It is decomposed by the halogens, with liberation of sulphur.
Group VII.: H (?), monovalent; the halogens F, Cl, Br, I, usually monovalent, but possibly also triand pentavalent; Mn, divalent and trivalent, and possibly heptavalent in permanganates.
Instances had already been recorded of cases where a halogen element replaced hydrogen with the production of a closely allied substance: Gay Lussac had prepared cyanogen chloride from hydrocyanic acid; Faraday, hexachlorethane from ethylene dichloride, &c. Here the electronegative halogens exercised a function similar to electro-positive hydrogen.
Long-continued treatment with halogens may, in some cases, result in the formation of aromatic compounds; thus perchlorbenzene, C 6 C1 6, frequently appears as a product of exhaustive chlorination, while hexyl iodide, C 6 H 13 I, yields perchlorand perbrom-benzene quite readily.
Methods for the estimation of the halogens and sulphur were worked out by L.
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