CaCO(3) was pptd. at 293 K for 2-30 min by addn. of the carbonates-contg. filtrate from the Solvay process to the Ca-contg. distn. residue from the same process under stirring (500 rpm). Processing of 400 mL of the distn. residue yielded 25 g of CaCO(3). The product showed low packing d. (800-900 g/l) and contained calcite and vaterite. The capacities of H(2)O, o-C(6)H(4) (COOBu)(2) and paraffinic oil adsorption (92,2, 94,0 and 108,8 ml/100 g, resp.) decreased while the av. particle size increased (from 24,590 mu m up to 39,997 pm) with increasing the pptn. time.