Drierite http://www.drierite.com/
Laboratory air and gas drying unit is an all-purpose drier. Vent Drier Systems for drums and small tanks, drying organic liquids, polyurethane reactants, gases and solids. Drierite is anhydrous calcium sulfate.
Dunn Products http://www.dunnproducts.com/
Online seller of scientific equipment: microscope, spectrophotometer, glassware, educational software, books, and test tubes.