ON THE ADIABATIC RELATIONS OF ETHYL OXIDE. 
173 
tube. This, of necessity, made the experiments somewhat tedious and difficult; but 
we venture to think they are as accurate as the method allows. 
11. Method of Ascertaining the Weights of Ether Employed. 
For each set of experiments with a single jacketing vapour, the tube had to be 
specially ffiled with ether. This involved a ditferent weight of ether each time, it 
was necessary to know the weight, in order to calculate the volume occupied by 
1 grm. of the vapour. 
To ascertain the weight, the volume at any given pressure and temperature was 
ascertained from an isothermal diagram showing from previous experiments, by 
IIamsay and A^oung, the relations between volume, temperature, and pressure. From 
this the weight was calculated at each different volume. All the results thus obtained 
were averaged, and the mean results accepted as the weight. 
To take an instance :—At the temperature 140° C., the actual observed volumes 
and pressure were found as in the first two columns. The volume of 1 grm., corre¬ 
sponding to the pressure in each case, is given in the third column, and is taken from 
the Memoir referred to ; and the weight, calculated from the volume of 1 grm., is to 
he found in the fourth column. The mean result of all these determinations was 
taken as the true weight. The volumes of 1 grm. were then calculated by dividing 
each observed volume by the mean weight. The details of one s^t of observations are 
given in the following table :— 
Temperature 140° C. 
Pressure. 
Actual volume. 
Volume of 1 grm. 
(from diagraui). 
Weight. 
Corrected volumes. 
Miiliius. 
' 4586 
2-279 
67-60 
-03371 
67”29 
5070 
1-973 
60-25 
-03275 
58-26 
5649 
1-791 
53-00 
-03379 
52-88 
6394 
1-552 
45-80 
•03388 
45-82 
6798 
1-433 
42-60 
•03364 
42-31 
7290 
1-315 
39-00 
•03371 
38-81 
7830 
1-197 
35-75 
■03348 
35-34 
8725 
1-079 
31-10 
■03470 
31-86 
9487 
09615 
27-80 
•03459 
28-39 
9912 
0 9027 
26-20 
•03445 
26-95 
Similar sets of observations at other temperatures with the same ether were 
taken, and from them the mean weight was ascertained. But it frequently 
happened that the results at one temperature did not coincide with those at 
another. It must be remembered that the tube lay horizontally, and that on tilting 
it, after a set of observations had been made, more ether wmuld escape up the tube. 
For the hot mercury in passing down gasified ether remaining in that portion of 
