January 4, 18; 3.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
52 7 
stituted of four, five, or six such weights ; it was only 
the suggestion of the simplest possible constitution for 
ozone that was consistent with the facts. 
A few years afterwards, in 1865-66, the probability of 
this being the real constitution of ozone was much 
strengthened by the results of some experiments con¬ 
ducted by Soret. Operating by a process very simple 
and ingenious, but scarcely calculated to afford precise 
results, Soret found that when electrolytically-obtained 
ozonized oxygen was allowed to act upon oil of turpen¬ 
tine, the absorption of the ozone hy the turpentine was 
attended by a diminution in the volume of the gas equal 
approximatively to twice the initial contraction,—as in¬ 
ferred, of course, from the iodine-titre of the ozonized 
gas, or from its permanent expansion after exposure to a 
temporary heat. Supposing the final diminution effected 
b} r the turpentine to have been exactly twice the initial 
contraction, inferred from the iodine-titre, it is clear 
that, while the original gas would have suffered alto¬ 
gether a diminution of three volumes, the ozonized gas 
would have suffered a diminution of only two volumes. 
Or there would have been ultimately_ abstracted from 
the original uncontracted gas three volumes of the 
matter of oxygen, occupying in the contracted or 
ozonized gas, submitted to the action of the turpentine, 
only the bulk of two volumes. But as a mean result oi 
Soret’s first set of five experiments, the final diminution 
-effected by the turpentine was 2*40 times the original 
contraction; while, as a mean result of his second set oi 
seven experiments, the final diminution was 1’81 times 
the original contraction. Assuming, however, ozone to 
have the constitution expressed by the symbol 0 3 , its 
specific gravity, and consequently its diffusion-velocity, 
would approximate closely to the specific gravity and 
diffusion-velocity of carbonic acid gas, C0 2 ; and in 
1867, Soret, in corroboration of his previous absorption 
results, satisfied himself that the diffusion-velocity or 
ozone really does approximate very closely to that oi 
carbonic acid. 
YI. During the last few years, the quantitative reac¬ 
tions of ozone have been made the subject of an elaborate 
study by Sir Benjamin Brodie, whose results constitute 
indeed “a body of exact information as to the chemical 
properties of ozone, through which it may be hoped that 
this important question will be finally removed from 
the domain of arbitrary speculation and brought within 
the precincts of science.” In Brodie’s experiments, a 
quantity of pure perfectly dry oxygen, after having 
been submitted to electrization by its passage through a 
modified form of Siemens’ induction tube, carefully 
maintained at a low temperature, was collected in an oil 
-of vitriol gas-holder, to the amount of four or five 
thousand cubic centimetres. From the store of ozonized 
gas thus collected, which was found to maintain its pro¬ 
portion of ozone without appreciable deterioration for 
some hours, portion after portion was allowed to pass 
into a pipette of about 250 c. c. capacity, by dis¬ 
placement of the oil of vitriol originally filling it; 
•and successive equal volumes of the store of ozonized 
gas so measured off, were submitted one after another 
to the action of the same or of different reagents, by the 
passage of each pipetteful of gas through a small bulb- 
tube containing the reagent in solution. The gas, freed 
from all ozone by its passage through the reagent, was 
next received into a mercurial measuring cylinder, in 
which it was expanded to a definite volume; and then, 
by reading off the pressure at which it occupied this 
volume, its proper volume was ascertained. Finally, the 
difference between the capacity of the pipette and the 
volume obtained in the mercurial cylinder showed the 
volume of the gas absorbed by the reagent,—the weight 
•of this gas being determined directly or indirectly by 
titrations of the reagent. Of course, very many points 
•of detail in the construction and use of the apparatus 
had to be attended to, in order to ensure trustworthy 
results ; but, both in its principle and general working, 
the process is exceedingly simple. One essential novelty 
consists in the application of that very useful instrument, 
the pipette, to the purposes of gas analysis: and by its 
aid, results having a degree of accuracy far greater than 
those furnished by any previous method of ozone inves¬ 
tigation, were found to be obtainable with both speed 
and facility. 
Operating, then, with the apparatus just described, 
Brodie has succeeded in establishing three perfectly de¬ 
finite classes of ozone-reactions,—the first of them in¬ 
cluding the instances previously made known by An¬ 
drews and Tait. In this first class of reactions, of which 
there are several distinct varieties, the absorption or de¬ 
composition of the ozone present in a mixture of ozone 
and oxygen, is unattended by any diminution in the 
volume of the gas; or a volume of ozone O'-’+.r, is 
resolved into an equal volume of free oxygen, and an 
indefinite weight of other oxygen, either absorbed or 
set free. This class of reactions accordingly does not 
afford any information as to the value of x , or, in other 
words, as to the relationship of the formula 0 2 -f.vto 
the formula O 2 . 
Unit-Volumes. 
O 2 -1- x = O 3 f- * 0 absorbed. 
In a second class of reactions, the absorption or de¬ 
composition of the ozone present in a mixture of ozone 
and oxygen, is attended with a diminution in the volume 
of the gas, equal to half the volume that the weight of 
oxygen absorbed would occupy in the free state. In 
this class of reactions, then, one of but two occurrences 
must happen: either the ozone present in the mixture 
of gases, is absorbed wholly without decomposition, in 
which case the density of ozone must be twice that of 
ordinary oxygen, and the formula O 3 + x become O 4 ; or 
the ozone present in the mixture is decomposed into half 
its volume of oxygen liberated, and into a quantity of 
oxygen, corresponding to its entire volume, absorbed; 
in which case the density of ozone must be one-and-a- 
half that of ordinary oxygen, and the formula O 2 + x 
become O 3 . 
Unit-volumes 
O 2 + * = 
2 (O 2 + * = 
In a third class of reactions, the absorption or decom¬ 
position of the ozone present in a mixture of ozone and 
oxygen, is attended with a diminution in volume of the 
gas, equal to two-thirds the volume that the weight of 
oxygen absorbed would occupy in the free state ; or the 
weight of the gas absorbed is to the weight of an equal 
volume of oxygen as 3 to 2. But consistently with this 
class of reactions, the density of ozone must necessarily 
be one-and-a-half times that of ordinary oxygen, and the 
formula O 2 + x must become O 3 . 
Unit- volumes. 
-- A -- 
(O 2 -j- x ) = nil + 3 0. 
This last and most important class of reactions, by 
which the formula of ozone as O 3 , is put beyond ques¬ 
tion, was established by a long series of experiments, 
made chiefly with a neutral or but slightly alkaline 
solution of hyposulphite of soda, and in a few cases with 
oil of turpentine. As a result, the ratio. of the entire 
diminution in volume suffered by the original oxygen, 
to the diminution in volume of the electrized or con¬ 
tracted oxygen effected by the reagent, was found to be, 
as a mean of twenty-seven concordant experiments made 
with the hyposulphite, 3’02 to 2'02 ; and as a mean 
of eight concordant experiments made with the turpen¬ 
tine, also as 3-02 to 2-02. But neither with the. hypo- 
sulphate nor with the turpentine, could the weight ot 
oxygen absorbed by the reagent bo determined, other¬ 
wise than by a calculation from the alteration in volume 
of the gas. 'A direct determination, however, was 
nil 
O 2 
+ 
+ 
40 
40 
absorbed. 
