Mr. Davy’s Lecture on some 
4 s 
gene disengaged. The negative energy of the copper and the 
positive energy of the zinc are consequently again exerted, 
enfeebled only by the opposing energy of the soda in contact 
with the copper, and the process of electromotion continues, 
as long as the chemical changes are capable of being carried 
on. 
This theory in some measure reconciles the hypothetical 
principles of the action of the pile adopted by its illustrious 
inventor, with the opinions concerning the chemical origin of 
Galvanism, supported by the greater number of the British 
philosophers, and it is confirmed and strengthed by many 
facts and experiments. 
Thus the Voltaic pile of 20 pairs of plates of copper and 
zinc exhibits no permanent electromotive power when the con- 
necting fluid is water free from air ; * for this substance does 
not readily undergo chemical change, and the equilibrium 
seems to be capable of being permanently restored through 
it. Concentrated sulphuric acid, which is a much more perfect 
conductor, is equally inefficient, for it has little action upon 
zinc, and is itself decomposed only by a very strong power. 
Piles, containing as their fluid element either pure water or 
sulphuric acid, will undoubtedly give single shocks, and this 
effect is connected with the restoration of the equilibrium dis- 
turbed by the energies of the metals ; but when their extreme 
plates are connected there is no exhibition, as in usual cases 
of electromotion. Water containing loosely combined oxygene 
is more efficient than water containing common air, as it enables 
* The experiments proving this fact, and the other analogous facts in this page, 
may be seen detailed in Nicholson’s Journal, 4to. Vol. IV. page 338 and 394; and 
Phil. Msg. Vol. X. page 40. 
