86 
SIR B. C. BRODIE ON THE ACTION OE ELECTRICITY ON GASES. 
back from the aspirator into the bulb, in which it was allowed to remain for some time 
until no further change in the volume of the gas occurred ; the gas was then retrans- 
ferred to the aspirator and again measured : the difference between the two measurements 
gives the volume of oxygen in the gas. The total volume of oxygen due to the changes 
occurring in the induction-tube is represented by the sum of this difference and the titre 
of the gas. The whole gas, or a portion of it, was transferred to a eudiometer of known 
capacity, oxygen added, and the mixed gases detonated. The contraction which occurs 
affords another and independent measure of the oxygen formed, the oxygen which 
disappears on this contraction being the volume of oxygen required to restore the gas 
to its original condition and reconstitute the state of things broken up in the induction- 
tube. I shall not now enter upon the further analysis of the gas, which presents pecu- 
liarities better reserved for future consideration ; but evidence will hereafter be given, in 
Section II., of the substantial identity of the results afforded by these two modes of 
estimation, although of the two measures that afforded by the contraction is undoubtedly 
the more exact. 
The following Table contains the experimental results obtained in these four experi- 
ments, which were made with the same coil, the same battery-power, and under the 
same general circumstances, no intentional variation being made in any of the conditions 
of the experiment. 
In column I. is given the volume of carbonic acid passed through the induction-tube, 
estimated (as are all other volumes of gas in these experiments) in cub. centims. at 0° C. 
and a pressure of 760 millims. In column II. is given the volume of gas unabsorbed 
by potash ; in III. the titre of the gas ; in IV. the oxygen absorbed by pyrogallate of 
potash ; in V. the total oxygen found by actual experiment — namely, the sum of the 
titre and the gas absorbed by pyrogallate. In column VI. the contraction is given which 
occurred on detonation with oxygen of the unabsorbed gas. 
I. 
II. 
in. 
IV. 
V. 
VI. 1 
Experiment. 
Carbonic acid. 
TJnabsorbed gas. 
Titre. 
Gas absorbed 
by pyrogallate. 
Total oxygen. 
Contraction. 
1 . 
1413 
29-89 
2-44 
7-98 
10-42 
10-49 
2. 
1385 
26-67 
1*55 
7-08 
8-63 
8-88 
3. 
1347 
37-66 
1-61 
10-99 
12-6 
13-47 
4. 
1390 
54-99 
3-38 
15-6 
18-98 
19*8 
Now if we assume two thirds of the sum of the titre and unabsorbed gas in the 
several experiments to be carbonic oxide, which is nearly although not quite the case, 
we have for the amount of carbonic oxide formed, and therefore of carbonic acid decom- 
posed, in the induction-tube in the four experiments respectively 
(1) 21-56 
(2) 18-81 
(3) 26-18 
(4) 38-92 
