Mr. Davy’s Hypothesis of Electro-chemical Affinity. 231 
If from the ends of two equally and differently electrified 
conductors be suspended two gilt pith balls, by gilt strings, 
the balls will attract each other ; but when they come into 
contact, a mutual annihilation of power takes place; the 
balls ‘separate, and no longer show signs of electricity. 
Ora metallic sphere on which is erected a quadrant elec- 
trometer may be insulated and positively electrified, the 
pith ball rises: if some negative sparks be thrown on, the 
ball-sinks, Were .another example necessary of so well 
known a fact, I would instance two jars differently electri- 
fied. Each of them separately produces the most violent 
effects. It will ignite, fuse and burn the most refractory 
metals. It will pour out torrents of fire on contiguous bo- 
dies, it will instantly deprive animals of life. When a 
proper communication with the other jar, which is equally 
charged, is formed, an explosion follows; and instead of 
either jar being possessed of the additional charge of the 
other, they are both found harmless and altogether deprived 
of electricity. All these instances demonstrate in the clear- 
est manner the destruction of forced states, when they come 
into contact. 
As to Mr. Davy’s example of Beccaria’s plates, it is 
plain that the cohesion depends entirely on the nonconduct- 
ing power of the glass; for the opposite powers are thus 
prevented from coming quickly into contact. The annihi- 
lation is effected in some time, and the plates separate. It 
will be shown, however, that combined particles are in cir- 
cumstances very different from Beccaria’s plates. 
If it be proved that matter after combination cannot re- 
tain a forced state, the doctrine of combination itself falls 
to the ground. For bodies in solution which possess affinity 
should, in the manner of other bodies differently electri- 
fied, first combine ; and afterwards, obeying any tendency 
towards separation, as difference of specific gravity, they 
should separate as soon as the annihilation took place. 
Tt might be imagined that when the bodies are in the fluid 
state, a separation and consequent evolution of new pow- 
ers might take place, which would still maintain the com- 
pound. ., 
It were unphilosophical to attribute unnecessarily the 
same natural effects to dissimilar causes. Combination, 
o - ¥ . 4 
whether betweey fluids o¢ solids, may reasonably be pro- 
nounceri the operation of the same power. There is, how- 
ever, a stronger objection. The particles@f combining sub-. 
stances are surrounded by a conducting medium (water), 
The moment that different electricities would be produced, 
od 
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