SIR B. C. BRODIE ON THE ACTION OF ELECTRICITY ON OASES. 
481 
bulb of protochloride of tin was estimated by running a bulb of the solution into a 
measured quantity of hypochlorite of soda, of which the oxidizing value had been pre- 
viously determined by effecting its decomposition by means of an acid solution of iodide 
of potassium, and estimating the iodine formed with a standard solution of hyposulphite 
of soda. A solution of iodide of potassium was added to the solution of hypochlorite 
of soda before the addition of the protochloride of tin. The bulb of protochloride of 
tin was then run into the solution, which was immediately acidified with hydrochloric 
acid, and the iodine estimated as before. A similar experiment was made after the 
completion of the experiment with each of the two bulbs of protochloride of tin 
employed in it ; the oxidation effected was calculated, as in the former method, from the 
difference between the two titrations. This method gives good and accurate results ; 
the contraction was not estimated. 
The experiments were made at 0° C. The strength of the protochloride of tin is given 
in the first column: Q is the oxidation in the second bulb, S — Q is the oxidation esti- 
Jg Q 
mated as due to the ozone, and the ratio — p — given in the last column is the ratio of this 
oxidation to the “ titre” of the gas. 
Strength of 
T 
S. 
Q. 
S-Q. 
S-Q 
the solution. 
T ' 
3-78 
8-98 
30-95 
1-28 
29-67 
3-3 
7-07 
8-98 
37-36 
7-06 
30-3 
3-37 
It will be observed that in the second of the two experiments the strength of the tin 
solution employed was nearly double the strength of the solution employed in the 
former of the two experiments ; and the oxidation effected by the passage of the associated 
oxygen was so greatly increased that the oxidation in the second bulb, in the latter 
experiment, amounted to nearly as much as six times the oxidation effected in the same 
bulb in the former experiment : nevertheless, when the correction has been applied for 
this oxidation, the number representing the oxidation due to the ozone is almost the same 
as in the former experiment ; and this oxidation, thus calculated, closely approximates 
to three times the “ titre” of the gas. The coincidence of this result in the two expe- 
riments affords a guarantee of the accuracy of the principles on which the process depends. 
The two following experiments were made with an extremely dilute solution of proto- 
chloride of tin, on which, under the circumstances of the experiment, pure oxygen has 
but very little action. In the second of the two experiments the solution was so dilute 
that no inconsiderable portion of the ozone passed unaltered through the solution. To 
estimate the amount of ozone actually effective for the oxidation of the tin, the gas after 
its passage through the bulb of protochloride of tin was passed through a second bulb 
of neutral iodide of potassium, in which the ozone which escaped from the deoxidizing 
influence of the tin salt was arrested and estimated. 
In these experiments the contraction as well as the oxidation was estimated with the 
following results:— 
