ELECTRONIC OSMOMETER WITH RIGID MEMBRANE OF COPPER FERROCYANIDE

Abstract

An electronic osmometer supplied with a rigid but leaky semipermeable membrane, and a semiconductor strain transducer was described. The leaky membrane so prepared responded rapidly to a colloid solution with reproducibil-ity of ± 1.7%. The continuous recording showed a monoexponential response up to a plateau followed by a gradual decrease. Our investigation showed that the maximum height of the plateau can be regarded as the product of the true osmotic pressure and the reflection coefficient, and that the reflection coefficient remained unchanged during repeated measurments. With this osmometer, it was possible to detect relative changes of osmotic pressure developed by a solute in water. After determining the reflection coefficient, native changs could be calibrated into absolute units of atm. Possible applications of the osmometer were described.