Abstract: The aim of the invention is to dry cellulose and cellulose-containing materials in the shortest possible time and with the lowest possible technical costs, without disruptive stress on the cellulose and without loss of stability and efficacy of any additive substances, for example medicaments, and to reswell it as required almost completely to the original structure and consistency. According to the invention for the purpose of drying and obtaining the swellability with almost complete reconstitution of the cellulose structure and consistency the dried cellulose to be prepared or the cellulose-containing material is subjected to the adsorbent effect of a moisture binder, in particular an osmotically and/or hygroscopically effective solution and then dried regardless of any structural change to the material.

Abstract: A partially hydrophobic precipitated silica having a methanol wettability of 10 to 49%, in particular with a DBP uptake on a dry basis of greater than 250 g/100 g and a mean particle size of 1 to 12 &mgr;m and/or a carbon content of 0.3 to 1.85% and/or a loss on drying of 2.6 to 10.0% and/or a pH value of 5.5 to 10.0, is prepared by mixing the amount of water-repellent agent with the precipitated silica suspension at very short residence time and low pH value, filtering off the solid substance, washing free of salt, drying, post-treating thermally and milling. The partially hydrophobic precipitated silica can be used in active substance formulations and active substance formulations of hydrolysis-sensitive substance and in defoaming agents.