58 Mr. E. H. Griffiths on the Influence of 



the change that was going on, and decided to withdraw the 

 water, for had the coil become useless from any cause, the 

 whole apparatus would have had to be taken to pieces and the 

 base of the calorimeter unsoldered, &c, involving a delay of 

 at least a week or two. 



During the time that the water was in the calorimeter 

 I performed a considerable number of experiments to deter- 

 mine the rise in temperature due to the work done by the 

 stirrer. With this form of stirrer and the low rates, tr 2 was 

 practically a constant, where t was the time of rising 1 centim. 

 of the bridge-wire and r the rate of revolution per second. 

 The resulting correction was comparatively small, amounting 

 to about -2^ of the heat generated by the current during the 

 water-equivalent experiments ; thus any small error in the 

 correction introduced when eliminating the heat supplied by 

 the stirrer became unimportant. 



After the water was withdrawn, the whole apparatus was 

 kept for three days at a temperature between 40° and 50° C, 

 while dried air was forced continuously through every part of 

 it. At the end of this time a sulphuric-acid bulb (through 

 which the air passed on its exit from the apparatus) showed 

 no increase in weight. I then introduced 294*1)9 grms. [in 

 vacuo) of aniline into the calorimeter *. 



I will at once state that no great pains were taken to secure 

 an absolutely pure specimen of aniline. For my subsequent 

 experiments the purity of the aniline was a matter of no con- 

 sequence, as I only required to know the actual capacity of 

 the calorimeter and contents at different temperatures. 



Again, as regards the purposes of this investigation I think 

 that it will be of greater service if I am able to supply experi- 

 menters with the specific heat of a quality of aniline at all 

 times procurable, rather than if I gave the constants of a 

 quality only to be obtained with difficulty. The sample I 

 used was supplied by Messrs. Harrington Bros., as " pure 

 colourless," and had but a light brown tinge. It was re- 

 distilled by me once before use, and I also determined its 

 boiling-point, which was in agreement with that of a specially 

 pure sample which I had examined on a previous occasion |- 

 Further (and this I have always found to be a fair test of the 

 purity), the temperature of the boiling-point did not change 

 during distillation. 



From the time that aniline was first introduced into the 



* The precautions observed in order that the mass introduced might 

 be accurately determined are fully described in paper J, p. 418. 

 t Trans. 1891 A, p. 64. 



