Emollients and Demulcents.

Petrolatum, Petrolatum, (commonly called Vaseline, Cosmoline, Petroleum Ointment, etc.),—is a mixture of hydrocarbons, chiefly of the marsh-gas series, obtained from petroleum by distilling off the lighter portions and purifying the residue. It is insoluble in water, soluble in boiling alcohol, ether, chloroform, oils, etc., and is official in three forms, viz.:—

Petrolatum Liquidum, Liquid Petrolatum.
Petrolatum Molle, Soft Petrolatum,—melts at 104°-113° F.
Petrolatum Spissum, Hard Petrolatum,—melts at 113°-125° F.

Mel, Honey,—is a saccharine secretion deposited in the honey-comb, by Apis mellifica, the honey bee, an insect of the order Hymenoptera. Honey consists of a strong aqueous solution of mixed dextrose and levulose, the sum of which, known as "glucose," amounts generally to 70 or 80 percent.

Mel Despumatum, Clarified Honey,—is Honey warmed, skimmed and strained, with 5 per cent. of Glycerin added.
Mel Rosa, Honey of Rose,—contains 88 per cent. of clarified honey.
*Oxymel (B. P.),—Honey 40, Acetic Acid 5, Water 5.

Linum, Linseed, Flaxseed,—the seed of Linum usitatissimum, Flax, a cultivated plant of the nat. ord. Lineae. Contains much mucilage in the covering of the seeds, and in the seed itself 1/4th to 1/3d by weight is the oil, Oleum Lini, Flaxseed or Linseed Oil, which is obtained by expression without the use of heat. Linseed-meal is the powdered cake, remaining after the oil has been expressed.

Oleum Lini, Linseed Oil, (See ante, page 52),—Dose, ad libitum.
*Infusum Lini, Linseed or Flaxseed Tea, (B. P.),—has of Linseed 150 grains, Liquorice-root 50 grains, infused in 10 ounces of boiling water for 2 hours, and strained. Dose, indefinite.
Linimentum Calcis, Lime Liniment (Carron Oil),—has equal vols. of Limewater and Linseed Oil, shaken together.

Adeps Lanae Hydrosus, Hydrous Wool Fat (Lanolin) ,—See ante, page 52, under Oils and Fats, for this and Cod-liver Oil, Cotton-seed Oil, Cacaobutter, and others.

*Ichthyolum, Ichthyol,—See ante, page 73, under Sulphur.

Physiological Action and Therapeutics. The substances, of which the above are only a few examples, have a medicinal action which is chiefly mechanical, forming a smooth and soft coating to an inflamed mucous membrane or to a portion of the skin denuded of its epidermis, protecting it from irritation by the air, and permitting the process of repair to proceed unchecked by any external interference. Some of them, in addition, soften and relax the tissues (emollients), thereby lessening tension, and consequently relieving pain. Flaxseed is the favorite material for poultices, which are simply local baths, conveying heat and moisture to the part. It has the additional quality of being emollient, due to its mucilaginous and oleaginous constituents; and hence is one of the most efficient agents of the class to which it belongs. Linseed Oil is frequently applied to burns, scalds, eczematous eruptions, etc., either by itself, or with lime-water, as in the old-fashioned "Carron Oil," now replaced by Linimentum Calcis. Internally, in doses of ℥ij morning and evening, it has been highly spoken of as a cure for hemorrhoids. Honey is chiefly used as a vehicle, and as an ingredient of gargles. It is laxative in full doses. A mixture of honey and vinegar (official in the B. P. as Oxymel) is a favorite remedy for colds and sore throats. Petrolatum, known commercially as Cosmoline, Vaseline, etc., is a valuable protective, and an excellent basis for ointments, having no acridity, and no liability to turn rancid. It mixes readily with the alkaloids, the phenol compounds, and many other active agents; but it does not penetrate the skin as readily as animal fats and fixed oils, (for which see page 52, ante.)

A Compend of Materia Medica, Therapeutics, and Prescription Writing, 1902, by Sam'l O. L. Potter, M.D., M.R.C.P.L.