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.
These seeds when dry have an aromatic sweetish odour, and a warm pungent taste, qualities residing in an essential oil, which is extracted by distillation with water and by digestion with alcohol; the bruised seeds yield their flavour to boiling water by simple infusion. The seeds are but rarely used. The distilled water is a valuable carminative for children.
ANISI SEMINA. L. E. D.
(Pimpinella Anisum. Semina.) Anise Seeds.
Like the dill seeds, warm and carminative; water extracts very little of their flavour; rectified spirit the whole. It may be remarked in this place that the value of aniseed, as well as all those seeds which yield essential oil by distillation, may be estimated by their specific gravity, the heaviest yielding the largest proportion of oil; a chrondrometer employed by corn-chandlers might be very conveniently applied to such a purpose.[[372]] The seeds imported from Spain, which are smaller than the others, contain most oil, and are to be preferred.
ANTHEMIDIS FLORES. L. E.
(Anthemis Nobilis.) Chamomile Flowers.