On the Constitution of the Electric Fluid. 211 



— an electricity, perhaps, the same in the number of its consti- 

 tuent elements as the ordinaiy electric fluid ; but so different in 

 the ratio of these to each other, or in theii- mode of combination, 

 as to constitute an entirely different power, — a power or agent, 

 sui generis, exerting its pecuUar energies, according to the pre- 

 dominant element. 



For a length of time after the invention of Schweiggei-'s mul- 

 tipher, aftei-wards improved by Melloni, Nobili and others, and 

 called the galvanometer, it was doubted if that instrument could 

 be at all affected by common electricity. At length CoUadon 

 proved that it could, by increasing the insulation of the coil of 

 wire ; that is, by enabling the coil to carry a greater quantity of 

 the electric fluid than in the ordinary state it is able to do ; or 

 in other words, by increasing the intensity of the electricity 

 conveyed. Hence the electricity which the common galvano- 

 meter coil is capable of carrying, when placed between the two 

 conductors of an electrical machine, will not without peculiar 

 contrivances be indicated by the galvanometer, no matter how 

 powerful the machine may be. 



Yet a bit of copper wire, weighing jt j^^id part of a grain, 

 arranged voltaically with a platinum wire almost equally small, 

 and a drop of nitric acid, as already described, caused the needle 

 to whirl round the circle three times. Does the particle of cop- 

 per, scarcely visible, generate more electricity in an instant of 

 time than the powerful electrical machine can supply ? CoUa- 

 don's experiment proves that intensity is the condition of com- 

 mon electricity which causes deflections ; and the sparks obtain- 

 able from the coil, while the machine is in action, prove the 

 high intensity of the electricity contained in it, — an appearance 

 totally out of the question in the case of the atom of copper. In 

 opposition to these well-ascertained facts, can it be consistently 

 maintained that quantity is the effective condition ? Admitting 

 for a moment that it is so, why does not the singly-insulated 

 coil of the galvanometer act on the needle when it is receiving 

 torrents of electricity from a powerful electrical machine ? Is the 

 quantity insufficient ? if it be, why does that insufficient quan- 

 tity become sufficient when the insulation of the wire constituting 

 the coil is doubled ? If it be answered, that it can now carry the 

 charge of electricity necessary to produce deflection, a greater 

 quantity being retained by the double silk than could have been 

 confined by a single one, I reply, that this is a plain acknow- 

 ledgement that it is intensity which acts, a state which the atom 

 of copper cannot, and is admitted not to confer ; and if the wire- 

 coil with single silk was incapable of carrying the necessary 

 quantity of electricity from the machine to produce deflection, 

 why is it capable of carrying it from the atom of copper ? But 



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