of the operation stirring with an iron rod. On cooling it was found that the tin had partially run together, but a good deal of it still remained mixed with the calcium oxide. Zilzc Oxide.-It was not possible to fire a mixture of calcium hydride and zinc oxide. The mixture was therefore placed in the furnace and heated to bright redness for about an hour.On cooling and examining the mixture it was found that no reaction had taken place. Tungstic Oxide.-Reaction takes place, but the temperature is not sufficiently high to melt the tungsten produced. Borort it-ioxide, when mixed with the equivalent of calcium hydride and strongly heated for two or three hours in a crucible furnace, is reduced. A brownish mass is obtained, and if this is ground up in water and repeatedly boiled with hydrochloric acid until the washings are practically free from calcium chloride, the boron is obtained as a light brown amorphous powder. We have, however, never succeeded in obtaining it free from calcium. Ignited borax is also reduced by means of calcium hydridc.CALCIUM HYDRIDE UPON METALLIC OXIDES, ETC.183 Silica.-Very finely divided silica can be reduced by heating it strongly in the furnace for some hours with calcium hydride. But on treating the mass so obtained with hydrochloric acid, inflammable gas is given off. The reaction in this respect is similar to that which is produced on reducing silica with metallic calcium (this vol., p. 116). Lead SuZphide.-The mixture could not be ignited by means of a fuse, but upon strongly heating in the furnace reaction took place. Only a small portion of the lead ran down to the bottom of the crucible, the bulk of it remaining interspersed thrbughout the reactive mixture or combined with the calcium sulphide- zPbS + CaH, = aPb + H,S + CaS. Aiztimoizy SuZ9hide.-This mixture is exceedingly readily ignited, it being sometimes possible to cause the action to commence by bringing a lighted taper in contact with it. As the reaction proceeds the mixture in the crucible swells up in an extraordinary manner, reminding one of the peculiar way in which mercury thiocyanate (Pharaohs serpents) behaves upon being ignited.The hydrogen sulphide evolved takes fire. Very little metal is actually obtained, although the reaction should, one would think, proceed as follows- 3Sb& + 6CaH, = 6CaS + 3 H,S + 6Sb. In all probability, however, to a certain extent a compound of antimony and calcium sulphide is produced, for example, Ca,(SbS,),. Products of a similar nature are also probably formed in the case of lead sulphide. The formation of such compounds would account for the small yield of metal in both cases (cf.p. 184). M eta1 tic Calcium . As the reactions between tungstic oxide and titanium oxide were not satisfactory, we tried the action of metallic calcium with these two oxides, and the results were much more satisfactory. Tungsten Oxide.-Metallic calcium and tungsten oxide were intimately mixed together in quantities corresponding to the following equation-- WO, + 3Ca = 3CaO + W. The mixture was fired by means of a fuse, and an extremely vigorous reaction ensued, an intense white heat being produced. On cooling, the product was removed from the crucible, and at the bottom a reguline ingot of metal was obtained which upon weighing was found almost to correspond to the theoretical amount of metal obtainable. I t was extremely hard, and could hardly be marked with a file.In this case the heat of reaction was so extremely high that the calcium oxide was actually fused. This is the only case which we have met with in which the calcium oxide has been completely melted. On the other hand, when mixtures of calcium and aluminium have been used as reducing agents, the mixed oxides have at times been obtained as a fairly readily fusible slag (this vol., p. 117).* Titanium Oxide.-The reaction in this case is much more vigorous than when the hydride is employed, but even in this case the temperature of the reaction did not rise sufficiently high to fuse the metal. Aluminium Oxide.-The heat of formation of this oxide A1,0, is 380,000 * Goldschmidt has patented the use of a mixture of calcium and aluminium (American Patent 875,345, December 31, 1907). The best results, he finds, are obtained by using the calcium and aluminium in the proportions necessary to form a calcium-aluminium slag of the composition 3CaO,,Al,O,, this slag readily fusing to a thin liquid.VOL. 111-T7184 REDUCING ACTION OF METALLIC CALCIUM AND cals. In order that this may correspond to CaO, which has a heat formation of 145,000 cals., the number for aluminium oxide should be divided by three, when we obtain 126,666 cals. ; therefore metallic calcium should theoretically be able to reduce alumina. As a matter of fact, when aluminium oxide and metallic calcium are mixed together according to the following equation- Al,O, + 3Ca = 3Ca0 + 2A1, and the mixture fired by means of a fuse, reaction proceeds throughout thc mass without further addition of external heat.The reaction, however, is by no means vigorous, and globules of metallic aluminium were not obtained. Strontium Oxide.-A mixture. of molecular proportions of strontium oxide and metallic calcium- SrO + Ca = CaO + Sr, is readily fired by means of a fuse, and the action completes itself without the addition of external heat. The same remark applies to a mixture of barium oxide and calcium. Although in both cases the reaction was very vigorous, no metal was produced. This at first sight seemed difficult of explanation, unless indeed the heat of reaction was sufficient to volatilise the metals produced. It occurred to us, however, that possibly a sub-oxide might be produced. We therefore took equimolecular proportions of metallic calcium and of calcium oxide according to the following equation, the oxide having been heated to redness in the furnace to decompose any hydroxide- CaO + Ca = Ca,O.This mixture was placed in a crucible and covered with asbestos to prevent the egress of air, and then heated in the furnace to bright redness for two hours. On cooling and emptying out the contents of the crucible it was found that the whole of the calcium had disappeared. Portions of the mixture were then treated with water and with hydrochloric acid, but there was no effervescence in either case. It appears, therefore, that a lower oxide of calcium had been produced. We are examining further into the matter. If a lower oxide is produced, then it explains why no metal was obtained with strontium and barium oxides.Sodium Hydroxide.-The reaction was onc of considerable violence, the metallic sodium produced being volatilised and burning at the edges of the lid of the crucible. Sub-sulphides may perhaps also be formed, The other alkali metals behaved in a similar manner. In the case of barium and strontium hydroxide the reaction was also very vigorous, but it was iievcr found possible to obtain the metals in the fused condition. The reaction with rubidium hydroxide was particularly vigorous. Bariziwt Chloride.-On mixing in an iron crucible equi-molecular propor- tions of anhydrous barium chloride and calcium and heating the crucible by means of the blow-pipe flame, as soon as the crucible gets well heated a vigorous reaction takes place, but the yield of metal is very small.This, as has already been stated, is probably due to the formation of a sub-chloride of barium and calcium. But if two atoms of calcium are used for everymoleculc of barium chloride taken, then the reaction is excessively vigorous, and a large quantity of a metallic regulus is obtained at the bottom of the crucible, which is an alloy of barium and strontium. Slrorttzum Chloride.-The reaction in this case is rather more vigorous than with barium. When two atoms of calcium are emploved, a large metallic regulus is obtained, but it contains considerable quantities of calcium.CALCIUM HYDRIDE UPON METALLIC OXIDES, ETC. 185 The chlorides of alkali metals-lithium, sodium, potassium, rubidium, and caesium-all react with calcium in a similar manner to the metals of the alkaline earths.But owing to the volatility of these metals, they were always vapourised, and the metals burnt round the edge of the crucible lid. Lead Chloride.-Using a mixture of calcium and lead chloride according to the equation- PbC1, + Ca = Pb + CaCl,, and starting the reaction by means of a fuse, a very vigorous reaction took place, a portion of the mixture being thrown out from the crucible. A piece of lead was obtained on removing the reaction mixture from the crucible. I t was, however, crystalline and brittle, and consisted of an alloy of calcium and lead. Aluminium Chloride.-Molecular proportions of calcium and aluminium chloride were placed in a crucible and fired by nieans of a fuse. The reaction was extremely intense.Aluminium, or an alloy of aluminium and calcium, was obtaincd on cooling. The yield of metal, however, was small, which would point to the formation of a mixed chloride of calcium and alumini um . Acfioiz of Calcium and Calcium Hydride upoit Sulphur, Plaosphorus, a i d Selenium. When sulphur and metallic calcium are mixed together according to the equation- Ca + S = CaS, and fired by means of a taper, the reaction is so violent that the whole of the product is ejected from the crucible. The reaction with red phosphorus and with selenium is also extremely vigorous. When calcium hydride is mixed with sulphur in the proportions. represented by the equation- CaH, + 2 S = CaS + H,S, and ignited by means of a fuse, the reaction is vigorous but well under control, a friable mass of calcium sulphide being produced. The calcium sulphide so produced does not show the phenomenon of phosphorescence. Red phosphorus and calcium hydride, when mixed in the proportions repre- sented by the equation- 3 CaH, + 3 P = Cap, + PH,, cannot be ignited by means of a fuse. A satisfactory reaction can, however, be caused to take place by taking a mixture of calcium and red phosphorus according to the equation- 3 Ca + 2 P = Ca,P,, and employing a mixture obtained by combining the two equations. Extremely active rusty red calcium phosphide is obtained in this manner. Calcium selenide can be produced by mixing molecular proportions of calcium hydride and selenium and igniting by means of a fuse. Since this paper was read our attention has been drawn to the paper by W. Muthmann and L. Weiss (Liebig's Annalen, 355, 137). In this paper they show, as we have done, that the chlorides of sodium, potassium, barium, and strontium can be reduced by heating with metallic calcium. They have also found that alloys of calcium and barium and calcium and strontium are produced and not the pure metals.

ISSN:0014-7672    

DOI:10.1039/TF9080300179

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

186 REDUCING ACTION OF METALLIC CALCIUM, ETC. DISCUSSION. Dr. R: Seligman hoped the authors would try the reducing effect of calcium hydride on alumina. There was, he believed, a French patent for preparing calcium hydride by absorbing hydrogen in molten calcium as opposed to the method described by the authors of maintaining the calcium in solid form for this purpose. Dr. Perkin, in reply, said that the authors would certainly try to reduce alumina with calcium hydride and with calcium. (This has since been done, and described in the paper as it passed through press.) The patent referred to in the paper was that of the Elektrochemische Werke, Bitterfeld (D.R.P. 188,570, 1907). According to this patent hydrogen gas is led into molten calcium. But the calcium hydride as obtained from Bitterfeld has not the appearance of having been made in this manner, because the form of the original rods is still retained in the calcium hydride.

ISSN:0014-7672    

DOI:10.1039/TF9080300186

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

NOTE ON A SERIES-PARALLEL LAMP RESISTANCE. Conimurticnted by N. T. M. WILSMORE, M.Sc. The accompanying diagrams represent a method of arranging lamp resistances, which has been found very convenient for electrochemical work. The arrangement was devised some years ago by Professor J. D. Cormack, of University College, London ; but, as no account of it has been published by him, and as it does not seem to be generally known, Professor Cormack has kindly allowed this note to be read before the Faraday Society. In the figures only three lamps with their connections are shown ; but the number of lamps may be increased indefinitely. The lamp sockets L,, L,, L,, &c., are connected permanently in series with each other and with the terminal TI ; but, by means of the two-way switches, S,, S,, S,, &c., they FIG.I. FIG. 2. may be connected up further in several different ways, so as to produce a wide variation in the total resistance between the terminals TI and T,. Thus, with three lamps of the same size, the following six combinations are possible : three lamps in series (Fig. I ) , two lamps in series, one lamp, one lamp in parallel with thc other two in series, two in parallel, or three in parallel (Fig. 2). If the lamps have a resistance of IOO ohms each, the resistances corresponding to the above steps will be respectively 300, zoo, 100, 66.6, 50, and 33.3 ohms, With lamps of different sizes, or with a larger number of lamps, the number of possible combinations becomes much greater. A further advantage of the system is that no movement of the switches can cause a short circuit between TI and T,. The two-way switches must have a well-defined central ‘‘ off ” position For this reason, and also because one can follow the connections from the positions of the knobs, Lundberg’s “ Duplex ” tumbler switches have been found suitable. UNIVERSITY COLLEGE, UNIVERSITY OF LONDON

ISSN:0014-7672    

DOI:10.1039/TF9080300187

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

A PHYSICO-CHEMICAL STUDY OF THE COMPLEX COPPER-GLYCOCOLL SULPHATES. BY J. T. BARKER, B.Sc.::: (From the Muspratt Laboratory of Physical and Electro-Chemistry, University of Liverpool.) ( A Pqkr read hcfore fltc Farndny Socieb O I L T u c s ~ ~ J , , December 17, 1907, DR. F. MOLLWO PERKIN, TREASURER, in the Chair.) It is well known that addition of glycocoll to aqueous solutions of copper sulphate produces a fine blue colour, similar in general character to that produced by excess of ammonia. That the concentration of the cupri-ions has been lowered by the presence of the glycocoll is rendered probable by the fact that caustic potash does not precipitate cupric hydroxide from solutions containing moderate amounts of glycocoll, whereas potassium ferrocyanide and ammonium hydrosulphide throw down precipitates of cupric ferrocyanide and sulphide respectively. It seemed probable that the reduction in the concentration of the cupri-ions is caused by the formation of complex cupri-glycocoll kations.The experimental work described in the present paper was undertaken with the object of investigating this question. I. E LECTROMETRIC M EASUREXIENTS. In order to arrive at some idea of the degree of complex formation, the following preliminary measurements of potential were made. A series of solutions &th molecular normal with respect to copper sulphate, but respec- it it ia 2 q 1 0 tively -) -, - with respect to glycocoll, was made up. By Poggendorff's Y compensation method, using a slide-wire bridge and a Lipprnann capillary electrometer, the potential differcnce between a clean copper rod and each of these solutions was determined.For this purpose each copper electrode was connected through a KCl solution with a normal calomel electrode, and the cells so constructed were measured with and against a standard cadmium cell in the usual manner. Taking the potential of the calomel electrode as +0*56 volt, and the E.M.F. of the cadmium cell as 1.0186 volt, the results shown on page 189 were obtained at 17OC. In calculating these values the potentials at the liquid junctions have been neglected (as a first rough approximation). o-oooIq8T c By means of the formula T== Log 2 we can now obtain 2 C, approximate values for the ratios of the cupri-ion concentrations in the several solutions examined.In the above formula 7r denotes the E.M.F. of a cell such as- Cu [ CuSO, I KCI I CuSO, + glycocoll 1 Cu, and c, and c, denote the respective cupri-ion concentrations. * Communicated by Dr. F. G. Donnan. r 88STUDY OF COPPER-GLYCOCOLL SULPHATES 189 1 2 5 Solution. 48 I 9 3 .- Concentration of CuSO+ It I 0 - n - I 0 It I 0 - 11 1 0 - 2oncentration of Glycocoll. Potential of Copper Electrode. Thus for the cell Cu I '5 - CuSO, I KCl I & CuSO, + It glycocoll I Cu Calling the concentration of the cupri-ion in the 2 --.CuSO, solution 100, I 0 I 0 T = 0'5 58 - 0'549 = 0'009 Volt. I 0 we obtain in this way the following table of relative values- TABLE I. h1ol;ir Ratio of Glycocoll to CuSO+ 1 Relative Coiicentratioii oi Cii.*-ion. These figures, though not pretending to be very accurate, suffice to show the progressive decrease of the Cu--concentration on continued addition of glycocoll, and appear to warrant the assumption that with a large excess of glycocoll the cupri-ion will be practically completely converted into some complex ion (or neutral compound).We shall assume first of all, as seems most probable, that a complex cupri- glycocoll ion kation is formed, and that its formula may be represented as CuG;., i.e., that it contains x mols. of glycocoll for every atom of copper. If the glycocoll be present in large excess relatively to the copper sulphate, we may assume, with a fair degree of probability, that practically all the copper sulphate will be converted into complex copper-glycocoll sulphate, and that, to a first approximation, we may take the final concentration of the glycocoll as equal to its initial concentration. Furthermore, if the solution be pretty dilute with respect to total dissolved copper salts, the complex sulphate (or sulphates) may be regarded as completely ionised, in which case the final molar concentration of the cupri-glycocoll ion will be equal to the initial190 A PHYSICO-CHEMICAL STUDY OF THE molar concentration of the copper sulphate.Let us suppose that the com- plex ion CUG;. dissociates (non-electrolytically) into glycocoll and cupri-ions. Denoting molar concentrations by square brackets, and writing i for initial total concentration of copper sulphate, we have- [CU..]~ . [G].r= k [CUG,**], = ki,. For another solution- [CuamJ - [GI: = ki,.Whence, dividing and taking logarithms- Although [Cu-1, and may be very small, their ratio is a definite quantity, which is found by measuring the potentials of a copper electrode in each of the two solutions, and then applying the formula- The only unknown quantity in Equation ( I ) is, then,x. In order to obtain the most accurate values, two corrections must be applied to Equation (I). In the first place, an allowance must be made for the amount of free glycocoll removed from the solution as complex ion ; and secondly, if the complex copper-glycocoll sulphate be not con~pletely ionised, the concentration of the complex copper-glycocoll ion is not equal to the initial total concentration of copper sulphate. The second correction will be dealt with later. Equation ( I ) , with the first correction, takes the form- In solving this equation, an approximate value of x is first obtained from Equation (I), and then the value of x which satisfies ( 2 ) is found by successive approximations.In the case of the preliminary data already given, any potential differences existing at the liquid junctions were ignored. These potential differences can probably be for the most part eliminated by comparing only solutioris having the same total copper content and a varying, though very large, relative excess of glycocoll, for in this case the two solutions will contain practically only complex sulphate, and that of practically the same concentra- tion in both cases. I t will be seen that the method here employed is substan- tially that first introduced by Bodlander.The results of the first measurements are contained in the following two tables. The E.M.Fs. of the concentration cells have been calculated frotn direct measurements of cells of the type Cu [ CuSO, + glycocoll I 3.5 11- NaNO, 1 calomel electrode. For the rest, the values of x given in Table 111. are seen to be considerably higher than those in Table 11. Probably only the values in Table 111. are deserving of weight, since these are derived from measurements of pairs of solutions of equal total copper content. More accurate measurements were rrow carried out, in which every effort was made to eliminate disturbing influences. The calomel electrode was dispensed with, the E.M.Fs. of the concentration cells being directly The value 1-35 is evidently too low.COMPLEX COPPER-GLYCOCOLL SULPHATES 191 TABLE 11.-Temperature 13" C .n - CuSO, + 212 glycocoll - C~SO, + glycocoll 5 C~SO, + 212 glycocoll C~SO, + zn glycocoll I 0 0 n I 0 0 I 0 0 I00 First Solution. 0.0138 om030 0.0421 0'0135 2- c u s o , + ~glycocoll -K cuso, + f glycocoll 2- c u s o , + ~glycocoll 2- c u s o , + ; glycocoll 200 200 2 00 200 CUSO, + 21t glYCOCOl1 I 0 0 5 CuSO, + glycocoll 200 E.M.F. of Corn bination. Second Solution. 0'0391 4'59 0.0289 3-39 x Calcu- ated from Equation (1). 2'62 1-35 2'97 2.58 TABLE 111.-Temperature 13" C. First Solution. 2- c u s o , + ; glycocoll -2- c u s o , + ; glycocoll 1 0 0 I00 -2- c u s o , + 12 glycocoll 200 2 Second Solution. I measured, with 3-5 n NaNO, solution as connecting liquid.The concentration cell waEs cnmhined with ;1 standard cadmium cell. and the E.M.F. of this com- bination determined, with the concentration cell acting both with and against the cadmium element. From these measurements the E.M.F. of the concen- tration cell was calculated. The means of the two values so obtained are given in the following table. As the E.M.Fs. of the concentration cells do not amount to more than 3-4 hundredths of a volt, and small errors in the values of the E.M.Fs. produce considerable errors in the values of x, it was found necessary to introduce corrections for any inequality of potential of the two copper electrodes when dipping in the same copper solutions. This inequality of potential did not ever appreciably exceed I millivolt. On making this correction, it was found that the values whose means are given in the following table did not differ by more than a few tenths of a millivolt, In order to eliminate errors due to the liquid potentials or to a varying degree of ionisation of the complex sulphate, only solutions of the same total copper content were compared, and these solutions contained large relative excesses of glycocoll.I92 A PHYSICO-CHEMICAL STUDY OF THE Since i, = i, = i, equations ( I ) and (2) reduce to- Conc'n.of CuSO4 in both Solutions. 200 It 250 It 250 it L o g w I , + . ~ L o g [ G L o . . . . . [CU"] m2 TABLE IV.-Final E.M.F. Measurements. [CIP p 2 2 It 12 I 4 2 5 4 2 5 2 It 3 E X F . of Concentration Cell. 0.033 5 0.0339 0.0355 0.03 I 8 0.0309 0.0327 reinperature 19" 19" 20'5O 20.5' 21° 19" Mean values ...... .r Calculated from (3). 3'85 4-12 4-05 3'63 3'53 3'76 3.82 * * (3) ' (4) x Calculated from (4). 3'75 4-00 3'95 3'54 3'45 3-65 3'72 It will be observed that the ratios of glycocoll to copper sulphate are the same for the different pairs of solutions, so that any pair of solutions could be obtained from a more concentrated pair by dilution. This was done with the intention of seeing whether the value of x varied with the dilution, the ratio of glycocoll to copper sulphate being constant. No variation within the above range of concentrations can be said with certainty to occur. The E.M.F. measurements point to the existence of complex ions of the formula [CuG4]" and their dissociation-products. To this ion corresponds the complex sulphate [CuGJSO,.The fact that x comes out somewhat less than 4 is probably due to the partial dissociation of the complex ion CuG;. into less complex ions such as CuG,, &c., i.e., the elementary Cu..-ions are converted by the excess of glycocoll partly into complex ions containing less glycocoll than CuG,". This conclusion requires to be supported by evidence obtained from some independent method, and with this object in view the freezing-point measurements described in the next section were undertaken. 2. FREEZING-POINT MEASUREMENTS. A few preliminary measurements of the freezing points of aqueous glycocoll solutions gave as a mean value for the molecular weight 73.5 (theoretical value 75), thus confirming the already known result that glycocoll exists sirbsfnnfially as simple molecules in aqueous solution.COMPLEX COPPER-GLYCOCOLL SULPHATES 193 In order to investigate the complex formation, the freezing-points of a series of strong glycocoll solutions of gradually decreasing concentration were determined, and the rise of freezing point produced by the addition of small quantities of copper sulphate to these solutions measured very care- fully.Let y denote the net number of active individuals removed from the solution per mol. copper sulphate added. As before let x denote the number of glycocoll molecules which combine with the Cu-atom to form a complex. We shall now assume that practically all the copper sulphate added is con- verted by the large excess of glycocoll present into complex sulphate and that at the fairly high dilution used the value of van't Hoff's factor i for the complex sulphate is the same as that for copper sulphate of the same total molar concentration. Then, per gram.mol. copper sulphate added, i new individuals enter the solution, whilst x individuals (glycocoll molecules) are removed. If the solution employed is so dilute with respect to total copper that we can assume complete ionisation of the complex or simple sulphate, x = y + 2. The practical range of this method of procedure is limited by the fol- lowing considerations : The rise of freezing point actually measured being dependent upon the amount of CuSO, present, as much of this salt as pos- sible must be added, in order to reduce the percentage error of the readings. But as it is imperative to have the glycocoll in large excess of the copper sulphate to ensure as complete as possible a formation of complex salt, the amount of copper salt that can be added will depend on the solubility of glycocoll at the temperature of the freezing points.The cryohydrate point of glycocoll was found to be approximately - 3", so that at this temperature the saturated glycocoll solution must contain about 2.3 grms. of glycocoll per 20 grms. water. In the experiments to be described the amount of glycocol! taken varied from 1.2 to 2.1 grms. per 20 grms. water, whilst the rises of freezing point observed varied from 0 - 0 2 1 O to 0.0880. Supposing the probable error of any one reading to be O'OOI~ and of any measured rise to be 0 ~ 0 0 2 ~ ~ the percentage error of the latter must vary from 9 s per cent.to 2-3 per cent. In order to obtain values of x of sufficient accuracy for our purpose it is clearly necessary that the rises of freezing-point must be determined very carefully. In the apparatus used the cooling bath of ice and brine was sur- rounded by a vessel containing finely crushed ice, the outer walls of which were enveloped in felt, so that its temperature did not vary as much as &* during a series of measurements. The stirring was done by an automatic stirrer driven at a constant rate, the Beckmanii thermometers were kept in ice for several hours before a measurement, and for every series of measure- ments with one solution the temperature of the ice-brine bath was carefully adjusted so as to give a convergence-temperature as nearly as possible equal to the freezing-point to be measured.The supercooling was kept within the limits O'I~--O'~". The following example well shows the general accuracy of the results- Freeziizg-Point of Piire G~COCOII Solution. Hence x -i = y, or x = y + i. Temperature of Cooling Bath. 1 Freezing Point. 4'5" 4 5" 4'5" - 4'5" 2'393 2'390 2'392 2'394 Mean = 2-392 - I Supercooling. -I--- 0.178~ 0' 150" 0.167" 0.162'I93 A PHYSICO-CHEMICAL STUDY OF THE Temperature of Cooling Bath. - 4'5" - 4'5" - 4'5" Freezing-Points of Glycocoll-copper Sulphate Solution. Freezing Point. Supercooling. ~ 2.415 0' 175" 2'413 0.171~ 2-412 0.157" - Mean = 2.413 Rise of freezing-point = 0 * 0 2 1 O . Concentration of copper sulphate =0.000886 gm. mols.per IOO grms. water. i for copper sulphate at this dilution = 1-89. Total no. of mols. glycocoll present in the solutioii per mol. CuSO,= 89.5. Calculated value of x = 3'17. The following table contains the results of the freezing-point measure- ments. TABLE V.-Freezing-poirat Measurements. Concentration of CuS04 in grm. mols. per 100 grnis. water. 0.000886 0.00 146 0.00Igq om023 o*oo t 82 0'00297 0'00346 000298 hi 01s. Glycocoll per mol. of cuso4. 89.5 844 63'5 60.6 54'4 46'5 40.0 33'3 Rise of Freezing Point. 0'02 I" 0.0355" 0'0555" 0'0393" 0'072" 0.0885" 0.0643" 0055" Values of i for CIISOJ. 1.89 1-81 1'7.5 1-70 I *76 I '63 1'59 1 '64 Means ... ... Value of x when i for Complex Salt has same Value as for CuSO4. 3'2 3'1 3'3 3'0 2'9 2'9 3'0 2.8 3'0 i for Complex Salt is taken as 2.3'3 3'3 3'5 3'3 3'2 3'3 3'4 3'2 3'3 The values of i for solutions of CuSO, have been previously determined, but it was deemed advisable to re-determine these cryoscopically for the present purpose, so as to ensure a high degree of comparability in the measurements. The values given in the above table have been obtained by graphical interpolation and extrapolation from the following measurements- TABLE VI. Concentration of CuS04 i n xnols. per 100 grnms. OF Water. 0.003 I 0.0067 0.0109 0.0 I 94 0'022'1 0.0264 Lowering of Freezing Point. 0'09j" 0'172~ 0'247" 0'523" 0'407" 0'457" Value of i. 1.62 1-38 1.14 1.09 1-07 1'22COMPLEX COPPER-GLYCOCOLL SULPHATES 195 The values of x in columns 5 and 6 of Table V. do not differ to any very considerable extent.The true mean will lie undoubtedly between 3.0 and 3'3. It will be observed that this number is considerably lower than 3-72, the mean of the values obtained from the electrometric measurements recorded above. This divergence admits, however, of explanation, when we consider that for the solutions used for the cryoscopic measurements the ratio of mols. glycocoll to mols. CuSO, varied from 33 to 89, whilst in the case of the solutions employed in the electromotive force measurements, this ratio varied from IOO to 200. I t is to be expected that in the former case the non- electrolytic dissociation of the complex ion or ions would be greater owing to the smaller excess of glycocoll present. In accordance with this explana- tion, it will be seen that the values of i given in column 5 of Table V.show a general tendency to decrease with decreasing values of the ratio mentioned above. 3. FURTHER ELECTROMETRIC MEASUREMENTS. In order to obtain a more direct comparison between the results of the electroinetric and cryoscopic measurements, pairs of solutions were taken in which the molar ratios of glycocoll to copper sulphate were 30 and 90. In other respects the same procedure was followed as described under the final measurements of Section I of this paper. The results obtained are given in the following table- TABLE VI 1 .-E.M.F. Neaszmvnenfs in Solutions diluter with respect to Glycocoll. Concentratior in both Solutions. of cuso, 1t - 80 I t - 80 I t I60 I60 Iz Concentration of Glycocoll in 1st Solution. 3 2 8 - 312 8 - 3't I 6 3 2 16 2nd Solution.92 8 9 8 w 16 - - 9 2 I 6 E.M.F. of Combination. 0.0458 0.047 I 0.0390 0.042 2 Temp. 14" I I" I 2 O 14" Mean totals ... ... Value of x from Equation (3). 3-38 3'51 2-90 3.12 I I Equation (4). 3'15 3'30 2-75 2'95 3'23 j 3-04 The mean value of x calculated from these E.M.F. measurements agrees very well with the mean value obtained from the freezing-point measure- ments, which shows that the explanation of the previously noted divergence given at the end of Section 2 is probably the correct one. 4. CONDUCTIVITY MEASUREMENTS. In order to throw further light on the complex formations, measurements It was of the electrical conductivity of the solutions were carried out.A PHYSICO-CHEMICAL STUDY OF THE expected that on continued addition of glycocoll to copper sulphate solutions a fall of conductivity would be observed, owing partly to the formation of slower moving complex kations and partly to the increased viscosity of the solution, although these effects might be to some sinall extent counter- balanced by an increased ionisation of the complex sulphate.As will be seen, the results obtained are extremely interesting, though they cannot be explained in the manner just indicated. The glycocoll (Kahlbaum's) was re-crystallised twice from ordinary distilled water and once from conductivity water ( R = 2 x 1 0 ~ ) . The specific conductivity of an 2 solution of this purified glycocoll was 6 x ro4 (temperature, 25O). I t was found that the conductivity of a pure glycocoll solution rises rather rapidly when kept in a conductivity vessel in the presence of the electrodes.This effect is probably due to oxidation a t the surface of the platinised electrode. It is interesting to note that it does not occur when CuSO, is present, so that the complex formation appears to protect the glycocoll from oxidation. The results obtained are given in the following table- The copper sulphate used had been re-crystallised three times. I 0 TABLE VII1.-Conductivity of Glycocoll-Copper Sulplade Solutions at 25O. it1 olar Concentration of CuSO, = ; Resistance Capacity of Vessel = 0.3658. Resistance (ohms). 210'12 172.56 179'42 168'44 16 5.5 j 166.18 168.33 171.13 167.25 Specific Conductivity of Solution (reciprocal ohms per ctiitimetre cube). 174.7 x 10-5 203'7 x 10-5 211'7 x 10-5 217'0 x 10-5 220.7 x 10- 219.9 x 10- 218.5 x 10- 217.1 x 10.- 213-5 x IO- Mols. Glycocoll per mol.CuSOJ. 0 I 3 5 I 0 20 30 40 50 The specific conductivities given in column 2 have been corrected for the specific conductivity of the water (2 x IO-~). The curve given in Fig. I shows clearly the relationship between con- ductivity and number of mols. glycocoll. present in the solution. In the case of CuSO, and ZnSO,, the ordinates in the diagram run from 174-7 to 222.7. Contrary to expectation, the first effect of the addition of glycocoll is to increase the conductivity of the solution ; thus on the addition of I mol. glycocoll the conductivity rises by no less an amount than 16.6 per cent. On the addition of 10 mols. glycocoll per mol. CuSO, the conductivity attains a maximum (increase of 26.3 per cent.), after which further addition of glycocoll produces a gradual decrease of conductivity.The sharp initial rise of conductivity is very marked. In order to see how far this behaviour is to be accounted for by complex formation, the effect of glycocoll on the con- ductivity of a ZnSO, solution was studied. The result of these measurements are contained in the following table-COMPLEX COPPER-GLYCOCOLL SULPHATES 197 TABLE 1X.-Conductivities of Glycocoll-Zinc Sulplaate Solutions at 25'. Molar Concentration of ZnSO, = ?- ; Resistance Capacity of Vessel = 0.4226. 80 Resistance (ohms). 245'40 244'55 242'89 239.82 236.84 233'30 231.95 228.66 231.36 232'58 Specific Conductivity of Solution. 172'0 x 10-5 172.6 x 10-5 173.8 x 10-5 176.0 x 10-5 178.2 x 10-5 180.9 x 10-5 181-5 x 10-5 182.0 x 10-5 184.6 x 10-5 182.5 x 10-5 Mols.Glycocoll per Mol. ZnS04. 0 I 3 I 0 20 30 40 50 60 The zinc sulphate-glycocoll curve, Fig. I , also shows a maximum, but the Thus on the addition effect is not nearly so marked as in the case of CuSO,. Specific Conductivity. Specific Conductivity. 6 12 i18 24 30 36 42 48 54 60 66 Mols. Glycocoll per Mol. CuSO,, ZnSO,, or 2KCI. of I mol. glycocoll to the &SO, solution the increase of conductivity is only 0.35 per cent, whilst the maximum increase is only 7.3 pcr cent. With these results may be contrasted the effect of glycocoll on the conductivity of a KCI solution, as shown in the following table-19s APHYSICO-CHEMICAL STUDY OF THE TABLE X.-Coizductivitics of Glycocoll-KCl Solutioizs a t 25".Molar Coltcert- tration o j KCl = 12 - Resistnrtce Capaciiy = 0'4005. 40 ' Resistance. 106.30 106. j 3 I o6@3 107.66 19-94 I t 1-74 T 13.80 14'37 19-38 Sp. Conductivity of Solution. 376.52 X 10-5 375.70 X 10-5 374'12 X 10-5 371.76 x 10-5 365-91 x 10-5 364.04 x 10- 358.18 x 10-3 351'68 x 10-5 376.27 x 10-5 Mols. Glycocoll per Double Mol. KCI. 0 I 3 5 I 0 20 30 40 50 As will be seen from the curve in Fig. I, the effect of glycocoll is to diminish the conductivity of the KC1-solution by an amount proportional to the concentration of the glycocoll. In the diagram the ordinates for KCJ run from 332.52 to $30'52. This diminution is probably due to the increased viscosity of the solution, and is a well-known effect of non-electro- lytes.This effect will also be present in the cases of CuSO, and ZnSO,, but thcxe is evidently also present some other cause which tends to iizcrease the conductivity, the maxima observed being due to the conflicting action of these two causes. Now both ZnSO, and CuSO, are perceptibly hydrolysed in aqueous solution. We may represent the hydrolytic equilibrium by the equation- CuSO, + 2 H,O(Cu (OH), + H,SO, or by- Cu .* + 2 H,O + Cu (OH), + 2 He. Evidently, since glycocoll, being an amphoteric substance, can act both 3s acid and base, it will disturb this equilibrium. It will tend to remove Cu(OH), by the formation of the copper salt of glycocoll, and it may be also supposed to tend to remove He ions by the formation of glycocoll sulphate. The case of ZnSO, is similar.Now it is known:;: that the copper salt of glycoccll is a peculiar salt, which, though the salt of a very weak acid, is preserved from much hydrolysis by an '' internal " complex formation. Hence there may be a considerable formation of this salt from the Cu(OH), and the glycocoll, whilst, owing to the fact that glycocoll is a very weak base, there will be only a very small degree of neutralisation of the free acid. The result is that addition of glycocoll to a CuSO, solution will increase the hydrolysis, producing an increase of H-ions, and hence a considerable increase of conductivity. Somewhat similar considerations will apply to ZnSO,, though in this case, owing to a very much smaller tendency to form complexes, the effect will be much smaller.It is not pretended that these remarks give a comprehensive analysis of this very interesting equilibrium, though they probably suffice to indicate qualitatively the nature of the reactions occurring. It is necessary, however, to prove that the addition of glycocoll actually does increase the H. concentration. Experiments bearing on the point are described in the next section. * Ley, Zcif.~clzr*iff~f. Elekimclzeni., 10, S) j4, 1904.COMPLEX COPPER-GLYCOCOLL SULPHATES 199 Time (minutes). 5. EFFECT OF GLYCOCOLL ON THE H'CONCENTRATION OF AQUEOUS SOLUTIOXS OF CuSO, AND ZNSO,. In order to test whether addition of glycocoll increased the H. concen- tration of a ZuSO, solution, the E.M.F. of the cell 6 CuSO4,5 per cent. Sugar. s C u S O 4 , g Glycocoll, 5 per cent, Sugar.I I f was measured at 17" and found to be 0.005~ volt (current in cell in direction indicated by arrow). The palladium electrodes were charged electrolytically to just visible gas-evolution in dilute H2S0,, then washed, and left short- circuited in dilute (&) HC1 overnight. They were found to show a small difference of potential when measured against each other in 12 HC1. This has been deducted in the above result. The E.M.F. of the above cell shows that the addition of glycocoll produces an appreciable increase in the H* concentration. If we neg- lect the small liquid potential, and calculate by means of the formula C ~ = o ~ o o o 1 9 8 T L o g ~ , we find 1-23 as a roughly approximate value for the c2 ratio of increase of the €3. concentration. This method cannot be applied'to the copper solutioiis owing to precipitation of metallic copper by the palladium-hydrogen electrode, so in this case comparative measurements on the rate of inversion of cane sugar were made. The solutions used were 5 per cent.with respect to recrystallised cane sugar. The polarimeter readings are given in the following table. 200 Temperature 60*so C. TABLE XI .-Iizversion of Carte Sugar by Copper-glycocoll Solutions. I I 0 70 66 '47 148 2 16 215 179" 413/ 179" 42' 179" 34l 1 79" 30' These results, though not pretending to great accuracy, are sufficient to show that the presence of the glycocoll has very appreciably increased the H. concentration of the CuSO, solution. 6. PRODUCTS OF ISOTHERMAL CRYSTALLISATION OF AQUEOUS SOLUTIONS CONTAINING CuSO, AND GLYCOCOLL.Solutions containing CuSO, and glycocoll were allowed to crystallise at room temperature over calcium chloride or concentrated sulphuric acid. The crops of crystals so obtained were drained on the filter pump, dried on porous plates, and then microsocopically examined and analysed. Copper was determined electrolytically or as Cu,S. Glycocoll was calculated from200 A PHYSICO-CHEMICAL STUDY OF THE the percentage of nitrogen found on combustion. Water was determined from the loss of weight on heating to 1 1 0 ~ - 1 2 0 ~ in vucuo, the substance being contained in a weighed glass tube connected with a gas washing flask containing concentrated sulphuric acid. SO, was determined gravi- metrically in the usual way. Exjminteizt I.-TWO solutions were made up, each from 12 grms..glycocoll, 5 grms. CuSO, . jH,O, and 75 C.C. water. The first crop of dark blue crystals from each solution was analysed. Crystals from Solution ( I ) . Crystals from Solution ( 2 ) . !- Copper ... 10.6 per cent. I 1037 per cent. H,O . . . . . . 4.8 I ,, , , j 3-41 ) * ,, Glycocoll ... 65-84 ,, ,, (by difference) 68.81 ,, ,, SO, . . . . . . 18.75 ,, ,, 18-01 ,, 7 , , For the crop of crystals from Solution ( I ) we have Mols* glycOcO1l- Mols. Cu -5'3' There is more SO, present than would, for the given copper content, correspond to CuSO, or any complex copper-glycocoll sulphate of the formula Cu(G),SO,. The amount of water of crystallisation in the crystals from the second solution corresponds pretty closely to I mol.water per mol. copper. If we calculate, taking the figures in the first column, from the Cu percentage the percentages of glycocoll and SO, corresponding to the formula Cu(4G) SO,. H,O, we get 50 and 16 respectively. The excesses over these, namely, 15-84 and 2-75, are in the molar ratio 1-84: I . Assuming these crystal crops to be chiefly heterogeneous mixtures of two phases, it seems possible, therefore, that they might coiisist chiefly of Cu(4G)S04 . H,O and (NH,-CH, . COOH),H,SO, (but see later). Ex$erimenf 2.-Solution made up from 18 grms. glycocoll and 10 grms. CuS0,5H,O in IOO C.C. water. The first crop of crystals was dried and extracted with ether in a Soxhlet apparatus. The weight of the substance before extraction was 2.2888 grms., after extraction 2'2700 grms.We may conclude therefore that it contains little, if any, free glycocoll. Analysis of extracted crystals- Copper . . . . . . . . . . . . 25'23 per cent. Glycocoll . . . . . . . . . . . . 68.29 ,, ,, so, . . . . . . . . . . . . . . . 3-04 ,, ), H,O {by difference) ... - a * 4'44 ,, 9 , The result of crystallising from a solution relatively richer in CuSO, (in comparison with glycocoll) is to more than double the copper percentage, whilst the percentage of SO, is reduced to one-ninth of its former value. I t is evident that this crop of crystals consists mainly of a compound of copper and glycocoll (see discussion of results of Experiment 3). Experiment 3.-Original solution the same as in Experiment 2. Successive crops of crystals were obtained, examined, and analysed.The crystals were not extracted with ether. First Crop.-It consisted of dark blue nodular clumps of crystals.COMPLEX COPPER-GLYCOCOLL SULPHATES 301 Analysis.-Copper . . . . . . 27-99 per cent. Glycocoll . . . . . . 61.88 ,, ,, (by difference) so4 . . . . . . 2‘34 ,, ,, Water . . . . . . 7‘79 ,> J , Sccoizd Crop.--In appearance siiiiilar to first crop. Analysis.-Copper . . . . . . 24’95 per cent. . . . . . . so4 3-19 9 1 J l Other constituents not determined. Third Crop.-Evidently heterogeneous. It coiisisted of dark blue needles mixed with almost colourless crystals. Analysis.-Copper . . . . . . 9-46 per cent. Glycocoll ... 66-65 ,, ,, SO4 . . . . . . 19‘93 ,, 9 , Water . . . . . . 2-26 ,, ,, Fozrrth Croj,.-Fairly large colourless crystals, with a sniall amount of dark blue lumpy solid.The colourless crystals were free from copper and contained 30.68 per cent. H,S04 (calculated from amount of SO, found). Fifrh Crop.-Consisted of a mass of dark blue silky needles, with here and there a small dark blue lumpy nodule. The blue needles contained 28-47 per cent. Cu. During the course of this work a solution containing glycocoll and CuSO,, which had been set aside to crystallise, became accidentally con- taminated with HC1. From this solution large very pale blue (monoclinic or triclinic) crystals were deposited. On analysis they yielded the following results- Glycocoll . . . . . . . . . . . . 69-57 per cent. . . . . . . . . . . . . 30.23 ,, .. Copper . . . . . . . . . . . . 0.10 . . . . Water . .. . . . . . . . . . 0.09 7, 7, Neglecting the copper and water found, these crystals consist to 99-56 per cent, of a sulphate of glycocoll of the composition, glycocoll=6~)*66 per cent., H,SO,=30’34 per cent., which corresponds with the known, so-called ‘I basic,” glycocoll sulphate, whose formula is (NHZ . CH, . CO,H),H,SO, (glycocoll=6y87 per cent., H2S0,=30*r3 per cent.). These crystals cor- responded closely in appearance with the colourless crystals observed i n the third and fourth crops (Experiment 3 ) , and from the percentage of H,SO, (30.68) found by analysis in the colourless crystals of the fourth crop, there can be little doubt that these colourless crystals were the “basic” glycocoll sulphate. The dark blue needles observed in the fifth crop were separated 3s far as possible from the rest by means of a mixture of methylene iodide and benzol.In appearaiice they closely resembled the well-known copper salt of glycocoll, Cu (NHZ. CH, . CO,), . H,O and con- tained 28-47 per cent. Cu, whilst copper glycocoll contains 27.7 per cent. Cu. Judging from the microscopical examination, there was now very strong presumption that the third crop consisted chiefly of copper glycocoll and There can be little doubt that these two substances are identical.202 A PHYSICO-CHEMICAL STUDY OF THE " basic " glycocoll sulphate. following figures :- This view is confirmed on examining the I. 11. Copper . . . . . . . . . . . . . . . 9-46 ... 9-46 Glycocoll . . . . . . . . . . . . 67.93 ... 68.73 H,SO, 20'35 20'3 5 . . . . . . .. . . . . . . . ... Water . . . . . . . . . . . . . . . 2426 ... 2.68 Colunin I. gives the composition of the crop as found by analysis. Now, 9.46 parts Cu as copper glycocoll correspond to 22-01 parts glycocoll and to 2.68 parts water, whilst 20.35 parts H,SO, as (NH, . CH, . COOH),H,SO, correspond to 46.72 parts glycocoll. Therefore, had the crop consisted of copper glycocoll and basic glycocoll sulphate, it would have had the com- position indicated in Column II., which agrees sufficiently closely with that given in Column 1. It is impossible to say from the experimental results what are the exact constituents of the first crop of crystals obtained in Experiment 3. It appears possible that they consisted of copper glycocoll admixed with a basic complex copper glycocoll sulphate, but as there is not sufficient other evidence to support such a conclusion, it is scarcely worth while to reproduce here the arithmetical details of the numerous calculations made.In conclusion, it may be stated that the crystals from Solution 2 (Experi- ment I ) might be looked upon as mainly a mixture of copper glycocoll and the basic glycocoll sulphate, for on analysis the conglomerate yielded 12-84 per cent. N, whilst had it consisted of the substances mentioned, a simple calculation from the other analytical data shows that it would have contained 12-44 per cent. N. 7. COSCLUSIONS. The crystallisation experiments described in Section 6 confirm the con- clusions arrived at in Sections 4 and 5 of this paper, namely, that the effect of the first addition of glycocoll to a solution of CuSO, is to disturb the hydrolytic equilibrium by the formation of undissociated copper glycocoll, with the consequent increase of free H,SO,.The maximum increase in the specific conductivity 2 CuSO,, produced by the addition of 10 mols. glycocoll per mol. CuSO,, was 26.3 per cent. If this CuSO, solution be regarded (to a first approximation) as completely ionised, then, since the ionic conductivities of 2H. and Cu- are about 2 x 347 and 80 respectively, the replacement of Cu.. by 2H' would increase the specific conductivity by 2 j6 per cent. The actually observed increase would correspond, therefore, to a conversion of only about 10 per cent. of the CuSO, present in the 80 solution into copper glycocoll and free sulphuric acid (which at this dilution would combine with very little glycocoll). It is clear, therefore, that this initial action is soon brought to a stop by the increasing H* concentration (which throws back the CU(OH)~ concentration), and that after this the further addition of glycocoll results mainly in the formation of complex copper glycocoll kations.This second action, therefore, constitutes the niain effect i n solutions which contain large excesses of glycocoll relatively to CuSO,. The conclusions arrived at in Sections I, 2, and 3 remain, therefore, practically undisturbed. The freezing-point measurements alone are s u 6 - 80COMPLEX COPPER-GLYCOCOLL SULPHATES 203 cient to show that in solutions rich in glycocoll the main actions occurring cannot be represented by the equation- CuSO, + z(NH, .CH, CO,H) = Cu(C0,. CH, . NH,), + H,SO, CuSO, + 4(NH,. CH,. CO,H) = Cu(C0,. CH, . NH,), + (NH, . CH, CO,H), . H,SO, ; or- for if so, the addition of I mol. of CuSO, to strong solutions of glycocoll' would involve a decided increase in the number of " osmotically active " units in the solution, whereas there was always observed a decrease. Moreover, the quantitative agreement between the results calculated from the E.M.F. and freezing-point measurements is strong evidence in favour of the theoretical basis on which these results were calculated. It must be confessed, however, that more work requires to be done before this complicated equilibrium is thoroughly cleared up. In the complex copper glycocoll sulphates the glycocoll molecules are doubtless related to the copper atom in the same manner as the ammonia molecules in the complex copper ammonia sulphates. In both cases the highest katic1ii.c compiex appears to contain 4 molecules per I atom of copper, and it seeins most probable that the glycocoll or ammonia molecules are related to the copper atom through the '' subordinate " valencies of the nitrogen atom. The case of copper glycocoll itself has been investigated by Bruni and Fornara : and by Ley.+ It appears probable that the constitution of this salt must be represented by the formula- 0 . CO . CH,. NH, ........ .... ._.. CU..: I .............. ...... .......... .... I ...... .... 0. CO .CH,. NH, where the secondary or lines. The deep colour resist the conclusion that exhibit is subordinate valencies are indicated by the dotted of all these salts is very striking. It is difficult t o the powerful selective light absorption which they intimately connected with the interplay of these secondary or subordinate affinities, and that this phenomenon is a very general one. The only way i n which one can a t present represent the constitution of the complex sulphate Cu(4G)S04 is therefore (in analogy with the above) as follows- NH, . CH,. COOH .................... COOH. CH,. NH, ...... CU-so, ........... ,,(..' '.._. COOH . CH,. NH,' NH,.CH,. COOH in which there exist secondary affinity relationships between the copper and nitrogen atoms. In conclusion, I have great pleasure in expressing my best thanks to Professor Donnan for his kind advice and assistance during the course of this work. LIVERPOOL, November 18, 1907: * G. Rruni and Fornara, Rend ti. K. Accnd. d. Liiicci, Roma, xiii. gal 26. t Zeitschr$t filr Elcktrochemie, 10, 954, 1904.

ISSN:0014-7672    

DOI:10.1039/TF9080300188

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

204 STUDY OF COPPER-GLI’COCOLL SULPHATES DISCUSSION. Dr. A. C. Cumming asked why the author had used 3.5 N sodium nitrate as the connecting solution in the electrometric measurements. It was his experience that it did not eliminate diffusion potential. Dr. F. G. Donnan, in reply, said that in the final experiments, on which alone conclusions were based, the diffusion potential was autoinatically eliminated because the solution on each side contained practically an equal number of current-carrying ions, The connecting solution had in this case no disturbing effect.

ISSN:0014-7672    

DOI:10.1039/TF9080300204

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE DISCOVERY OF T H E ALKALI METALS BY HUMPHRY DAVY: THE BEARING OF T H E DISCOVERY UPON INDUSTRY. BY F. MOLLWO PERKIN, PH.D. ( A Paper read before the Faratlay Society, Tuesday, Dccenrber 17, 1907, Dr. H. BORNS in the Chair.) Humphry Davy was born on December 17, 1778, at Penzance. The Davys originally came from Norfolk, but settled down some generations earlier in Cornwall. Edmund Davy, the grandfather of Humphry, was a builder in the west of Cornwall, and Robert, his father, had a small property at Varfell, but he was thriftless, and when he died his affairs were found to be in a very embarrassed state ; so that upon Humphry, the eldest son, who at the time of his father’s death was sixteen years of age, fell the responsibility of looking after the family. Before this time Davy appears not to have been very studious, but of rather a restless disposition and by no means fond of restraint, but upon the death of his father he at once settled down to hard work and study, and a few weeks afterwards was apprenticed to an apothecary and surgeon who practised in Penzance.Not only did he whole-heartedly throw himself into the study of his profession, but he also mapped out for himself an arduous course of general study. In 1797 he commenced the study of natural philosophyand turned his attention to chemistry, as it helped him in the work of his profession. From the reading of chemistry to the practice with such crude apparatus as tea- cups and tobacco pipes was but a step, but beyond the fact of spoiling his sister’s dress with acids and frightening his friends by the noises of explosions which proceeded from his experinienting room, little is known of the outcome of his work at this time, which, in any case, was probably not much more than seeking in the dark with but little light to guide him.It was meeting with Gregory Watt, the son of the engineer James Watt, who had been educated at the University of Glasgow, that finally decided Davy to devote himself to science. Mr. Gilbert, who afterwards occupied the Presidential Chair of the Royal Society in succession to Davy, helped him also by allowing him the use of his library and physical apparatus In 1798 Dr. Beddoes, who had been trained as a medical man, and had many strange and unpractical ideas, founded a kind of sanatorium in Bristol, which he called the Pneumatic Institution, and asked Davy if he would take charge of the laboratories.The main object of the Institution was to study gases and their effects upon different ailments. Davy, with his energetic disposition, threw himself heartily into the work, and in 1799 we find him studying the action of nitrous oxide upon the human system. He first of all experimented upon himself and then tried its action upon others. About this time Maria Edgeworth, who was visiting her sister, Mrs. Beddoes, wrote :- ‘‘A young man. a Mr. Davy, at Dr. Beddoes’, who has applied himself 205206 DISCOVERY OF ALKALI METALS BY H. DAVY: much to chemistry, has made some discoveries of importance, and enthusi- astically expects wonders will be performed by the use of certain gases, which inebriate in the most delightful manner, having the oblivious effects of Lethe and at the same time giving rapturous sensations of the Nectar of the Gods.Pleasure even to madness is the consequence of this draught.” She adds, however, that some found nothing but a sick stomach and ;I giddy head. Although there are many points of great interest in Davy’s early days and in the gradual development of his power as he went on from step to step until he matured into one of the most brilliant experimenters, if not the most brilliant, which the nineteenth. century was to see, it is not my intention to describe the life of Davy, but to dwell upon his researches in connection with electrochemistry and to indicate the enormous progress in industry which SIR HUMPHRY DAVY.has been gradually evolved from his small, but record-breaking, com- mencements. In October of 1800 he wrote a letter to Mr. Gilbert, addressed from the Pneumatic Institution, in which he refers to experiments upon galvanism. This letter is of particular importance, because it fixes the date at which he commenced to work at electrical phenomena, and which, as it afterwards turned out, was to be the monument of his most enduring fame. He says in this letter :- “Galvanism I have found, by numerous experiments, to be a process purely chemical, and to depend wholly on the oxidation of metallic surfaces, having different degrees of electric conducting power. “Zinc is incapable of decomposing pure water ; and if the zinc plates be kept moist with pure water, the galvanic pile does not act ; but zinc is capable of oxidating itself when placed in contact with water, holding in solutionREARING OF THE DISCOVERY UPON INDUSTRY 207 either oxygen, atmospheric air, or nitrous or niuriatic acid ; and under such circumstances the galvanic phenomena are produced, and their intensity is in proportion to the rapidity with which the zinc is oxidated.“The galvanic pile only acts for a few minutes, when introduced into hydrogen, nitrogen, . . . that is, only as long as the water between its plates holds some oxygen in solution : immerse it for a few seconds in water con- taining air and it acts again.” This shows that Davy had already a very acute insight into the working of the primary battery, and in this connection it must be born in mind that it was only in May, 1800, that the discovery of the Voltaic pile was made known by Volta in a letter to Sir Joseph Ranks, the then President of the Royal Society. On February 16, 1801, Davy was clected to the post of Assistant Lecturer in Chemistry at the Royal Institution, Director of the Laboratory and Assistant Editor of Journals of the Institution.It is of particular interest to notice that the first lecture lie gavc was upon “Galvanic Phenomena.” Davy at this time was rather ungainly in appearance and not particularly taking in manner. So much so, in fact, that Count Runiford, the head of the Royal Institution, was by no ineatis prepossessed when he first met him. But after hearing him lecture he exclaimed, Let him command any arrangements which the Institution can afford.” The chemist appointed to the Royal Institution in those days had not 311 altogether enviable position, because the Board of Managers were wont to meet and draw up suggestions as to the class of work which should he lectured upon and upon which research work should be carried out.::: Davy was, for example, asked to lecture upon the “ Principlcs and Art of Tanning,” then upon “ Agriculture,” and the work entailed upon these subjects must have prevented him from giving so much time as he probably otherwise would have done to the subject of electricity, although i n 1806, i n the Bakerian Lecture before the Royal Society, the subject of his paper was upon the decompositions and chemical changes produced in substances of known composition by electricity.He had also shown that it was due to impurities in the water used by Nicholson and Carlisle when they succeeded in deconiposiiig it electrolytically, that caused the appearance of acidity at the positive electrode and alkalinity at the negative electrode. Beside this he had advanced his theory of electro-affinity, so that it is obvious he had had the subject of electricity and its applications to chemistry continually before him. In October, 1807, he commenced the study of the action of Voltaic electricity upon the alkalis, a subject which he had evidently considered before, because we find in one of his note-books under thc date August 6, 1800 :- (‘ Would not potash dissolved in spirits of wine become a conductor ? ” To-day we know that potash dissolved in absolute alcohol is an electrolyte, although an extremely poor one.On November 19, 1807, Davy delivered the Bakerian Lecture before the Royal Society and astonished the scientific world by describing the metals potassium and sodium.+ The lecture was entitled, “ On some New Phenomena of Chemical Changes produced by Electricity, particularly the Decomposi- tion of the Fixed Alkalies, and the Exhibition of the New Substances which * The Royal Institution was originally founded on philanthropic lines to benefit t The first intimation of his discovery is found in his laboratory note-book, the poor. preserved at the Royal Institution under the date October 19, 1807.208 DISCOVERY OF ALKALI METALS BY H. DAVY: constitute their Bases ; and on the General Nature of Alkaline Bodies ( P l d .Traits., 1808, vol. 98, pp. 1-44). Davy commenced by referring to the lecture delivered by hini the previous year where he described a number of deconipositions and chemical changes produced in substances of known composition by electricity, when he also stated with prophetic foresight that “the new methods of investiga- tion promised to lead to a inore intimate knowledge than had hitherto been obtained concerning the true elements of bodies.” He then describes the “ methods used for the decomposition of the fixed alkalies.” The first attempts were made upon saturated aqueous solutions of the metallic hydroxides, using the highest electrical power he could command. This I‘ was produced by a combination of Voltaic batteries belonging to the Royal Institution, containing 24 plates of copper and zinc of 12 in.square, 100 plates of 6 in., and 150 of 4 in. square, charged with a solution of alum and nitrous acid (nitric acid) ; but in these cases, although there was a high intensity of action, the water of the solution was affected and hydrogene and oxygene disengaged with the production of much heat and violent effervescence. He therefore had a cell of 274 pairs, which was probably coupled up in series, so that the voltage obtained would be considerable. I find that if a zinc and copper plate are placed, the one in a saturated solutioii of alum and the other in 30 per cent. nitric acid, that an E.M.F. of 1.2 volts is obtained. If Davy had used such a battery composed of 274 cells he would hare obtained an E.M.F.of 328 volts. Davy, however, probably used very much weaker nitric acid and also employed a mixture of alum and nitric acid, the zinc and copper plates not being separated by a porous cell, as porous cells do not appear to have been used in these early days. In fact, Faraday in his first electromagnetic experiments used a battery consisting of concentric plates of zinc and copper separated from contact with each other by means of cloth. The first reference to porous earthenware cells which I can find is in 1836, when they were employed by Becquerel (Pogg. Aizia. Plzys. Chem. Now by placing zinc and copper plates in a saturated solution of alum and 5 per cent. of nitric acid an E.M.F. of 0.8 volt is shown. Therefore with such a battery the potential at Davy’s disposal odd have been 219.2 volts.The current shown by two such cells when shorted through a low-resistance ammeter is only 0.8 to 0.9 ampere. With 10 per cent. nitric acid, which acts violently on the plates, a current of 3-2 amperes was obtained, the E.M.F. being o.8j volt per cell. The batteries used by Davy, which are still preserved at the Royal Institution, were in the %oC form of a trough of baked wood, as shown i n Fig. I. The plates of zinc and copper were connected face to face and then slipped into slots and FIG. I . - fastened leak - tight with pitch or some similar sub- stance, the electrolyte being placed in each compartment. Thus i n the electrolyte zinc faced copper and vice versd. Davy recognised that the presence of water interfered with his experi- ments, and he therefore resolved to try the action of the electric current upon potash in “igneous fusion.” The potash was placed ir.a platinum 1836, 37. 429).BEARING OF THE DISCOVERY UPON INDUSTRY 209 spoon and was melted by heating it with a spirit lamp, a stream of oxygen gas being applied to the flame. The spoon was in connection with the positive pole of a battery of roo 6-in. plates “highly charged.” The connection with the negative side was made by a platinum wire. The potash appeared a conductor in a high degree, and some brilliant phenomena were produced. So long as connection was preserved a most intense light was exhibited at the negative wire, aiid a column of flame which seemed to be owing to the development of combustible matter arose from the point of contact.“When the order was changed, so that the platina spoon was made negative, a vivid and constant light appeared at the opposite point : there was no effect of inflammation round it ; but xriform globules, which inflamed in the atmosphere, rose through the potash.’’ But as the potash was dry this inflammable matter apparently arose from its decomposition. Davy also noticed that the platinum was considerably acted upon. Although a number of experiments were carried out under these conditions it was not found possible to collect any of the products of decom- position. He noticed that potash dried by ignition w3s a non-conductor, but was rendered conducting by the presence of a very small trace of moisture, and that it then readily fused and was decomposed by strong electricai powers.Davy now altered the experiment as follows : “ A small piece of pure potash, which had been exposed for a few seconds to the atmosphere, so as to give conducting power to the surface, was placed upon an insulated disc of platina, connected with the negative side of the battery, power 250 of 6 and 4 in a state of intense activity; and a platina wire, communicating with the positive side, was brought in contact with the upper surface of the a1 kali.” This experiment is easily shown if a piece of dry potassium hydroxide is placed upon a nickel plate connected with one pole of a lamp resistance and a piece of nickel wire connected with the other pole is placed in contact with the side of the hydroxide furthest away from the plate.No action then ensues. But if one now breathes upon the potassium hydroxide so as t o moisten it externally, action almost immediately commences and the hydroxide fuses. Electrolysis then takes place, and the metal as it is produced rises to the surface of the fused alkali often inflaming explosively. I n carrying out this experiment it is therefore wiser to wear glasses. Davy noticed under these circumstances that the “ potash began to fuse at both its points of electrisation. There was a violent effervescence on the upper surface ; at the lower or negative surface there was no liberation of elastic fluid, but sinall globules having a high metallic lustre, and being precisely similar in visible characters to quicksilver appeared, some of which burnt with explosion and bright flame as soon as they were formed, and others remained and were merely tarnished, and finally covered by a white film which formed on their surfaces.” From a number of experiments Davy managed to collect enough of the, what he termed, “ inflammable principle ” of potash, in order to experi- ment with it.He then tried caustic soda and found that similar phenomena were produced. But in this case the action was less intense, and it was necessary to work with thinner pieces of the substance. The potassillin produced by Davy remained fluid at ordinary tempera- tures, which shows that it must have been contaminated with sodium, because an alloy of sodium and potassium is liquid at ordinary temperatures.So great was Davy’s joy when he saw the globules of potassium ascending through the fused potash that we are told he danced round the210 DISCOVERY OF ALKALI METALS BY H. DAVY: room, and it was some minutes before he was calm enough to continue his experiments. With Davy’s theoretical considerations we will not here concern ourselves. He studied the properties of the new substances, and his experi- mental work with the minute quantities of the substance at his disposal is little short of the marvellous. He noticed that in all “ sensible properties ” these substances resembled the metals. The action upon oxygen, hydro- chloric acid gas, water, and mercury was noticed. It was fused with sulphur, heated with various oils, also with metallic oxides, and its power in reducing these was noticed.Less than a year later-June 30, 1808-Davy presented another paper before the Royal Society upon the ‘( Electro-chemical Researches on the Decomposition of the Earths ; with Observations on the Metals obtained from the Alkaline Earths and on the Amalgam produced from Ammonia” (PhiE. Tram., 1808, 98. p. 333). Although he never obtained the metals calcium, strontium, and barium in the pure state, he did obtain them in the form of their amalgams. He likewise obtained the metal magnesium as an amalgam. His method of procedure was to “slightly moisten the earths (that is, the oxides of the alkaline metals), mixed with one-third of the red oxide of mercury, the mixture was placed on a platina spoon, a cavity was made in the upper part of it to receive a globule of mercury .. . the whole was covered by a film of naphtha, and the plate was made positive, the mercury negative.” He distilled the amalgams which he obtainccl in this manner in plate-glass tubes, the tubes being bent in the middle and the extremities enlarged and rendered globular so as to act as a retort. The amalgam was introduced into the tube ; it was tlieii filled with naphtha, which was expelled by boiling through a small orifice in the receiver end. When all the naphtha except vapour had been driven out the tube was sealed up. Davy found no difficulty in separating the bulk of the mercury, but he was never sure, even after prolonged heating, whether he had actually driven it all off. He, however, describes the metals as being of a silver colour.In further experiments he showed that ammonium behaved like the metals and prepared the amalgam. History, it is usually considered, does justice to the work of men. It places upon an eminence those who have in their own day and generation been scoffed at, whilst others who stood high in popular esteem are thrown down. But ;in reference to scientific pioneers history may not always be able to judge, because those who to-day have to examine into the claims of those who lived in bygone generations cannot enter properly into the diffi- culties which beset their work. There was practically no theory ; what there was had often been erected upoii an erroneous basis, and therefore hindered rat her than helped investigators. Apparatus and material were defective. The wonder, therefore, is not that they did not do more, but that, seeking as they often did in an Egyptian darkness, they did so much.There was one thing, however, which was to their advantage : they knew nothing of the rush and headlong hurry of the present day, and that must have counted for much. It is often said, what marvels a Faraday or a Davy would have produced if they had had the apparatus at their disposal which we have to-clay. They might not have done ; they were pioneers and had pioneering instinct ; they knew how to sweep aside the entangling under- growth which blocked their path. But if all had been cleared away, it is His best results were obtained with barium.BEARING OF THE DISCOVERY UPON INDUSTRY 211 possible they would not have made their mark as they did.Each generation has those who meet its needs. D a y , thc acute thinker, the rapid and impatient worker, was the man for his time. He had also, what is not for every one who strives after scientific truth, recognition in his day. He loved popular applause and he loved fame-these he had in full measure. He was acknowledged in his lifetime, we acknowledge him to-day. And now let us look at the enormous harvest which we to-day reap from the seed sown by Davy, seed which took a long time to germinate, but when once the roots of the plant had taken hold of the soil, the face of an industry, nay of many industries, was changed. Cheiiiical Metkods. The first alkali metal to be produced upon nn industrial scale was potassium in 1827, by Wohler, who wanted to use it for the production of aluminium.Wohler hcated an intimate mixture of potassium carbonate with carbon- KZC03 + 2C: = 2 K + 3CO. About 18j4 Saiiite Claire Deville manufactured sodium in a similar manner. The process was first carried out at Salindres, in France, the method being to heat anhydrous sodium carbonate and chalk with charcoal. The manufacture was carried on in this manner for over thirty years. At the end of this time some 5,000 to 6,000 kilos. of metallic sodium were aniiually manufactured at Salindres. In 1886 the process of Castner was introduced in England, the method being to reduce sodium hydroxide with an iron carbide, prepared by heating a mixture of iron oxide and tar to red heat. This mixture was then heated to 1,000~ with the sodium hydroxide. The iron, however, according to Roscoe, took no part in the reaction, which may therefore be formulated as- 3NaOH + C = Na,C03 + Na + 3H.Netto, about the same time, introduced n somewhat similar method. I n this process melted sodium hydroxide was allowed to flow down over red hot coke. This caused decomposition to take place at the moment of contact between the molten hydroxide and the coke. The appa- ratus (Fig. 2) consisted of a cast-iron retort b filled with coke and wood charcoal, and heated to redness. The molten sodium hydroxide was run in from the container e through the funnel d, the sodium vapour being condensed in the receiver g. In order to produce 100 kg. of sodium, 1,000 kilos. of sodium hydroxide and 150 kilos. of carbon was required as reducer. The chief object in manufacturing sodium at this time was to employ it in the manufacture of aluminium, because the cheapening in the cost of sodium meant a corresponding drop in the price of aluminium.FIG 2. Electrolytic Methods. In 1890 Castner introduced his method for maiiufacturing sodium by the electrolysis of sodium hydroxide.212 DISCOVERY OF ALKALI METALS BY H. DAVY: Other attempts had been made to electrolyse salts of the alkali metals- Thus, in 1848, Linnemann (Yourr~fiir Prnktisclze Chenz., 1848, 415), suggested electrolysing fused potassium cyanide. He found if the temperature was held sufficiently low so that the surface had a solid skin upon it, that the metal collected below the surface, and was not therefore oxidised by the atmos- phere.In 1851 Charles Watt in this country patented an apparatus (Eng. Pat. 13,755) by means of which he hoped to produce sodium on a manufacturing scale by the electrolysis of fused sodium chloride. The apparatus consisted of a vessel A , which was madc of earthenware, or of iron lined with earthenware, to protect it from the action of the heat. F is the distilling head for the metal. C C are the electrodes, which, it will be noticed, are partially separated by means of the division E . The electrode beneath the still head consisted of carbon, the other one of gold. One recognises at once that a gold electrode would be useless if used for the electrolysis of an alkali halogen salt. The temperature of the apparatus was to be kept sufficiently high to cause the metal to volatilise as it was produced ; this, of course, would also be an objection, The motive power was to consist of 10.FIG. 3. Daniel1 cells. One point of particular note about this cell is the partiaP partition. Within ihe last few years cells with partial partitions have been patented for quite a number of diverse operations, in order to get over the difficulties always at tendant with the use of diaphragms. I t will be remembered that Davy was not able to isolate potassium so long as he employed external heat in order to fuse the alkali hydroxide, but that when he used the current first to fuse and then to electrolyse the fused salt he obtained the metal. The reason, as is now well known, was due to the fact that at high temperatures the metal dissolves again in the fused electrolyte, whereas it can be separated if the temperature is only allowed to rise a little higher than the fusing point of the hydroxide.In the Castner apparatus, although in the first place gas or other firing is used to melt the sodium hydroxide, very little heat is required after the passage of the current, because the heat generated is sufficient to keep the material fused, and one of the particular points of the patent is the temperature at which the electrolysis is to be conducted. The apparatus consists of an iron holder A for the fused hydroxide, which is narrowed to an opening at the bottom and connected with the opening is aBEARING OF THE DISCOVERY UPON INDUSTRY 213 cast-iron continuation B. Through this the iron cathode C passes.The anodes D D are of iron or ferro-nickel, which withstands the action of the evolved gases ; this anode is concentric with the cathode. E is a collecting vessel for the metallic sodium, which is closed at the bottom by means of an iron gauze net, shown in the dotted line. This net harigs down at the sides and forms a cylinder which encloses the cathode, thus preventing diffusion, and the gases from the anode coining into con- tact with the sodium produced at the cathode. The sodium as it is produced being molten and speci- fically lighter than the electrolyte, rises to the surface and passes through the gauze into the con- tainer E. From this it is removed from time to time by means of perforated ladles, which allow the molten alkali to drain out, but not the sodium.The gases pro- duced at the anode pass out at the opening P; this opening is also FIG. 4. ' useful for inserting-a thermometer in order to test the temperature of the electrolyte. The electrolyte is kept from leaking out at the cathode by the elongation B, which is in the first place filled with molten sodium hydroxide ; it, however, solidifies owing to this portion of the apparatus being kept cool. In order that the process may be satisfactorily carried on, it is necessary to regulate the distance apart of the electrodes and also their size according to the current to be employed. If the surfaces of the electrodes are too great then a portion of the sodium is absorbed by the fused alkali-this, of course, means loss of electrical energy.On the other hand, if the electrodes are too small, then the temperature of the bath becomes too high and again loss takes place. Pure sodium hydroxide contains only the ions Na. and OH'; hydroxyl is therefore given up at the anode. This causes the formation of water and the evolution of oxygen zOH= H,O + 0. At the high temperature of the electrolyte only a portion of the water will dissolve, but this will also take part in the electrolysis and yield H and 0, which, of course, is explosive. If no secondary reactions take place then only oxygen should be given up at the anode and sodium at the cathode ; but owing to the formation of water a certain quantity of hydrogen is invariably given up at the cathode, As a matter of fact this is not altogether a disadvantage, because it helps to cause the sodium to rise up into the catch box through the gauze.As, how- ever, the hydrogen also mixes with the oxygen and therefore tends to form an explosive mixture, explosions do frequently occur, but as a rule they are harmless. Probably for this reason it has not been found advisable to build electrolysers which will take more than 1,000 to 1,200 amperes. Owing to the fact that for every two equivalents of sodium hydroxide decomposed, one equivalcnt of water is produced, it is not possible to obtain more than a 50 per cent. yield of sodium-as a matter of fact 40 per cent. is as high as is usually obtained. The E.M.F. at the terminals of the apparatus is from The process is worked in this country by the Castner Kellner Company at 4 to 5 volts.214 DISCOVEKY OF ALKALI METALS BY H.DAVY: Weston Point, in Cheshire, and at Wallsend-on-'l'yne ; in Germany by Farbwerke vorm. Meister, Lucius and Brunning at Hochst, near Frankfurt, by die Elektrochemischen Werke Natruni, in Rheinfelden ; in France by the Cie. d'Electro-Chimie at Gavet ; also in America by the Electro- Chemical Company at Niagara Falls. Another process for the production of sodium by the electrolysis of sodium hydroxide is that of Rathenau and Suter, which has been in operation since 1895 at the Elektrochemischen Werken at Bitterfeld, aiid also in a modified form in the Aluminiumaktiengesellschaft a t Neuhausen. We have already noticed that one of the chief difficulties in obtaining sodium by the electrolysis of sodium hydroxide is the tendency of the sodium as it is produced to dissolve in the molten electrolyte. Castner gets over the difficulty by surround- i n g the cathode with gauze, which prevents the metal from diffusing throughout the electrolyte, and directs its path upward to the col- lecting recepticle, also by paying attention to the temperature of the bath.Rathenau and Suter get over the difficulty by allowing the electrodes to just dip in the molten electrolyte, Fig. 5. The surface tension causes the electrolyte to rise up slightly, SO that the electrodes are not actually below the surface of the molten hydroxide. On passing the current metallic sodium is produced at the ends of the electrodes, and here it partially solidifies and can be removed by means of ladels. In order to prevent over-heating at the electrode the inventers state that the current should not be of greater intensity than 10 amperes per square centimeter.The process of Becker, which is worked in France (Usines de Rioup&oux), is cf interest. It differs from the Castner method in that a mixture of sodium car- bonate and hydroxide is electrolysed. The apparatus employed is depicted in Fig. 6. The method of making the cathode tight so that the molten electrolyte may not leak out is much the same as that in the Castner apparatus. The cathode, however, is cone-shaped, so that the metal as it is produced may readily ascend to the collecting hood d ; or the cathode may be made of a number of slightly coned rods. By this means a greater surface is obtained and the metal ascends hetter.The hood is of iron or ferro-nickel, and is connected to the FIG. 6. negative source of current through a resistance. Thus, when thc metal comes into contact with the sides of the hood, it is in electrical connection with the negative pole, and, consequently,.. T _ _ - - FIG. j. 1BEARING OF T H E DISCOVERY UPON INDUSTRY 215 is not further acted upon by the molten electrolyte. The hood is air-cooled, or, if necessary, cooled by water dropping upon it so as to prevent the metal from actually distilling over, through the tube f, should the temperature rise too high. The metal, being specifically lighter than the electrolyte, rises up in the hood arid flows out through the side tube f l . The temperature of the electrolyte is much higher than in the Castner process, where it is only molten sodium hydroxide which is being electrolysed, whereas the average temperature of the Castner electrolyte during electrolysis is about 325'.In this case the temperature of the electrolyte between the anode and the cathode is about 550~. Every cell is worked with 1,250 amperes. Each apparatus produces about 40 kilos. of metal every 24 hours, and one man can work three such apparatus, consequently over IOO kilos. can be produced in one day by one furnace attendant. Many attempts have been made to produce metallic sodium on a com- mercial scale by the electrolysis of the cheaper sodium chloride in place of the more expensive hydroxide. In this case, however, owing to the very much higher temperature of fusion of the electrolyte, there is tendency for the sodium to be vaporised.The temperature at which sodium chloride melts is about yo', and metallic sodium distils at a little over v', conse- quently it is necessary to have the temperature of the bath very carefully regulated. Another drawback is the production of chlorine which at the high temperature at which it is produced is intensely active. But, of course, once the difficulty of dealing with the chlorine is surmounted, instead of being a disadvantage, it is an asset, being a useful by-product. The apparatus of Grabau-which, I believe, is not at present worked-was originally patented in 1889. I t is illustrated in Fig. 7. The decomposition vessel A, made of porcelain or other fire-resisting mate- rial, is externally heated by furnace gases which pass round it by means of the flues G, the decomposition vessel itself being placed in an air bath L L.The anodes of carbon C C are separated from the cathode by means of a porcelain partition which reaches down in the electro- lyte as far as the bottom of the electrodes, and is hollow so that heated air or gases may be passed through it. This prevents the sodium produced at the cathode and the chlorine at the anode froin diffusing and recom- FIG. 7. bining during the electrolysis. This pole partition is connected air-tight round the iron head E, which has a side tube connecting it with the receiver M. The alkali metal being very fluid at the high temperature, almost at its distilling point, rises up in the tube E and flows out through the tube a.The chlorine gas passes out by d. Fresh supplies of sodium chloride::: * Grabau suggests a mixture of NaC1, SrC1, and KCl as having a Iower melting- point. With such a mixture, however, pure sodium could not be produced. VOL. 111-T8216 DISCOVERY OF ALKALI METALS BY H. DAVY: can be added from time to time through e. As the temperature at which the metal flows into the receiver is very high it is advisable to lead an indifferent gas through it by c. J. D. Darling, in America, in the works of the Brothers Harrison, a t Phila- delphia, electrolyses sodium nitrate. The difficulty in this process is that the sodium when liberated reacts with the fused nitrate, and in the first place reduces it to nitrite, further electrolysis results in pure sodium being obtained.At the anode NO, is give!i up, and this then splits up into NO, and 0. Tlie nitrogen peroxide is absorbed i n water, and from this nitric acid is produced. I t was not found possible to work successfully with a common electrolyte for anode and cathode owing to the reduction referred to above. Darling therefore divided his cell up by meaiis of a diaphragm, the anode com- partment contained fused sodium nitrate, aiid the cathode compartment fused sodium hydroxide. It is, therefore, only necessary to feed sodium nitrate into the anode cell, and here decomposition takes place, NO', anions being given up and the Na cations passing to the cathode cell where they in turn are yielded up. The difficulty which now faced Darling was to obtain a diaphragm which could be employed in a fused electrolyte.The form of cell adopted is n . c B FIG. 8. illustrated in-Fig. 8. It consists of an iiiiier cell of perforated sheet iron ~vhicli is placed in an outer cell also of perforated iron. Tlie spaces between the two cells may he filled in with sand, magnesia, or brokeii glass, but the substance actually used is a mixture of Portland cement and magnesium oxide. The product is made by heating magnesite until it becomes hard and dense. It is then broken up so that it will pass through a ao-mesh sieve, but not through one of 30 meshes. This is mixed with Portland cement, moistened with water, and filled in between the two portions of the cell. The cell is made the cathode compartment, and is numbered 17 i n the diagram, Fig.9. It is placed within a closed iron vessel which coil- tains the fused sodium nitrate, fused caustic soda being in the cathode cell. The cathode compart- ment is surrounded by the iron anode, and the gases produced in the anode chamber'pass out through the tube marked with two arrows. It is found that the life of the metal part of the diaphragm is very much prolonged if about 5 per cent. of the current is allowed to pass through it. This, of course, meaiis a certain waste of energy, but it well repays itself by preventing the destruction of the cell. As shown in the diagram, the current which passes through the diaphragm is regulated by the resistance 3 1 . In practice twelve such cells are worked together, each cell taking 400 amperes at 15 volts. Every apparatus is made of an outer iron cell 55 cm.in diameter. The bottom of the cell is covered to a depth of 15 cm. with insulating material, such as Portland cement. The cathode cell rests upon this, and has a height of 75 cm., aiid an outer diameter of 40 cm., the inner diameter being 20 cm., and the depth 65 cm. The iron outer cell is connected with the + source of the current, the cathode, which consists of a 10 cm. iron tube, with the negative pole, At the coinnieiiceineiit of the electrolysis the cell is externally heated. Potassium is only innnufactured upon a very small scale, either elec-BEARING OF THE DISCOVERY UPON INDUSTRY 217 trolytically or by purely chemical processes. When it is manufactured by electrolytic means it is made by the electrolysis of potassium hydroxide, in similar apparatus to that used for the production of sodium.The practical difficulties, however, are greater than those met with in the manufacture of sodium, owing in part, at any rate, to the more ready oxidisability of the metal. The advance in these manufactures within the last decade is enormous, and the astonishing fact is that the process originally employed by Davy when he discovered the metals one hundred years ago is that adopted to-day. The process of Becker, in which a mixture of sodium hydroxide and carbonate is electrolysed is really only a modification of the Castner process. Darling's process by the electrolysis of sodium nitrate is the only one worked to-day in which an electrolyte other than sodium hydroxide is employed. The present-day production of metallic sodium is about 5,000 tons annually, and the price is 8d. per lb.; fifteen years ago it was nearly as many shillings. The preparation of the amalgams of the metals calcium, strontium, and barium has already been mentioned, p. 210. Davy prepared these amalgams by the electrolysis of the oxides. The only successful methods proposed for preparing these metals to-day are by means of the electrolysis of their fused salts. In 1856 Bunsen and Matthiessen succeeded in preparing small quantities of calcium by electrolysing the fused chlorides ; but Moissan, in 1898, was the first to prepare any quantity of calcium by means of the electro- lysis of fused calcium iodide.;k Owing to the high price of calcium iodide, this method cannot be employed on a commercial scale.On the other hand, it is a good laboratory method, because the calcium so obtained possesses a high Comfit. rend%, 1898, 126, 1753. VOJ;. III--T8*218 DISCOVERY OF ALKALI METALS BY H. DAVY’: degree of purity. Borchers and Stockem ::: obtained the metal as a spongy mass by electrolysiiig fused calcium chloride at a temperature below the melting-point of the metal. The spongy product so obtained contained from 50-60 per cent. of metal. By compressing this the excess of calcium chloride was forced out and a metal of c)o per cent. calcium obtained. The object of electrolysing the calcium chloride at a temperature below the fusing-point of the inelal was to prevent reaction ensuing between the calcium chloride and the metal. At a high temperature, a sub-chloride being produced- Ca + CaC1, = Ca,Cl,.Suter and Redlich have succeeded in getting over this difficulty by employing an electrode after the samc principle as that adopted by IZathenau and Suter for the manufacture of sodium, which has already been referred to, €7. 214. This kind of electrode might perhaps be describcd as as a surface-tension electrode, in Gcrniany it is called ‘‘ Berulirungselektrode.” Calcium chloride is thoroughly dehydrated, and then fused in a suitable electrolysing cell, modes of carbon being employed. The cathode is of iron, and is arranged to just touch the surface of the fused salt. Shortly after the current has been passed a globule of metallic calcium forms at the end of the cathodc. The cathodc is now slowly raised, so that the connection between the electrolyte and the electrode is between the metallic calcium.As iiior~: calcium is deposited out so the electrode is raised, until finally a long rod of the metal is produced at the ciid of the iron cathode. The bath being hot, and ;L heavy current being employed, the electrode remains This prevents the thin protective coating of calcium chloride which clings the calcium is unacted upon by the atmosphere during FIG 10. the course of the operation. Fig. 10 represents the elec- trode as it appears after the electrolysis has been in progress for some time. A is the iron cathode, I3 the metallic calcium, and C the electrolyte. At the comnienceinerit of the operation it is advisable not to employ too high a current density, or the temperature may rise too high and cause the calcium to redissolve as it is formed.According to P. Wohlcr,+ the commencing current should be 40 amperes per square centimeter, which should be gradually raised to 250 aniperes per squarc centinieter. This process is carried out at the Elektrochemischen Werke, at Bitter- feld. In France Poulenc Frkres also manufacture metallic ca1cium.f In this case a cathode of molten aluminium is employed, and an alloy con- taining 97 per cent. of calcium is produced. J. H. Goodwins has also described a laboratory furnace, from which very good results can be obtained. The furnace itself is made of Acheson graphite, and this constitutes the anode. The cathode is of iron, and can be raised or lowered by means of a screw arrangement. ‘l’he electrolyte consists of calcium chloride. The furnace is depicted in Fig. 11. E is a copper coil for circulation of water, through which is a thick piece of asbestos C, holding by the blocks D, the copper coil E well up in the Acheson graphite anode F, and insulated from it by the asbestos G. For __ hot and the calcium also keeps hot. -_ .. - - ___ -. - - - to the metallic calcium from delequescing, consequently * German Patent 144,667. German Patent 144,777. t Zeifschrift f u r Elektrocltemic, 1()05, 612. 5 Elecfrocltcrtricnl nrzd Mcinllurgicul lrtdustry I l l . , 80.BEARING OF THE DISCOVERY UPON INDUSTRY 219 the rest the apparatus explains itself. A metal of over 98 per cent. is obtained in this manner. The metals barium and strontium are also made from the electrolysis of their fused chlorides, but so far therc have been considerable difficulties in preparing them in the pure condition, and they have not been manufactured on a commercial scale. Davy also endeavoured to prepare mag- nesium by electrolysis, and apparently did prepare an amalgam of this metal with mercury. He was unsuccessiul in his attempts to prepare pure magnesium, but to-day both of these metals are manufactured by electrolytic methods. Calcium carbide was also iirst pre- pared by Davy, and now, as every one knows, this substmce is tnanufacturcd upon a very large scale by electrothermic methods. The work of Davy upon pieces of metal the size of pin hcads has resulted in the manu- facture of one of these metals by thousands of tons, and has branched out and borne fruits, which have resulted in the eiiiploynient of thousands of persons in various new indus- tries ; furthermore, science has been enriched in a manlier that even Davy in his wildest dreams could not possibly have foreseen. FIG. 11. NoTE.-The biographical portion of this paper was taken from Thorpe’s “ Life of Davy.” The other portions in connection with Davy’s work from two original papers. The portrait of Davy is reproduced from Ostwald’s Elecirochemie. Figs. 8 and 9 have been taken from Die EIektrometallurgie der Alkalimetalle, by H. Becker.

ISSN:0014-7672    

DOI:10.1039/TF9080300205

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

REVIEWS OF BOOKS. Monographien uber angewandte Elektrochemie. Band XXVIII. Die elektrochemische und elektrometallurgische Industrie Grossbritanniens. By J. B. C. KERSHAW. Translated into German by Dr. MAX HUTH. (Halle : Wilhelm Knapp. 1907. Price 9 M.) This monograph will certainly be useful to many who are interested in electrochemistry, as it gives a fair idea of the work which is being done in this country. Some parts of it are well up to date, but in other parts the author has relied too much upon old articles which he has at one time or another contributed to various technical journals, and seems to have forgotten that things have moved forward during the intervening years. For example, in speaking of the Hermite system for the production of hypochlorites, he says that the process was experimented with at Worthing, Lytham, Ipswich, and in Netley Hospital in the years 1890-1896, but he says nothing of the successful installation which has been in operation for the last two years at Poplar.Further on he refers to the want of success of the Hermite process, and quotes his own remarks of 1898, when he prophesied that the process could not compete with other methods of disinfection or sterilisation for sewage. I t may certainly be too expensive for treating sewage upon a very large scale, but so are all chemical methods of treatment. But as a deodoriser and for use in cases of sickness, owing to its odourless and non-corrosive character, there is no doubt but that it has great advantages. Our idea is that “monographs” upon different branches of electro- chemistry or upon any other subject should be written so as to give a clear idea of the work which is or has been done.The author of such a work cannot possibly be an expert in all branches of the subject, and therefore he should be very careful in his criticisms. We do not mean there should be no criticism, but where the subject is criticised, all sides of the matter should receive careful consideration ; and this can hardly be the case when prophecies made by the author of the monograph a decade ago are raked up to show his great foresight. Now, having criticised-and our remarks do not apply to the chapter on hypochlorites alone-we have pleasure in being able to praise a great part of the monograph. In the first place the illustrations are very good, and the author has evidently been at great pains to collect his material. Those who have not carefully watched the development of electrochemistry in this country may be surprised at the comparatively large amount of work which has been, or is being, actually carried on.For example, there is the aluminium industry, the alkali industry, the carbide-which, however, is very small at present, although there are signs of a revival, the electro- lytic refining of copper, the ilianufacture of phosphorus, the recovery of tin from tin scrap. Electrolytic iron is actually made in this country, although Mr. Kershaw does not mention this fact. The monograph can therefore be recoiiimended as stimulating reading. 220REVIEWS OF BOOKS 221 Deutsches Patentrecht fur Chemiker. By Dr.JULIUS EPHRAIM. Pp. 608 + xxvii. (Halle-a-S. : Wilhelm Knapp. 1907. Price 18 M.) This ponderous volume forms one-No. 25-of the well-known Monogm- phien i‘iber angewandte EEektrochemie, published by the enterprising firm of Wilhelm Knapp. We have specially added the term “ enterprising,” for it must require considerable courage to undertake the publication of a work of such dimensions as the one under review, devoted to the somewhat obscure subject of the German Patent Law. Would any English firm take a similar risk ? As the title explains, the book treats of the German Patent Law in its special relation to the great chemical industry; and, as the author says in his Preface, it is the only one of its kind devoted to a special technical branch.Making its appearance as it does just at the time when our own Patent Laws have been revised, the volume must naturally receive increased interest. At the same time it must remain a work intended more for the guidance of our German friends than for ourselves, for the number of usejjrl patents taken out in Germany by English people is very small compared with the number taken out by Germans. Rut be that as it may, the volume should be in the library of every chemist of an inventive turn of mind, as well as in thc libraries of all chemical manufacturers, as it contains a wealth of useful information for them. The plan of the book is laid out as follows :- There are in all eighteen chapters and an Addendum, with the following headings : (I) Invention in general.(2) The reality or individuality of the invention (Die Eigenart). (3) Limitations to the protection by patent. (4) Novelty. ( 5 ) Application for a patent. (6) The Patent Office. (7) Pro- cedure in patent matters. (8) The additional patent (Zusatz patent). (9) Inventor and applicant. (10) Annulment. (11) The working of the patent. (12) Rights of a patentee. (13) Limitations of those rights. (14) Transference of patents. (IS) Fines and compensations. (16) Duration of patent. (17) Samples and specimens. (18) International agreements. (Addendum) The German Patent Law. This summary of the contents is sufficient to show the thoroughness with which the author has carried out his task. It is not easy to review a work of this nature, as probably no one would sit down and read through over six hundred pages dealing with the ins and outs of patent law machinery, especially as by far the greater part must, from the very nature of the subject, be “dry” reading. All we can do is to record general impressions obtained, ‘‘ beim Durchblattern,” to use a con- venient German phrase.The first thing that strikes one is the number a11d variety of the examples quoted from actual patents to illustrate the text; and as these are always given in smaller print they are easily picked out. Interesting is the way in which the author shows the difference between an invention ” and a “ discovery ” (pp. 4 and s), and then how an invention results from a discovery (p. 7). Pp. 25-33 deal with the usefulness of the invention, and on pp. 89-91 the author points out the difference between “ Rentabilitat und I‘euvertbarkeit,” Le., between the technical and econo- mical use of a patent-two very different things.On p. 32, lines 16 and 25, there seems to bc a slight misprint-in the one case (line 16) we have ‘ I D.R.P. 26,012,” and in the other (line 25) (‘ D.R.P. 26,612 ”-and this is the only misprint we have noticed. Of course it is impossible to check the numbers of the different patents quoted, but from the care which the author222 REVIEWS OF ROOKS has bestowed on the work in general, we are inclined to believc that such errors are few and far between. Chapter IV., dealing with the novelty of an invention, will no doubt be of great service to all contemplating the taking out of a German patent. As regards prior publication, Dr.Ephraim thinks this can be in any language which can be “ understanded of the people,” even if it be unintelligible to the members of the Patent Office, such as Japanese, Chinese, Indian, and so on. Fulton, on (‘ Patents,” 2nd edn., p. 58, excludes such languages as Arabic or Chinese, and admits only those languages which are “ ordinarily known to an educated Englishman.” Apparently no case bearing on the point has ever been tried in the Courts of either country. Chapter V. discusses fully the methods for applying for a patent, and gives hints on the preparation of the specification, although this is perhaps best left to an experienced patent agent. The two following chapters, on the constitution and powers of the Patent Office and procedure in patent cases, arc probably of more interest to legal gentlemen than to chemists.Still, it was quite right to include them, as any unfortunate chemist who may be ensnared into a patent action in Germany can then console liiinself by studying the subject a little beforehand. Another interesting chapter for the inventor is Chapter X., dealing with the annulment of a patent, and over fifty pages are devoted to this subject. The remaining chapters are a11 of more or less importance, according to what particular question is under discussion. Their contents are sufficiently indicated by the summary given above. The Addendum on the German Patent Law is, of course, quite in place, and takes up about thirty pages. A 22-page index completes the work, which can be unhesitatingly described as an excellent contribution to the legal literature necessary for the inventor in the domain of chemistry.We cannot but praise the author for the extremely thorough way in which he has compiled such a mine of information, and congratulate him on the results of his labours. In conclusion, we would express the hope that his monograph-it is more than a monograph, it is an exhaustive text-book-may find its way to many libraries, and that he may thus be rewarded for the great service he has done to the chemical inventor. Monographien uber angewandte Elektrochemie. Band XXIX. Die englischen elektrochemischen Patente. Dr. P. FERCHLAND. (Halle : Wilhelm Knapp. Pp. vii. + 176. 1907. Price 9 M.) It is of considerable interest to have a collection of all.the patents which have been taken out over a certain number of years in any one branch of an industry. In an Introduction to the present volumc we learn that, although in a very slipshod manner, the English were the first to have Patent Laws. Since 1883 five different Patent Acts have been passed, and now again, in 1’307, another, and let us hope more satisfactory, change has been made in the Patent Laws. The patents are arranged in chronological order, commencing with No. 9,374 of the year 1842, the patent being that of H. B. Leeson, and is entitled, ‘( Deposition of Metals, particularly Platinuiii.” It was hoped, and we are sure it never got beyond a hopc, to deposit electrolytically platinum from its ores. So far back as 1852 we find patents takcn out for the manufacture of sulphuric acid.This patent of A. Wall is of considerable interest, bccause the intention of the inventor was to obtain the nitric acidREVIEWS OF BOOKS 323 iiecessary to oxidise the sulphurous acid by means of electric discharges, the object of these discharges being to oxidise atmospheric nitrogen. In 1855 a patent was taken out to obtain aluminium by electrolysis of aqueous solutions of aluminium salts; since that day many patents have been taken out on similar lines, which, of course, are absurd. In 1865 Elkington took out his patent for the electrolytic refining of copper, and this has been one of the most successful of all processes. We might go on picking out patents here and there, and showing how electrochemical prac- tice was gradually built up in this country, although it must be remembered that a considerable number of the patents taken out in this country were never meant to be worked. We mean they were taken out by foreign com- pctitors, simply to prevent manufacturers in this country working by these processes.We trust that by the new Patent Act of 1907 this will be no longer possible. Dr. Ferchland is to be congratulated upon the trouble he has taken, and British electrochemists would do well to obtain this book, and also the corresponding one which deals with the German patents. Study of these two books may suggest ideas, and will certainly help to prevent the taking, or the attempt to take, out patents upon subjects which have already been patented. Organic Chemistry. By J.B. COHEX, Ph.D., B.Sc. Pp. viii. +632. This book will be welcomed by all teachers who have classes of advanced students in organic chemistry, or who themselves require an advanced refer- ence book. While on the Continent there are many books on organic chemistry, there is rather a dearth of such books in this country. It is true there are several more or less elementary text-books, which are excellent in themselves, but there are very few which enter more deeply into the subject. Dr. Cohen has now supplied that want, and given us a very useful work. Owinq to the exccllent way in which the references are supplied the book will become to a considerable extent one of reference. It really consists of a series of essays upon different branches of organic chemistry, each subject being treated historically and brought right up to date, so that the gradual evolution of the theory and practice is elaborated.Being written in essay form, there are, of course, a good many subjects left out which some might desire to have included ; but taken altogether, the book contains a very large amount of useful matter. Stereochemistry is very much to the fore, there being sections on isomerism and stereochemistry, stereochemistry of unsaturated and cyclic compounds, stereochemistry of nitrogen, isomeric changes, steric hindrance, &c. The sections upon fer- mentation and enzymic action and upon the proteins deserve mention, and that upon the terpenes and camphors is also of particular interest The book is well got up and printed, but the binding might very well have been rather stronger.This work is quite sure of a hearty reception, and will certainly lighten the labours of lecturers in the higher branches of organic chemistry. (London : Edward Arnold. 1907. Price 21s.) Handbuch der Praktischen Elektrometallurgie. Von Dr. ALBERT NEUBURGER. Band 9. Series Oldbourgs Teclznische Handbibliothek. (Miinchen und Berlin : 1907. Pp. xx. + 466. Price 15 M.). To those engaged in technical electrometallurgy this book will be of great interest, as it is written by one who knows his subject well and has evidently taken much trouble to bring his facts well up to date. The electrometallurgy224 REVIEWS OF BOOKS of the metals is dealt with both in connection with electrothermic methods and in processes in which the metals are deposited from aqueous solutions.The first subject dealt with is the electrometallurgy of iron, and this is the first book which we have come across which treats of the subject in such detail, no fewer than 112 pages being devoted to the subject of iron and steel alone, and another twenty pages to alloys of iron, Possibly in his anxiety not to miss out any process which has been suggested or patented the author has included a good deal cf material upon processes which are not and never will be worked. This, of course, docs not matter to those who know, but is apt to be a little misleading to others, ;and they may go away with the idea that there are many successful methods, when actually there are only two or three. The subject, however, is made very clear and the diagrams are good.The theoretical considerations i n connection with the manufacture of the alkali metals might, we think, have been brought out a little more fully. Also the process of Acker might have been rather more fully described, and it would have been bctter to have included diagrams. There is a very good and thorough description of the electrolytic refining of copper, and a useful account of the various methods which have been experimented with in connection with the attempts which have been made to produce pure copper directly from its ores by electrolysis. The last forty pages of the book deal with the obtaining of the rarer metals from their compounds by electrolytic or electrothermic methods. As so many of the so-called rare elements are now coming into use commercially, e.g., tantalum for lamp tilaments, this section of thc book is one of special interest. The book is well illustrated and well printed, and we have pleasure in recommending it to students of electrochemistry.Handbook of Metallurgy. By Professor C.irir, SCHXABEL, Ph.D. Trans- lated by Professor HEXRY LOUIS, M.A. Second edition. (London : Macmillan & Co., Ltd., St. Martin Street, W.C. Vol. i., 1cp5 ; vol. ii., 1907. Vol. i.-Copper, Lead, Silver, Gold-pp. 1123. Price 25s. net. Vol. ii.--Zinc, Cadmium, Mercury, Bismuth, Tin, Antimony, Arsenic, Nickel, Cobalt, Platinum, Aluminium-pp. 867. Professor Louis's well-known first English edition of Schnabel's fine and comprehensive treatisc on Metallurgy appeared in 1898, and the grateful acknowledgments of all metallurgists are due to him for issuing this second edition, which brings the subject as far up to date as is possible in a large work of this kind.The descriptions of the various electrometallurgical methods in use are largely derived (some may think too largely) from the writings of Dr. Borchers ; naturally these sections, particularly in vol. i., are already somewhat behind the times, so rapid is electrochemical progress at present ; and the reader who looks here for the last word on this branch of metallurgy is likely to be disappointed, for many such processes familiar by name to the average mcmber of the Faraday Society-it is unnecessary to specify them-are here not referred to at all) and where they are the treatment is mainly historical.But Schnabel and Louis is sound and complete on the old lines, and we may be well content with that. Price 2 IS. net.) Steel Works Analysis. By Professor J. 0. Arnold and I?. Ibbotson. Third (London : 1907, Whittaker & Co., 2, White Hart Street, Pater- This, the third edition of a well-known and most useful little book, is a distinct advance on the two previous editions, and will certainly prove of Edition. noster Square. Pp. 468. Price 10s. 6d. net.)REVIEWS OF BOOKS great service both to the budding and experienced works chemist. The processes are practical, and such as are used every day in the steel works laboratory, and do not include a bewildering collection of alternative methods of analysis suggested by authors who probably mean well but have absolutely no idea of the routine work of such a laboratory, nor of the demands on the time of the chemist in charge.On the other hand, certain old and well-known methods given are now obsolete in laboratories where a great deal of rapid determinations are required, and in such cases the more rapid and equally accurate methods might well have been given. The section devoted to gas analysis is most useful, as also is the portion devoted to calorimetry of fuels. A new feature of this edition is the inclusion of methods for the analysis of brasses, bronzes, and white metal. A chapter on the analysis of high-speed steels is also useful, as is the chapter devoted to the analysis of ferro-vanadium, ferro-titanium, ferro-tantalum, &c. On the whole the handbook will prove a valuable addition to the works chemist’s library, and the processes given may be accepted as thoroughly tested and perfectly reliable. Electrons ; or, The Nature and Properties of Negative Electricity.(London : 1906, George Bell By Principal Sir OLIVER LODGE, F.R.S. and Sons, Portugal Street, W.C. Pp. 230. Price 6s. net.) The Corpuscular Theory of Matter. By Professor J. J. THOMSON, F.K.S. (London : 1907, Archibald Constable BE Co., Ltd., 10, Orange street, W.C. Pp. 167. Price 7s.6d. net.) With these two delightful books to read, one written by a brilliant exponent of physical science, himself a distinguished physicist, and the other by one of the foremost investigators of our day, nobody can complain that there is no opportunity for becoming acquainted with what the most modern science has to tell about the mysteries of matter and electricity.Sir Oliver Lodge’s book is an expansion of a lecture he gave to the Institution of Elec- trical Engineers in 1902, and his exposition is skilfully developed from the fundamental properties of a moving electric charge, Professor Thomson’s book is based on a course of lectures given at the Royal Institution in I@. While Sir Oliver Lodge’s treatment of the subject deals more particularly with the properties of the individual electron, Professor Thomson treats more fully on the properties of electrons en maw, the bulk of his book being devoted to metallic conduction and the number and arrangement of cor- puscles in atoms-two most beautiful adaptations of the electron theory, the latter of which in particular can never cease to excite wonder.The two books thus more or less unconsciously complement one another, and if anybody at all interested in the fundamentals of physical science has not yet studied these little books, we can only advise him to read them and meditate on them as soon as he possibly can.The Faraday Society was founded in 1903 to promote the study of Electro- chemistry, Electrometallurgy, Chemical Physics, Metallography, and in general those branches of pure and applied physical chemistry which do not come precisely within the scope of existing scientific and technical Societies. The subscription to the Faraday Society is L 2 a year for Members, and Lr a year The Society publishes quarterly Tmnsacfions, containing in full Papers which have been read with the discussions thereon, and reviews of books, and monthly Proceedings, containing Reports and Notices of Meetings, with abstracts of the Papers read during the previous month and of the discussions thereon, and abstracts of English and American Patents bearing on electrochemistry and electro- metallurgy. Advance proofs of all Papers are sent to every Member of the Society before they are read, the Papers being afterwards published in permanent form in the quarterly Transactions. for Students ; Members also pay an entrance fee of 61. Members also receive, free of charge, the Transactious of the Antcrican Electvo- clzemicn2 Socie~v, of which at present two volumes are published annuallv. I I Notice to Advertisers The Sole Advertising Agents for the Transactions of the FARADAY SOCIETY Electrical Press, Limited, are Advertising Agents and Publishers,

ISSN:0014-7672    

DOI:10.1039/TF9080300220

出版商:RSC    

年代:1908

数据来源: RSC