Sur un hydrate de soufre

Spring, W. Recueil des Travaux Chimiques des Pays-Bas (1906), 25, 253-9 ; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010).

The sulphur which is formed together with polythionic acids when hydrogen sulphide and sulphur dioxide react in aqueous solution is a mixture of soluble sulphur and a definite hydrate, S8,H2O, and not a new allotropic form of sulphur, "sulphur δ", as described by Debus (Chem. News, 1888, 57, 87). In order to separate the hydrate from the soluble sulphur, the mixed precipitate in washed by dialysis until it is neutral to litmus, and dried in a vacuum at the ordinary temperature until the weight is constant; the yellow mass thus obtained is powdered, sifted through silk, again dried in a vacuum, and finally extracted with carbon disulphide, which dissolves 51.6 per cent. of the total mass. The residual sulphur hydrate, S8,H2O, when compressed into cylinders, has a sp. gr. 1.9385 at 19°/4°, loses its water at 80°, and has a slight vapour pressure at the ordinary temperature, the powdered substance losing 2.41 per cent. and the compressed substance 1.33 per cent. when kept over sulphuric acid for 205 days. The partially dried powder contains 3.1 per cent. and the compressed substance 5.8 per cent. of sulphur soluble in carbon disulphide. If, however, the hydrate consisted of octahedral sulphur combined with water, the amount of soluble sulphur in the partially dried powder would be 35.186 per cent.; it is probable, therefore, that the hydrate is derived from an amorphous unstable variety of sulphur which is transformed slowly under ordinary conditions, and more rapidly under pressure, into soluble sulphur.

Reprinted with the permission of the American Chemical Society. Copyright © 2010 American Chemical Society (ACS). All Rights Reserved.