These are compounds of carbon, hydrogen, and oxygen (hydrocarbons), obtained from the organic kingdom, and chiefly distinguished by their insipidity, unctuosity, insolubility in water, and being lighter than that fluid. Olive oil, obtained from the vegetable, and spermaceti oil, from the animal kingdom, may be taken as types of the rest. The fixed oils are chiefly found in the fruit and seeds of plants, and in thin membranous cells in various parts of the bodies of animals. Some of these oils are solid at ordinary temperatures; as palm oil, cocoanut oil, etc..; but the majori ty are fluid, except when considerably cooled, when they separate into two portions: the one solid, consisting mostly of stearine, and the other liquid, consisting chiefly of oleine. Nearly all the fixed oils, when freely exposed to the air, absorb oxygen, and either gradually harden, or become rancid. The former are termed drying oils, and are used by painters ; the latter are used in cookery, for machinery, lamps, etc.. The fixed oils, except where otherwise directed, are obtained from the bruised or ground fruit or seed, by means of powerful pressure, in screw or hydraulic presses, and are either allowed to clarify themselves by subsidence, or are filtered. Another method is by boiling the bruised seed in water, and skimming off the oil as it rises to the surface. This is the plan adopted for castor oil in the West Indies. The specific gravities of the fixed oils range between 0.865 and 0.970. (Cooley.)

1488. Davidson's Process of Deodorizing Putrid Whale Oil

1488.    Davidson's Process of Deodorizing Putrid Whale Oil. This cheap method of purification consists in the employment of chloride of lime, the quantity depending on the degree of putrefaction of the whale oil. In general 1 pound is sufficient for 112 pounds oil; but if it is in a state of great putrefaction, there may be 11/2 or 2 pounds required. With 1 pound chloride of lime about 12 times the quantity of water must be employed. The chloride is bruised in a mortar, and the water added by degrees till it forms a soft and liquid paste, and afterwards by the addition of the remainder of the water it takes the consistency of cream. This is to be mixed with the oil and often carefully stirred. After some hours 1 pound sulphuric acid, diluted with 20 or 30 times its bulk of water, is poured on the mixture, and the whole brought to a boil over a moderate fire, and stirred continually until drops of oil run off at the end of the stirring pole. It is then left for some hours for the oil to precipitate, and the acidulated water is drawn off. A common cast-iron boiler, with sheets of lead at the bottom, is the best for the purpose, or a copper or iron vessel may be used when the quantity of acid is not too great. The chloride of lime must not be bruised in a copper or iron mortar.

1489. To Restore Rancid Oil and Fat

1489.      To Restore Rancid Oil and Fat. Rancid oil and fat may be recovered by agitating them, at a gentle heat, with fresh-burnt and coarsely-powdered charcoal (which has been thoroughly freed from dust by sifting and fanning), followed by filtration through flannel; or by simple filtration through charcoal in bags of Canton flannel, according to the common method.