Process for preparing organosilicity soil and materials obtained from such soil

The method comprises hydrolyzing an initial Vsi volume of a precursor material comprising at least one polyalkoxysilane with a quantity of water such as (CF DRAWING IN BOPI) where x H2 O and x Si represent the number of moles of H2 O and Si present, respectively, the concentration of the hydrolyzate to a volume substantially equal to the initial volume Vsi, the quiescence of the concentrated hydrolyzate until demixing into an aqueous phase and an organosilicon phase and the recovery of the organosilicon phase . Application to optics.