216 _ REPORT—1840. 
as changes proceeding only from certain substanees being in 
some way or other deposited upon those metallic bodies. If, 
for instance, platina becomes positively polarized in an at- 
mosphere of hydrogen, and negatively in one of chlorine or 
bromine, that metal itself does not undergo the least change 
with regard to its natural voltaic properties; and it is only the 
film of hydrogen or chlorine that surrounds the metal, which is 
to be considered as the seat of the electromotive power, or as 
the cause of the polarity. Exactly the same remarks apply to 
the negative polarity which gold and platina seem to assume 
when put into an atmosphere of ozone. By a sort of capillary 
action that substance adheres to the metal, and the latter being 
voltaically associated with another piece of the same metal (in 
its natural state) and plunged into water, the latter will be acted 
upon by ozone just in the same manner as under similar cir- 
cumstances it would be by chlorine or bromine. The film of 
ozone covering the platina will unite with the hydrogen of 
water, and produce by that action a current. This current will 
last until all the ozone adhering to the platina stripe unites with 
hydrogen, but the quantity of that principle being exceedingly 
small, the duration of the current cannot be long. 
Having fully developed my views on the chlorine and bro- 
mine circuits in the Philosophical Magazine (August, 1839), 
and everything said there applying to an ozone arrangement, I 
have no occasion to enter into further details respecting this 
branch of the subject. 
As to the depolarizing action which an atmosphere of hy- 
drogen exerts upon gold and platina when negatively polarized 
by ozone, it perhaps may depend upon the combination of the 
latter with hydrogen. In order to account for the disappear- 
ance of the polar state, it is, however, not necessary to pre- 
sume the taking place of such an action. As platina becomes 
positively polarized by hydrogen, and negatively by ozone, it is 
obvious that the opposite voltaic actions of these two elements 
must, under certain circumstances, exactly balance each other. 
It is manifest that the facts considered throw a new light 
upon what is usually termed negative voltaic polarization. The 
results which I obtained some time ago on that subject are 
pretty generally known. They seemed to prove that the nega- 
tive polar state assumed by the positive electrode in water 
(holding oxi-acids dissolved) is due to a film either of oxygen 
or of peroxide of hydrogen. ‘To the same cause I was inclined 
to ascribe the negative polarity excited in that portion of aci- 
dulated water which is near to, or in contact with, a positive 
electrode. From the facts above stated, it now appears that, in 
