HEAT OF EVAPORATION OF WATER. 331 
If we assume 
tr* = 336000, 
we get 

dé, 7 
C= aa: a Cea tnem alee adc 310/753) 
And here again the differences between the experiments and the results from (B) 
are much below 1 per cent. at rates between 5:2 and 5°5, and again the experiment 
at higher speeds (Expt. V.) indicates that tr* is more constant than ¢7%, 
Applying formule. (A) and (B), we can deduce the rise for a rate of 5°300. 
Values of (d@,/dt), at rate 5°300 :— 


| Temperature. | (d6, /dt),. 
| 40°1 001608 
| 002348 

Now (see Appendix I., Experiment IV.) it was found that when a similar experiment 
was performed at 40°°1, where the heat supply was that due to a potential difference 
of three Clark cells at 15° together with a stirring supply (at rate 5277), then 
(d@,/dt).,; = °14853 (mean bridge-wire millim.). 
Now (from A) we get 
(d0,/dt), = °00158 at rate 5°277, therefore (d6,/dt),, = °14695, 
therefore 
(d6,/di), == 
= 016335 
hence 
(d0,/dt), 161 
(d0,/dt). 1633 

at rate 5°300 (supra) = ‘0986. 
Now the corrected resistance at this temperature (Table VIII.) was 10°376 ohms 
where the D.P. was that of one Clark cell, and since 
e 143422 , 
yy UE See, We have 10376 x 4198 — 04728 thermal gram, 

therefore 
Q, (rate 5300) = 04723 X °0986 = 004659 thermal gram. 
2 wi 2 
