i88o.] 
History of Ozone. 
151 
preceding experiments on electrolytic ozone had been vitiated 
by the presence of a small but appreciable quantity of car- 
bonic acid, which, unless very great precautions be taken, 
is always present in the evolved gas. In very numerous 
experiments he showed that the weight of adtive oxygen 
equivalent to the weight of the iodine set free in the absorp- 
tion apparatus, was equal to the entire gain in weight of 
the apparatus, and therefore no hydrogen as well could have 
been present ; also that the properties of electrolytic ozone, 
and that obtained by the aCtion of the electrical spark on 
pure and dry oxygen, were identical. More especially, it 
was shown that both were converted into ordinary oxygen 
at a temperature of about 237 0 C. ; and from the whole in- 
vestigation the author drew the conclusion, which was con- 
firmed by the still more elaborate experiments of Soret in 
1863, and is now universally adopted, “ that ozone, from 
whatever source derived, is one and the same substance, 
and is not a compound body, but oxygen in an altered or 
allotropic condition.” 
III. The Exact Nature of the Relations existing between 
Ozone and Ordinary Oxygen . 
We have seen that Marignac and De la Rive, as the result 
of their experiments performed in 1845, had enunciated the 
view that ozone was oxygen in a peculiar eleCtric state. 
They proposed to abandon the name “ ozone,” which as- 
sumed an independent chemical existence for this body, and 
to call it merely “ eleCtricised oxygen.” This view of the 
constitution of ozone was one not readily susceptible of 
investigation by usual chemical methods. But the case was 
different with the hypothesis which was shortly afterwards 
advanced by Dr. T. Sterry Hunt, in 1848. Since his intui- 
tion of a truth, not fully demonstrated until twenty years 
later, is of a very striking character, it will be interesting to 
quote it as originally announced. In a paper on the anoma- 
lies presented in the atomic volume of sulphur and nitrogen, 
Dr. Hunt says — “ In considering such combinations as S 0 2 
and Se 0 2 , which contain three equivalents of the elements 
of the oxygen group, it was necessary to admit a normal 
species which should be a polymer of oxygen, and be repre- 
sented by 0 3 = ( 000 ). The replacement of one equivalent 
of oxygen by one of sulphur would yield sulphurous acid 
gas (OOS), and a complete metalepsis would give rise to 
(SSS). The first compound is probably the ozone of Schon- 
bein, which the late researches of Marignac and De la Rive 
