This photograph shows four important sulfide compounds immersed in water in a comparative fashion. From left to right: Ammonium Sulfide, (NH4)2S, is seen to be a clear yellow liquid and soluble in water. Cadmium sulfide, CdS, is bright yellow and insoluble. Antimony sulfide, Sb2S3, is orange/yellow and insoluble. Lead sulfide, PbS, is black and insoluble. The photo is useful for showing the colors of metal sulfides and also that metal sulfides are generally insoluble while sulfides of generally soluble cations dissolve in water.