Starch, a vegetable substance found in most plants, particularly in the seeds, bulbs, tubers etc. For commercial purposes starch is obtained from numerous plants, chief among which are wheat, corn, rice and potatoes. It has the same elements as sugar—carbon, hydrogen and oxygen—but in different proportions. It is made of small round grains or granules, which differ in shape in each species of plant. As usually prepared, it either is a white powder or irregular white columns, which come from the breaking up of a dried cake of the material. It does not dissolve perfectly in cold water, but with hot water the granules burst, forming a clear paste, which is the starch used in the laundry. When heated to about 320°, it is changed into dextrine, the gum used on postage-stamps. Starch is found especially in cereals, potatoes, carrots, parsnips, sage, tapioca and rice. Potatoes are about one-fifth starch; rye, oats, wheat and corn nearly two thirds; and rice about nine tenths. Starch is made from corn by soaking it 48 hours in water, then grinding it and straining through sieves, after which the starch is allowed to settle in vats, when it is washed, bleached and dried.  Potato-starch is made by grating potatoes, adding water and straining, settling, washing and drying.  Wheat-starch and rice-starch are made by slightly different processes, to remove the gluten they contain.  Arrowroot, tapioca, sago and cornstarch are forms of starch used as food.  Starch is also used in the manufacture of calico and other cloths, in mounting photographs and in the laundry.  It is also used in the manufacture of glucose, (q. v.).  Cornstarch was first made in the United States in 1842.  The factories at Oswego, N. Y., and Glen Cove on Long Island are the largest starch-factories in the world.  There are about 100 starch-factories in the United States, making corn, wheat and potato starch, of which 10,000,000 pounds are exported yearly.