446 
SIR B. C. BRODIE ON THE ACTION OF ELECTRICITY ON GASES. 
“ titre ” had sunk to 23 cub. centims., after ninety hours to 20 cub. centims., and 
after 114 hours to 18-75 cub. centims.; and it is highly probable that the electrized 
gas might be preserved over perfectly pure sulphuric acid in a cool place with very 
slight and gradual alteration. In the present experiments, however, no error could 
arise from such alteration of the gas, as the “ titre ” of the gas was invariably taken 
immediately before any series of experiments was made ; and if the experiments were 
extended over a time in which, judging from previous experience, the “titre” of the 
gas might be altered, this “ titre ” was again taken at the conclusion of the experi- 
ments. The “ titre ” is quite independent of the strength of the solution of iodide of 
potassium employed ; it is not, however, desirable to operate with a strong solution, as 
in this case errors may arise from the oxidation of hydriodic acid during the process of 
titration by means of atmospheric oxygen. 
In the following Table the results of eight experiments are given, in which the volumes 
of the electrized gas before and after passing through a solution of iodide of potassium 
are compared, the volume before being that read in the pipette, the volume after being 
that read in the aspirator ; these volumes, and all other similar volumes referred to in 
these experiments, are given in cubic centimetres reduced to 0° C. and 760 millims. 
pressure. In the first column I have given the “titre” of the quantity of gas employed 
in cubic centimetres of oxygen similarly reduced. 
“ Titre.” 
Volume before the 
experiment. 
Volume after the 
experiment. 
13-58 
269-55 
269-57 
7*53 
271-33 
271-32 
10-52 
276-68 
276-11 
5-82 
272-28 
271-89 
5-47 
271-46 
271-46 
13-17 
274-18 
273-84 
13-17 
273-87 
273-45 
13-17 
273-90 
274-00 
Mean 10-30 
Mean 272-906 
Mean 272-705 
Assuming the mean as the correct result, it appears that for every 100 cub. centims. 
of gas in the pipette 99-93 cub. centims. appear in the aspirator, and 3-77 cub. centims. 
of oxygen are absorbed by the iodide of potassium without any appreciable diminution 
of the volume of the gas, the slight difference found in the mean value of the volumes 
before and after the experiment being fully accounted for by the absorption by the 
alkaline liquid of minute quantities of oxygen. 
[To increase the percentage of ozone was, for the purpose of the present experiments, 
no great object ; indeed to a certain extent it was even disadvantageous, as a gas rich 
in ozone is move readily subject to decomposition than a gas containing a smaller pro- 
portion. The average amount of ozone in the gas as actually employed in these experi- 
ments was about 4 per cent., but occasionally much higher. The following Table contains 
me record of a few estimations of ozone in the gas after collection in the gas-holder. 
