292 MR. E. H. GRIFFITHS ON THE LATENT 
Let ¢ be the time of rising through a small range of temperature from below to 
above the surrounding temperature (6). 
If the heat supply is in one case due to both an electric current and the stirring, 
and in another to the stirring only, we have 
(d6,/dt)., — (d0,/dt), = (d0,/dt). .... - = 2 ey 
where 6, is the temperature of the calorimeter, and the suffix denotes the nature of 
the supply. 
And (using the notation on pp. 272 and 273) 
(d0,/dt), = Q./C,,, and (dé,/dt), = Q,/C,, 
therefore 
Qe (dO, /dt), Ey 
Ce CCC Perna (TIT), 

Eq. (II.) will be true on any scale, and thus it is unnecessary to convert the 
bridge-wire readings into degrees C., and since 
Q;=70. eo os) ee eee 
if e, n, and R, be known, we can find Q,, for 
QrS er Ry 2 ee. oe 
Thus Q, can be found, although the capacity for heat of the calorimeter and 
contents and also the scale of temperature are unknown. 
If we convert the bridge-wire degrees into C. degrees (N. thermometer) then, since 
(d0,/dt)., — (d0,/dt), = Q./C,, 
we get 

m2 Qe 
Co = (ja. — (dB, ]dl), Ree oi)? 
and thus C,, can be found. 
In Appendix I. I give particulars of the experiments by which the values of Q, for 
different values of 6, were found. I regret that the observations are so few in 
number. Unfortunately I did not adopt this mode of experiment until the eleventh 
hour, and as these experiments were very lengthy, I should consequently have been 
unable to complete sufficient direct determinations of L to establish its value at the 
two points to which want of time compelled me to limit the investigation. 
On comparing the results with those obtained in oil by the previous method, 
I found that the agreement was sufficiently close to warrant a postponement of further 
