CaCO(3) was pptd. at 293 K for 2-30 min by addn. of the water-dild. carbonates-contg. filtrate from the Solvay process (1:1 up to 3:1) to the water-dild. Ca-contg. distn. residue from the same process (2:1 and 4: 1) under stirring (500 rpm). The diln. of the raw materials resulted in an increase in the av. CaCO(3) particle size and a decrease in the H(2)O, o-C(6)H(4)(COOBu)(2) and paraffinic oil absorption capacities. The capacities decreased while the average particle size increased with the increasing the pptn. time. The nucleation of the solns. with CaCO(3) crystals resulted in an increase of the packing d. of the product.