1819.] Sur UIdentité des Forces Chimiques et Electriques. 459 
the quantity of electricity is proportional to the surface ; but the 
intensity is inversely as the space over which a certain quantity 
of force is spread. 
The greater the intensity of electricity the more easily must it 
spread itself in space. Hence an electricity infinitely weak 
would be isolated by all the bodies in nature ; because no body 
is a perfect conductor. The greater the quantity of electricity 
the more difficult is its complete transmission. The complete 
transmission becomes also more and more difficult the worse a 
conductor the body is through which it has to pass. Hence, 
however different the conducting power of two bodies may be, 
we can always find two quantities of electricity such that they 
will be transmitted by the two bodies in the same time. 
If we wish to act chemically on different bodies, we must 
give them a quantity of electricity proportional to their conduct- 
ing power, with an intensity inversely as that power. The 
electric spark exhibits the smallest quantity of electricity with 
the greatest intensity. In the Leyden phial, and still more in the 
electrical battery, the quantity of electricity is greater relative to . 
its intensity. When electricity is communicated by contact, the 
quantity is often great, but the intensity very weak. 
These principles are well exemplified in the action of electri- 
city on water. Whena current of electricity from a machine is 
made to traverse water by means of two opposite wires, the 
water is not decomposed, because the whole electricity is con- 
ducted by the liquid. But if we cover the wires with glass, 
except their very extremities, the whole of the electricity cannot 
be conducted by the water, and in consequence that liquid is 
decomposed. When water is made a part of the voltaic circle, 
the intensity is so small, and the quantity so great, that it is not 
wholly conducted ; and hence the decomposition of water by the 
voltaic battery. 
Indeed all the oxidations and deoxidations, the attractions of 
the opposite conductors for the acids and alkalies, &c. show, 
that the chemical and electrical actions are produced by the same 
forces. 
Cuap. V.—Of the Production of Heat and its Laws. 
This chapter is one of the most important in the whole work, 
as its object is nothing less than to give a new theory of heat. 
At the same time I must acknowledge, that the views of the 
author on this subject possess a certain — of obscurity 
through which I am not quite certain whether | have been fortu- 
nate enough to penetrate. Whether this be owing to Professor 
CErsted not having expressed himself with sufficient clearness, 
or to my too little acquaintance with the dynamical theory of 
prec Ph on which his reasoning depends, I cannot pretend 
to say; but 1 have read over the chapter three times without 
being able to see clearly the validity of the consequences which 
