90 
PROFESSOR W. RAMSAY AND DR. S. YOUNG 
From some of these the heats of vaporisation were calculated by help of the formula 
given for calculating specific heats. 
Heats of Vaporisation. 
Temperature. 
Observed. 
Calculated. 
E. and Y. 
Temperature. 
Observed. 
Calculated. 
E. and Y. 
O 
- 37 
94488 
94-296 
94-4 
1745 
92-12 
92-40 
88-8 
+ 7-51 
91-38 
93-36 
91-3 
34-83 
90-333 
90-21 
384-5 
12-9 
90-41 
92-85 
89-9 
120-9 
72-49 
, # 
62-5 
15'5 
90-53 
92-57 
89-25 
It is noticeable that the agreement between Regnault’s observed and calculated 
numbers is much less good at low than at high temperatures, with the exception of 
the first at —3'7°; and, as the four first determinations were made with the purest 
sample, more stress has been laid by Regnault on his observations with the less pure 
than with the purer ether. 
The heats of vaporisation thus calculated are widely different from the results 
obtained by us, with the single exception of that at the lowest temperature; but it is 
also remarkable that the individual experiments with the purer substance exhibit 
much closer concordance with our results. 
As the results about the temperature 35° by all observers exhibit fairly close agree¬ 
ment with the observations of Regnault, but differ widely from our calculated values, 
it appeared desirable to submit them to proof by translating Regnault’s results into 
vapour-densities ; and for this purpose the values of dpjdt were calculated by means of 
Biot’s formula, using Regnault’s constants. By thus doing, the work is entirely 
Regnault’s. The results are given in the following Table :— 
Temperature. 
dp 
dt 
dp 
dt 
dp t 
dt J 
L 
Sl-S 2 
Vapour- 
density. 
o 
0 
mms. 
844 
grammes. 
11-47 
0-07388 
94-0 
1272-4 
1273-8 
36-12 
10 
12-22 
16-615 
0-11063 
93-12 
841-7 
843-1 
36-37 
20 
17175 
23-35 
0-16099 
92-08 
572-0 
5734 
36-69 
30 
2347 
31-91 
0-22749 
90-86 
399-4 
400-8 
37'01 
35 
27-155 
36-92 
0-26756 
90-18 
377-05 
338-5 
37-15 
As the minimum value of the vapour-density of ether is 37, the first three results are 
impossible ; and, on consulting the Table on p. 64, giving the results of our measure¬ 
ments at 12'9°, and Table 58, p. 80, it will be seen that the density of the saturated 
vapour rises to 38'25 at 12'9°, and 39'95 at 50°. At 35° the vapour-density read from 
the curve is 39'05. 
