GALVANISM. 411 



all other artificial lights -^vould bo extinguished. It may even be produced 

 under "water. To excite the electricity, however, which occasions this light, 

 zinc or some other mital must be oxydized, or what is the same thing burnt, 

 the same as oil ia our lamps, or coal in the gas retorta for the production of 

 other species of artificial light. 



The effects of the galvanic battery upon the 



"VVTiat are the j •■ /^ ,^ • i , 



physiological ncFves and muscles oi the animal system are 

 .v.uic*eLctricI of the same character as those produced by 

 ^' ordinary electricity. 



On grasping the two ends of the connecting wires of a battery of some 

 force with wet hands, a peculiar tremor will be felt in the joints of the arm 

 and hand, accompanied by a slight contortion of the muscles, and increasing 

 to a violent shock. This shock is repeated every time a contact between the 

 hand and the wire is broken and renewed. The concussion of the nerves of 

 the body is, therefore, produced by the entrance and exit of the currents of 

 electricity ; for they evidently must pass through the body the moment it forma 

 the connecting link between the two poles. 



By a particular arrangement, the circuit may be closed or interrupted at 

 pleasure, and in such a manner that the current may be made to pass alter- 

 nately through the wires and the body ; the latter being thus exposed to a 

 series of shocks which are considered particularly adapted for the cure of 

 diseases arising from the injury or derangement of the nervous system. It is, 

 moreover, a highly valuable remedy in cases of suffocation, drowning, paraly- 

 sis, etc. , and numerous arrangements have been at various times proposed 

 for the construction of medico-galvanic machines. 



The effects of galvanic electricity on bodies recently deprived of life is very 

 remarkable, and it was through an accidental observance of its action upon a 

 dead frog that galvanism was discovered. By connecting the muscles and 

 nerves of recently-killed animals with the poles of a battery, many of the 

 movements of life may be produced. Some remarkable experiments of this 

 character were made some years since upon the body of a man recently 

 executed for murder at Glasgow, in Scotland. The voltaic battery em- 

 ployed consisted of 270 pairs of plates, four inches square. On applying 

 one pole of the battery to the forehead and the other to the heel, tho 

 muscles are d.?scribed to have moved with fearful activity, so that rage, 

 anguish, and despair, with horrid smOes, were exhi'jited upon the counten- 

 ance. 



781. Galvanic electricity is a powerful agent in effecting chemical decom-. 

 positions, and in its application to such purposes, it is most practically usefuL 



Can galvanic Wlieu a currcnt of galvanic electricity ia 

 fecfchemirai "oi^^^ to pass through a compound conducting 

 dLcompositiou? substance, its tendency is to decompose and 

 separate it into its constituent parts. 



