Properties of Gelatine.—Gelatine softens and swells up in cold water, but does not dissolve until heated: the hot solution, on cooling, forms a tremulous jelly. One ounce of cold water will retain about three grains of Isinglass without gelatinizing; but much depends upon the temperature, a few degrees greatly affecting the result.
When long boiled in water, and especially in presence of an acid, such as the Sulphuric, Gelatine undergoes a peculiar modification, and the Solution loses either partially or entirely its property of solidifying to a jelly.
GLYCERINE.
Fatty bodies are resolved by treatment with an alkali into an Acid—which combines with the alkali, forming a soap,—and Glycerine, remaining in solution.
Pure Glycerine, as obtained by Price's patent process of distillation, is a viscid liquid of sp. gr. about 1·23; miscible in all proportions with water and Alcohol. It is peculiarly a neutral substance, exhibiting no tendency to combine with acids or bases. It has little or no action upon Nitrate of Silver in the dark, and reduces it very slowly even when exposed to light.
GLYCYRRHIZINE.
Glycyrrhizine, obtained from the fresh root of Liquorice, is a substance intermediate in properties between a sugar and a resin. Sparingly soluble in water but very soluble in Alcohol. It precipitates strong solution of Nitrate of Silver white, but the deposit becomes reddened by exposure to light. Its preparation is described in the larger works on organic chemistry.
GOLD, CHLORIDE OF.
Symbol, AuCl3. Atomic weight, 303.