On the Electricity of Metallic Sulstcmces. 121 



a necessary consequence, the metal acquires the contrary 

 kind of electricity, and retains it at least for a moment, be- 

 cause it is insulated : for example, if tin be -employed to 

 rub a silk ribband, it produces in it vitreous electricity, in- 

 stead of the resinods electricity which would be excited by 

 friction with the hand ; and, on the contrary, the tin is 

 electrified in the resinous manner. Having then observed 

 that the different metals tried, acquired in this manner some 

 vitreous, and others resinous electricity, I thought that this 

 diversity of states might increase the number of distinguish- 

 ing characters which mineralogy borrows from natural phi- 

 losophy. 



To make experiments on this subject, I insulate the 

 agment of metal I intend to try, affixing it by common 

 wax to the extremity of a stick of gum-lack, or Spanish 

 wax; then holding the stick in my hand, I make the metal- 

 lic fragment pass several times over a piece of cloth. If the 

 surface of the fragment be rough, it will be necessary to 

 smooth it by means of a file : after rubbing it five or six 

 times, I make the metallic fragment touch the knob of the 

 collector, a well-known instrument, invented by Volta, to 

 serve at the same time in electric and galvanic experiments, 

 as a condenser and electrometer. Havlna; repeated this ope- 

 ration several times, and removed the disk which performs 

 the office of condenser, I determine in the usual manner 

 the kind of electricity which produces the separation of the 

 two straws of the electrometer. 



I shall now present a table of the different metals which 

 I subjected to experiment, with an indication of the result 

 given by each. I comprehend in this list metals which 

 have not yet been found naturally in the metallic state, and 

 which are not obtained in that state bui by separating them 

 from the principles by which thev are n)ineralized. I took 

 care to note the substances in which friction excites the 

 electric virtue with more facility and in a more energetic 

 planner than in others : 



Metals which acquire vitreous Electricity. 



Zinc, strong. 



Silver. 



Bismuth, strong. 



Copper. 



Lead . 



Oligist iron, 



' Metals 



