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KALMANN (W.). Standardising Iodine Solutions: estimating Sulphurous

Acid in Presence of Thiosulphuric Acid

WEIL (F.). Volumetric Estimation of Sulphides

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JOURNAL

OF

University of Michigan

THE CHEMICAL SOCIETY,

ABSTRACTS OF CHEMICAL PAPERS PUBLISHED IN BRITISH AND FOREIGN JOURNALS.

General and Physical Chemistry.

Production of White Light by Mixing the Colours of the Spectrum. By STROUMBO (Compt. rend., 103, 737-738).-The spectrum is produced by means of a prism which is arranged so that it can rotate about an axis parallel with its faces. When the prism is made to rotate with sufficient rapidity, the spectrum is replaced by a band of white light. The extreme red of the spectrum, however, always remains coloured, because whilst all the other colours pass their position of minimum deviation, the red, which is the least refrangible, does not become mixed with any other colours. It is advisable to intercept this portion of the spectrum by means of a small C. H. B.

screen.

Spectra of the Methyl-derivatives of Hydroxyanthraquinone. By C. LIEBERMANN and S. v. KOSTANECKI (Ber., 19, 2327-2332).— The compounds are best examined in solution in pure concentrated sulphuric acid. The eight known dihydroxyanthraquinones can be distinguished from one another by the spectra of their sulphuric acid. solutions.

The methyl homologues have almost exactly the same properties as the original substances, and as this analogy extends to the spectra it is often possible to determine the constitution with very small amounts of substances. The difference in the spectra caused by the substitution of one methyl-group is extremely small, but this difference increases visibly with the number of methyl-groups.

The relation of chrysophanic acid to chrysazine, previously suggested (Annalen, 183) on the strength of their similar chemical properties, is supported in a striking manner by the spectra of the two compounds.

A table of spectra of methyl homologues and the compounds from

VOL. LII.

b

which they are derived, and tables showing the relation of the trihydroxyanthraquinones to each other and to their methyl-derivatives, are given (compare also Krüss, Abstr., 1885, 949). N. H. M.

Preparation of Calcium Sulphide with a Violet Phosphorescence. By A. VERNEUIL (Compt. rend., 103, 600-603).-20 grams of finely powdered calcium oxide prepared by heating the very dense shell of Hypopus vulgaris, is intimately mixed with 6 grams of sulphur and 2 grams of starch; and 8 c.c. of a solution of 0.5 gram of basic bismuth nitrate and 100 c.c. of absolute alcohol acidified with a few drops of hydrochloric acid, are added. The mixture is exposed to the air until the greater part of the alcohol has evaporated, and is then heated in a covered crucible at a cherry-red heat for 20 minutes. When completely cooled, the upper layer of calcium sulphate is removed, and the calcined mass powdered and again heated at the same temperature for 15 minutes. If the temperature has not risen too high, the product is granular and friable; if powdered a second time, the brilliancy of the phosphorescence is considerably diminished. The violet colour of the phosphorescence is due to the presence of the small quantity of bismuth.

The phosphorescence of calcium sulphide is not materially increased by the presence of 0.1 per cent. of the sulphides of antimony, cadmium, mercury, tin, copper, lead, uranium, platinum, zinc, or molybdenum, but these substances impart a bluish-green or yellowishgreen tinge to the phosphorescence. Sulphides of cobalt, nickel, iron, and silver diminish the phosphorescence, whilst manganese produces the orange shade observed by Becquerel.

A mixture of calcium oxide 100 parts, sulphur 30 parts, starch 10 parts, and lead acetate 0.035 part, yields a sulphide with a beautiful yellowish-green phosphorescence, but if the proportion of lead acetate is increased to 04 part, the green colour disappears and the phosphorescence becomes yellowish-white, and diminishes considerably in intensity. With 16 part of lead acetate, the yellow tint is more marked, and with 35 parts the phosphorescence is orange-yellow. With a greater proportion of the lead salt, the product has a greyish tint and does not phosphoresce at all.

Calcium sulphide obtained by reducing the pure sulphate in a current of hydrogen or carbonic oxide, shows no phosphorescence, and that prepared by heating the sulphate with starch shows only very slight phosphorescence; hence it would seem that pure calcium sulphide is not phosphorescent, and that the phenomenon is due to the presence of small quantities of silica, magnesium, phosphates, and alkalis derived from the shells from which the lime is prepared.

As a general rule, substances which cause the calcium sulphide to frit slightly when heated, increase the brilliancy of the phospho

rescence.

The product obtained by heating a mixture of strontium carbonate 100 parts, sulphur 30 parts, and arsenious oxide 5 parts, shows a greenish-blue phosphorescence if the strontium carbonate has been prepared from the chloride and ammonium carbonate, but the phosphorescence is greenish-yellow if the strontium carbonate has

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