Starch

(stahrch.) [From A. S. ste arc.) (Chem.) A substance of constant occurrence in the vegetable kingdom. It is chemically one of the carbo-hydrates, or bodies containing carbon, and oxygen and hydrogen in the proportion to form water. It is a white glistening powder, which when pre ed in the hand has a peculiar grating feel. Under the microscope it is seen to po e organization, consisting of a nucleus surrounded by concentric envelopes. Examined with polarized light it shows a black cro . It is insoluble in cold water, but in hot water it disintegrates and forms a jelly. S. is colored blue by iodine; under the influence of heat or dilute acids it is converted into dextrin and sugar. Form. C12H10010- [s. 852]