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taken, and the values for n calculated as before. From these values = p is calculated from the equation p x

the ratio

n-1

2

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KCI
KCIO3

KCIO
KCI

=

and the values compared with those obtained from analytical data. They agree well in two cases out of three; in the third case the value for n was large.

If the weight of chloride that of oxygen, then r = 1. If the values for n be now calculated from the two equations they are found to be reciprocal, hence the perchlorate reaction is the exact inverse of the chlorate reaction. H. K. T.

Influence of Temperature on the Coefficient of Speed of Inversion of Cane-sugar by Hydrochloric Acid. By F. URECH (Ber., 20, 1836-1840).-The author shows that this influence as deduced from his experiments (Abstr., 1883, 174; 1885, 41) is not expressed by the formula arrived at by Spohr (Abstr., 1886, 502), K = a+b, in which t is reckoned from 0° and b is arbitrary. In the series of experiments quoted, the calculated value of a is nearly constant throughout, whilst b increases rapidly both with the temperature and with the concentration of the acid. On the other hand, Van A t'Hoff's formula, log K = - + BT+ C, expresses the results for

T

any particular strength of acid fairly well when the constants A, B, and C are determined from observations at wide intervals of temperature. These constants, however, vary for acids of different strengths, and even for any particular concentration their values depend on the temperatures for which they are calculated. Сн. В.

The Spheroidal State. By GOSSART (Compt. rend., 104, 1270 -1272).—The author has repeated Luvini's experiments (Il Nuovo Cimento, 17) with an apparatus so modified that the volume of the liquid, the temperature, and the pressure remained constant, and the two latter can be accurately measured.

Below 33° the temperature of the spheroid is higher than the boiling point of the liquid at the particular pressure. From 33° to 50° the two numbers are practically identical, the differences being sometimes positive and sometimes negative. From 50° up to 90° the temperature of the spheroid is always lower than the boiling point of the liquid under the existing pressure. At low temperatures the differences increase somewhat regularly, but at high temperatures the variations are comparatively irregular.

Under a pressure of 0.5 mm. a drop of water weighing 2 grams was completely frozen whilst in the spheroidal state, and was kept in this condition for 15 minutes, notwithstanding the fact that the dish on which it was supported was heated by means of a blowpipe.

C. H. B.

Decrease of the Compressibility of Ammonium Chloride Solutions with Increase of Temperature. By F. BRAUN (Ann. Phys. Chem. [2], 31, 331-335).-The measurements were made with

an Oersted's piezometer, the solution being contained in a dilatometer. Care was taken to expel as far as possible all air from the solution, and to diminish errors arising from this source, large pressures were employed. A rise of temperature of about 18° produced a diminution of about 3 per cent. in the compressibility, whether the liquid surrounding the dilatometer was water or ammonium chloride solution. This alteration cannot be ascribed to errors of experiment, and it is shown that the thermal effect of compression would not produce so large a change, although it would affect the absolute value of the coefficient. The comparison of the author's results with those obtained in the recent research of Schumann shows that the coefficients found are smaller, but that in cach case the temperature coefficient of compressibility has the same sign. C. S.

Lecture Experiments. By A. MERMET (Bull. Soc. Chim., 47, 306310). Silicon hydride may be conveniently prepared in small quantity for a lecture experiment by placing a piece of magnesium ribbon in a glass tube about 6 cm. long, and closed at the lower end, and heating in a Bunsen flame; after cooling, a few drops of hydrochloric acid are poured on the small globule of the silicon and aluminium compound formed, when an evolution of silicon hydride takes place, the bubbles burning in the air with decrepitation, and leaving a cloud of silica. If it be wished to prepare the gas in larger quantity it may be done by twisting one end of a stout wire round the rim of a steel thimble, and fixing the other end in a suitable support; a mixture of silica or sand and magnesium powder is then heated in this small improvised crucible, and the experiment conducted as before.

Potassium ferrate may be prepared in quantities sufficient to demonstrate its properties by adding excess of a concentrated solution of potash to 05 c.c. of a strong solution of ferric chloride, then a good pinch of bleaching powder, and finally a fragment of potassium hydroxide of the size of a pea, the solution is next filtered through asbestos, and the reddish-violet solution obtained contains sufficient potassium ferrate with which to demonstrate all the characteristic reactions of that salt. The author further calls attention to a violent explosion which took place when preparing hypochlorous anhydride, with use of a mixture containing liquid methyl chloride to condense the gas. A. P.

Inorganic Chemistry.

Methods for obtaining Sulphurous Anhydride and Oxygen by the Use of a Kipp's Apparatus. By G. NEUMANN (Ber., 20, 1584-1585).-Sulphurous anhydride can be generated in a Kipp's apparatus by the action of ordinary concentrated sulphuric acid on cubes prepared by Winkler's method (this vol., p. 442) from a mixture of 3 parts of calcium sulphite and 1 part of gypsum. Economy in

VOL. LII.

3 j

the use of the cubes is effected, if only the number required for the generation of the amount of gas needed are wetted with the acid at the commencement of the operation.

To prepare oxygen in a Kipp's apparatus, cubes consisting of a mixture of 2 parts of barium dioxide, 1 part of manganese dioxide, and 1 part of gypsum are used with hydrochloric acid (sp. gr. = 1·12) diluted with an equal volume of water. The oxygen evolved contains traces of chlorine, and must therefore be washed with an alkali.

It is not advisable to replace the gypsum in the cubes by starch or other similar cementing material.

W. P. W.

Vapour-density of Tellurium Tetrachloride: Valency of Tellurium. By A. MICHAELIS (Ber., 20, 1780-1784).-Tellurium tetrachloride boils constantly at 380°. The vapour-density was determined in V. Meyer's apparatus at the temperature of boiling sulphur (448°) and of boiling phosphoric sulphide (530°). The density found in each case was that required by the formula TeCl, so that the vapour of tellurium sulphide does not suffer much dissociation even at 150° above its boiling point. From this result it follows that tellurium is at least tetravalent. The result is the more important, seeing that sulphur tetrachloride is only stable in the liquid state at -21°, and that selenium tetrachloride gives at 218° a vapour-density showing dissociation into selenium chloride and free chlorine (Se,Cl2 + 3C12). The densities determined for tellurium tetrachloride were

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Nitrogen Fluoride. By H. N. WARREN (Chem. News, 55, 289). -Oily-looking drops found on the negative pole on electrolysing a solution of ammonium fluoride were supposed to be nitrogen fluoride. When connected with the positive electrode (a thin gold wire) these drops exploded with great violence, and the same thing occurred when they were brought into contact with glass, silica, or organic matter. No analyses seem to have been attempted.

R. R.

Regeneration of Acid Residues in the Manufacture of Guncotton. By E. ALLARY (Bull. Soc. Chim., 47, 102-103).—The acid residues, which have a mean density of about 58° Baumé, are filtered through sand to remove a small amount of nitrocellulose, and then distilled. 100 kilos. yield 10 077 kilos. of nitric acid of 50° Baumé, 6.279 kilos. of nitric acid of 10° Baumé, and 82.302 kilos. of colourless sulphuric acid of 62° Baumé, the loss amounting to 1:342 kilos.

These acid residues may also very economically replace sulphuric acid in the manufacture of nitric acid from crude commercial sodium nitrate, nitric acid of 48.45° Baumé being obtained at the first distillation. There appears to be no danger of any explosive action caused by the presence of nitrocellulose dissolved in the acids.

A. P.

Influence of Pressure and Temperature on the Action of Potassium Chloride on Crude Methylamine Carbonate. By J. A. MULLER (Bull. Soc. Chim., 47, 379–382).—The crude amines employed contained 1 per cent. of ammonia, 30 per cent. of methylamine, 50 per cent. of dimethylamine, 2 per cent. of trimethylamine, and about 17 per cent. of higher amines containing a considerable amount of amylamine. The dilute carbonic anhydride employed was obtained from a limekiln, and contained 25 per cent. of carbonic anhydride. The potassium chloride employed was Stassfurt salt, containing 97.3 per cent. of potassium chloride. 2:14 mols. of the methylamine carbonate were taken to every 2 mols. of potassium chloride. Under these conditions it was found that the conversion of the potassium chloride into hydrogen potassium carbonate took place most satisfactorily, either under ordinary pressure at a temperature of 0°, or at the ordinary temperature under a pressure of about 3 atmospheres.

A. P.

Artificial Production of Trona or Urao. By P. DE MONDÉSIR (Compt. rend., 104, 1505-1508).-A mixture of crystallised sodium carbonate 27 parts and sodium hydrogen carbonate 8 parts, is added gradually to a boiling solution of 28 parts of sodium chloride and 28 parts of crystallised sodium carbonate in 100 parts of water. The liquid is boiled until solution is complete, water being added to replace that lost by evaporation, and is then allowed to cool slowly, care being taken that the temperature does not fall below 20°. The carbonate, 3Na2O,4CO2,5H2O, is deposited in long, white needles, which are usually matted together. This compound is stable in saturated solutions of sodium chloride, in which it is only slightly soluble, and in presence of which it loses carbonic anhydride very slowly, even when boiled. If a mixture of the 3: 4 carbonate and sodium chloride is treated with water, part of the carbonate dissolves unchanged, and part is decomposed into the normal carbonate and the hydrogen carbonate. The 3: 4 carbonate can, however, be separated from the chloride by dissolving the mixture in hot water, and allowing to cool, when the unaltered carbonate separates almost immediately, and is purified by washing with cold water. With the proportions given above, the carbonate is obtained practically free from chloride.

This artificial carbonate is identical in composition, crystalline form, &c., with natural trona or urao. C. H. B.

Silver Suboxide. By G. H. BAILEY (Chem. News, 55, 263).— The author thinks that Pfordten's results (this vol., p. 699) fail to establish the existence of silver suboxide, as they do not include the preparation of any definite salt of the base, but merely a partial analysis of a black powder of problematic constitution. R. R.

Solubility of Calcium and Magnesium Chlorides in Water at 0°. By R. ENGEL (Bull. Soc. Chim., 47, 318-320).-The results given by various authors who have examined the solubility of these salts are very discrepant, the author finds, as the result of very careful experiment, that 100 parts of water at 0° dissolve 60:3 parts of calcium chloride, the solution having a sp. gr. of 1:367. 100 parts of water

at 0° dissolve 52-2 parts of anhydrous magnesium chloride. The saturated solution has a sp. gr. of 1.3619 at 15°. A. P.

Solubility of Lead Chloride in Solutions of Mercuric Chloride. By J. FORMÁNEK (Chem. Centr., 1887, 270-271).Results are given to show that the solubility of lead chloride in a solution of mercuric chloride is greater than in water, although the increase in solubility seems not to be due to the formation of a double salt. V. H. V.

Ammonium Copper Iodides. By A. SAGLIER (Compt. rend., 104, 1440-1442).-100 grams of ammonium iodide is dissolved in 10 times its weight of water, and mixed with 10 to 15 grams of copper hydroxide, which partially dissolves in the cold and is completely soluble on heating. The liquid is then boiled with a large excess of copper until it becomes colourless, concentrated, and allowed to cool slowly, when it deposits long, white needles, of the composition Cu,I2,2ÑH1I + H.O. These crystals can only be preserved in the mother-liquor, and even under these conditions become brown after some time. In air they lose ammonia and ammonium iodide, and when heated, yield black cuprous iodide. They are decomposed by water with separation of cuprous iodide, and also by alcohol. When the original mother-liquor is exposed to the air it deposits black crystals of the composition Cu2I2,2NH,I,2NH3 + 4H2O.

If the solution of cupric oxide in ammonium iodide, obtained as above, is allowed to cool without being boiled with metallic copper, it deposits black needles of the composition Cul2,2NH,I,2NH, + 2H2O, which may be preserved in the mother-liquor, but alter when exposed to air. They are insoluble in water and ethyl alcohol, and dissolve with difficulty in ammonia. When the ammoniacal solution cools it deposits blue crystals of the composition Cul2,4NH, + H2O, which are decomposed by heat, the final product being cuprous iodide.

If cupric hydroxide is dissolved in ammonium di-iodide, analogous compounds containing the di-iodide are obtained. A solution of ammonium iodide is mixed with an equivalent quantity of iodine and treated as above, the solutions being somewhat more dilute. The product consists of violet-black needles of the composition Cul2,2NH,I2,2NH, + 6H2O, which are red by transmitted light. They are more stable than the corresponding compound containing ammonium moniodide, but alter when exposed to air, and are even decomposed by water. They dissolve with difficulty in dilute

ammonia.

The ammonium cupric iodides yield black cupric oxide when treated with potassium hydroxide; the cuprous iodides yield cuprous oxide. C. H. B.

Solubility of Copper Sulphate. By A. ÉTARD (Compt. rend., 104, 1614-1616).—The curve which represents the percentage composition of the saturated solution of a salt at different temperatures is usually a straight line. In the case of copper sulphate the direction of the line changes at three points.

Starting with the ordinary hydrate, CuSO, + 5H2O, the quantity

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