Temperature on the Specific Heat of Aniline. 57 



generate the least heat compatible with efficient mixing. The 

 stirrer was supported in the same manner as that described in 

 a former paper ; that is, its bearings were entirely external to 

 the calorimeter except at the base, where, to check vibration, 

 an agate cylinder hung within a ring *. 



In place of the 2000 revolutions per minute used in my 

 former work I confined myself, for the reasons above stated, 

 to a comparatively slow rotation of from 500 to 300 revolutions 

 per minute. The revolving shaft was electrically connected 

 with the chronograph in such a manner that the time of every 

 1000 revolutions was automatically recorded on the tape. 



Before commencing the observations on aniline 1 introduced 

 299*35 grms. (in vacuo) of water into the calorimeter, and, 

 with a view to ascertaining the water-equivalent, performed 

 a few experiments to determine the rate of rise when a known 

 current was passed through the coil. The point was not of 

 great importance, as I proposed to determine the specific heat 

 of aniline by a method requiring no knowledge of the water- 

 equivalent, which, however, when the specific heat of aniline 

 was known, could be deduced from the experiments, and thus 

 a previous determination by means of water would serve as 

 an independent test of the accuracy of the results. I had not 

 covered the german-silver coil with any insulator, since, 

 aniline being itself an insulator, the precaution was un- 

 necessary ; and this freedom to use the naked wire was one 

 of the chief reasons which led to the adoption of aniline as a 

 suitable liquid for my subsequent work. J was therefore 

 aware that I could not expect very satisfactory results from 

 the use of water. The polarization was considerable, as shown 

 by the back E.M.F. at the termination of an experiment, and 

 also by the difficulty experienced in making any accurate 

 determination of the coil-resistance. However, it was sub- 

 sequently found that the experiments gave very fair results. 

 The temperature w^as raised from about '5° C. below to *5° C. 

 above the surrounding temperature (i. <?., through about 

 12 centim. of the bridge-wire), and the times of passing the 

 several divisions of the bridge- wire were recorded on the chro- 

 nograph. Five experiments were performed, and the results of 

 the first three gave a water-equivalent of 80*1, and Nos. 4 and 5 

 of 79*8. They were thus divided into groups before the results 

 were calculated, as the coil showed decided signs of change in 

 resistance between the two batches of experiments. I had 

 proposed to continue these experiments with a different mass 

 of water, but became alarmed as to the effect on the coil of 



* A portion of the shaft of the stirrer was constructed of ivory, to 

 diminish its thermal conductivity. 



