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Par′af-fine.

A solid hydrocarbon, crystalline and white at ordinary atmospheric temperatures, discovered by Reichenback, in 1829, in the tar derived from the dry distillation of beechwood. It has since been obtained in large quantities from coal, from bituminous shale, and especially from petroleum, by distillation and rectification by treatment with solution of caustic soda, and subsequently with sulphu- [1630] ric acid. Several oily products analogous in composition but differing in appearance result from these processes, and are used for illuminating or lubricating purposes. The solid paraffine is derived from the densest of these oils; the paraffine crystallizing on standing a length of time. It is farther purified by the centrifugal machine and by treatment under pressure with a small percentage of sulphuric acid. Solid paraffine is employed, either alone or in combination with the fatty acids, for making candles. Its cognate hydrocarbon oils, the various derivatives from petroleum, are well known and largely employed for illumination, etc.

The name is from parum affinis, on account of the few substances for which it has an affinity.

The stronger acids, as nitric, sulphuric, or hydrofluoric, the former of which act energetically upon most of the metals and the latter upon glass, exert no destructive action upon paraffine; nor does aqua regia, a mixture of hydrochloric and sulphuric acids, by which gold is readily dissolved. It equally resists the action of alkalies, such as potash and soda, and is therefore adapted and used for the purpose of making joints which shall be impervious to acids and alkalies; for bottle-stoppers, which may be made of solid paraffine, or may consist of corks covered with it; and as a coating for labels and for surfaces exposed to acids or acid fumes. For this purpose it may be simply melted and applied with a brush. It may also be applied in a similar way to paper showbills, etc.; permeating the pores of the paper, it renders it water-proof, and efficiently protects it against the effects of rain.

The process of obtaining paraffine on a large scale from coal or bituminous shale was discovered and patented by James Young about 1850. That employed in the works of Mr. Young at Bathgate and Addiewell, Scotland, is briefly as follows: The shale is broken small in a crusher and then placed in the retorts; these are commonly flattened cylinders of cast-iron, about 12 feet long and contracted toward the ends, which are open, the lower one dipping in a pan of water; heat is applied by a furnace until the middle part of the retort is at a red heat; at a temperature of 300° the hydrocarbons are disengaged in the form of gas, most of which is condensible, and is collected as an oil, which is again distilled and agitated with sulphuric acid in closed vessels, where a black tarry substance resulting from the combination of the acid with the impurities of the oil subsides to the bottom. The clear portion is similarly treated with caustic soda, and again distilled in combination with vitriol and soda, the result being a thin, light, and colorless liquid known as paraffine oil.

Solid paraffine is obtained from the heavier and thicker oil, of which about 20 gallons are derived from each 100 of the crude oil; this is refrigerated by a machine in which a stream of brine is cooled below 32° by a cold-air blast, when the paraffine assumes the solid form.

1877.

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