The process of claim 7, wherein the mercapto-functional organosilicon compound thus obtained is equilibrated with at least one organopolysiloxane containing units of the general formula R9 g (R10 O)h SiO.sub.(4-g-h)/2 (VI) in which R9 is a hydrogen atom or a monovalent organic radical, R10 is a hydrogen atom or a monovalent organic radical, g is 1, 2 or 3 and h is 0, 1 or 2, with the provi