[AS.] One of the main constituents of plants. It is composed of carbon, oxygen, and hydrogen, the last two in the proportions required to form water. It is near to sugar in chemical composition and is converted into it in the life history of the plant. Wood fibre belongs to the same class of compounds. These make up the great bulk of the plant, the remainder being its oily matter and its nitrogenous substance, which forms the protoplasm of its cells. Starch for commercial use is chiefly obtained from wheat, maize, rice, and potatoes; and in France from horse chestnuts. Starch in maize is from 60 to 80 per cent.; wheat, 60 ; rye, 60; oats, 46; barley, 57 ; rice, 61; potatoes, 61. Starch is found in the form of little grains contained in the cells of plants. It is insoluble in cold water ; but in hot water the grains swell up until they burst and form a jelly-like mass. Corn starch is made in the United States by soaking Indian corn in water containing caustic soda and hydrochloric acid to dissolve the gluten, grinding, washing on sieves, and finishing by various processes. Rice starch is largely made in England, France, and Belgium. Starch is useful for stiffening cloths, sizing paper, making paste, dextrine, glucose, detecting iodine, and as an article of food. (See Rice, Sago.)
POTATO STARCH CORPUSCLES.