The stills used in the process of refining the crude oil are horizontal two-flued cylinders, 30 ft. in length by 10 ft. in diameter, provided with six 2 in. vapor pipes.  The charge is 260 barrels, and the following is an outline of the method of working.  Assuming the still to be charged on Monday morning, heating is commenced about 7 A.M., and the naphtha begins to come over about 8 A.M.  Of this product about six barrels is obtained in the case of Petrolia crude, or 71/2 barrels in the case of Oil Springs crude.  The distillation of the naphtha takes from 2 to 3 hours, say till 10:30 A.M.  The heat is then increased, and the distillation of the kerosene commences about noon, and continues till about 10 P.M.  Of the kerosene distillate about 80 barrels are obtained.  The first portion of the kerosene distillate is usually collected separately, is steamed to drive off the more volatile hydrocarbons, and is then mixed with the remainder of the kerosene distillate.  The product which then commences to distill is known as tailings.  This is collected separately and is redistilled.  The distillation of the tailings continues till about 5 A.M. on Wednesday, by which time about 80 barrels has been obtained.  Steam is then passed into the still through a perforated pipe extending to the bottom, and about 21 barrels of “gas oil” is distilled over.  The additional quantity of kerosene obtained on redistilling the tailings brings up the total yield of this product to about 42 per cent. of the crude oil.  The gas oil is sold for the manufacture of illuminating gas.  The residue is distilled for lubricating oils and paraffin.

The agitator in which the kerosene distillate is treated commonly takes a charge of 465 barrels.  To this quantity of distillate two carboys of oil of vitriol is added, and the oil and acid are agitated together for 20 minutes.  The tarry acid having been allowed to settle is drawn off, and seven carboys more of acid is added.  Agitation having been effected for 30 or 40 minutes, the tarry acid is removed as before.  Another similar treatment with seven carboys of acid follows, and occasionally a fourth addition of acid is made.  The oil is next allowed to remain at rest for an hour, any acid which settles out being drawn off, and cold (or, in winter, slightly warmed) water is allowed to pass down through the oil in fine streams, this treatment being continued, without agitation of the oil, for half an hour, or until the dark color which the oil assumed on treatment with acid is removed.  The water is then drawn off, 10 barrels of solution of caustic soda (sp. gr. 15 deg.  B.) is added, and agitation conducted for 15 minutes.  The caustic soda solution having been drawn off, 30 barrels of a solution of litharge in caustic soda is added.  This solution is made by dissolving caustic soda in water to a density of 18 deg.  B. and then adding the litharge.  Agitation with this solution is continued for about six hours, or until the oil is