Bismuth Thiocyanate, Bi(CNS)₃

Bismuth Thiocyanate, Bi(CNS)₃, is obtained when thiocyanic acid is neutralised with bismuth hydroxide. It is possible that a basic compound is also obtained. Dilute thiocyanic acid solution must be used; basic substances are probably formed first, but on cooling, bright orange or amber-coloured rhombic crystals of normal bismuth thiocyanate separate, having the elements

a:b:c = 0.76134:1:0.28423

The crystals are decomposed by water, and on heating. The hydrate Bi(CNS)₃.14H₂O is obtained in the form of deep-red transparent needles by the action of excess of thiocyanic acid upon bismuth carbonate; when the acid is saturated with bismuth carbonate, basic bismuth thiocyanate, Bi(CNS)₂OH.5H₂O, separates in glistening plates on addition of alcohol.