This section is from the "A Handbook of Useful Drugs" book, by State Medical Examining and Licensing Boards.
True fats, chiefly those of animal origin, form an important class of ointment bases. They are especially valuable when penetrating ointments are desired for softening the skin for inunctions, etc. Lard is the chief fat thus used. Like all animal fats, it is very liable to become rancid. To mitigate its odor and to hinder the occurrence of rancidity the following preparation is used: