Silica Gel 4 : A porous substance consisting of SiO3. Used on occasion as a dehydrating agent in air or gas drilling where small amount of water is encountered. (Bul D11)
The Mudblogger (Oilfield, Energy and Related Photographs), Oil Field Glossary, TX, USA 2014. http://mudblogger.com/oilfield-glossary/, (Oil - Amer) {777}