BUTTER-FAT, the fatty constituent of cows' milk. But ter, which is a solid emulsion containing fat, water, curd, milk sugar and inorganic salts, is melted and allowed to settle ; the clear butter-fat rises to the top and is separated by decantation. It does not become rancid as readily as butter, for the albumi nous curd and the water present in the latter favour the growth of the organisms which promote rancidity. Butter-fat is chiefly manufactured in India and Egypt; before the war it was also pre pared in Siberia (whence it was exported to Turkey), and to a less extent in Germany (Schmelzbutter). In India, where it is prepared in large quantities, butter-fat is known as "gJii"; it is Commonly mixed with the milk-fat of the buffalo, while in Egypt the chief adulterants are the milk-fats of sheep and goats. In the latter country the fat is termed Samna. Butter-fat occupies a unique position among the natural animal fats because it con tains considerable amounts of the glycerides of the water-soluble fatty acids—butyric, caproic, caprylic and capric acids. The Reichert-Meissel (Reichert-Wollny) value, which is a measure of the amount of these acids, is a valuable characteristic in butter fat analysis. Especially characteristic is the presence of butyric acid, which is absent from coconut and palm-kernel oils, from which butter-fat is also distinguished by its smaller content of lauric acid. (See also OILS AND FATS.)