﻿188 Mr. Horace H. Poole on the 



to which the chart GHJKLMN refers the calorimeter and 

 its contents were kept approximately at 0° (J. 



Daring the periods GH, JK, and MN the heater was not 

 in use. During HJ the resistance in series was 4000 ohms 

 and the voltage of the battery measured on a Weston 

 voltmeter was 4"03 ; these figures give a heat evolution of 

 0*106 calorie per hour. 



During KL the resistance in series was 6000 ohms and 

 the voltage 4*00, giving a heat evolution of 0'0475 calorie 

 per hour. 



On the day marked M the accumulator voltage was found 

 to have suddenly fallen to 2*4, which explains the 1ow t reading 

 observed. The heater was then turned off. In the following 

 table the various columns have the same significance as 

 before : — 



A. 

 GH .. 



B. 



Scale- 

 divisions. 



.. 19-75 



C. 



Calorie* 

 per hour. 

 



D. 



Scale- 

 divisions. 



E. 



Calories 

 per hour. 



HJ . 



. . 40-85 



0-106 



21-5 



0-00493 



JK . . 



. . 18-95 









KL . 



. . 28-15 



0-0175 



955 



000497 



MN .. 



. . 18-3 









Unfortunately the period KL was unduly curtailed by the 

 failure of the accumulator, and the experiment was brought 

 to an end at N by the breaking of one of the wires of the 

 couple (probably owing to a strain set up by some movement 

 of the ice). 



From this and the previous series there seems to be little- 

 doubt that each scale- division represents a generation of 

 0*0049 calorie per hour, so for the periods GH, JK, and MN 

 the heat evolved by the orangite is 20*2 x 10 -5 , 19*3 x 10" 5 , 

 and 18*7 x 10 ~ 5 calorie per hour per gram respectively. 



These figures, while lower than the preceding ones, are 

 still very much higher than was to be expected. The dimi- 

 nution also noticeable in these results is probably due to 

 variations in the ice round the outer junctions. An exactly 

 similar effect was often noticed with pitchblende when the 

 calorimeter had been buried for a long time in the ice. The 

 final period MN was so short that little weight attaches to it, 

 and, as will be noticed, the lowest temperature recorded 

 occurred in JK. 



The calorimeter was finally opened and everything found 

 in perfect order except for the broken wire. An attempt to 

 connect the copper vessel to a pressure-gauge failed owing 



