These two papers cover the author's investigations at the Courtauld Institute on the effect of solvents on specially prepared drying-oil films. There are many tables and graphs summarizing swelling, leaching, density changes, effects of temperature, thickness and pigment, correlation with solubility parameter, and effect of aging up to 117 weeks at 32°C. A very wide range of solvents was used. Results are compared with theoretical swelling and diffusion equations. The three questions concerning which restorers would like quantitative results - Does the cleaning solvent penetrate the oil film? How much of an old oil film is soluble? How does leaching affect mechanical properties? - cannot yet be answered. Stolow, however, has covered a great deal of the important preliminary work.