SIR B. C. BRODIE ON THE ACTION OF ELECTRICITY ON OASES. 
475 
the probable error of a single experiment = \/Yi X the probable error of the result 
= \/l7x 0*017 
= 0-07 cub. centim. 
It appears, therefore, from these experiments that it is an equal chance that the true 
value of the ratio lies between the limits 2 , 00 and 2*04. The theoretical value 
of this ratio, 2, is within these limits, and the experiments are in accordance with 
theory. At the same time it cannot be doubted that here also, from the causes pre- 
viously indicated in the case of the similar experiments made with alkaline hyposulphite 
(Section III.), the mean experimental value of this ratio, 2 - 02, is somewhat too high ; 
also, from the calculated value of the probable error of a single experiment, 0 - 07, half the 
V— Y 
values of — given in the preceding Table might theoretically be expected to be 
found within the limits 2-09 and T95. Of the seventeen experiments, nine are within 
these limits, and eight outside them. The experiments, therefore, in this point also 
agree with theory. 
The solution of hyposulphite of soda, originally neutral, is found, after the passage of 
the ozone, to have become strongly acid. Considering that the acid thus formed might 
exercise some important influence upon the reaction, I experimented with solutions of 
hyposulphite of soda rendered slightly alkaline with carbonate of soda. The influence 
of a great excess of carbonate of soda is, as has been shown, to reduce the oxidation, so 
that the contraction in the case of the strongly alkaline solution is only half the con- 
traction in the case of the neutral solution. I therefore (with the view of adding only 
a slight excess of alkali) estimated by titration the amount of carbonate of soda required 
to render the solution neutral after the passage of the gas, and added to the solution 
employed in the experiment two or three times that amount. This amount of carbonate 
of soda was sufficient to keep the solution alkaline during the experiment, without, as 
will be seen, sensibly reducing the oxidation effected by the electrized gas. When about 
this quantity of carbonate is added the solution is spoken of as slightly alkaline. The 
following ten experiments were thus conducted. The Table below is of the same nature 
as the preceding. 
o T 
MDCCCLXXII. 
