Sulphides of cobalt of composition C04S3, CoS, C03S4, C02S3 and CoS 2 are known.
The most common of these sulphides is cobaltous sulphide, CoS, which occurs naturally as syepoorite, and can be artificially prepared by heating cobaltous oxide with sulphur, or by fusing anhydrous cobalt sulphate with barium sulphide and common salt.
Silver has been discovered in all the states, either alone or in the form of sulphides, antimonial and arsenical ores, chloride, bromide,.
In Western Australia the lead occurs in the form of sulphides and carbonates of great richness, but the quantity of silver mixed with it is very small.
This precipitate is insoluble in cold dilute acids, in ammonium sulphide, and in solutions of the caustic alkalis," a behaviour which distinguishes it from the yellow sulphides of arsenic and tin.