12,769. Wurster, C. June 22. Sizing.-When paper is sized by means of a resin or fatty soap, the soap is decomposed by means of an acid sulphate, preferably sodium bisulphite, used either alone or in conjunction with aluminium salt, such as aluminium sulphate. Other alkaline bisulphates, or the bisulphates of the alkaline earths or of magnesium or zinc, may be used. When a fatty soap is employed, the hot soap solution is first mixed with the pulp, and then a solution of the bisulphate is added until the pulp gives a distinctly acid reaction with litmus.