52 6 
THE PHARMACEUTICAL JOURNAL AND TRANSACTION?. 
[January 4, 1873. 
% 
lion hitherto made to an exact knowledge of the nature 
of the ozone. In their experiments, a quantity of per¬ 
fectly pure and dry oxygen, contained in a straight glass 
tube with a pressure-gauge appendix, was ozonized by 
means of the silent electric discharge passed through the 
gas for some time. Coinciaently with the passage of the 
silent discharge through it, the quantity of gas contained 
in the glass tube was observed to undergo a marked con¬ 
traction in volume. This contraction proceeded at first 
rapidly, but afterwards more slowly, till it attained a 
limit which, in one of their experiments, was estimated 
at one-twelfth the original volume of the gas. And as 
whenever the gas, contracted in this manner, was ex¬ 
amined, it was found to be proportionately ozonic, the 
general fact was established that the production of ozone 
from ordinary oxygen is attended with a contraction in 
volume. The converse result was also obtained. It was 
found that when oxygen, contracted by the passage of 
the electric discharge, was exposed for a short time to 
the temperature of 270°-300°, it was restored to its origi¬ 
nal volume. And as whenever the gas, re-expanded in 
this manner, was examined, it was found to be free from 
ozone, the general fact was established that the con¬ 
version of ozone into ordinary oxygen is attended with 
an expansion in volume. And this alternate contraction 
of a given quantity of oxygen by exposure to prolonged 
electrization, with production of ozone, and re-expansion 
of the gas to its original volume by exposure to a tem¬ 
porary heat, with destruction of ozone, could be repeated 
an indefinite number of times. Now the only possible 
conclusion to be drawn from these experiments would 
appear to be that, the matter of ozone being identical 
with the matter of oxygen, ozone is oxygen in a denser 
form,—that is to say, in the form of a more complex 
unit. Some years afterwards, this conclusion was con¬ 
firmed in a very interesting manner by Professor Tyn¬ 
dall, in the case of ozone obtained electrolytically'. He 
found that the absorptivity for radiant heat of electro¬ 
lytically obtained oxygen, when rich in ozone, was up¬ 
wards of a hundred times greater than that of ordinary 
oxygen—a result indicating ozone to have a more com¬ 
plex molecular constitution, and consequently a greater 
density, than ordinary oxygen. Moreover, after this 
same electrolytically obtained and richly ozonic oxygen 
had been subjected to the action of heat, so as to have 
its ozonic character destroyed, it then exhibited merely 
the absorptivity for heat of ordinary oxygen,—the ob¬ 
served absorptivity not going at all beyond that of ordi¬ 
nary oxygen, as would have been the case if the ozone 
originally present in the electrolytic gas had been decom¬ 
posed into ordinary oxygen and aqueous vapour. 
Referring to the statement already made, that in 
Messrs. Andrews and Tait’s experiments, the oxygen 
gas, more or less contracted by the electric discharge, 
was found to be proportionately ozonic, this point was 
ascertained in the following way: — A small thin glass 
bulb, containing a solution of iodide of potassium, was 
introduced into the oxy'gen-holding tube, prior to its 
being filled with the gas, which, after having been more 
or less contracted by the process of electrization, was 
next submitted to the action of the solution, released 
on the breaking, effected by concussion, of the small 
bulb wherein it was contained. And on estimating the 
quantity of iodine set free from the iodide of potassium 
solution by its reaction with the contracted gas, it was 
found to be the exact chemical equivalent of a weight of 
oxygen equal in volume to the amount of contraction 
•which the original gas had experienced during the pro¬ 
cess of electrization; so that if in the process of 
electrization, there had been one, two, or three 
cubic centimetres of contraction, the quantity of iodine 
liberated was chemically equivalent to the weight of one, 
two, or three cubic centimetres of oxygen; whence it 
results that to ascertain the iodine-titre of the ozonized 
gas is to learn the contraction of the original gas effected 
by its electrization, or the correlative expansion of the 
electrized gas effected by its exposure to heat. In the 
case also of electrolytically obtained ozonized oxygen, it 
was shown firstly by Andrews and Tait, and subse¬ 
quently' by Soret, that the iodine-titre of the gas is the 
measure of its expansion by heat, consequent on the 
conversion of its constituent ozone into ordinary 
oxy'gen. 
Y. It has just been remarked that in the action of the 
contracted gas on iodide of potassium solution, there is 
absorbed by the reagent, with equivalent liberation of 
iodine, a weight of oxygen corresponding to a volume 
equal to that of the original contraction; but very curi¬ 
ously', the absorption by the reagent of this weight of 
oxygen from the contracted gas was found by Messrs. 
Andrews and Tait not to produce any further contrac¬ 
tion or alteration of its volume; or the weight of oxy¬ 
gen which acted on the iodide of potassium solution ap¬ 
peared to occupy no part of the volume of the contracted 
gas, its removal from the contracted gas by means of 
the reagent not affecting any alteration in that volume. 
Since this remarkable result was first announced by 
Messrs. Andrews and Tait in 1860, it has been abun¬ 
dantly' confirmed by Yon Babo and Claus, by Soret, and 
by Sir Benjamin Brodie—the modes of experimenting 
adopted in the original investigation of Andrews and 
Tait and in the three subsequent investigations, being 
all different from one another. And moreover, not only 
has the fact been established by the four several investi¬ 
gations with regard to iodide of potassium, but by one 
or other of the investigations with regard also to iodine, 
to mercurous salts, to ferrous salts, to arsenides, and to 
ferrocyanides. So that, when a given volume of ozonized 
oxygen is allowed to act upon these different oxidizable 
bodies, the oxidation effected by the ozone present in 
the gas is found to be unattended by any' diminution in 
the volume of gas. An interpretation of this singular 
result was put forward by the speaker soon after the 
publication of Messrs. Andrews and Tait’s experiments, 
to the following effect: Ozone being proved to be a con¬ 
densed form of oxygen, it is clear that any volume of 
ozone will contain a greater weight of the matter of 
oxy'gen than is contained in the same volume of ordinary 
oxy'gen. And since in the action of ozone upon iodide 
of potassium, the volume of the reacting gas does not 
undergo any alteration, it is obvious that the oxidation 
effected must be effected by only so much of the matter 
of oxygen contained in the volume of ozone, as is in 
excess of the matter of oxy'gen contained in the same 
volume of ordinary' oxygen. This interpretration, so 
far as it w'ent, w'as consideied to be demanded by Messrs. 
Andrews and Tait’s experiments, as the only satisfactory' 
explanation of them. With regard to the weight of 
the matter of oxy'gen contained in a given volume of 
ozone, in excess of the weight of the matter of oxy'gen 
contained in the same volume of ordinary oxy'gen, no 
data whatever existed to show what this weight really' 
is. But relying upon the fact that the weight of oxygen 
contained in a standard volume of free oxygen is com¬ 
posed of two simple weights of the matter of oxygen, 
it was conjectured that the weight of oxygen contained 
in a standard volume of ozone might not improbably be 
constituted by an introduction into the standard volume 
of ordinary oxygen of another simple weight of oxygen 
—equal volumes of ozone, free oxygen, and nitric oxide, 
for example, being expressible by the comparable for¬ 
mulae 0 3 , 0 2 , and NO respectively. In accordance with 
this supposition, the action of ozonized gas upon iodide 
of potassium, etc., is explicable as follows: —The ozone 
which acts is decomposed into a weight of free oxygen 
equal in volume to the volume of the ozone, and into 
another weight of absorbed oxy'gen, assumed to be one- 
half of the former weight. The suggestion as to the 
standard volume of ozone being constituted thus of three 
simple weights of the matter of oxygen, was admittedly 
not a necessary deduction from the then known facts, 
which were indeed equally consistent with its being con- 
