OF DILUTE SOLUTIONS OF ELECTROLYTES. HEBB. 427 



same angle to the thermometer. This one sees when he takes 

 into consideration, that the distance between the mercury column 

 and the scale, which is back of it, is at least 120 times as great 

 as the smallest distance read on the scale. In order to keep the 

 microscope always at the same inclination to the thermometer, I 

 had two arms rigidly attached to the microscope one above 

 and one below it. Before a reading was taken, the stand of 

 the microscope was so adjusted that the arms touched the 

 thermometer. 



Directly over the top of the thermometer was placed aw 

 electric hammer, driven by a current from a Samson battery, 

 It gave quick, sharp taps and, hence, prevented the mercury 

 from sticking at one place. 



The following method was used to find the convergence 

 temperature. The apparatus, as described, was set in order with* 

 a mixture at 0C. in the protection bath, and water in the 

 freezing-tubes, and then the stirring was begun and kept run- 

 ning until the apparatus arrived at a state of thermal equili- 

 brium. With the apparatus working at 50 complete strokes per 

 minute, I found it to be .005 degree above that of the protection 

 bath. Hence in all of my determinations of freezing-points, the 

 temperature of the protection bath was kept .005 degree below 

 the freezing-point of the solution under experiment it having: 

 been approximately determined beforehand. This convergence 

 temperature is much smaller than that found by other experi- 

 menters. Its smallness may be due to two things : (1) the 

 freezing-tubes may be too easily affected by the protection bathv 

 or (2) the apparatus may be free from friction and other sources- 

 of heat. I am fully convinced that its snmllness in my case was 

 noi due to the former, but due to the fact that the amount of 

 friction was very small, and that the nir temperature was 0C. 



The following was the method used in making a determina- 

 tion of the freezing-point. The approximate freezing-point of 

 the solution having been found, the temperature of the protec- 

 tion bath was brought to be .005 degree below this. The portions 

 of the apparatus, in contact with the solution were then- 



