1,200,711. Chlorinating P.V.C. MANIFATTURA CERAMICA POZZI S.p.A. 27 March, 1968 [1 April, 1967], No. 14826/68. Heading C3P. In the dry chlorination of P.V.C. using an activation energy source such as ultra-violet light, the polymer is a dry mix of P.V.C. and a swelling agent, e.g. chlorinated hydrocarbon, chlorination is effected at 0-65‹ C. and the swelling agent recovered. Preferred swelling agents are chloroform, carbon tetrachloride and mixtures thereof, and they are blended with the P.V.C. in amounts up to 60 parts per 100 parts of polymer by weight.