Soluble oil as used in finishing cotton goods may be made by mixing 2 parts by weight of castor oil with 1 part of strong sulphuric acid. The pan in which the mixing is done should be placed in a tank of water and kept cool by allowing the water to flow through the tank. Allow the mixture to stand for about a day, then add brine (salt solution); wash by stirring thoroughly, pour off the oil, and wash two or three times with brine. Now add ammonia or a solution of washing soda in small portions at a time until a portion of the oil taken out and mixed with water readily emulsifies with it.