_ ON OZONE. 91 
parts. In passing round, the opening exposes regularly to solar influence 
different parts of the photographic paper,—the smallest part of the opening 
allowing the influence to be exerted for considerably less than a minute, 
whilst the largest part admits of the action of the sun’s rays for more than 
an hour. The paper, by experiment, is so adjusted, that the greatest amount 
of actinic power darkens it completely during the shortest exposure, whilst 
the weak light of winter is just sufficient to produce the effect during the 
passage of the longest part of the opening. The degrees between these 
points become of course, under the ever-varying conditions of solar radia- 
tion, unequally darkened, and the paper being carefully marked to the hours 
of the day, it is quite easy to register numerically the varying effects pro- 
duced. It will not therefore be necessary to have recourse to any plan of 
fixing the impressions made, which is always an uncertain process. It is 
hoped that by the next meeting of the Association the author will be enabled 
to furnish registers complete for twelve months, and he thinks he shall then 
be enabled to show that the actinic influence is one which must be taken 
into account in many inquiries, and to prove that thé actinic or chemical 
power, and the phenomena of luminous and thermic action, are not found 
in any constant ratio in the solar rays, but that they are liable to continual 
variation. 
On Ozone. By Professor ScHONBEIN of Basle. 
Tue British Association has done me the honour of inviting me to prepare 
a report on my researches regarding a peculiar agent to which I have given 
the name “Ozone.” Flattering as such a charge must have proved to me, I 
undertake its execution with great diffidence, less on account of the subject 
of the report itself, than in consequence of my being obliged to make use of 
an idiom which I am not in the habit of speaking. Having fully experienced 
on former occasions the kindness of the same Association I have now the 
honour to address, I count upon your indulgence, and am convinced that 
you will receive with your wonted urbanity the very imperfect communica- 
tion of a man who is certainly in one respect an alien to this country, but who 
feels himself nevertheless intimately connected with your land by many ties 
of friendship and scientific intercourse, and considers old hospitable England 
as his second home. 
Were I not actuated by such feelings, I would not have ventured to come 
forward on this occasion, and it is to those feelings alone*that I owe the 
courage requisite for a stranger who is to speak before an Association count- 
ing amongst its members the very essence of British philosophers. In taking 
the liberty to give you an account of the results obtained from researches 
_ with which I have been occupied these last six years, I shall chiefly keep in 
' view the most novel facts I have been fortunate enough to ascertain, and I 
shall try to be as concise and clear as possible in stating them. Now and 
then, as the occasion occurs, I intend to enter into theoretical considerations 
and draw inferences from the phenomena observed. After having made you 
fully acquainted with the subject of my report, I need not say how much you 
will oblige me by making any observation or suygestion calculated to clear 
up a matter which I readily allow is yet very far from being thoroughly un- 
derstood and sifted to the bottom. I shall feel myself fully repaid for the 
many pains I have taken these last five or six years in investigating the 
nature of the electrical smell, if I happen to succeed in convincing you that 
_ my subject is worthy of philosophical research and likely to open a new field 
— 2. >= 
eS 
