The Bureau of Mines wrote a computer program which calculates the saturation curves and condensation characteristics of gaseous mixtures consisting of binary organic vapor and air. The program assumes an equilibrium mechanism for condensation, and the degree of fractionation obtained is predicted on the basis of relative volatility. The program allows the user to examine the fractionation resulting from condensation as a function of the size of the temperature increments over which condensation is assumed to occur. If a single temperature interval between the dewpoint of the mixture and the outlet temperature of the condenser is assumed, the results obtained will be those resulting from a single equilibrium condensation. If the condensation is assumed to occur over a number of temperature increments, the results obtained will approach those predicted by the rayleigh equation as the magnitude of the temperature increments approaches zero. The results from calculations performed on vapor mixtures from organic heavy liquid solutions used in beneficiating potash and brucite ores are presented. The liquids are solutions of dibromomethane in trichloroethylene or perchloroethylene. The results show the degree of liquid recovery which is possible by cooling mixtures of organic vapor in air. Compositions of the vapor range from 10 to 95 percent air, and assumed condenser exit temperatures range from 110 deg to 50 deg f.