cases of Voltaic Action. 433 
of hydrogen, or of the metal formed, and the combined radical 
is evolved. This law is a general one, and holds good equally 
in ordinary chemical action; but here the result is modified 
from the circumstances in which the action takes place. Thus 
when Cl is added to KO, no oxygen is evolved; but this dis- 
appearance of the oxygen is entirely a secondary result; the 
oxygen at the moment of its evolution is in contact with 
Cl and; KO, by which it is absorbed, giving rise to the 
chlorate of potash: but no such result can occur in the vol- 
taic arrangement; for the oxygen, at the moment of its evo- 
lution, is not in contact with Cl, and therefore appears as 
gas. Another difference between voltaic and chemical ac- 
tion is, that in the former, substances unite which are without 
action on each other when simply mixed, for example—oxygen 
and hydrogen; but this arises from the powerful attraction of 
the ‘molecules of the platina, re-acting on the hydrogen and 
oxygen. The intensity is thus raised to the point necessary 
to cause combination. 
It will now be evident why no current should result from 
the union of an acid and an alkali; thus if hydrochloric acid 
and potash be in contact, we have simply an exchange of the 
elements (Fig. 5.) SB) 
liberated O unites with the H of the hydrochloric acid, and 
the current is confined within the four elements, which cannot 
in this case be separated; the same is true of sulphuric acid, 
substituting SQ, for Cl. Nitric, chromic and several other 
acids are capable of acting in a very different manner from 
this. The whole atom of acid NO, + H is capable of acting 
in the same manner as Cl, uniting with the basyle of the 
substance in contact with it, and evolving the radical, as in 
the pile of nitric acid and potash of Becquerel, but in this 
case the acid is reduced to the state of peroxide of nitrogen 
or nitric oxide. The increase in the intensity of the action, 
by using potash in contact with nitric acid, seems to be due to 
the affinity of the potash, for an additional quantity of oxygen 
and the formation of peroxide of potassium, which is imme- 
diately decomposed by the water; on substituting caustic ba- 
rytes, no oxygen is evolved. ‘ 
The changes which take place when organic substances are 
arranged so that a current is formed, afford an interesting 
subject for inquiry, and it appears probable that many of the 
effects described as catalytic, are the result of actions of this 
nature; for it is not necessary that the substance connect- 
Phil. Mag. 8, 3. Vol, 22, No. 147. June 1843. 2G 
Cl unites with K, while the 
Water 
