A Revision of the Atomic Weights of Sodium and Chlorine |
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A Revision of the Atomic Weights of Sodium and Chlorine Theodore William Richards,Roger Clark Wells No preview available - 2015 |
Common terms and phrases
Acad adsorbed AgCl ammonia ammonic chloride ammonic formiate amount analysis argentic chloride argentic nitrate asbestos shreds atomic weight average bicarbonate cent Chem chloric acid chlorplatinate cipitate containing Corrected excess counterpoise crystals curdy decanted determined dilute dissolved distilled electrolyte end-point error experiments filter final series flask fusion glass Gooch crucible grams Hence hydrochloric acid hydrogen ignition impurity later lime liter loss material metal method milligram mother liquor NaCl nephelometer nitric acid obtained occlusion of sodic Oeuvres opalescence oxide oxygen platinum possible precautions precipitate prepared present probable Proc pure water purest silver purity quantity RATIO OF SODIC recrystallized residue Richards salt sample seems silica silver chloride silver nitrate slight sodic carbonate sodic chloride sodic hydroxide sodic nitrate solubility of argentic specimen Stas substances sulphate synthesis of argentic temperature tion tube vacuum wash waters weight of argentic weight of silver weight of sodium
Popular passages
Page 19 - This copper solution, in its turn, flows over old scrap iron for the precipitation of the copper. In the precipitation of the silver a certain amount of copper is found mixed with the silver in the form of cuprous oxide and of small scales and scraps of metallic copper, and a process of refining is necessary previous to melting. This copper is removed by prolonged boiling with water containing a small quantity of sulphuric acid, into which air is injected by means of a small jet of steam. Sulphate...
Page 19 - The white metal from this concentration-smelting contains, on an average, from 700 to 800 ounces of silver and 10 ounces of gold per ton and 60 per cent, of copper. Each ton of this matte represents from 20 to 21 tons of ore. This white metal is now ready for the extraction of the silver, which comprises the following operations: Rough roasting. Fine grinding. Fine roasting for sulphate of silver. Leaching, and the precipitation of the silver. Refining and melting of the cement silver. The metal,...
Page 17 - No metals were found in it by electrolytic treatment. The sodic hydroxide used, after settling and decantation, had been electrolyzed until iron was completely removed. This slow but effective way of removing foreign metals was hastened by using a rotating cathode, while a fixed anode stirred the solution. The argentic chloride was precipitated from a somewhat dilute solution, to avoid the occlusion of impurities, and must be thoroughly washed. It is best to wash...
Page 24 - The preparation of pure lime upon which to fuse the silver was a matter of great importance, because of the danger that any impurity in it might contaminate the silver. Its preparation was begun by dissolving marble in nitric acid, boiling with an excess of calcic hydroxide, filtering, neutralizing, and twice recrystallizing the calcic nitrate.
Page 69 - Fused argentic chloride probably contains traces of dissolved air, but not enough to affect essentially its weight, since subsequent fusion in vacuum caused no appreciable loss of weight. 7. The most difficult question in the purification of silver was found to be the elimination of the inclosed mother liquor without introducing other impurities. Fusion on pure lime, first in pure hydrogen and then in a vacuum, is the safest method. Stas's silver must have contained at least as much oxygen as Dumas...
Page 18 - ... from which it was deposited.* This important impurity, consisting wholly of water and argentic nitrate, can be eliminated only by fusing the silver, a matter which will soon be discussed. Besides this very pure material used in the work on sodium, several new samples of at least equal purity were made for the even more critical work on chlorine. Three of these new preparations were made from thrice crystallized pure argentic nitrate.
Page 63 - ... with the precipitate could be weighed. Accordingly, a new method was devised, a modification of one of those used by Stas, employing quartz vessels instead of glass. A quartz dish was accurately weighed by substitution of a counterpoise of a similar composition, surface area, and weight. A watchglass to serve as its cover was weighed in a similar fashion separately. A weighed piece of silver was placed in the dish, which was supported in a large empty "desiccator," whose bottom and sides were...
Page 58 - ... silver chloride. The weighed silver was dissolved with all the precautions used in previous work and precipitated as chloride by hydrochloric acid at concentrations of about fifth normal. Hydrochloric acid was added in excess and the precipitate was washed three times with dilute hydrochloric acid, in order to diminish as much as possible the solubility of the silver salt. After collection on a Gooch crucible, drying at 150°, and washing the bulk of the precipitate was fused in a porcelain or...
Page 19 - After solution in nitric acid, it was crystallized fifteen times from acid solutions with centrifugal draining. The solubility in cold nitric acid is so slight that this train of purification could be effected without serious loss. Even after the second crystallization the salt was free from any observable trace of copper, and all other metallic impurities must have been eliminated before the last crystals were obtained. The pure argentic nitrate was dissolved in pure water and precipitated by hot...
Page 70 - Havard work are explained by thorn, and the atomic weight of nitrogen computed from ammonia is brought nearer to the value required by Avogadro's rule. Other anomalies appear in other places, however, and it is clear that many new atomic-weight investigations must be instituted to explain them, with due attention to hitherto unheeded dangers, especially of occlusion. Authors. 130. Parsons, Ch. L. — „Notiz über das Atomgewicht von Kohle und Beryllium.