AbstractThe solubility of water in methylene chloride and I: 2‐dichloro‐ethane over the temperature range ‐ 20° to 40° and 80° respectively has been determined. The vapour pressures of the solvents, alone and in admixture, have been measured, and the composition of the varour phases of the mixed solvents determined at 10° intervals. over the range 20‐50°. Evidence of the formation of azeotropes with water is given; boiling point: composition and vapour pressure: boiling point relationships are derived. Mixtures of the two solvents are found closely to obey Raoult's law. The results are discussed in the light of Hildebrand's theor