FAT

Syn. Adeps , L. The fat of animals is a concrete oil contained in the cellular membrane of their bodies, more especially round the kidneys, in the folds of the omentum, at the base of the heart, upon the surface of the intestines, and among many of the muscles. Fat varies in consistence, colour, and odour, with the animal from which it is obtained. That of the carnivora is usually soft and rank-flavoured; that of the ruminant i a solid and nearly scentle . It is generally whitest and most copious in the well-fed young animal, and yellowish and more scanty in the old. That under the skin and surrounding the kidneys (suet) is also more solid than that in the neighbourhood of the movable viscera. In the cetacea, or whale tribe, the fatty secretion a umes the form of oil. These variations in consistency depend upon the relative proportions of solid stearin and liquid olein present in the fat. The vegetable fats are found in various parts of certain plants, but are generally most abundant in the seeds. They are extracted by simple pre ure or else by boiling. Two kinds of vegetable fat, namely, palm-oil and cocoa-nut oil, are extensively employed in the useful arts. All fats are lighter than water. They are all soluble in ether, benzol, and turpentine, and may be mixed with each other in any proportion. In former times the fats of many animals were employed in pharmacy, but at present those principally used are lard and suet. In perfumery, in addition to these, beef marrow and bear’s grease are employed. For both these purposes the crude material is cut into small pieces, and freed as much as po ible from all extraneous membranes; after which it is placed in a boiler with water, and heated until it is completely fused, when the whole is strained, and allowed to cool very slowly. By this means a cake of cleansed fat is obtained, which may be readily separated from any adhering water. Fats and the fat oils are best preserved by being run into glazed jars, and secluded from the action of the air. A little benzoic acid or gum-benzoin, di olved in them by heat, will generally prevent, and in all cases greatly defer, the acce ion of rancidity. We introduced this method into the laboratory in our early days of manipulation, and ourselves, and others to whom we have made it known, have since employed it with undeviating advantage in the manufacture of cerates, ointments, and other preparations containing fatty matter or the fixed oils. It has been shown by Dr Griesler that nitric ether, and its alcoholic solution, act in the same manner. A few drops are not only sufficient to prevent rancidity, but, it is said, will even destroy the disagreeable odour of rancid fat. When heated to remove the alcohol, they immediately become bright, clear, and scentle . See Oil , Glycerin , Olein , Palmitin , Stearin , Tallow , ., also below .