The velocity of inversion of sucrose has been determined in the presence of salts of different ion-types at 25°. In the solutions used the concentrations of three components are definitely fixed, namely: sucrose 0.1 m., hydrochloric acid 1.0 m., and water 1000 grams. The salt concentration is the only variable. The salts used were LiCl, NaCl, KCl, BaCI2 and Al(No3)3. For equal molal concentrations of the different salts the velocity coefficients increase in the order: KCl23)3. The salt effect appears to be explained best on the basis of ionic hydration due to the attraction between the ions and the water dipoles. While it was not possible at the time to determine the activity of the solvent in the inversion solutions, the reaction velocity increases inversely and practically linearly with decrease in the activity of the solvent due to the salt alone
