Hengar Plain Boiling Granules are made of high purity, white, amphoteric alundum. Extremely hard porous surface that will not crumble. When boiling liquids, inert and insoluble, Hengar Boiling Granules effectively prevent super-heating with its attendant dangerous explosive vaporization. A few Hengar Granules in any boiling liquid permit a steady copious stream of bubbles to escape without spasmodic splatter. Evaporation or distillation proceeds quietly and smoothly. Flask breakage is reduced. Insoluble, Hengar Granules cannot contaminate the liquid. They remain at the bottom of the flask or beaker, permitting liquid to be readily poured off. After use, the granules are simply discarded.