foam glass[′fōm ‚glas]
a cellular material that is obtained by heating to fusion finely ground glass powder with a pore-forming material, such as coke, chalk, or dolomite. It is a good thermal and acoustic insulator and is easily worked and cemented. The average density varies from 100 to 700 kg/m3.
Foam glass is used for the thermal insulation of refrigeration cars and underground piping and as a buoyant material in rescue devices and pontoons. Filters for acids and alkalies are made from foam glass with open pores.