One hundred gallons of the crude oil are placed in a tank, and 3 gallons of caustic potash-lye, of 45° Baume, are gradually added and well stirred for several hours; or the same quantity of oil is treated with about 6 gallons of soda-lye of 25° or 30° Baume, and heated for an hour or more to about 200° or 240° Fahr., under perpetual stirring, and left to settle. The clear yellow oil is then separated from the brown soap stock, and this dark soap sediment is placed into bags, where the remainder of the oil will drain off; and the sediment has a marketable value of 3 or 4 cents a pound for soap-makers. The potash-lye has to be made in iron pots, but the oil and lye may be mixed in wooden tanks.