PART II. PHARMACEUTICAL CHEMISTRY. The Presence of Selenium in Sulphuric Acid of French Manufacture. J. Personne. (Compt. Rend., lxxiv., 1199.) The rarity of the occurrence of selenium as an impurity in sulphuric acid induced the author to publish the following note respecting the presence of this metalloid in certain samples of vitriol manufactured in the Department of the Seine. Its presence was first suspected from the fact that, on the addition of crystals of ferrous sulphate to the pure distilled acid, a brownish coloration was produced, similar to the reaction which would ensue were nitrous compounds present; and further, that when the acid was used for the preparation of hydrochloric acid, the distillate, having first acquired a deep yellow colour, gradually deposited a red powder. The examination of this coloured deposit led to the detection of selenium. The selenium was afterwards separated from the vitriol, by diluting the latter with four times its volume of water, and adding a solution of sulphurous acid. The precipitate thus produced was then taken up by agitating the liquid with carbon disulphide, and the selenium finally recovered from the solvent by evaporation. In this manner 0.2 gram of selenium was obtained from three litres of sulphuric acid. The author is still in doubt respecting the origin of the pyrites from which this sulphuric acid was manufactured, but expects shortly to be able to offer some satisfactory information upon this important point. M. Lamy (Compt. Rend., lxxiv., 1285) states that the occurrence of selenium in sulphuric acid of French manufacture was observed by Kuhlmann and himself ten years ago; and M. Scheurer-Kestner (ibid., 1286) says that the same fact was noticed by himself in two papers, published in 1868 and 1870, in the Bulletin de la Société Chimique de Paris. The Concentration of Sulphuric Acid. R. Hasenclever. (Chem. News, xxvi., 174.) As is well known, sulphuric acid as it comes from the leaden chambers, is concentrated first in leaden apparatus of varying forms and sizes, and lastly in utensils made of either glass or platinum. It is to the concentration in these leaden vessels that the author chiefly directs attention. The apparatus most commonly in use are (1.) Evaporating pans of sheet-lead placed on pans of cast-iron, below which a fire is heated. The objection to this method is that the acid is very liable to be overheated, and so rapidly destroy the leaden pans. Besides contaminating the acid largely with lead, it is not to be recommended either for economy in the consumption of fuel, or in loss of acid. (2.) Leaden pans heated by a reverberatory furnace, the flames playing over the surface of the acid. By this method the acid is readily overheated, while with smoke and other products of combustion much sulphuric acid is carried away and lost. It has on this account been much discontinued. (3.) Concentration by high-pressure steam. This method of concentration is superior to the other plans. It consists essentially in causing super-heated steam to circulate in a coil of leaden pipes placed at the bottom of a wooden lead-lined tank containing the acid. In a tank four metres in length and width, five tons of chamber acid may be concentrated to 1.7 in 24 hours. The steam in the boiler is at a pressure of 45lbs., and the quantity of fuel consumed is very small. This process yields therefore a purer acid at considerably less expense. (4.) Concentration by means of heated sulphurous acid gas. In this process advantage is taken of the heat of the sulphurous acid as it is liberated from the pyrites kilns. The concentration pan is placed between the kilns and the chambers, so that should it require repairs they can be effected without stopping the manufac ture of the acid. By the direct action of the heated kiln gases evaporation ensues; the sulphurous acid is strongly cooled before it enters the chambers; the sulphuric acid which is evaporated, and also the steam, enter the chambers, so that no loss of gas ensues; while, at the same time, less steam need be supplied to the chambers. The acid thus concentrated is not quite pure, which for certain purposes is objectionable, but for sulphate of soda making, dissolving coprolites or other native phosphates, it is quite pure enough. Action of Phosphorus on Alkaline Solutions of Metals. A. Oppenheim. (Deut. Chem. Ges. Ber., v., 979-981, and Journ. Chem. Soc., 2nd series, xi., 244.) When an ammoniacal solution of copper oxide, nickel oxide, silver oxide, or cadmium oxide is heated with phosphorus and a little benzine in a vessel connected with a reversed condenser, dark precipitates are formed, which may be washed with water, alcohol, and carbon sulphide, and dried in vacuo. The copper precipitate consists chiefly of metallic copper and copper oxide. Nickel gives a black precipitate consisting of a mixture of nickel phosphide and a salt of one of the acids of phosphorus. From the silver solution metallic silver is reduced. The cadmium solution gives a brown precipitate, of varying composition, which is decomposed by hydrochloric acid with evolution of hydrogen phosphide, and explodes with nitric acid. On heating it in a current of hydrogen, it leaves cadmium phosphide (Ca, P2), as a grey crystalline mass with metallic lustre. An ammoniacal solution of zinc oxide is not acted on by phosphorus, even when heated with it in closed tubes. A solution of lead oxide in caustic potash gave, when boiled with the phosphorus, a black precipitate of metallic lead, containing only about 04 per cent. of phosphorus, and from a solution of stannous oxide in potash, a white slimy body separated out. Cyanogen in Bromine. T. L. Phipson. (Chem. News., xxviii., 51.) The author has recently discovered in bromine, issued as pure for pharmaceutical use, a notable amount of cyanogen. It has long been known that in the manufacture of iodine, a certain quantity of that beautiful but dangerous compound, iodide of cyanogen, sometimes finds its way into one of the glass condensers; and it would appear that a similar compound may occur in liquid bromine-all the more dangerous from its being dissolved in and masked by the liquid. The presence of cyanogen in bromine may be detected in the following manner : Take (sayoz.) equal weights of bromine and iron filings; add to the filings four or five times their weight of water; mix in the bromine very gradually, stirring all the time; filter rapidly while warm from the reaction; place the filtered liquid in a partly closed bottle; and in the course of some hours a deposit of ferricyanide of iron (Berlin blue) will have formed, and may be collected in a filter. In the course of two days (with the above quantity), the whole of the cyanogen is thus eliminated. The author has found from 0.5 to 1 per cent. of cyanogen in samples examined by him. If perfectly pure bromine were used, the same process would admit of the detection of cyanogen in steel. On the Hypophosphites. C. Rammelsburg. (Journ. Chem. Soc., 2nd series, xi., 1.) In this paper, which is printed in full in the Journ. Chem. Soc., the author gives the results of his investigations |