1048 Dr. tngenhousz’s Experiments , Sec. 
its acquired ftate of electricity leaves the metal without 
robbing it of that quantity of fluid which it had ac- 
quired. 
If thefe two coatings, feparated from the glafs, are 
brought near one another, they attract each other; a 
fpark enfues, becaufe the coating, which has acquired a 
fuper-abundant quantity of eledtric fluid, imparts it to 
the other, which had loft as much ; and thus a perfect 
equilibrium is reftored between them. 
If both thefe coatings are applied as before upon the 
fame glafs, a pofitive fpark may be obtained from the up- 
permoft coating, and a negative one from the other. If 
they are feparated again from the glafs, as in the firft cafe, 
the uppermoft coating will afford a negative fpark, and 
the undermoft a pofitive; and thefe alternate fparks may 
be continued a very long while. 
This explanation or theory agrees perfectly with the 
experiments exhibited by our deceafed member, the late 
Mr. canton, with elder pith balls hanging by linen 
threads from a wooden box, which balls are excited 
either negatively or pofitively by a piece of excited glafs. 
