January 4, 18?3.J 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
525 
by Schonbein successively, as a minute constituent of tlie 
oxygen gas resulting- from the electrolysis of water 
effected by a current of high tension; as a minute con¬ 
stituent of air or oxygen through which electric discharges 
have taken place; and as a minute constituent of air in 
which moist phosphorus has been undergoing slow 
oxidation. To Schonbein then is due the great merit of 
recognizing ozone as a distinct form of matter, having 
an identity of its own by whatsoever means prepared— 
as also the merit of discovering the most important means 
for the prodiiction of ozone, and of establishing its prin¬ 
cipal properties and reactions. 
The general properties of ozone are those of an active 
oxygonant. Thus, like chlorine and peroxide of nitro¬ 
gen,. it bleaches colouring matters, corrodes fabrics, 
tarnishes or otherwise attacks metals, and liberates iodine 
from iodide of potassium. Its special properties are its 
characteristic pungent odour, its destructibility by a 
moderate heat, and its non-manifestation of any acidulous 
reaction. 
II. The nature of ozone was at first the subject of much 
speculation, Schonbein inclining to the view that it was 
a new elementary body, and a component of nitrogen. 
But in 1845, Marignac, in a series of most exact experi¬ 
ments, made partly in association with De la Rive, 
brought the question as to the nature of ozone within a 
very narrow compass. The experiments of these investi¬ 
gators, in which they established, among other points, 
that by exposure to the action of ozone, moist silver was 
converted simply into oxide of silver, and iodide of potas¬ 
sium into its oxidized form of iodate of potash, were 
susceptible only of one or other of two interpretations— 
either the interpretation which they themselves put on 
their results, that the matter of ozone is identical with 
the.matter of oxygen—or, else the interpretation put on 
their results by Schonbein, that ozone is constituted of 
oxygen, plus the elements of water, or in other words, 
that it is a peroxide of hydrogen. For a long time, ex¬ 
periment seemed quite incompetent to decide between 
these two views—opposite conclusions being arrived at 
almost alternately by the different investigators engaged 
on the inquiry. Corroboration, however, if any were 
needed, of the fact that ozone is really formed from 
oxygen itself with or without water, and not from any 
trace of nitrogen or other foreign matter that might 
possibly be present, was afforded by a remarkable experi¬ 
ment conducted by Fremy and Becquerel in 1853, being, 
indeed, the first recorded quantitative experiment made 
with ozone. By passing a long series of electric dis¬ 
charges through a given volume of oxygen standing- 
over an aqueous solution of iodide of potassium, Messrs. 
Fremy and Becquerel succeeded in causing the whole of 
this oxygen to assume the form of ozone ; as was shown 
by its ultimate complete absorption by the solution, with 
correlative liberation of iodine from the dissolved iodide 
of potassium. 
The difficulty experienced in those early days of mak¬ 
ing out the real nature of ozone—of ascertaining whether 
it is a form of oxygen or a peroxide of hydrogen—de¬ 
pended mainly on the very small degree to which it was 
then possible to charge air or oxygen with the ozone to 
be examined, and on the necessity for the exclusive em¬ 
ployment in the investigation of apparatus in which 
neither metal nor organic matter was pr esent for the ozone 
to react with. The apparatus had consequently to be 
constructed entirely of glass, and all the junctions to be 
made before the blow-pipe or by grinding. Now-a-days, 
by improvements in the methods of conducting the pro¬ 
cesses of electrization and electrolysis, it is possible to 
charge oxygen with ozone in very considerable propor¬ 
tion ; while by means of paraffin, a substance on which 
ozone is without recognizable action, junctions of the 
glass apparatus employed may be made and unmade with 
the greatest facility. 
III. Assuming the ozone furnished by the three prin¬ 
cipal processes for its production to be one and the same 
I substance, it was not until the year 1863 that the abso¬ 
lute freedom of ozone from any proportion of hydrogen 
was so definitely established as not to allow of any fur¬ 
ther question. In this year, Soret showed that although 
ozonized oxygen obtained by electrolysis, after having 
been desiccated as thoroughly as possible, frequently 
yielded some water as a product of its decomposition by 
heat, yet that when certain precautions were taken, and 
certain sources of error in the production and collection 
of the electrolytic oxygen were recognized and avoided, 
a uniformly negative result was obtained, and not a trace 
of moisture or other compoxmd of hydrogen resulted 
from the decomposition by heat of the ozone present in 
the oxygen. 
This conclusion of Soret’s was confirmatory both of 
the previous result of Andrews with regard also to elec- 
trolytically obtained ozone, and of the yet earlier result 
of Schonbein himself with regard to the ozone obtained 
by the slow oxidation of moist phosphorus. For in op¬ 
position to the view enunciated first by himself, and in 
seeming discrepancy with the undoubted fact that for 
the production of ozone by means of phosphorus the 
presence of moisture is essential, Schonbein, in 1849, 
showed by repeated experiment, that when ordinary air 
in quantities of several hundred litres, ozonized as strongly 
as possible by its passage over moist phosphorus, was 
transmitted first through a desiccating tube, then through 
a tube heated to 400°, so as to effect the destruction of 
the ozone present, and finally through another desiccating 
tube to absorb any moisture that might result from the 
destruction of the ozone, this last desiccating tube did 
not show, by an increase of weight or other change, any 
absorption of moisture whatever, notwithstanding the 
largeness of the absolute quantity of ozone destroyed in 
the experiment. From this time forth, Schonbein aban¬ 
doned the notion of hydrogen being a constituent of 
ozone ; and while making a valid distinction between 
his own view and that of Marignac and De la Rive, ad¬ 
mitted with them that the matter of ozone is identical 
with the matter of oxygen. These last-named investiga¬ 
tors, in their research already referred to (1845), showed 
that perfectly dry oxygen, submitted to the influence of 
electric discharges, experienced an alteration of character, 
whereby it acquired the property of liberating iodine 
from moist iodide of potassium,—a result afterwards con¬ 
firmed by. Fremy and Becquerel. But they did not 
regard this alteration of character as due to the forma¬ 
tion in small proportion of a new substance within the 
mass of oxygen, but rather to the assumption by the 
mass of oxygen of a peculiar electric condition. More¬ 
over, the fact of dry oxygen being capable of some modi¬ 
fication by the action of electric discharges, coupled with 
the fact of the inability of the so modified oxygen to act 
upon iodide of potassium save in the presence of water, 
was not inconsistent with the notion of this modified oxy¬ 
gen having to unite with water in order to produce a 
compound identical with the ozone obtained immediately 
from moist or watery reagents. That the effect of electri¬ 
cal discharges, and more particularly of the silent dis¬ 
charge, on perfectly dry oxygen, is really to convert a 
small proportion of this oxygen into ozone identical with 
that furnished by electrolysis, and capable of acting upon 
certain substances, as mercury and iodine, when in the 
dry state, and on certain other substances, as iodide of 
potassium and metallic silver, only when in the moist 
state, was first put beyond question by Andrews and 
Tait, in a research next to be considered. 
IV. In tho spring of 1860, Dr. Andrews and Prof. 
Tait made a joint communication to the Royal Society 
on the volumetric relations of ozone. The primary ob¬ 
ject of this research wa3 to ascertain whether any, and 
if so what, alteration of volume took place in the con¬ 
version of a given quantity of oxygen into ozone. They 
thus attacked the problem from an entirely new point of 
view, and, with admirably direct pains and skill, suc¬ 
ceeded in making probably the most important contribu- 
