The cobaltous salts are formed when the metal, cobaltous oxide, hydroxide or carbonate, are dissolved in acids, or, in the case of the insoluble salts, by precipitation.
It is somewhat readily oxidized; nitric acid gives carbonic and oxalic acids, and chromic acid, carbonic and acetic acids.
The secondary and tertiary amides of the types (RCO) 2 NH and (RCO) 3 N may be prepared by heating the primary amides or the nitriles with acids or acid anhydrides to 200° C. Thiamides of the type R.
The free acid, which is obtained by treating the salts with acids, is an oily liquid smelling like prussic acid; it is very explosive, and the vapour is poisonous to about the same degree as that of prussic acid.
The per-acids of sulphur were first obtained in 1898 by Caro (Zeit.