IN VOLTAIC ELECTRICITY AND ELECTRO-MAGNETISM. 
287 
the gases are non-conductors of voltaic electricity. The increase of effect, 
then, which is gained by the addition of nitric acid, seems to result from this 
circumstance, whilst the sulphuric acid, by dissolving the oxide, keeps the 
surface comparatively clean. When diluted sulphuric acid alone is used, and 
the plates in an elementary battery placed at different distances from one 
another, the quantities of hydrogen disengaged at the surface of the copper 
plate are within certain limits inversely proportional to the square roots of 
the distance between the plates ; a law which has been found to connect the 
distances of the plates with the electro-magnetic effects *. 
If the plates be removed to a very great distance, they will be unable to 
arrange the molecules of the fluid in the definite order which seems essential 
to the development of voltaic electricity, when all action will, of course, cease. 
As we approach this limit, the diminution of effect goes on more rapidly than 
the square root of the distance. When the plates, on the other hand, are 
brought very near each other, the increase of effect goes on more slowly than 
the square root of the distance, probably on account of the small space being 
partially filled with gaseous matter. Had these exceptions to the general law 
not taken place, there would have been no limit to the increase of effect till 
the plates had been brought into actual contact; nor would there have been 
a complete destruction of voltaic effect till the plates had been removed to an 
infinite distance. 
PART II. 
INVESTIGATION OF THE FUNDAMENTAL PRINCIPLE AND LAWS OF ACTION 
OF THE VOLTAIC BATTERY. 
11. In every theory of the battery which has yet been proposed, an actual 
transfer of electricity is supposed to take place, and a continued circulation 
kept up through the entire circuit. According to the two theories, the battery 
is supposed to be charged before the poles are connected, and the electricity 
- thus accumulated is ready to rush along the connecting wire the moment the 
poles are brought in contact. I can find no proof either for this accumulation 
or actual transfer, nor have we any proof that voltaic action takes place till 
the circuit be completed. Nor does any theory of the battery which has yet 
* Journal of the Royal Institution, No. 1. New Series. 
2 p 2 
