The use of silver vanadates as absorbents for sulphur dioxide

A new solid absorbent for sulphur dioxide is described which is effective at room temperarures, and which does not absorb carbon dioxide. Exhaustion of the filling is indicated by a change in colour from green to brown.The reagent is prepared by heating molecular quantities of silver oxide and silver metavanadate together at 150° C. Evidence is given that on such treatment the two silver salts combine, forming a product having the same empirical composition as silver orthovanadate but different as regards its properties from the orthovanadate produced by the usual precipi-tation method.