Modification of the Apparatus Used for the Baldes Thermoelectric Method of Measuring Osmotic Pressure

Abstract

The apparatus employed with the Baldes method for determining osmotic pressure has been modified by substituting a breaker‐type d.c.‐a.c. amplifier for a sensitive galvanometer, thereby permitting its use under conditions where galvanometers are impractical. Precise temperature control of the water bath in which the thermoelements are immersed has been shown to be unnecessary provided the bath is stirred vigorously. A switch made from one block of electrolytically pure copper provides a satisfactory current‐reversing mechanism with low interfering contact potentials arising from non‐thermostated portions of the circuit.