BUTTERMILK, the liquid residue after removing the butter from cream by the churning process. It consists mainly of water, some 9o%, together with milk sugar, about 5%, and casein, about 3%. In addition it contains small quantities of butter fat and lactic acid. To the latter, which is formed during the ripening of the cream, buttermilk owes its slightly acid taste. In North America until about 1900 buttermilk was used chiefly for feeding pigs, especially in the leading dairy districts, but, owing to its healthful and nutritious qualities, it has since become widely popular as a beverage. In the United States and Canada it is extensively bottled for the market and sold at dairies, grocery stores, delicatessens, soda fountains and restaurants. In some sections, most of the buttermilk sold commercially is "cultivated." Certain bacteria are added to skimmed milk to produce fermenta tion. The resulting product is somewhat thicker than natural buttermilk, but is in other respect similar. (See DAIRY.) the fruit of the North American white wal nut (Iuglans cinerea), a native of rich woods from New Bruns wick to North Dakota and southward to Delaware, Georgia and Kansas. The nut is oblong with a hard, rough shell. The meat has a buttery flavour, pleasing to the taste when used in caramels or molasses candy. The name is applied also to the tree itself. But ter-nut is likewise the commercial name for the fruit of various species of the genus Caryocar (f am. Caryocaraceae), native to South America, known also as souari-nut. (See WALNUT.)