MECHANICAL ELECTRICITY. 293 



removing the wire at the end of the Bismuth, next 

 to the copper disc, and attaching it to the spring 

 which connected the mandril with the galvano- 

 meter, for mechanical Electricity, a current 

 was instantly produced hy the same friction. 

 Repeated, and with like results.* 



Exp. 45. Repeated a similar experiment with 

 iron. The sharp iron of exp. 36, was attached 

 to the two galvanometer wires, one at each end. 

 On turning with its sharp extremity, the copper 

 disc for some time, which produced an instanta- 

 neous current in exp. 36, no deviation of the 

 needle was at all observed. But by holding the 

 same end of the iron for a few moments in the 

 spirit flame, a constant deviation commenced, 

 which gradually progressed to T^". 



Repeated the experiment with like results. 

 Yet, when the end adjoining the disc was dis- 

 connected, and attached to the spring in contact 

 with the mandril, i. e. the ordinary connexion 

 for mechanical Electricity^ being made (as in 

 36) an instantaneous current of 8° (stationary) 



* The metals here employed are the crystalline, which 

 have been shown to be the only bodies evolving the phenomena, 

 copper being only a simple conducting body. 



