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When fragments of the compressed cylinders were heated at 160° for some hours and then again analysed, the percentage of barium sulphate was found to have been very much diminished. The author intends further to investigate this influence of heat; and also the double decomposition of mixtures of dry substances under ordinary pressures. He finds that when dry copper sulphide is shaken with dry silver nitrate, double decomposition takes place. L. T. T.

Calcium Silicostannate. By L. BOURGEOIS (Compt. rend., 104, 231-233).—Three parts of silica and four parts of stannic oxide are heated with an excess of calcium chloride to bright redness for about eight hours, and the cooled mass extracted with water. If the time of fusion has been short, the residue is a mixture of tridymite and cassiterite, but if the reaction has proceeded further the residue consists of calcium silicostannate, whilst if the heating has been too far prolonged, the products are calcium bisilicate and calcium. stannate.

Calcium silicostannate, CaO,SiO2,SnO2, analogous to sphene, is obtained as a brilliant white powder consisting of monoclinic prisms somewhat less birefractive than those of sphene; sp. gr. 4·34. They are not attacked by acids, potassium hydrogen sulphate, or solutions of alkalis, and are less fusible than sphene.

A mixture of silica, stannic oxide, and titanic oxide, with calcium chloride, yields similar crystals, which contain all three of the dioxides. Crystals of cassiterite form on the upper part of the crucible, and if the action is prolonged icositetrahedrons of the composition 3CaO,Al2O,,3SiO2 are formed by the action of the fused mixture on the crucible.

C. H. B.

Solubility of Gypsum in Solutions of Ammonium Salts. By S. COHN (J. pr. Chem. [2], 35, 43–56).—Droeze has already shown (this Journal, 1877, ii, 112) that the solubility of gypsum in solutions of salts decreases with the concentration of the salt solution, except in the case of ammonium nitrate solution, when the solubility first increases and then decreases. The author has determined the solubility of gypsum in solutions of different ammonium salts of varying strength. The results of several experiments point to the following conclusions:-1. The irregularity observed by Droeze in the case of ammonium nitrate exists also in the case of the chloride, but not in the case of the sulphate; this difference is possibly due to a chemical reaction taking place with the gypsum. 2. Ammonium sulphate increases the solubility of gypsum, probably forming readily soluble double salts. 3. Ammonium chloride, nitrate, and acetate, increase the solubility of gypsum by double decomposition, readily soluble calcium salts being formed. 4. The decomposition of the gypsum by the ammonium salts increases with decreasing concentration. 5. Gypsum dissolves most readily in ammonium acetate, then in nitrate, chloride, and sulphate. 6. This order holds good for the readiness with which gypsum is decomposed by the salts.

The methods employed in preparing the solutions and determining the amount of gypsum are described. N. H. M.

Crystallography of Cadmium Borotungstate. By G. LINCK (Zeit. Kryst. Min., 12, 442-446). Two kinds of crystals are obtained from the concentrated solution of cadmium borotungstate, which, according to Klein (Abstr., 1881, 1168), has the composition 9WO,B2O3,2Cdo + 18H2O. The crystals which separate out first are of a bright yellow colour and tabular in form (Analysis I); whilst the others are of a yellowish-brown colour, and have a pyramidal form (Analysis II). Analysis gave the following results:

[blocks in formation]

Neither of the salts analysed correspond with Klein's formula, in that they contain much less water of crystallisation and more chemically combined water.

The yellow crystals belong to the monosymmetric system; the axial ratio being a b c = 1.3321: 1: 1·1383; B = 57° 47'. The forms observed were OP, coPco, coRco, Poo, R∞o, 6Pcs.

The brown crystals belong to the asymmetric system; a: b:c= 0.6261 1 0·4398. : a = 114° 56′; 8 = 92° 47', y = 94° 57'. The following planes were observed:-OP, coPco, coÏco, co'P, cop', P, P'.

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B. H. B.

Higher Oxides of Copper. By T. B. OSBORNE (Amer. J. Sci. [3], 32, 333-342).-The various coloured hydrated oxides of copper obtained by treating cupric hydroxide with hydrogen peroxide, are all mixtures in varying proportions of the brown dioxide, CuO, H2O, with cupric hydroxide. The author has also experimented on the so-called sesquioxide, obtained by the action of alkaline solutions of hypochlorites on copper compounds, but has not obtained any conclu

sive results.

A. J. G.

New Elements in Gadolinite and Samarskite. By W. CROOKES (Proc. Roy. Soc., 40, 502-509).-An account of the differentiation in the absorption and the phosphorescent spectra obtained by the process of systematic fractionation of the earths present in gadolinite and samarskite. By the evidence of absorption spectra, Welsbach has concluded that didymium is separable into two elements, designated præsodymium and neodymium, which give green and rose-red salts respectively. The method adopted by the author does not lead to the same conclusion, although it is suggested that didymium can be resolved in more than one direction according to the method adopted. Evidence has, however, been afforded of a blue line, 1451 5, characteristic of the element named dysprosium by Boisbaudran, as also of absorption-bands 1475 and 1443, which can be obtained separate from 1451·5, and thus belong to some element.

By systematic fractionation, and examination of the various portions by the phosphorescent spectrum method, it is shown that the spectrum bands hitherto considered to belong to yttria vary in intensity among themselves, as also that the element called Ya or gadolinium,

by Marignac, is probably composed of at least four simpler substances. The spectrum of this Ya is that of yttria with the chief characteristic, namely, the citron band, left out, and with the double green band of samaria added to it. A provisional list is given of eleven elements, inclusive of ytterbium and gadolinium, with the mean wave-lengths of their dominant band.

Attention is also drawn to the delicacy of the phosphorescent spectrum method as applicable to substances which have been approximately separated but not yet completely isolated by chemical processes. In accuracy, it is unsurpassed by spectrum analysis; in economy, it possesses the advantage that the specimen examined is not destroyed, whilst continued experience confirms its trustworthiness.

V. H. V.

Note. For a further account of the experiments described above and the theoretical conclusion drawn therefrom, compare the address of the author to the Chemical Section of the British Association, Report, 1886.-V. H. V.

Chemistry of Manganese and of Fluorine. By O. T. CHRISTENSEN (J. pr. Chem. [2], 35, 57-82; comp. Abstr., 1886, 854). -When chlorine is passed into absolute ether containing pure manganese peroxide in suspension and cooled by means of water, the liquid acquires after some time a violet colour so intense that it appears almost black and opaque. If the treatment with chlorine is prolonged, and the cooling insufficient, a reduction takes place, and manganous chloride gradually separates. The mixture should be shaken frequently, and kept from much light. If the dark liquid is poured off, a substance is obtained partly soluble in ether with inteuse violet colour; the insoluble residue is unchanged manganese oxide. The ether poured off, gives after some hours an abundant separation of manganous chloride, and loses its colour. When strong hydrochloric acid (sp. gr. 1·19) is shaken with absolute ether, two layers are obtained, the lower, a solution of ether in hydrochloric acid, and the upper, a solution of hydrochloric acid in ether. When these are treated separately with manganese peroxide, the ethereal hydrochloric acid solution acquires a green, whilst the hydrochloric acid containing ether acquires a violet colour. Hence the colour appears to depend on the amount of water present (comp. Nicklès, Ann. Chim. Phys. [4], 5, 161).

A number of experiments are described which were made to determine the valency of the manganese in the compounds obtained by the action of hydrochloric acid on manganese peroxide. The result points to the formula Mn,Cle. When the reaction takes place at 10°, more chlorine is taken up, and it is probable that the compound MnCl, is formed.

Manganese sesquioxide, MnO3, yielded the same chloride, Mn,Cle, when treated with ether containing hydrochloric acid.

Manganese fluoride, Mn,F. + 6H2O, is obtained in the

pure state

by dissolving artificial manganese peroxide in hydrofluoric acid; the product is filtered through spongy platinum, evaporated down and kept over sulphuric acid.

Manganese potassium fluoride, 4KF,Mn2F + 2H2O, is prepared by treating manganous hydroxide (Otto, Annalen, 93, 372) with pure dilute hydrofluoric acid; the product is filtered and treated with excess of potassium fluoride, when a rose-coloured, crystalline precipitate is formed. This is washed with water containing hydrofluoric acid, and dried on platinum. It is decomposed by water at the ordinary temperature. Hydrochloric acid decomposes it with a dark colour; when the solution is treated with water, the solution becomes transparent and bright yellowish-red. The salt dissolves in sulphuric acid, yielding an amethyst-coloured liquid, which becomes red on the addition of water. The solution in phosphoric acid is red. The salt is identical with the one to which Nicklès (Compt. rend. 65, 107) ascribed the formula 2KF,MnF. The salt, 2KF, MnOF2, is obtained by adding manganese tetrachloride to a boiling solution of potassium fluoride; it is probably identical with Nicklès' salt, 4KF,Mn2OF..

The salt, 4KF,Mn2F。 + 2H2O, was also prepared by heating manganese peroxide with hydrogen potassium fluoride, and by precipitation from a solution of potassium fluoride with a solution of manganese peroxide in hydrofluoric acid.

N. H. M.

Action of Potassium Permanganate on Sodium Thiosulphate. By M. GLÄSER (Monatsh. Chem., 7, 651-654).-According to Hönig and Zatzek (Abstr., 1886, 504), a boiling neutral solution of sodium thiosulphate is not completely oxidised to sulphate by potassium permanganate. Experiments in which sodium thiosulphate was boiled with solutions of permanganate, show that when 1 c.c. of the solution contains 0·007487 gram of permanganate, and the boiling is continued for 15 to 20 minutes, 1.98 to 2.69 per cent. of the thiosulphate is not oxidised to sulphate, whilst when concentrated solution of permanganate is employed, the oxidation is complete. In alkaline solution, and at the ordinary temperature, the oxidation is almost, but not quite, complete.

The compound manganite formed in the reaction is stable, and is not decomposed by cold or hot water. Numerous analyses confirm the formula KH,MnO10, previously assigned to it. The author adheres to the equation previously suggested by him (Abstr., 1885, 957), and considers that it holds good whether the reaction takes place in the boiling concentrated solution of permanganate or in a more dilute solution. N. H. M.

Compounds of Stannic Oxide. By A. DITTE (Compt. rend., 104, 172-175).-Stannic hydrate, produced by the action of alkalis on a solution of stannic chloride, dissolves readily in warm dilute sulphuric acid (1: 8), forming a limpid solution, which when concentrated until it contains not more than 3 or 4 vols. of water to 1 vol. of sulphuric acid, deposits at first colourless, radiating needles, then rhomboïdal lamellæ, and eventually hexagonal prisms with two parallel faces largely developed. All the crystals have the composition SnO2,2H2SO..

The same compound is obtained by the action of sulphuric acid

of suitable concentration on the hard, vitreous hydrate SnO2,2H2O, obtained by dissolving gelatinous stannic hydrate in ammonia, and evaporating the liquid; on metastannic acid obtained by treating the metal by nitric acid; and on strongly heated anhydrous stannic oxide. In the last case the rate of solution is very slow. The form of the crystals varies in the manner already described with the relative proportions of acid and water in the liquid.

The crystals are decomposed by water, but the stannic oxide is kept in solution by the sulphuric acid which is liberated, and a precipitate is only obtained when water is added in such quantity that the liquid does not contain more than about 43 grams of sulphuric acid per litre. The crystals are very deliquescent, and form a colourless, transparent liquid when exposed to the air; this solution does not crystallise on evaporation, but forms a hard, vitreous mass. however, some sulphuric acid is added to the liquid, crystals of SnO2,2H2SO, are readily obtained. They dissolve readily in dilute sulphuric acid, especially on heating, are not affected by ether, but are decomposed by alcohol with removal of sulphuric acid.

If,

If the sulphuric acid is not in large excess, but has dissolved a considerable proportion of stannic oxide, it forms a transparent jelly on cooling, which is sometimes opalescent. This liquefies when heated, but gelatinises again when cooled. The jelly is strongly acid, and does not become crystalline even after several weeks. If, however, it is mixed with an excess of ether, it yields a precipitate of slender, white needles of the compound SnO2, H2SO4. This compound dissolves in cold water, and the solution is at first limpid, but soon becomes turbid, owing to the separation of gelatinous stannic hydrate.

A compound of the same kind containing selenic acid is readily obtained by dissolving gelatinous stannic oxide in a warm solution of selenic acid, and evaporating to a syrup. When the liquid is cooled, it deposits transparent rhomboïdal lamellæ or hexagonal prisms of the composition SnO2, H2SеO. These crystals are hygroscopic, and are decomposed by excess of water, with separation of stannic hydrate. This compound is formed even in presence of a large excess of selenic acid. Titanic and zirconic oxides yield similar products. C. H. B.

Titanium. Part II. By O. v. D. PFORDTEN (Annalen, 237, 201— 235). The yellow colour of titanium tetrachloride is due to the presence of vanadium oxychloride. This impurity may be removed. by treatment with sodium amalgam. The pure chloride is a colourless liquid boiling between 135° and 136°. It is not decomposed by dry oxygen, but fumes in moist air. Titanium tetrachloride is miscible with alcohol, and on the addition of water the solution remains clear. A yellow precipitate is formed when the chloride is poured into hydrochloric acid; it is soluble in an excess of acid. Titanium chloride does not conduct electricity.

A gelatinous modification of hydrated titanic oxide is occasionally obtained by fusing titanium dioxide with potassium carbonate, and adding hydrochloric acid to the aqueous solution of the product. When sodium amalgam is left in contact with titanium tetrachloride,

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