Scientific Serials

Abstract

THE Journal of the Chemical Society for March contains the following papers read before the Society:—On the preparation of standard trial plates to be used in verifying the composition of coinage, by W. Chandler Roberts, chemist of the Mint. The author had been instructed by the Lords of the Treasury to prepare new plates of gold and silver for comparing annually with the coinage being issued, in order to guarantee the fineness of the latter. The gold plate consists of an alloy of copper and gold ranging in composition in its different parts from 916.5 to 916 7 parts of fine gold in 1,000 (the standard is 916.66). This plate did not present much difficulty in its preparation, since the two metals were obtained in a state of perfectly homogeneous mixture after repeated meltings. The silver plate presented much greater difficulty owing to the tendency of the silver to concentrate itself in the centre of the mass. The difficulty was overcome by casting the alloy into a plate, which was then planed down on both surfaces and afterwards greatly extended by rolling; a portion cut out from the side of this plate served for the new trial plate. Its composition ranges from 924.6 to 925.1 parts of pure silver per 1,000 (925 being the standard). The author has also constructed supplementary plates of pure silver and gold. An interesting table of assays of trial plates from 1477 down to the present time is given.—Mr. J. Hannay contributes a description of a sp. gr. apparatus for temperatures other than atmospheric.—Dr. Gladstone and Mr. Tribe give the fourth part of their researches on the action of the copper-zinc couple on organic substances. They have now turned their attention to the series containing the C_nH_2n—₁ radicals, the first body acted upon being iodide of allyl, which yields with the dry couple a resinous body of the formula n(C₃H₄), but when mixed with ether rapid decomposition sets in at ordinary temperatures, and the ethereal solution gives zinc oxide on mixing with water. All attempts to isolate zinc-allyl have, however, failed. Allyl iodide and water acted upon by the couple give propylene C₃H₅I₊ H₂O + Zn=ZnI.HO + C₃H₆. The iodide mixed with alcohol is acted upon violently by zinc alone yielding propylene C₃H₂I + C₂H₆0 + Zn=Zn {C₂H₅O + C₃H₆.-On ferrous anhydro-sulphate, by T. Bolas. A mixture of 10 per cent, of a saturated aqueous solution of ferrous-sulphate with oil of vitriol deposits, on cooling, small white prismatic crystals having the formula FeS₂O₇. When exposed to moist air the anhydro-sulphate yields granular crystals of the formula FeS0₄.6H₂O.- On tetranickelous phosphide, by Dr. R. Schenk. This substance (Ni₄P₂) was obtained by adding a sufficient quantity of tartaric acid to a solution of nickelous chloride, to prevent precipitation by potash, boiling the potash solution with phosphorus and then drying the precipitate in a stream of hydrogen. The remainder of the journal is devoted to the usual abstracts from other journals, British and foreign.