THE ANALYST. 161 INORGANIC ANALYSIS. The Precipitation of Metals by Bismuth Oxide. J. Aloy. (Bzdl. soc. China., 1902, xxvii., 136, 137.)-Lebaigue (Jouriz. de Pharm., xxxix., 51) stated that bismuth oxide, when boiled for about fifteen minutes with solutions of metallic salts, pre- cipitated ferric, aluminium, and chromium in the form of hydroxides, but W&S without action upon ferrous, cobalt, nickel, copper, and lead salts. He recommended the reaction as a means of separating these classes of metals in analysis. The author, however, finds that the reaction is not so simple as Lebaipe supposed, and that it is not applicable to analytical work. On boiling freshly-pre- cipitated bismuth oxide for an hour with solutions of the different salts, he obtained the following results : Ferric Salts.-The iron was only completely precipitated from very dilute solutions.Ferroz~s Salts.-Bismuth oxide precipitated the iron in the cold, and more rapidly on boiling, as a, white amorphous precipitate, probably consisting of a mixture of basic salts. llilaw ya9zese yielded a precipitate of hydroxide, but the precipitation was only partial. Copper was also partially precipitated from concentrated solutions, yielding bluish- green basic salts in the case of the chloride, sulphate, and nitrate, and as black hydroxide from a solution of the acetate. Cobalt, nickel, lead, zinc, and cadmium were also partially precipitated from solutions of their salts. Anhydrous bismuth oxide behaved in the same way as the hydroxide, but the reactions took place more slowly. The precipitate consisted of oxide.Aluminium was only completely precipitated from very dilute solutions. C. A. M. On the Influence of Hydrochloric Acid on the Precipitation of CuproU8 Thiocyanate. R. G. van Name. (Zeits. anorg. Chern., xxx., 122.)-Continuing his investigations on the precipitation of cuprous thiocyanate (Zeits. anorg. Chem., xxvi., 230), the author found that the precipitation is practically complete, provided the amount of free hydrochloric acid left after the addition of the ammonium bisulphite and thiocyanate does not exceed 0.5 per cent. of the total volume of the solution, and also provided that the solution does not contain an excessive amount of ammonium salts, which exert a solvent action on the precipitate. The addition of a moderate excess of ammonium thiocyanate, however, is recommended if the above conditions cannot be satisfied, as cuprous thiocyanate is more insoluble in weak solutions of this salt than in pure water, solutions of other ammonium salts, or dilute hydrochloric acid.A. G. L,162 THE ANALYST. Use of Phosphoric Acid in Analysis of Iron Alloys. T. H. Byron. (Journ. SOC. Chem. Ind. , xxi., 214.)-Ferrosilicon, spiegeleisen, etc., dissolve readily in phos- phoric acid, but the silica is left in such a gelattinous condition that filtration is impracticable. Phosphoric acid may, however, be used with advantage to determine chromium in ferro-chromium alloys and in chrome iron ores. The chromium is oxidized with permanganate and titrated with ferrous sulphate and bichromate.The results agree with those obtained by the older, more laborious method. A. M. Estimation of Sodium Thiosulphate, Sulphite, and Sulphide.-Duprd and W. Korn. (Zeits. f. angew. Chem., xv., 225.)-In order to estimate thiosulphate in the presence of sulphite the latter is decomposed, by boiling with about four equivalents of acetic acid and twelve of sodium acetate for one or two hours. Under these conditions thiosulphate is not decomposed and can therefore be titrated with iodine solution. The time of boiling may be reduced to about half an hour if the last traces of sulphite are removed by oxidation with potassium chlorate. About a gramme of chlorate is added, and the boiling is then discontinued. If thiosulphate, sulphite , and sulphide all be present, they are first all determined by running into iodine solution acidified with hydrochloric acid, In a second portion the sulphide is precipitated by the addition of cadmium carbonate. The solution is filtered, and the filtrate is divided into two portions.In one portion thio- sulphate + sulphite are determined, and in the other thiosulphate is estimated a ~ ) above. From the three values thus obtained the individual constituents can be calculated by subtraction. A. M. The Quantitative Separation of Hydrochloric and Hydrocyanic Acids. Theodore William Richards and Sidney Kent Singer. (Amer. Chem. Journ., xxvii., 205.) - The authors find that hydrocyanic and hydrochloric acids can be quantitatively separated by boiling their aqueous solution for some time, preferably in a common retort, the neck of which is directed upwards at an angle of 45", the evaporated water being replaced from time to time.The solutions should not be more than tenthnormal in regard to the hydrochloric acid. When little or no hydrochloric acid is present, as in the estimation of the chloride contained in potas- sium cyanide, two hours' boiling is sufficient to remove all the hydrocyanic acid; but when the solution contains a fair quantity of hydrochloric acid eight or nine hours' boiling is requisite. The difference in the behaviour of the two bodies on boiling is due to their very great difference in dissociation in aqueous solution ; and the fact that in the presence of hydrogen chloride a longer boiling is necessary to expel all the hydrocyanic acid appears to be due to the formation of complexes between the chlorine ions and the undissociated hydrocyanic acid.A. G. L. The Behaviour of Nitric and Nitrous Acids with Brucine and Sulphuric Acid. (Zezts. f. angew. Chem., xv., 170.)-In reply to Lunge's paper (&id., xv., l), Winkler finds that the reaction of nitrous acid with brucine L. W. Winkler.TEE ANALYST, 163 and sulphuric acid depends upon the proportion of sulphuric acid present. If equal volumes of concentrated acid and water be used deep red coloration results. With 2 volumes acid to 1 of water-the proportions recommended by Winkler for water analysis-a rose coloration is produced. With stronger acid the colour becomes less pronounced, and when 4 volumes sulphuric acid are present to 1 volume water-the proportions used by Lunge (Zoc. &.)-there is no reaction in consequence of the fornia- tion of nitrosylsulphuric acid. The results obtained by Lunge are thus brought into agreement with those of Winkler. With 2 volumes water to 1 volume sulphuric acid there is no coloration, but with 1 volume water to 2 volumes sulphuric acid a nitrate gives a coloration equal in intensity to that given by an equivalent amount of nitrite. By taking advantage of these pecu- liarities it is possible to test a water separately for nitrates and nitrites, using the same reagents, brucine and sulphuric acid. Lunge (Zeits. f. angew. Chem., xv., 241) confirms Winkler’s results and withdraws his previous remarks. On the other hand, nitrates give no reaction unless the acid be strong. A. M.