Temperature on the Specific Heat of Aniline. b'l 



Reduction of the Results. 



Let O be the temperature of the surrounding envelope and 

 Y that of the calorimeter at any time t. Let the change in 

 temperature per second due to the work done by the stirrer 

 be <r, and let p equal the gain in temperature per second due 

 to the combined effects of convection, conduction, and radiation 

 when the difference in temperature between the calorimeter 

 and the surrounding envelope is unity. 



Let a wire whose resistance is R at O and R x at l be im- 

 mersed in a liquid contained in the calorimeter, and let the 

 mass of the contained liquid be M and its specific heat S, 

 when the temperature is V 



Let the capacity for heat of the calorimeter be iv± when 

 the temperature is V 



Thus the thermal capacity of the calorimeter and contents 

 at any temperature X is S 1 M + «7 1 i 



If the ends of the wire be kept at a constant potential- 

 difference of E, then we get (paper J, v. 361) : — 



E 2 dO 



j.r 1 (S 1 m+«. 1 ) -H°-p(*i-*»M=-ar- 



Since a is small and we can make Q x — O of any magnitude 

 we please, it is always possible to obtain a value of X such 

 that a — p(0 l — o )=O, and in that case 



E 2 ,( d h\ 



j.R^M+zri) ~\dt ); 



the suffix denoting the nature of the supply. 



This temperature (viz. that value of 6 [ which causes 

 <r — p(0 1 —0 o ) to vanish) I shali denote throughout this paper 

 by the term u null point," by which I mean that value of l 

 at which the observed rate of rise is due to the electrical 

 supply only, and I shall use 0% to indicate that temperature. 



Two or three methods of finding 0^ suggest themselves. 

 If the stirrer be set working when there is no electrical 

 supply, then 1 will gradually approximate to 0^, and a few 

 observations as to the rate of change in X will supply sufficient 

 information to enable the observer to set the value near to 

 0s, and the calorimeter can then be left to gradually assume 

 the true value. I have given this method a fair trial, for the 

 apparatus has been left working for twenty-four hours at a 

 time, and the value of 0^ ascertained with precision. 



For example, at the rate of 9 "10 revolutions per second it 

 was found that the value of 0x — o (expressed in terms of the 



