252 Observations and Experiments concerning 
_ /Epinus found that when two plates of glass, such as are 
used for looking-glasses, were pressed together and after- 
wards separated, they acquired a strong electricity, but dif- 
ferent in each plate. 
These experiments can be only performed under certain 
circumstances of the atmosphere, as when the air is dry and 
the sun shining strongly. 
If Mr. Davy’s experiment be sufficient to ground the 
supposition that sulphur and copper combine by the attrac- 
tion of their different electricities, | have the same grounds 
for supposing that copper and glass, sulphur and glass, or 
glass and glass, unite chemically ; since by contact they 
produce different states of electricity. 
Having made a statement of the principal objections 
which occurred respecting the electro-chemical doctrines 
of combination, [ shall now proceed to notice whatever re- 
mains on decomposition, 
The manner of decomposition in general has been already 
noticed. [am now prepared to enter on this branch of 
the inquiry more minutely. 
Mr. Davy has, in different parts of bis writings, given 
two modes in which decompostion is effected, each: of 
which I conceive to be essentially different from ihe other. 
1. That the electricity of each pole attracts that princi- 
ple of the compound which is an opposite state of itself, 
and repels the principle which is a similar state; and that 
this happens at both poles. 
2. That the electricity of each pole, where it is in con- 
tact with the compound, brings the component principles 
into similar states, and that ‘they ote some link hi repel each 
other. 
I shall endeavour to show that decomposition cannot be 
produced according to either of these positions. This I 
ai to accomplish by proving, 
. That the interchange of ‘electrical powers ought not 
to cause electro- motion in the principles of the compound ; 
and, allowing clectro-motion, that combination and not de- 
composition “ought to take place. 
2. That, if the decomposition of combined bodies be 
caused by the repulsion of similar states artificially ac- 
quired, both principles of the compound ought to be found 
in a separate state collected round the polar wires. 
Beginning with electro-motion, it is evident that, in the 
solution of a salt, we must suppose a number of particles. 
surrounded by water. That water 1s a conductor of that 
electricity 
