HEAT OF EVAPORATION OF WATER. 333 
Now, if we assume L at 40° = 573 and L at 30° = 579, we can deduce the values 
of Q,, which are as follows :— 
At 40°, Q, = 00460 
» 30°, Q, = -00658. 
These results differ from those obtained without any weighing or passing of air 
(equations Cand D supra) by 1 in 77 and 1 in 94 respectively. As an order of 
accuracy of 1 in 50 was sufficient for my purpose, I considered this independent 
evidence valuable, although I believe the former method to be by far the most exact. 
T also performed a determination of Q, at 50° by an evaporating experiment. This 
gave ‘00000521 gram per sec, Assuming L = 567, this would give Q, = ‘00295, 
far too high a value as compared with that given by equation (EZ). This evaporation 
experiment was a very unsatisfactory one, however, and I attach but little importance 
to it—in any case, the doubt would not affect the values of L. 
To conclude this portion of the subject, I admit that it would have been advisable 
to perform more of these stirring experiments at 30° and 40°, but at the same time, 
I think the evidence is sufficient to warrant the assumption that the values of Q, 
cannot be in error by as much as 1 in 50 and are probably correct to better than 
1 in 100. 
Appendix IJ.—Deraits oF THE EXPERIMENTS BY WHICH THE CAPACITY FOR 
HEAT OF THE CALORIMETER AND CONTENTS WAS ASCERTAINED. 
The temperature of the calorimeter was adjusted in the same manner as that 
described in Appendix I. 
The time of transit across five bridge-wire divisions about the readings 50, 60, and 
70 centims. was taken, and the times at 50, 60, and 70 deduced. I give particulars 
of Experiment IV.,as that was the one quoted in Appendix I., from which the 
value of Q, at 40°1 was deduced. 
