The Starch procured from the seeds of common wheat, Triticum vulgare.

Characters and tests. -In white columnar masses. When rubbed in a Wedgwood mortar with a little cold distilled water, it is neither acid nor alkaline to test-paper, and the filtered liquid does not become blue on the addition of solution of iodine. Mixed with boiling water and cooled, it gives a deep blue colour with iodine.

Preparations.

1. Glycerinum Amyli

Glycerinum Amyli. 1 part to 8 by measure; made by heating the mixture to 240°; a jelly-like preparation.

2. Mucilago Amyli

Mucilago Amyli. 1 in 40.

Amylum is also contained in Pulvis Tragacanthae Compo-situs (1 in 6).

Action And Uses

Starch is a nutritive material of the first order, but is introduced into the Pharmacopoeia for medicinal and pharmaceutical purposes only. Externally it is protective and absorbent, in the form of "dusting powder" for delicate or diseased conditions of the skin. The glycerinum is an excellent basis for ointments. Internally the mucilage is the vehicle of all the officinal Enemata, except those of tobacco and assafoetida. It is also an antidote in poisoning by iodine, but must be followed by an emetic.

Hordeum Decorticatum-Pearl Barley.-The husked seeds of Hordeum distichon. Cultivated in Britain.

Characters.-White, rounded, retaining a trace of the longitudinal furrow.

Composition.-Barley consists of starch, gluten, sugar, gum, etc.

Preparation.

Decoctum Hordei. "Barley Water."-1 to 15 of water.

Action And Uses

Barley water is nutritive and demulcent, and is chiefly used in inflammatory affections of the throat, and respiratory and urinary organs.