the Decomposition of the Earths, &c. 34,7 
bodies, and to search for analogies by which the principles of 
research might be guided. 
Alumine very slowly finds its point of rest at the negative 
pole, in the electrical circuit ; but silex, even when diffused 
in its gelatinous state through water, rests indifferently at the 
negative or positive poles. 
From this indifference to positive and negative electrical 
attractions, following the general order of facts, it might be 
inferred, that if these bodies be compounds, the electrical 
energies of their elements are nearly in equilibrium ; and that 
their state is either analogous to that of insoluble neutral salts, 
or of oxides nearly saturated with oxygene. 
The combinations of silex and alumine, with acids and alka- 
lies, as well as their electrical powers, were not inconsistent 
with either of these ideas ; for in some respects they resemble 
in physical characters, fluate and phosphate of lime, as much 
as in others, they approach to the oxides of zinc and tin. 
On the idea that silex might be an insoluble neutrosaline 
compound, containing an unknown acid or earth, or both, and 
capable of being resolved into its secondary elements, in the 
same manner as sulphate of barytes, or fluate of lime, I made 
the following experiments. 
Two gold cones,*' connected by moistened amianthus, were 
filled with pure water, and placed in the electrical cir- 
cuit, a small quantity of carefully prepared and well washed 
silex was introduced into the positive cone : the action was 
kept up from a battery of two hundred plates, for some hours 
till nearly half of the fluid in each cone was exhausted ; the 
remainders were examined ; the fluid in the cone containing 
* The same as those described in Phil. Trans. 1807, p. 6. 
Yya 
