Cocoanut-butter
Cocoanut-butter is not extensively used in America as a food product, owing to the fact that the exposed fat globules oxidize very rapidly. It is extensively used in Germany, however, and with the introduction of better methods of preservation, we expect to see cocoanut-butter more generally used in this country, as the source from which it is derived is almost unlimited.
Palm-oil
Palm-oil comes from a different species of the palm plant than that which produces the cocoanut. It is a very inexpensive product and one which is chiefly used in the production of soap and candles, although it is perfectly wholesome as a food. Such products have not been utilized in this country as food, because our boundless prairies and corn-fields have made the production of cattle and swine cheap, and our fat supply has swung toward points of least resistance.
Not all vegetable oils are edible or wholesome. Some contain, in addition to olein, stearin and palmitin, and other fats quite as undesirable. Castor-oil, for example, contains ricinolein, which is a poison, and to which its purgative action is due. Croton-oil is the most powerful laxative known to medicine, owing to the fact that Nature abhors a poison.
Linseed-oil
Linseed-oil contains large quantities of linolein, which is the substance that oxidizes, forming the stiff, rubbery coat on the surface of linseed-oil when exposed to the air. This makes linseed-oil valuable matter to the painter, but objectionable as a food.