Cerous sulphide, Ce₂S₃

Cerous sulphide, Ce₂S₃, may be prepared by heating ceric oxide to bright redness in a stream of dry hydrogen sulphide, the oxide, contained in a porcelain boat inserted in a porcelain tube, being heated until its weight ceases to alter. An alternative method is to use cerous sulphate instead of ceric oxide and heat to 750°-800° in hydrogen sulphide.

Cerous sulphide is a dark reddish-purple solid of density 5.02 at 11° (Muthmann and Stutzel). When heated in the air it roasts to cerous sulphate and ceric oxide, but in hydrogen or nitrogen it is stable till 1400°-1500°, when it melts and decomposes.