Though the oil is now free from acid, it still contains coloring matter and other substances which would prove injurious. It is then mixed with very strong alcohol, ten parts of the former to two of the latter, and thoroughly mixed by shaking. The bottle containing the mixture is then placed in the sun and the mixture shaken several times a day. In the course of two or three weeks the oil will have become white as water, when it is withdrawn from the alcohol, on the surface of which it floats. The purified oil is placed in small bottles, tightly corked, and kept in a dark, cool place. (68.) [Illustration: _Fig. 3.--Relative Size of a Blackfish and Man._] [Illustration: _Fig. 4.--D. C. Stull's Watch Oil Factory, Provincetown, Mass._] ~11. Mineral Oils~ have of late years taken immense strides in the popular and merited estimation of consumers, for general lubricating purposes. Their application in horology will be discussed in another part of this volume. They are obtained from the residuum of petroleum distillation, and vary so greatly in their properties that many of them are not applicable to delicate mechanism; but as the lighter varieties seem to fulfill all the necessary conditions, the writer will here consider their source and method of treatment. ~12. Petroleums~ are obtained from many different localities, being fluid, bituminous oils, all having the same general characteristics and origin. They are all hydrocarbons, and contain little or no oxygen. As their origin is thoroughly discussed in many works on that subject, and as there is such a diversity of opinion regarding it, the reader is referred to such works.[3] ~13. Paraffine~, both liquid and solid, is obtained by the distillation of crude petroleum by means of superheated steam. When the heavier hydrocarbons begin to come over the receiver is changed and the butyraceous distillate is filtered through a long column of well dried animal charcoal. The first portion of the percolate is colorless or nearly so. The distillate is made water white by some refiners by an acid treatment, followed by a water-and-alkali washing. On exposing this mass to a low temperature it becomes thick, somewhat like "cosmoline" but white. (59.) It is then shoveled into cotton bags of very strong material and subjected to powerful pressure by means of a hydraulic press. This operation divides the paraffine into two parts: the solid paraffine wax from which candles, etc., are made remaining in the bags, while that which is expressed is paraffine oil. If the operation is carefully performed the oil will be free from crystaline paraffine at a very low temperature. [Illustration: _Fig. 5.--Extracting Oil from the Head of a Porpoise._]