Sevum (U. S. P.)—Suet.
"The internal fat of the abdomen of Ovis Aries, Linné (Class, Mammalia: Order, Ruminantia), purified by melting and straining. Suet should be kept in well-closed vessels impervious to fat. It should not be used after it has become rancid"—(U. S. P.).
COMMON NAMES: Suet, Mutton suet, Sheep tallow.
Preparation, Description, and Chemical Composition.—Prepared suet (Sevum praeparatum, Br. Pharm.), mutton suet or sheep tallow, is the adipose matter of the domestic sheep, Ovis Aries. For medicinal purposes the kidney fat is melted at a gentle temperature and then strained, in order to separate the membranous portions. It may be rendered still purer by heating it in water at 100° C. (212° F.). By a special process, the fatty substance in the state in which it is removed from the animal is heated with a small quantity of sulphuric acid of specific gravity 1.3 to 1.45. The acid dissolves the membrane and other impurities present, acquiring a dark color and thick syrupy consistence, while the fat separates in a state of purity. Prepared suet is somewhat similar in its properties to lard, but is harder and more compact. To meet the demands of the Pharmacopoeia it should be "a white, solid fat, nearly inodorous, and having a bland taste when fresh, but becoming rancid on prolonged exposure to the air. Insoluble in water or cold alcohol; soluble in 44 parts of boiling alcohol, in about 60 parts of ether, and slowly in 2 parts of benzin. From its solution in the latter, kept in a stoppered flask, it slowly separates in a crystalline form on standing. An alcoholic solution of suet is neutral or has only a slightly acid reaction with litmus paper moistened with alcohol. Suet melts between 45° and 50° C. (113° and 122° F.), and congeals between 37° and 40° C. (98.6° and 104° F.)"—(U. S. P.). Suet consists chiefly of stearin and palmitin (70 per cent) and olein (30 per cent), with a trace of hircin, which is a liquid oil, probably a mixture of the glycerides of capric and caprylic acids (also see Adeps).
Action and Medical Uses.—Suet is nutritive and emollient. but not so easy of digestion as the fat of the pig or ox; yet it may be made into a broth, with or without aromatics, and used in diarrhoea, dysentery, and general debility. It is sometimes used as a dressing to blisters, and may be applied to most of the purposes for which lard is used, on account of its superior hardness, and higher melting point. For forming an ointment, it will be found preferable to lard, especially when it is to be applied to several forms of cutaneous disease. The addition of benzoic acid, sulphite of sodium, or sweet gum, will prevent its tendency to become rancid and disagreeably odorous.