TANK AND BATH 



A 5-gallon tank contained the two-layer system. Temperature was main- 

 tained at 21.00 (±0.1) °C by immersion of the 5-gallon tank in a 15-gallon aquarium 

 tank. The latter tank was insulated from the atmosphere by a 3-inch layer of 

 Microlite, a commercial form of spun glass. A window cut into the side of the 

 Microlite enabled measuring with the cathetometer, and a small aperture cut into 

 the top admitted the microcell. Water maintained at 21.00 (±0.02) °C flowed 

 through copper tubing coiled around the 5-gallon tank. The temperature was regu- 

 lated by a controlled-temperature bath manufactured by the Precision Scientific 

 Company (fig. 1). 



Figure 1. Test setup, showing insulated aquarium tank, temperature control system, 

 and conductivity cell. Photograph at right shows conductivity cell in entirety. 



