Cadmium Silicate, CdSiO₃

When cadmium nitrate is heated in a glass tube at about 300° C., the hydrated cadmium silicate, 2(CdSiO₃).3H₂O, forms on the inner surface in long scales which break between the fingers into microscopic needles. The compound is soluble in hydrochloric acid with the separation of silica. Under strong ignition it finally leaves a residue of silica, but there is very little loss, even of water, until it melts and intumesces at an orange-red heat.