GYLCERINE.

Rodney and Otamatea Times, Waitemata and Kaipara Gazette, 21 August 1912, Page 7

GYLCERINE.

Many years ago, in an. obscure village in Sweden, an apothecary was making- lead plaster in the ordinary way by heating olive oil with litharge and water, when he chanced to notice that the liquid which* was mingled with the pasty lead compound, had a strangely sweet taste. On further investigation, he found that the sweet taste was caused by the presence of an oily liquid which was dissolved in the water. No such substance was described in the books of the day.

Scheele, the apothecary, knew that he had discovered a new substance. He soon found that this sweet liquid was not the product of olive oil alone, but that other oils and fats would yield it under the same treatment. So he named it the "sweet principle of fats," or "oil-sugar."

More than a century has passed since Scheele's discovery, yet it is but little over sixty years since "oil-sugar" was found to be of practical value, except for a very limited use in medicine. Chemists have given it the more formal name of glycerin.., derived from a Greek word meaning sweet.

Everyone to-day is familiar with the clear, thick liquid so commonly used for toilet purposes. Its soothing and softening effect on dry or inflamed skin is the quality for which it is best known in most households; but few people have any idea of the variety of purposes to which it is applied.

Among its most striking, and valuable properties are its- great solvent power, its chemical stability, and its sweetness. Moreover, it is digestible, will not evaporate, and owing to this end and its hygroscopic qualities, will prevent the drying and hardening of materials with which it is mixed.

These peculiar qualities make it most valuable in the preparation of medicine, unguents, and various food products, as preserves and mustards; likewise in beer, wines, and other bottled goods, where it is said to act as a preservative. The fact that strong- solutions of glycerine and water will not freeze in' the lowest winter temperatures has caused its use in our wet "gas meters."

In a pure state glycerine is onefourth heavier than water. After long exposure to a freezing temperature, glycerine will deposit rhombic crystals resembling those of sugar candy. Its boiling point is 490 deg. F. Pure glycerine will burn readily if first heated to about 300 degrees. It gives a pale blue flame similar to that of alcohol, and to the chemist it is an alcohol.

. There is a process by which animal fats are directly decomposed into steric acid and glycerine, by subjecting the fat to the action of superheated steam, at a temperature of several hundred degrees. The resulting glycerine is concentrated, and purified by steam distillation, while the steric acid, which much resemble wax, and in no way answers to our ordinary conception of acid, is in great demand for "avidles.