In modifying previous methods for obtaining pure ricinoleic acid, the authors were able to prepare the compound with a degree of purity which had not previously been reached and discovered that very pure sodium ricinoleate may be crystallized from its alcoholic solution.The authors determined a series of physical properties of pure ricinoleic acid, the specific gravity, refractive index, and viscosity at various temperatures. These determinations make it possible to establish the degree of purity of this chemical species rapidly and certainly, or, on the other hand, to draw comparisons between them and the properties of other fatty acids which would give us more accurate and broader knowledge of their constitution.