This section is from the book "Materia Medica And Therapeutics: An Introduction to the National Treatment of Disease", by John Mitchell Bruce. Also available from Amazon: The pharmacology and therapeutics of the materia medica.
The purified fat of the Hog, Sus scrofa.
Characters and tests.-A soft white fatty substance, melting at about 100°. Has no rancid odour. Dissolves entirely in ether.
Impurities.-Common salt and starch.
Composition.-Lard consists of 60 per-cent. of olein, and some palmitin and stearin. Olein is a fluid oil, a compound of oleic acid, C18H33C2, and glyceryl, C3H5. Palmitin and stearin are solid oils, compounds of glyceryl with palmitic acid (C16H32O2), and stearic acid (C18H36O2) respectively.
Adeps Benzoatus. 1 of Benzoin in 64 of Lard.
Unguentum Simplex. 3 in 8, with White Wax and Almond Oil. Hither Lard or Benzoated Lard is contained in almost all ointments.
Lard is a simple emollient, forming the basis of most of the officinal ointments. Benzoated lard does not become rancid like ordinary lard, which for the same reason is now in a measure replaced by vaseline.