QUALITIES. _Form_, white columnar masses; _Odour_ and _Taste_, none. CHEMICAL COMPOSITION. Fecula is one of the proximate principles of vegetable matter, and _Starch_ is the fecula of wheat.[371] SOLUBILITY. It is soluble in boiling water, forming with it a semi-transparent, insipid, inodorous, and gelatinous paste, very susceptible of mouldiness, but which is retarded by the addition of alum; it is insoluble, but falls to powder in cold water; nor is it dissolved by alcohol or ether; although potass dissolves starch, yet the solution of it is not disturbed by potass, carbonate of potass, nor ammonia, but an alcoholic solution of potass produces a precipitate; acetate of lead, and infusion of galls occasion also precipitates. Starch is susceptible of several interesting and important changes; thus, if it be exposed to heat until its colour becomes yellow, its properties are so far altered that it is no longer insoluble in cold water; and according to the experiments of Saussure, if it be mixed with water, a spontaneous decomposition takes place, and a quantity of sugar is formed, amounting in weight to one half of the starch employed, in addition to which a peculiar gummy matter results, and a substance intermediate between gum and starch, to which the name of _Amidine_ has been given. Starch moreover is convertible into saccharine matter by the agency of sulphuric acid. USES. Being demulcent it is generally employed as a vehicle for the exhibition of opium in the form of enema. The ordinary blue starch is coloured by a solution of smalt and alum, and is unfit for medicinal use; formerly it was tinged yellow with saffron or turmeric, but this went out of fashion on the execution of the famous midwife Mrs. Collier, who was hanged in a ruff starched with that colour. OFFICINAL PREPARATIONS. _Mucilago Amyli._ L.E.D. _Pulvis Tragacanth: comp:_ (=B=) L. _Pil: Hydrargyri_ (=M=) E. _Troschisi Gummos:_ E. It has been lately observed that _Iodine_ is a delicate test of the presence of starch; if a drop or two of a solution of this substance in alcohol be added to an aqueous solution of starch, a blue compound is formed which eventually precipitates. Iodine may therefore be employed for ascertaining the goodness of starch, a test which is very important, for much of what is sold under the name of starch, does not possess its peculiar characters; it ought however to be stated, that the blue indication is prevented from taking place by a variety of different bodies, as _Arsenious acid_, _corrosive sublimate of mercury_, &c. &c. ANETHI SEMINA. L. E. (_Anethum Graveolens._ _Semina._) Dill Seed.