CONTACT OR CHEMICAL ACTION? 
19 
num plates decomposed iodide of 'potassium, 
protochloride of tin, chloride of silver, but 
water acidulated with sulphuric acid, solu- 
tion of muriatic acid, solution of sulphate 
of soda, fused nitre, and the fused chloride 
and iodide of lead, were not affected by a 
single pair of plates excited only by dilute 
sulphuric acid. All these substances were, 
however, readily decomposed by adding a 
little nitric acid to the dilute sulphuric acid. 
It is sufficiently obvious that the addition of 
the nitric acid operated by increasing the inten- 
sity or power of the current. 
By the reference which is thus made of the 
intensity of the electric current to the inten- 
sity of the chemical action, the conclusion is 
drawn that by using bodies such as fused 
chlorides, salts, &c., which may act upon the 
metals with different degrees of force, effects 
would be obtained due to different intensities, 
which would serve to assist in the construc- 
tion of a scale, so as to supply the means of 
determining relative degrees of intensity ac- 
curately in future researches. The bodies 
which have been examined are decomposed 
in the following order, the first being disunit- 
ed by the current of the lowest intensity. 
Iodide of potassium (solution.) Chloride of 
silver (fused.) Protochloride of tin (fused.) 
Chloride of lead (fused.) Iodide of lead 
(fused.) Muriatic acid (solution.) Water 
acidulated with sulphuric acid. 
Another proof that metallic contact has 
nothing to do with the production of electri- 
city, and that electricity is only another mode 
of the exertion of chemical forces, is the pro- 
duction of the electric spark before the metals 
are brought in contact, and by the influence 
of pure chemical agency in an experiment 
where the spark is obtained by placing in con- 
tact a plate of zinc and a plate of copper, and 
plunging them in dilute sulphuric acid. 
The principles which the author endea- 
vours to establish in the course of his research- 
es are that the electricity of the voltaic pile 
is not dependent either in its origin or its 
continuance to the contact of the metals with 
each other. It is entirely due to chemical 
action, and is proportionate in its intensity 
of the affinities concerned in its production, 
and in its quantity to the quantity of matter 
which has been chemically active during its 
evolution. The production of electricity is 
a case of chemical action, while electric de- 
composition is simply a preponderance of one 
set of chemical affinities over another set 
which are less powerful. The source of the 
electricity exists in the chemical action which 
takes place directly betvveen the metal and 
Uie body with which it combines, and not 
in the subsequent action of the substance so 
produced with the acid present. 'I’hus if zinc, 
platinum, and muriatic acid are employed, 
the electricity depends upon the affinity of 
the zinc for the chlorine, and circulates in 
proportion to the number of atomsof the zinc 
and chlorine which unite. But for this direct 
action upon the metal itself, it is essential 
that the oxygen or other body be in the state 
of combination, and limited to the state of an 
electrolyte, that is a body which is decompos- 
ed when the electric current is transmitted 
through it. 
Some bodies there are which are capable of 
exerting chemical action upon the metals 
which are not electrolytic ; but these must 
be chosen from among the metals ; char- 
coal also answers. No electric current is 
however induced by these means. An elec- 
trolyte is always a compound body, and can 
act as an electric conductor only when de- 
composing. Water is the most familiar elec- 
trolyte. The attraction of the zinc for the 
oxygen is greater in the case of water than 
that of the oxygen for the hydrogen, but in 
combining with it, it tends to throw into circu- 
lation a current of electricity in a certain di- 
rection. lire sulphuric acid used in the vol- 
taic circuit is not capable of producing any 
sensible portion of the electricity of the cur- 
rent, by its combination with the oxide form- 
ed, because in it forms no part of an electro- 
lite, nor is it in relation with any other body 
present in the solution which will permit of 
the mutual transfer of the particles, and the 
consequent conduction of the electricity. 
Now, an electrolyte conducts in consequence 
of the mutual action of its particles, but the 
elements of the water and sulphuric are des- 
titute of this relation. This corroborates the 
statement of Sir H. Davy, that no electric 
current is induced by the combination of acids 
and alkalies. If the acid and base be dissolv- 
ed in water, it is possible that a small portion 
of electricity, proceeding from chemical ac- 
tion, may be conducted by the water without 
decomposition, but the quantity will bear no 
proportion to the equivalents of chemical 
force. If a hydrogen acid be used, then a 
current may be induced by the chemical ac- 
tion of the acid on the base, for both bodies 
now act as electrolytes. 
This view of the oxidation of the metal be- 
ing the cause of the electric current, is proved 
by the effects of alkaline and sulphuretted 
solutions when used as conductors. It can- 
not be supposed that the alkali acts chemical- 
ly as an acid to the oxide formed, because our 
knowledge leads to the conclusion that the 
ordinary metallic oxides act rather as acids 
to the alkalies. Ammonia as well as potash 
produced the same electric currents. Alka- 
lies seem not to be inlluenced by the acids, in 
effecting electrical currents, but are superior 
in force and in bringing a metal into what 
is called the positive state. It is proved by the 
tact that if zinc and tin be used, or tin and 
lead, whatever metal is put into the alkali 
becomes positive, that in the acid being ne- 
gative. Davy shewed that ifiron and copper 
were plunged into dilute acid, the current 
passed from the iron through the fluid to the 
copper. In the solution of sulphuret of po- 
tash it is reversed. Two experiments in ad- 
dition complete the series of proofs of the 
origin of electricity on the voltaic pile. A 
fluid amalgam of potassium containing not 
more than ^ of that metal was put into 
pure water, and connected through the gal- 
vanometer with a plate of platinum in the 
same water ; a current passed from the amal- 
gam to the platinum, which must have been 
owing alone to the oxidation. Again, a plate 
of clean lead and a plate of platinum were 
placed in pure water, a current, passed from 
