66 Mr. E» H. Griffiths on the Influence of 



and 



T 



hence 



Bi= 



T,-T 2 



JCMx-Ma)" 



We can now find the value of SxM^ and therefore 



T 



Thus both the specific heat of the liquid and the water- 

 equivalent can be found if two groups of experiments with 

 different masses of liquid have been performed at the same 

 temperature. 



Since J = 4*198 x 10 7 * ergs, when the unit of heat is u the 

 quantity of heat required to raise 1 grm. of water through 

 1° C. of the air-thermometer at 15° C," it follows that the 

 results obtained at different temperatures are all expressed in 

 terms of that unit, and are not dependent upon our knowledge 

 of the changes in the specific heat of water. 



Corrections. 



Before proceeding to plot the results the following cor- 

 rections had to be made : — 



I. For changes in the temperature of the steel chamber 

 during the time of an experiment. For temperatures below 

 26° C. a mercury-thermometer labelled A was used, situated 

 as described on p. 56, and 1 millim. change in A was equi- 

 valent to 4*05 millim. in the bridge-wire reading. Thermo- 

 meter IT. was used for temperatures above 26° C v and 

 1 millim. change in II. was equivalent to 5*5 millim. of the 

 bridge-wire. The resulting correction had to be added or 

 subtracted from the bridge-wire value of d0 u and it rarely 

 exceeded 0'2 millim. 



II. The correction to the " mean bridge centimetre." This 

 correction was given with great exactness by the table result- 

 ing from the calibration of the bridge-wire previously referred 



to. It is applied as a factor to —?r * 



III. The normal rate of stirring during experiments 1 to 8 



* Proc. Roy. Soc. lv. p. 26. 



