It is also obtained when sebacic, stearic and oleic acids are oxidized with nitric acid.
It is most conveniently obtained from olive oil, after removal of the oleic acid, or from Japanese beeswax, which is its glyceride.
Hydriodic acid reduces both oleic and elaidic acids to stearic acid.
These enabled him to elucidate the true nature of soap; he was also able to discover the composition of stearin and olein, and to isolate stearic and oleic acids, the names of which were invented by him.
Linoleic acid, C18H3202, found as glyceride in drying oils, and ricinoleic acid, C18H33(OH)02, found as glyceride in castor oil, closely resemble oleic acid.
The process of manufacturing soaps by boiling fatty acids with caustic alkalis or sodium carbonate came into practice with the development of the manufacture of candles by saponifying fats, for it provided a means whereby the oleic acid, which is valueless for candle making, could be worked up. The combination is effected in open vats heated by a steam coil and provided with a stirring appliance; if soda ash be used it is necessary to guard against boiling over.
In the mixture of unsaturated fatty acids, by means of some more refined methods, clupanodonic acid, linolenic acid, linolic acid and oleic acid can be recognized.
The unsaturated fatty acids which occur chiefly in oils and fats are oleic acid, iodine value 90.07; erucic acid, iodine value 75.15; linolic acid, iodine value 181.42; linolenic acid, iodine value 274.1; and clupanodonic acid, iodine value 367.7.