OILS: are divided according to their sources as Animal, Vegetable and Mineral, or for various specific purposes, as Edible and Industrial, Cold Drawn and otherwise, Fixed and Essential, Drying and Non-drying, etc.
Animals Oils may be divided into those from (1) fish and marine mammals, as Menhaden and Whale Oil for industrial purposes, and Cod Liver Oil ; and (2) land animals, as Lard Oil, Oleo Oil and Neatsfoot Oil.
The chief Vegetable Oils are almond, castor, cocoanut, corn, cotton-seed, hemp, linseed, olive, palm, palm kernel, peanut, poppy-seed, rape, sesame and walnut. Cold Drawn or Cold Pressed oil, the highest grade of vegetable fixed oil, is that obtained by the first expression, without heat or chemical additions. The general rule in the treat ment of fruits and seeds which give edible oils, is to use cold-expression first to obtain the edible grades, then to extract the remaining oil-content after heating or chemical treatment, or first one and then the other, for industrial purposes. The hot expression always changes the character of the oil and in some cases entirely alters the flavor.
Mineral Oils, as benzine, gasoline, kerosene, etc., are in this country obtained chiefly by the distillation of PETROLEUM (which see).
Fixed Oils are those which, under ordinary temperature, leave a permanent greasy residue on any substance, as paper, etc. The classification includes the major
ity of the vegetable oils of general use, the heavier mineral oils and all the animal oils.
Essential or Volatile Oils speedily evaporate in ordinary temperature. They are divisible into two main classes, vegetable and mineral. Vegetable essential oils, obtained from herbs, fruits, flowers, seeds, etc., are used in great variety by the per fumer (see PERFUMERY), in medical practice and in the manufacture of flavoring extracts for food purposes (see EXTRACTS). They are soluble in alcohol, ether and fixed oils, but only to a limited extent in water. The mineral volatile oils include the lighter Petroleum products.
Drying Oils—as hemp, linseed, poppy, walnut and some whale oils—are those which on contact with the air form a tough skin and are therefore suitable for use in the manufacture of paints and varnishes. Castor, corn, cotton-seed, rape, sesame, sun flower and most whale oils, are Partial or Slow Drying. Almond, lard, mineral oils, oleo oil, olive, peanut and sperm oils, are Non-Drying. In temperate climates, cocoa nut, palm, palm kernel and kindred types are nearly solid fats.