Glycerol

Glycerol or Glycerine, colourless, odourless, sweet-tasting alcohol, C₃H₈O₃, with a relative density of 1.26. It boils at 290° C (554° F) and melts at 18° C (64.4° F). Liquid glycerol resists freezing but may crystallize at low temperatures. It forms a solution with water in any proportion, and dissolves in alcohol in all proportions, but is insoluble in ether and many other organic solvents. The term glycerol refers specifically to the compound, the formula of which is given above, whereas glycerine may also refer to glycerite (glycerol in solution) or other solutions of or preparations made from glycerol.

Simple fats and oils are esters of fatty acids and glycerol. Obtained as a by-product of soap manufacture, after fats and oils have been treated with alkali to form the soap, crude glycerol is purified by distillation.

The most common use for glycerol is in the making of alkyd resins (see Plastics). Other important applications are in the preparation of drugs and toilet articles, including toothpastes; as a plasticizer in cellophane; and as a moistening agent in tobacco products. Because cheaper products are now available, only 5 per cent of the production of industrial glycerol goes into the making of nitroglycerol explosives. Because of its affinity for water and its high viscosity, glycerol is a valuable constituent in stamp pad inks. Pumps for petroleum products are lubricated by glycerine because it resists dissolving in petroleum liquids. Because of its high viscosity and its non-poisonous character, glycerine is a suitable lubricant for food-processing machinery.