RESEARCHES IN ELECTRO-CHEMISTRY. 219 
struck by lightning. As far as my observations go, they in- 
cline me to consider the odoriferous gaseous substance set at 
liberty by the agency of lightning as ozone. Lightning being 
the same phenomenon on a large scale as the electrical spark 
or brush is on a small one, and our supposed electrolytic com- 
pound penetrating the whole atmosphere, electrolysis must 
take place, and consequently ozone be disengaged to a con- 
siderable amount, as often as lightning crosses our atmospheric 
air. The assertion of some observers, that the odour is of a 
sulphureous kind, and the statement of others, comparing it 
with the smell of phosphorus, may easily be reconciled to each 
other; for I have remarked that ozone, when somewhat con- 
densed, is rather pungent, whilst the same substance mixed up 
with a large quantity of air, possesses a phosphorus smell. It 
is well known that the generality of people call any pungent 
odour sulphureous. Hence, if it happens that the odoriferous 
principle set free by lightning reaches the observer in a con- 
densed state, he will describe it as sulphureous, but like phos- 
phorus when inhaled mixed up with a good deal of air. Hence 
it follows, that the nearer the observer happens to be plaeed to 
the spot where a stroke of lightning takes place, the more pun- 
gent will be the smell perceived by him. ‘The property of pla- 
tina to assume negative polarity in a medium containing free 
ozone, seems to offer an excellent means to ascertain the pre- 
sence of that principle in the atmosphere. It appears, there- 
fore, to be desirable to make experiments on that subject, and 
to place, for that purpose, platina stripes (not being insulated) 
in elevated regions, particularly on days when thunder-storms 
are taking place. 
Before closing this paper, I must not omit to put a question 
of some importance. Does the electrolytic compound men- 
tioned exist in our atmosphere quite independent of its aqueous 
vapour, or is it (the electrolyte) carried into the air by the eva- 
poration of water? It is a matter of course, that this question 
can only be answered by experiments, and I have not yet found 
time enough to make them. Supposing the electrolyte to be 
‘earried into the atmosphere by the evaporation of water, the 
electrical brush should not produce any smell when passing into 
absolutely dry air, and the quantity of ozone disengaged would, 
ceteris paribus, be proportional to the quantity of aqueous 
vapour present in the atmosphere; 7. e. would depend upon the 
hygrometric state of the latter. It is hardly necessary to say, 
that problems of the highest scientific importance would be 
raised, in case it should turn out that ozone can be produced in 
dry air. Be that, however, as it may, the ubiquity of our elec- 
