in thiocarbonic acid: in derivatives, as mono-thiocarbonic acid, di-thiocarbonic acid, tri-thiocarbonic acid: the last, H2CS3, is a dark yellow strongly smelling oil, very easily decomposed by heating into CS2 and H2S; esters of dithiocarbonic acid, H2COS2, and of monothiocarbonic acid, H2CO2S, are known.