284 MR. HE. H. GRIFFITHS ON THE LATENT 
for heat of the calorimeter and its contents throughout my range of temperature, and 
as far as regards the purposes of the present enquiry, a great portion of my work on 
aniline was rendered useless. The method employed during the aniline investigation 
necessitated a repetition of the experiments with different masses of aniline and with 
different electromotive forces. As, however, those experiments had given me a very 
exact determination of the capacity for heat of the calorimeter itself throughout the 
range of temperature 15° to 52° C., the whole of the labour had not to be gone 
through again, for (the “water equivalent ” of the calorimeter being known) it was not 
necessary, when using oil, to repeat the experiments with different masses. 
In Appendix II., I give particulars of the method employed for determining the 
capacity for heat of the calorimeter and contents at different temperatures. 
The following table gives the results, and as the value of the specific heat of this 
oil at different temperatures may be of use to other experimenters, I have also given 
(in terms of a thermal unit at 15° C.) the capacity for heat (C,,) of calorimeter and 
contents at temperature 6, (N scale), and the specific heat of the oil S,;. The mass of 
oil (corrected to vacuo) = 474°02 grams. 



TABLE III. 
| a, Ow. S. -4830 + (0, — 20) x -00087, | 
20 307°50 | -4830 -4830 
| 30 312:38 | -4917 ‘4917 
40 31779 | 5006 5004 
50 323-14. 5092 5091 



The tables in Appendix II. show that the numbers in Column III. are durect 
experimental results, not “smoothed” in any way. 
It is noticeable that the value of S, is a linear function of @, throughout the above 
range, although the curvature of the line giving the capacity for heat of the 
calorimeter is very marked. 
Probably these results are correct to better than 1 in 1000 (see Appendix IT.), but, 
as an inspection of Table II. will show, an order of accuracy of 1 in 10 would have 
been sufficient. As, however, the accurate determination of C, and 8, involved (by 
the method adopted) little more labour than an approximate determination, I thought 
it advisable to ascertain the specific heat of the oil with accuracy. 
Since Yq = C,, {(0 — 0”) + (dt —d”)} and C,, varied from 307 to 323, it is 
obvious that if Sg was to be kept small, the changes in # and d must be very 
limited, and that such changes must be measured with extreme care. Having 
already described the manner in which the temperature of the surrounding walls was 
kept constant, and the way in which any small variations in 4) were ascertained, 
I now indicate the method of measuring the values of d’ and d” (ue., the initial and 
