10 



ELECTRICAL CONDUCTITIVES, ETC. 



The second temperature at which the conductivity measurements were made was 

 at first taken as that of the hydrant water. A reasonably constant temperature 

 could be obtained by allowing a rapid stream of hydrant water to flow through a 

 large vessel of water. This was soon abandoned and a temperature of 10, 12.5 

 or 15 was obtained as follows: A stream of hydrant water was allowed to flow 

 through a large tub of water, which was warmed by a small flame placed beneath, 

 and the temperature was regulated by the thermoregulator described by Reid.* 



The higher temperatures, 25, 35, 50 and 65 were obtained as follows: The 

 water-bath used had the form shown in fig. 4. It consisted of a double- walled 



Fig. 4. 



metal tub, the outer walls being 18 inches apart and the inner tub being 14 inches 

 in diameter. The space between the two walls was filled with asbestos cement, 

 which is a very poor conductor of heat. The inner vessel was filled with water, 

 heated by a flame placed beneath and regulated by a thermoregulator. The top of 

 the bath was covered with a neatly fitting piece of asbestos board. It was possible 

 to keep any one of these baths to within 0.02 to 0.03 of the temperature desired. 

 When working over the higher range in temperature the cells were kept over night 

 in the 50 bath. 



Amer. Chem. Journ., 41, 148 (1909). 



