Sulphur Thiocyanate, S(SCN)₂

Sulphur Thiocyanate, S(SCN)₂, is formed as colourless, pearly crystals, when a solution of thiocyanogen in ether reacts with dry hydrogen sulphide. It decomposes at atmospheric temperatures. Heated in an open tube on a water-bath it darkens rapidly and then suddenly decomposes, evolving orange fumes. A solution of sulphur thiocyanate in a mixture of ether and benzene does not react with powdered iron, but on the addition of a drop of water the characteristic red colour of ferric thiocyanate develops immediately. By this reaction sulphur thiocyanate can be distinguished from free thiocyanogen.