This is a white, insipid, combustible substance, insoluble in cold water, but forming a jelly with boiling water. It exists chiefly in the while and brittle parts of vegetables, particularly in tuberose roots, and the seeds of the gramineous plants. It may be extracted by pounding these parts, and agitating them in cold water; when the parenchyma, or fibrous parts, will first subside, and these being removed, a fine, white powder, diffused through he water, will gradually subside, which is the starch. Or the pounded or grated substance, as the roots oft arum, potatoes, acorns, or horse chestnuts, for instance, may be put into a hair sieve, and the starch washed through with cold water, leaving the grosser matters behind. Farinaceous seeds may be ground and treated in a similar manner. Oily seeds require to have the oil expressed from them before the farina is extracted.,If starch be subjected to distillation, it gives out water impregnated with empyreumatic acetous acid, a little red or brown oil, a great deal of carbonic acid, and carburetted hidrogen gas. Its coal is bulky, easily burned, and leaves a very small quantity of potash and phosphat of lime. If when diffused in water it be exposed to a heat of 66" F., or upward, it will ferment, and turn sour: but much more so if it be not freed from the gluten, extract, and colouring matter. Thus in starch-making the farina ferments and becomes sour, but the starch that does not undergo fermentation is rendered the more pure by this process. Some water already soured is mixed with the flour and water, which regulates the fermentation, and prevents the mixture from becoming putrid; and in this state it is left about ten days in summer and fifteen in winter, before the scum is removed, and the water poured off. The starch is then washed out from the bran, and dried, first in the open air, and finally in an oven.