A new storage battery “duro,” made by the Chicago Battery Co., was 
used and showed no variations in EK. M. I. during the entire time. 
The density of the oil was determined by a specific gravity bottle and 
found to be .8370. 
The temperatures were read on a standard thermometer graduated to 
1-10 degree. 
As to the question of the accuracy of the thermo-couple in registering 
the instantaneous temperature we have to consider the couple itself, its 
behavior under known conditions, and the results obtained. 
The couple was of Fe-Cu, one millimeter in diameter, so its heat ca- 
pacity was very small. In calibrating it a defiection was regularly noted 
when the change of temperature of the bath was less than 1-100 of a 
degree. It was found that for small changes in temperature considerable 
time, several seconds, elapsed before there was any heating due to radiation, 
ete. This was due largely to the size of the vessel. Using a smaller one 
the time required to warm up was small. 
The exneriment is now being repeated under yastly better conditions. 
The temperature of the bath is regulated by an electric thermostat, the 
resistances, barometer and thermometer, have been checked up by the 
Bureau of Standards at Washington and the voltage of the “duro” cell tested 
immediately before and after cach observation, by means of a potentiome- 
ter of the Leeds Northrup type and a standard Weston cell. The results 
from the new determination will be published later. 
Wabash College, 
Crawfordsville, Tid. 
