Abstract: High purity, particulate silica gel is formed by the hydrolysis and condensation of a silicon alkoxide in a non-metal lined tumble dryer. The silica gel is then dried in the tumble dryer, is washed with an aqueous solution to remove trace contaminants, and is dried again to form the particulate product.

Abstract: A granular directly compressible anhydrous dicalcium phosphate having a particle size sufficient for efficient direct compression tableting, preferably at least 90 percent greater than 44 microns, a dentin abrasion value of less than 150 and a surface area of greater than 5 meters.sup.2 /gram can be prepared by dehydrating particles of soft dicalcium phosphate dihydrate of a particle size insufficient for direct compression tableting, preferably at least 10 percent less than about 44 microns such as by heating at a temperature sufficient to form anhydrous dicalcium phosphate. The dehydrated particles are then granulated with a binder. The product is a granular anhydrous dicalcium phosphate exhibiting good compressibility and flowability while being in an anhydrous state.