An osmometer with an ideal semipermeable boundary

Abstract

An osmometer has been constructed in which the only possible transition from one cell to the other is through the vapor phase. In this way the problem of passage of solute is completely eliminated. In order to obtain a sufficient rate of transition of solvent, the distance between the cells has been made as small as possible. An osmometer with a vapor “membrane” of 0.05 mm. thickness is described and measurements with this osmometer are reported.

Polyacrylonitrile capillary membranes for membrane osmometry

“…Depending on the solvent permeability of the membrane, this process can be very time consuming and is the main source of the slow response times of conventional osmometers with flat membranes. One way to work around this problem is an active compensation of the osmotic pressure with a counter-pressure [4], which prevents solvent permeation to a large extent.…”