3 ° 
Mr. Davy's Lecture on some 
These experiments I have very often made, and the results 
are perfectly conclusive ; and in the case, page 2 6, in which 
sulphuric acid seemed to pass in small quantities through very 
weak solutions of strontites and barytes, I have no doubt but 
that it was carried through by means of a thin stratum of pure 
water, where the solution had been decomposed at the surface 
by carbonic acid ; for in an experiment similar to these in 
which the film of carbonate of barytes was often removed 
and the fluid agitated, no particle of sulphuric acid appeared 
in the positive part of the chain. 
It is easy to explain, from the general phenomena of de- 
composition and transfer, the mode in which oxygene and hy- 
drogene are separately evolved from water. The oxygene of a 
portion of water is attracted by the positive surface, at the same 
time that the other constituent part, the hydrogene is repelled 
by it ; and the opposite process takes place at the negative sur- 
face ; and in the middle or neutral point of the circuit, whether 
there be a series of decompositions and recompositions, or 
whether the particles from the extreme points only are active, 
there must be a new combination of the repelled matter : and 
the case is analogous to that of two portions of muriate of soda 
separated by distilled water ; muriatic acid is repelled from the 
negative side, and soda from the positive side, and muriate of 
soda is composed in the middle vessel. 
These facts seem fully to invalidate the conjectures of M. 
Ritter, and some other philosophers, with regard to the 
elementary nature of water, and perfectly to confirm the 
great discovery of Mr. Cavendish. 
M. Ritter conceived that he had procured oxygene from 
water without hydrogene, by making sulphuric acid the me- 
dium of communication at the negative surface ; but in this case, 
