98 REPORT—1845. 
a number of gaseous substances being mixed with common air, phosphorus is 
prevented from shining in the dark. Gaseous, nitrous, or sulphurous acid, 
sulphuretted hydrogen, olefiant gas, hydro-iodice acid gas, vapour of ether, or 
alcohol, have this effect. Now according to the results of my experiments, 
all the substances mentioned instantaneously take up or destroy ozone, and 
such being the case, we can easily conceive why those gases and vapours 
present in the atmospheric air do not prevent phosphorus both from shining 
in the dark and from being changed into phosphatic acid, No ozone is or 
can be produced under those circumstances ; for if that compound did ever 
happen to exist in that air, it would be instantaneously destroyed by the 
agents mentioned. Any gaseous substance therefore which readily unites 
with free ozone will prevent phosphorus from shining in that atmosphere, 
and of course also hinder the formation of ozone, Water being an indis- 
pensable ingredient for the generation of ozone, we can now easily see why 
in completely dry air the shining of phosphorus is nearly imperceptible. It 
is true, under these circumstances, some emission of light takes place, but it 
is exceedingly slight if compared to that exhibited in moist air. It is possible 
that that feeble phosphorescence results from a very small portion of oxygen 
directly uniting with phosphorus. 
As ozone, in its action upon metals and a variety of other bodies, exhibits 
a very striking similarity to that which chlorine exerts upon the same sub- 
stances, and as the remarkable analogy existing between these two principles 
extends itself even to the way of producing them, I shall take, on a future 
occasion, the liberty to submit to you some considerations regarding that 
subject, and bearing upon the two rival theories which have been founded 
with reference to chlorine. 
On the part which Ozone acts in the Atmosphere. 
Paste of starch, being mixed up with some chemically pure iodide of potas- 
sium and exposed for some time to the action of the open air, turns blue, 
whilst the same paste, shut up*in a bottle filled with atmospheric air, re- 
mains colourless. Pieces of white linen, having been drenched with a so- 
lution of pure iodide of potassium, and left for some time in the open air, 
assume a brownish tint, which is due to iodine set free under the cireum- 
stances mentioned. That elimination of iodine does not, as far as my expe- 
riments go, take place in air inclosed within a bottle, though that air should 
contain even half its volume of carbonic acid gas. Iodide of potassium, 
after having for some time been exposed to the action of the open air, re- 
tains traces of a peculiar peroxide of potassium, of iodate and carhonate of 
potash, whilst in iodide of potassium kept in well-closed vessels nothing of 
the kind is found. From these facts it appears that the before-mentioned 
elimination of iodine, and the formation both of peroxide of potassium and 
jiodate of potash, are not due to the action of free atmospheric oxygen nor to 
that of carbonic acid. According to my former experiments, air having 
been artificially ozonized, and made to pass through a solution of pure iodide 
of potassium, eliminates iodine, and causes the production of the said perox- 
ide, iodate and carbonate of potash. Hence it follows that ozone produces, 
with the iodide of potassium, the same chemical changes as those which are 
effected by the open air, and between the two actions there is a difference of 
degree only and ‘not of kind. 
Now neither free oxygen, nor azote, nor carbonic acid being able to pro- 
duce that effect, we must conclude that there is something peculiar in the 
atmosphere which causes the decomposition of our iodide, and has up to this 
present moment escaped the attention of chemists. But of what nature is 
