Personal- und Vorlesungsverzeichnisse der Technischen Hochschule und Universität Stuttgart: Technische Hochschule Stuttgart. Personal- und Vorlesungsverzeichnis für das Sommersemester 1935

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Titel:: Personal- und Vorlesungsverzeichnisse der Technischen Hochschule und Universität Stuttgart

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Persistenter Identifier:: 1530689129952_1935_1

Titel:: Technische Hochschule Stuttgart. Personal- und Vorlesungsverzeichnis für das Sommersemester 1935

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Cn aro} Researches in Chemical Equivalence. causing a nuisance to the surrounding neighbourhood, al- | freshly precipitated mercuric oxide, which throws down :hough a similar result might be obtained by colle@ing the nickel as oxide and cyanide. The cobalt in the filtrate and liquefying the sulphurous acid. is then precipitated as mercurous cobalticyanide. On the The more incombustible materials it is found pradicable gnition ofthese precipitates, nickelous oxide and cobaltic to employ without too great a loss of temperature, the Oxide are respectively left behind. We converted the wider will become the application for the process; for xides into sulphatesand weighed them as such. (Through- there are many ores, including silicates and carbonates, >ut the whole of these experiment the nickel and cobalt containing metals in the form of oxides, which might be were always weighed as sulphates.) We found, however, conveniently smelted by mixing them with a sufficient ‘hat after the expulsion, by ignition, of the mercury in the proportion of pyritous ores to effect their reduction; in nrecipitates, the oxides were left in so dense and compact ‘ad, one of the chief practical questions connetted with a state that it was only with the greatest difficulty that this process is how far it may be trusted to effet the they could be converted into sulphates. To remedy this smelting of ores or furnace-charges containing compara- a weighed quantity of pure baric sulphate was added to tively moderate proportions of sulphides. It is evident :he liquid before precipitation; the precipitate, becoming that it will almost entirely obviate the necessity for using mixed with the baric sulphate, was thus spread over a carbonaceous fuel, at least as far as the produdion of a ‘arge surface, so that the oxide was obtained in a finely regulus is concerned, and consequently the localities in divided state, and easily converted into sulphate. which smelting operations may be advantageously carried In the experiments with this process, the nickel was in- on are thus greatly multiplied. One of its chief merits is rariably found too high. This was at first thought to be that it is equally applicable, with comparatively little extra due to alkali which might cling to the precipitated oxide ; cost in the working, to very poor and very rich ores; for and, on testing, some potash was actually found in the however small the resulting regulus, it will contain nearly orecipitate, which had been thoroughly washed. To re- the whole of the cobalt, nickel, copper, silver, and gold move this source of error the nickelous sulphate, instead present in the furnace-charge, while any lead, zinc, anti- of being weighed as such, was dissolved in water, excess mony, and arsenic will be obtained as sublimates. of ammonia added, and the nickel deposited on a platinum zrucible by means of two Grove’s cells. Bat the nickel was, with this method, still found too aigh, and we then thought that the separation had not been serfe@. On testing the deposit, a considerable amount of sobalt was, in fa&@, found in it, and the operation re- quired to be repeated three times before the separation was zomplete. The next process we tried was devised by Rose.* It sonsists in saturating with chlorine a very dilute solution »f the mixed salts, adding baric carbonate in excess, and allowing to stand from twelve to eighteen hours, with sccasional shaking. The cobalt then falls as sesquioxide, ‘he nickel remaining in solution. But the results obtained by this method, as was also the zase with Henry’s modification of it (which consists in substituting bromine for chlorine) were very variable. In ‘he former case the cobalt was generally found too low, aven after standing over eighteen hours; the result ap- searing to depend a good deal on the liquid being shaken ap at regular intervals, which cannot be very conveniently ione during an entire period of eighteen hours. In the latter case the cobalt was generally found too high, nickel heing precipitated along with it. The last method tried, and the one finally adopted, is jue to Gibbs.t In this the neutral solution of the sul- phates is boiled with plumbic peroxide. The cobalt is then precipitated as a higher oxide, while the nickel re. mains in solution, along with a small quantity of lead. “The author of this process does not claim very great accuracy for it, but we have found it to be of adequate accuracy. The manner in which we operated was as follows ;— The perfectly neutral solution of the mixed sulphates was soiled for half an hour with plumbic peroxide, about 7 grms. of the peroxide being taken to 1 grm. of cobaltous sulphate, and the volume of the liquid being about 100 cub. centims. The liquid was then filtered, and the fil- trate evaporated to about 20 cub. centims. Some aqueous hydric sulphide was then added, and the small quantity of plumbic sulphide formed filtered off. The solution of nickelous sulphate was then evaporated to dryness in a weighed crucible, ignited, treated with a little hydric sul- shate, heated to very dull redness, and weighed. The Srecipitate containing the cobalt, with excess of plumbic Seroxide and some sulphate, was boiled with hydric chlo- ‘ide until dissolved. Water was then added, and the lead precipitated with hydric sulphate and alcohol. The fil- trate from the plumbic sulphate was then evaporated to dryness, heated till the excess of hydric sulphate was * Pogg. An. 1xxi., 545. - + Silly Ate Fir BiV:; 205+ ALTHOUGH the chemistry of nickel and cobalt is interest. ng from many points of view, it is more especially attrac. tive from the probable isomerism of these metals. Their :ombining proportions, in fa&, according to the most valuable evidence we possess,} appear to be entirely the same. We, therefore, thought it very advisable to inquire on what terms they might prove to be mutually equiva- ent; and the particularequivalence we have examined has seen equivalent precipitability of the sulphates, by sodic hydrate, from an aqueous solution. I. Preparation of the Salis. The pure cobaltous salt was prepared by converting some excellent commercial crystallised chloride into luteo- chloride, the process employed having been already described by one of us.§ The luteochloride was purified ay precipitation with hydric chloride, and the mixture of oxides it left behind on ignition was evaporated with re- distilled hydric sulphate. The pure nickelous salt was prepared from a sample of nickelous chloride which contained copper, lime, and iron, but no cobalt, The copper present was precipitated with hydric sulphide, and the nickel in the filtrate was precipitated by hydric oxalate, in an acid solution, The nickelous oxalate was washed thoroughly with dilute hydric nitrate, ignited, and the oxide so formed heated with pure hydric sulphate, and so converted into sulphate. LI. Method of Separating Nickel from Cobalt. We had next to seled a method for the quantitative separation of nickel from cobalt. The first to which we had recourse was Liebig’s,|| which consists in adding hydric tyanide and potash to the mixed saline solutions, thereby forming nickelopotassic cyanide and potassic cobalticvanide : these new compounds are boiled with A Paper read before the Royal Society, June 19, 1879. > LE Part 11. see Proceedings of the Royal Society, vol, xxviii. 1 Russell, Journal e i et: + 204. § Pham Rs Lui sy oy (S800 Pao J Ann, Ch, Pharm. 1xv., 244.

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Metadaten: Chemical news and Journal of physical science (Volume 40, 1879 (July - December))

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