has made an elaborate review of the chemical literature on cod liver oil, citing 90 papers in his bibliography.
This oil was originally obtained by natural disintegration or "rotting" of the livers.
This process was displaced, first by the steam kettle, then by direct steam rendering.
The "stearine " is removed from the crude product by chilling and filtration.
The occurrence of 17 fatty acids in cod liver oil has been reported ; the presence of 9 of these acids is reasonably well established, the presence the remaining 8 acids less well established.
All the known acids fall into a broad series C,Hz._2,02 where n has a value between 14 and 22 and x is the number of double bonds which may range from o to 6. Morrhuic acid or sodium morrhuate, which has been used in the chemotherapy of tuberculosis and leprosy, is really a cod liver oil soap prepared for intravenous administration.
The oxidation and consequent rancidity of cod liver oil is an autocatalytic process accelerated by the formation of organic peroxides and retarded by foreign substrates; they are most readily avoided by expeditious rendering.
Cod liver oil may be hydrogenated ; this process destroys both the vitamins and the fishy smell.
Inorganic constituents may be present in the oil, such as iodine (0.0001 to 0.0005 per cent.), bromine, chlorine, nitrogen, phosphorus, organic sulphur, zinc, and the alkalies.
The unsaponifiable fraction contains cholesterol, other complex alcohols, a hydrocarbon (squalene or spinacene), a lipochrome or pigment, and vitamins (fat-soluble A and fat-soluble D).