Notices respecting New Books. 59 
®. That there is a mutual action between the electricities ex- 
cited in the opposite conductors, since their-effects are more 
powerful when directed at the same time to our conducting 
body. 
3. That the same relation which is observed between the 
opposite conductors exists also between either of them and 
the ground, but in a different degree. From these phenomena 
the following propositions are deduced : 
1. The cause of electrical phenomena is material, and’ pos- 
sesses the properties of an elastic fluid. 
2. The electric fluid attracts and is attracted by all other 
matter, and in consequence of such attraction exists in all known 
substances. 
3. The attraction of different bodies for the electric fluid is 
various; and so is that of the same body under different cireum- 
stances: consequently the quantity of electricity naturally exist- 
ing in different substances may be unequal; and the same body 
may attract more or less than if alone when combined with other 
matter: but its original attraction will be restored by destroying 
the artificial combination. 
4. From some peculiarity in the nature of the electric fluid,. 
its attraction by and for common matter is more influenced by 
figure than by mass; and is consequently stronger in extensive 
than in limited surfaces. 
5. From the same peculiarity, the electric fluid moves with 
great facility over the surface or through the substance of some 
bodies, and is arrested in its progress by others. 
6. When the attraction ef any substance for electricity is equal 
to the electric fluid it contains, that substance will evince no elec- 
trical signs; but these are immediately produced when there is 
either more or less electric fluid than is adequate to the satura- 
tion of the existing attraction: if there be more, the electrical 
signs will be positive; if less, they will be negative. 
This leads to the following theory of excitation. ‘The 
hodies employed have each a certain quantity of the electric 
fluid proportioned to their natural attraction for it. This they 
retain, and appear unelectrified so long as they remain in their 
natural state. Now if two such bodies are brought into con- 
tact, their natural attractions are altered, one of them attracts 
more than in its separate state, and the other less; the electric 
fluid diffuses itself amongst them in quantities proportioned to 
their relative attractions, and they consequently appear unelec- 
trified. But if they are suddenly separated, the new distribu- 
tion of the electric fluid remains, whilst the original attractions 
are restored ; and as these are not equal to each other, the bodies 
will 
