These are carbohydrates of very slight pharmacologic action and of little importance as remedies, but of importance in dietetics and the arts.

Cane-sugar or common sugar (Latin, saccharum), C12H22O11, is employed to make the various syrups and as a sweetening agent. It is found in abundance in the sap of the sugar maple, in sugar-cane, in sorghum, and in the root of the sugar-beet. It dissolves in half its weight of water and is insoluble in alcohol. It ferments with yeast, but does not reduce Fehling's solution.

Sugar of milk (Latin, saccharum lactis), C12H22O11, is obtained from milk, and requires for solution five times its weight of water. It reduces Fehling's solution, but does not ferment with yeast. It is not very sweet, and is chiefly used as a nutritive in infant feeding and typhoid fever. In pharmacy it is employed as a diluent. Cheap brands of sugar-of-milk may contain lactic acid and traces of milk proteins, which form a nidus for bacterial growth, or they may be adulterated with cane-sugar or glucose.

Glucose (Latin, glucosum), C6H12O6, is described in Part II.

Levulose, C6H12O6, a form of sugar abundant in honey and some fruits, is a carbohydrate which has been found in many instances to be more easily appropriated by diabetics than are cane-sugar, glucose, and many starchy foods (von Noorden). It has been used by Strauss as a test of the functional power of the liver, the assertion being made that if the levulose is recoverable from the urine unchanged, the liver is seriously impaired. In Foster's experiments 3 out of 10 normal cases responded with levulosuria, and only 14 out of 20 cases of well-marked cirrhosis. Churchman, Frey, and others obtained similar results. The test cannot, therefore, be depended upon.

Manna, derived from a tree of the ash family (Fraxinus ornus), contains the sugar, mannite, C6H14O6, and is laxative.

Cornstarch (amylum), C6H10O5, is the starch in common use. It is employed as a dusting-powder for the skin, or for pills to prevent their sticking together, or in the form of starch water as a soothing injection in irritative conditions of the lower bowel. To make starch water, the starch should first be hydrolyzed by mixing about a teaspoonful with two ounces of water, boiling until it forms a translucent paste, then diluting with water to one-half pint. It may be made by simply boiling a teaspoonful of starch with the requisite quantity of water at the outset, but by this method the starch does not so readily hydrolyze. Cornstarch and arrowroot starch (maranta) are used as foods. The latter has long had the reputation of being the best kind of starch for the feeding of children and invalids, but it is not now so much employed as formerly.

The gums are chemically closely related to the sugars and starches. There are two official, viz., acacia, which consists chiefly of arabinose, C12H22O11Ca, and tragacanth, which can be made to yield arabinose.

Acacia (gum arabic) is soluble in water and is demulcent. Its chief uses are pharmaceutic, as in the manufacture of mucilage and emulsions, and to give increased viscosity to mixtures containing heavy insoluble powders (so that the powder may be held in temporary suspension in the liquid during the pouring of the dose). Its solutions ferment readily, turn sour, and become ropy; and it is precipitated from aqueous solution by alcohol.

Tragacanth does not dissolve in water, but swells up and makes an adhesive paste.

Dextrin (C6H10O5), known as British gum, is prepared from starch, being an intermediate stage in the change of starch to maltose or glucose. It is soluble in water, is sweetish to the taste and slightly laxative, and is the chief ingredient of some of the proprietary infant foods. It is the gum generally used on postage-stamps, and in paste form is frequently employed for attaching labels.

Cherry-gum is an insoluble type of gum of no medical interest.

A mucilage is an adhesive, aqueous liquid or paste made from a gum. The official mucilages are those of acacia and tragacanth, both used for mechanical purposes.