Mr. Davy’s Hypothesis of Electro-chemical Affinity. 257 
is overcome by that of sulphuric acid; sulphate of soda 
is formed. From this it appears that sulphuric acid, being 
more negative with regard to soda than muriatic acid is, 
exerts a more powerful attraction, and with this attraction 
existsi n sulphate of soda. When muriatic acid is added; 
which has a weaker energy, it is impossible to conceive 
how the weaker electrical energy could displace the stronger. 
The soda possesses as strong an attraction to the sulpburic 
acid as the latter does to the soda. Here there are two at- 
tractions, either more powerful than that which is supposed 
to break the combination. Were the soda in a free state; 
its electricity might he saturated by a great quantity of a 
weak power. But it were absurd to suppose that the soda 
would separate in order to unite with a weaker electricity 
for which it can have no attraction, being already saturated 
with the opposite stronger power of the sulphuric acid. 
The attractions of electricity obey imtensity, not quantity ; 
and it may be proved by a decisive experiment. This law 
alone is sufficient to establish a difference between electric 
attraction and affinity. 
The intensity of electricity is in the inverse ratio of the 
surface charged compared with the quantity. If a battery 
and a small jar be electrified with the same quantity of 
fluid, the intensity of the jar will be to that of the battery 
inversely as the superficial contents of the former are to 
those of the latter. Thus if the jar be = 1, and the battery 
= 3, the quantity of fluid = 6 ineach; thus the intensity 
of the jar will be =6, and that of the battery =2, or three 
times greater. This superior itensity, although not the 
ratio, may be easily shown by attaching electrometers to 
the jar and battery. When the quantities thrown in are 
alike, the electrometer of the jar rises to its maximum, 
while that of the battery is not affected. The application 
of the experiment now becomes extremely easy, and its force 
manifest. 
Let a jar-be charged by a certain number of revolutions 
of an electric machine; when rémoved, let a battery re- 
ceive the quantity produced by an equal number of revo- 
Jutions. The ball of the battery is to be placed at some 
distance from that of the jar, and midway between them 
as to ‘hang a gilt pith-ball suspended by a gilt thread from 
a negatively charged jar above. The pith-ball may be con- 
fined in its position by means of a silk thread extended by 
a hand underneath. When the silk thread is let loose, the 
gilt ball will be attracted to the jar. The same thing hap- 
pens if the battery contain twice, or perhaps twenty limes 
Vo). 37. No, 156. April 1811. R the 
