50 grains of each of the above salts were dissolved in 100 c.c. of water, and the amount of decinormal silver nitrate solution taken to obtain the reaction with potassium chromate is given in the table. In the last three cases the author has deducted the amount of silver chromate dissolved by the water alone, and has given the amount due to the solvent action of the respective nitrates. From all these solutions the silver chromate crystallized out again on cooling.

Silver containing Bismuth. W. Gowland. (Proc. Chem. Soc., March 17, 1887.) An account is given of assays and metallurgical experiments made with the object of determining the effects produced by the presence of small quantities of bismuth on the ductility of silver, and on the uniformity of composition of silver bullion when in ingots of the form and size ordinarily met with in commerce. It was found: a That when silver is obtained from copper containing bismuth by the liquation process, with subsesequent cupellation of the argentiferous lead, it contains part of the bismuth which was present in the copper; ẞ that this silver is brittle, even when containing bismuth in but small amounts; y that ingots of such silver are not uniform in composition throughout their mass, the parts which have solidified last being richer in silver than the others; and 8 that when coinage bars of 900° millesimal fineness are prepared from it, they cannot be rolled without special treatment, and even then are hard and unsuitable for mintage.

γ

Silver Subchloride. S. B. Newbury. (Amer. Chem. Journ., viii. 196.) The author has continued his research on the so-called subchloride of silver (compare abstract, Year-Book of Pharmacy, 1886, p. 35), and arrives at the conclusion that there is no satisfactory evidence of the existence of such a compound.

Silver Carbonate. G. S. Johnson. (Chemical News, liv. 75.) Silver hydroxide suspended in water and exposed to the air in a loosely covered vessel was found after two months to have deposited large, glistening, yellow, prismatic crystals of silver

carbonate. These melt at a low red heat, and soon afterwards decompose rapidly, with the evolution of abundance of gas. Silver carbonate precipitated from solutions by means of sodium carbonate is amorphous, but resembles the crystalline form in other properties. 1 litre of water saturated with carbonic anhydride at 15°C. dissolves 0.846 gram of pure precipitated silver carbonate, and when this solution is exposed to the air for twelve hours, a yellow precipitate of crystalline silver carbonate separates. Silver Phosphates and Arsenates. A. Joly. (Comptes Rendus, ciii. 1071-1074. From Journ. Chem. Soc.) Precipitated and amorphous silver phosphate dissolve in phosphoric acid solution, the solubility increasing with the concentration of the acid and the temperature. If a liquid containing less than 38 parts of phosphoric anhydride to 100 parts of water is saturated with silver phosphate at 80°, and allowed to cool, it deposits tri-silver phosphate in pale yellow rhombic dodecahedrons modified by faces of the icositetrahedron. The mother-liquor deposits no more crystals on standing, but will dissolve a further quantity of amorphous silver phosphate if heated, and thus the same solution of phosphoric acid can be used for the crystallization of an unlimited quantity of silver phosphate.

If the solution contains 40 parts of phosphoric anhydride to 100 parts of water, it deposits di-silver hydrogen phosphate, Ag, HPO4, in colourless crystals derived from an hexagonal prism. They generally form long prisms with rhombohedral terminations. In contact with water or alcohol they become yellow, and decompose into tri-silver phosphate and phosphoric acid, but they are not affected by ether. If the concentration of the phosphoric acid solution differs much from the strength given, the product is a mixture of crystals very difficult to purify.

When the crystals of di-silver hydrogen phosphate are heated to 110-150°, they yield silver pyrophosphate, Ag, P207, which can also be obtained by heating the syrupy solution of the silver phosphate to the same temperature. Hurtzig and Geuther obtained the same compound by adding ether to the solution which had been heated. The pyrophosphate is not, however, formed in the wet way, as these authors supposed, since under the given conditions of concentration, the fused acid salt, and not its solution, is decomposed. The experiment simply shows that di-silver hydrogen phosphate yields the pyrophosphate at a lower temperature than that at which phosphoric acid is converted into pyrophosphoric acid.

Silver arsenate is much less soluble than the phosphate in the free acid. If the solution contains less than 70 parts of arsenic anhydride to 100 parts of water, the solution saturated with amorphous silver arsenate at 80° deposits very brilliant, black, opaque crystals of tri-silver arsenate, which are unmodified rhombic dodecahedra. A solution of arsenic acid of the composition H3 As 04+H2 0, when saturated with silver arsenate, yields white monoclinic crystals of silver dihydrogen arsenate, a compound which is very readily prepared. It is decomposed into tri-silver arsenate and arsenic acid by a trace of water, and if heated to 100° yields silver metarsenate in the form of a white powder, which absorbs water very slowly. Before losing water, the crystals of the acid salt become red, probably owing to the formation of arsenic acid and di-silver hydrogen arsenate, Ag, H As O4. In fact, if a solution from which silver dihydrogen arsenate will crystallize is saturated with silver arsenate at a temperature a little below 100°, it deposits orange-red hexagonal prisms with rhombohedral terminations. Their form agrees with that of di-silver hydrogen phosphate, and indicates that they are di-silver arsenate, but they could not be purified.

When a syrupy solution of silver arsenate in arsenic acid is heated above 100°, it yields a white granular powder similar in appearance to the compound Ag2 O, 2 As2 05, described by Hurtzig and Geuther.

Arsenic Pentasulphide. L. W. Mc Cay. (Chemical News, liv. 287.) When a solution of an alkaline arsenate, strongly acidified with hydrochloric acid and saturated with sulphuretted hydrogen, is heated in a closed vessel at 100° for one hour, the arsenate is completely converted into pentasulphide. It contains no trisulphide, and, if due precautions have been taken to exclude air, no free sulphur. Pure arsenic pentasulphide is lemon-yellow in colour, does not yield any sulphur to carbon bisulphide, and dissolves in ammonia without separation of sulphur. When the ammoniacal solution is agitated with silver nitrate, and filtered, a clear filtrate is obtained, from which nitric acid precipitates silver arsenate. The formation of arsenic pentasulphide in this manner confirms Bunsen's results, he having obtained it by the action of sulphuretted hydrogen on hot solutions of arsenic compounds.

Combination of Stannic Chloride with Hydrochloric Acid. R. Engel. (Comptes Rendus, July 19, 1886.) The compound obtained by the author is a chlorostannic acid, corresponding in its composition to chloroplatinic acid.

Preparation of Cuprous Chloride. A. Cavazzi. (Gazz. chim. Ital., xvi. 167.) This salt may be very readily obtained by heating 4 grams of copper sulphate with 2 grams of sodium hypophosphite, and about 50 c.c. of water acidified with 30 drops of fuming hydrochloric acid. Copper hypophosphite is first formed, which is then acted upon by the hydrochloric acid, yielding cuprous chloride and phosphorous acid. The product thus deposited may be purified in the usual way.

Higher Oxides of Copper. T. B. Osborne. (Amer. Journ. Sc. [3], xxxii. 333.) The hydrated oxides of copper which have been described as resulting from the action of hydrogen peroxide on cupric hydrate, are found by the author to be mere mixtures, in different proportions, of cupric hydrate with the brown dioxide, Cu O2, H2 O.

Mercurous Sulphate. G. Buchner. (Chem. Zeit., x. 759, 760, and 790, 791; Journ. Chem. Soc., 1886, 852.) Mercurous sulphate was exposed under various conditions to air, light, moisture, and darkness: numerical data are given from observations extending over three years, and it is shown that light acts to a certain extent on this salt, but nevertheless when exposed under the most adverse conditions, the change produced-the decomposition extending only in one case to 14 per cent. of the mercurous sulphate-was never so great as to justify the classification of this salt amongst the very unstable compounds. It is best preserved in a moist state in presence of metallic mercury; or if dry it should fill a well-stopperd bottle and should be kept in the dark. The change into mercury and mercuric sulphate is reversed by the action of water, therefore for electrical purposes the slight decomposition of mercurous sulphate is of no consequence. For analysis, the mixture of mercurous and mercuric sulphates is digested with dilute hydrochloric acid; the mercuric salt remains in solution whilst the mercurous salt is precipitated as chloride. In the presence of mercury, the mercuric sulphate is also changed into mercurous chloride; therefore when such a change would be detrimental to the results required, titration with iodine and potassium iodide is resorted to. Treating the mixture with water, and observing the formation of yellow Hg SO4, 2 Hg O, does not answer with less than 10 per cent. of mercuric salt present.

Ammonio-Mercuric Chromates. C. Hensgen. (Rec. Trav. Chim., v. 187-198.) On dissolving mercuric oxide in ammonium dichromate, Hirzel obtained a compound to which the formula (N Hg2, H2O)2, 4 Hg Cr 04, was ascribed, although based only on

determinations of the mercury and chromium. In this paper, it is shown that mercuric oxide dissolves readily in a saturated solution of ammonium dichromate; golden, crystalline leaflets or needles separate out; these are insoluble in water, alcohol, and ether, very soluble in hydrochloric acid, but only sparingly soluble in dilute nitric or sulphuric acid. Analytical results showed the atomic ratio, Hg: N: Cr=1: 2: 2; and that three-fourths of the total nitrogen was in the form of ammonium, and the remainder in an amido-group, results which point to the composition (N Hg2, H2 O)2, Cr2 073 (N H ̧)1⁄2 Cr2 O7. These crystals when treated with excess of ammonia yield a canary-yellow powder, which no longer contains nitrogen in the form of ammonium, and to which the formula (N Hg2, H2 O), Cr O, is ascribed. If mercury chromate be digested with a warm, concentrated solution of ammonium dichromate, a brown solution is obtained, from which, on pouring into an excess of cold water, a yellow powder is deposited; the composition of the substance is (N Hg2, H2 O), Cr 04, the analogue of the selenate, (N Hg2, H2 O), Se 04.

Platinum Salts. E. Prost. (Bull. de la Soc. Chim., xlvi. 156– 160.) An acid solution of platinic sulphate, absolutely free from nitric acid, after standing for several days, yields an abundant brick-red precipitate, having the composition Pt S 0, (O H)2, 4 Pt (OH), 3 H2 O, the liquid becoming almost colourless; if, however, the solution of the sulphate is boiled, a precipitate having the composition Ptg S O4 013, 16 H2 O, is formed.

Double sulphates of platinum and the alkali-metals were prepared by mixing cold concentrated aqueous solutions of the alkaline and platinic sulphates, the latter being in excess; they are all pulverulent brown substances, the ammonium and rubidium compounds being soluble in water, whilst those of potassium are insoluble. The salts prepared were:

2

2 (NH4)2SO4, Pt. (SO4)3+25 H2 O; Pte Rb (SO4), +17 H2 O ; 3 K, SO4, Pt10 010(S O4)2 +34 H2 O;

2

5 K2 S 04 Pt18 O22 S O4+34 H2 0.

(Journ. pract. Soc., 1886, 985; Germanium is

Germanium, the New Element. C. Winkler. Chem., [2] xxxiv. 177-229; from Journ. Chem. compare also Year-Book of Pharmacy, 1886, 19.) obtained by heating finely powdered argyrodite with calcined sodium carbonate and flowers of sulphur at a moderate red heat. The product is extracted with water, and the solution treated with the exact amount of sulphuric acid necessary to decompose the