Page:Popular Science Monthly Volume 9.djvu/172

152 partly the result of an accident. The condenser of a still heated by direct fire and charged with 900 gallons of mixed heavy and light oils, became partially closed, and the pressure caused leakage at the bottom of the still. The fire was very gradually drawn, after 250 gallons of light oil had passed off. The next day the oil in the still was found to be light-yellow, nearly odorless, neutral, and dense; the light, odorous hydrocarbons having been removed, at this low temperature, without decomposing either the distillate or the oil in the still. Further experiments perfected the process, which is greatly aided by the admission of steam from an open pipe into the body of the still during distillation.

Mineral sperm-oil was the result of experiments by Messrs. J. and R. S. Merrill on burning heavy lubricating oil and paraffine in lamps, especially constructed for the purpose. The light was very good, but the liquid was too thick to ascend into the wick. To obviate this the oil was subjected to a partially destructive distillation, "cracking" it enough to render it mobile, but not volatile.

The manner in which the crude petroleum is treated to obtain these various products is briefly outlined here from Prof. Hayes's sketch: The crude oil is heated by steam in upright, wrought-iron cylinders, incased in wood, of 12,000 gallons capacity. About 15 per cent. of distillate passes off and is condensed in pipes surrounded by water, yielding gasolene and A, B, and C naphthas, which are separately collected. From the gasolene rhigolene can be obtained by a second distillation with steam-heat, condensing the first portions of the distillate by ice and salt; ten per cent, is obtained from the gasolene. The steamed oil is pumped from the naphtha-stills into small stills, holding 1,000 gallons each, and heated by direct fires. Only carbon remains in these stills, some uncondensable gas escapes, and the other products are: No. 1, crude illuminating oil; No. 2, intermediate oils; No. 3, crude lubricating oil. Each of these is redistilled in the same sort of still. No. 1 is agitated with sulphuric acid, then with caustic soda, and distilled, yielding 80 per cent, of its volume of finished kerosene (refined illuminating oil) and mineral sperm-oil, and nearly 20 per cent, of denser oil. No. 2 is at once redistilled, yielding chiefly crude lubricating oil. No. 3 is agitated with sulphuric acid and then distilled with caustic soda in the still, yielding mainly dense paraffine-oil. This is kept in wooden barrels in ice-houses from seven to ten days, and deposits crystalline paraffine, which is pressed in strong cloth bags, one above another, with sheet-iron between, and yields crude paraffine-wax and heavy oil. The paraffine is repeatedly recrystallized from solution in naphtha and pressed, until it is white and pure enough for sale. The heavy oil is heated in stills by direct fires, slowly increased, but kept as low as possible, and generally with the admission of steam, until 20 to 30 per cent, has passed over. The residue is ready for sale,