This section is from the book "A Practical Treatise On Friction, Lubrication, Fats And Oils", by Emil F. Dieterichs. Also available from Amazon: A practical treatise on friction, lubrication, fats and oils.
These include cod-liver oil, tanner's cod oil from different fish, menhaden oil, porpoise oil, shark oil and whale oil.
The whale and train oils are obtained from the blubber of various species of whale, the polar whale, the humpback whale, the common whale. The blubber varies in thickness from 8 to 20 inches around the body of the whale, and after being cut into pieces, is boiled with water for about an hour, to liberate the oil from it. The specific gravity of the oil is from 0.920 to 0.931, at about 60° F., or 20° to 22° Baume.
A large amount of oil of similar character as the foregoing fish oils is obtained from endless varieties of the smaller salt and fresh water fishes, which is used in the manufacture of soaps and lubricating oils, and known in the market as "Fish Oils." They are all oxyhydrocarbons and belong to the class of " fixed oils."
Wool fat is obtained by the washings of the wool of sheep. It is the fatty substance produced by the absorption of large amounts of alkali with the feeding of the sheep, thereby producing a secretive matter in the body of the sheep, which is discharged through the skin by transpiration and is deposited in the wool as suint, a quasi-saponified compound of stearic, oleic, and some palmitic acids. Weak alkaline solutions are used to.extract this suint from the wool, from which in turn it is obtained by precipitating the alkali with sulphuric acid.
The wool fat when first obtained is a creamlike mass, which requires purification and freeing from moisture. As this is usually accomplished over an open fire, it imparts to the product a dark color.
A considerable amount of wool fat is also obtained from the soapsuds used in the washing process of woolen goods, by precipitating the alkali with sulphuric acid to liberate the fat.
Degras is also obtained in the process of chamoising skins in the manufacture of chamois leather. The fermentation produced during the manipulation of the skins with fat or fish oils, causes the fat or oil to be split into fatty acids and glycerin. About fifty per cent of the fat or oil employed in the process is recovered in the form of a greasy, fatty mass by wringing and pressing it from the skins. This constitutes the best quality of degras.
A large amount of fatty mass is still retained in the skins, which is obtained by treating them in a warm solution of potassa, whereby the fatty matter is partially saponified, and is separated from the resulting white bath by treatment with sulphuric acid.
An inferior, factitious degras is made from the elain obtained in the manufacture of stearin for candles, mixed with train oils and other fatty matter, by agitation with strong decoctions of tan-bark and partial saponification with alkalies and subsequent separation by means of sulphuric acid.
Degras contains 80 per cent of fatty acids, 10 per cent of glutinous and extract-like substances, 2 per cent of lime, 0.5 per cent of potassa, besides water.
Castor-oil is obtained from the seeds of the castor-oil plant, Ricinus Communis, which contain from 50 to 60 per cent oil when separated from the capsules in which they are enclosed. The seeds are roasted over a slow fire and boiled with water, from which the oil is skimmed off; later the seeds are subjected to cold or hot pressure, a better quality and of lighter color being obtained by cold pressure than when pressed warm or extracted with solvents. Castor-oil is the most viscid of all the fixed oils. By long exposure to the air it becomes rancid and thick, and is ultimately transformed into a yellow mass. It has a mild, finally acrid taste, and a nauseous odor, and it is of a somewhat semi-drying character. Exposed to cold a solid, white crystalline fat (margaritine) separates from the liquid portion, and when cooled to 0° F. it congeals to a yellow, transparent mass, which does not liquefy again until the temperature rises to about 18° F. It consists of ricinoleic, stearic, and palmitic acids. Its specific gravity is 0.961, or 15° Baume. It is soluble in alcohol and in four volumes of rectified spirit. It mixes with fatty oils, but will not mix with mineral oils, unless previously combined with fat or fatty oils.
Olive oil is obtained from the fleshy part and the kernels of the fruit of the olive tree of southern Europe, Palestine and California. They furnish from thirty, to fifty per cent, of oil. The olives are subjected to a gentle pressure, whereby the best qualities of olive oil are obtained. The resulting cake is treated with hot water, from which an inferior oil is skimmed off.
Most of the olive oil of commerce is obtained by allowing the olives to ferment in heaps, and then subjecting them to heavy pressure. The remaining cake or mark is boiled with water, and more oil is obtained of a darker yellowish or brownish-green color. Olive oil is also obtained by extraction from the crushed and dried pulp with hydrocarbon solvents.
Olive oil is of a pale, greenish-yellow color, with scarcely any smell or taste, except a sweetish, nutty flavor. Its specific gravity is from 0.915 to 0.920 at 60° F., or 23° Baume. Olive oil mixes with disulphide of carbon, benzol and chloroform in all proportions. When cooled down it deposits stearin and solidifies at 25° F. Its boiling-point is about 600° F.
Sunflower oil is obtained from the seeds of the sunflower, especially from the Black Sea regions. The seeds are roasted and crushed, and the pulp is separated from the woodlike shells. They contain from twenty-eight to thirty per cent of oil. The oil obtained by cold pressure is of a clear yellow color, nearly odorless, and of a pleasant, mild taste. Its specific gravity at 60° F. is about 0.9260, or 21° Baume. It thickens in the cold and solidifies at 60° F. to a white, yellowish mass. It is a very slightly drying oil, and is mostly composed of oleic, stearic and palmitic acids.