On the FhcBno-77icna of the Electrophorjis. 30S 



its increased capacity will enable it to hold : on its removal 

 it yields to the hand the superfluous quantity it had pre- 

 viously obtained; and thus the process inav be repeated till 

 the surfare of the electric becomes so much neutralized that 

 its capacity is not increased by the contact. On the removal 

 of the cover the sole electrometer becomes negative, and 

 will receive a spark : and if, after the process above de- 

 scribed be so often repeated that the cOTer will not any 

 longer give a sp^ark on removal ; if the sole and cover be 

 touched together, the attraction to the upper surface is re- 

 stored in nearly its former vigour, and the cover on removal 

 again yields positive sparks to a conductor. 



Whenever the sole or cover is touched, the electrometer 

 in either will of course become neutral, because the fluid is 

 abstracted or supplied with- the utmost facility, awd its di- 

 stinctive characters are lost in the general mass of circula- 

 tion. 



There are two objections to the foregoing theory which 

 seem to require some solution. 



1. When the cake, in conseqaence of excitation, acquire* 

 an increased attraction for the electric fluid, why is it not 

 sooner rendered inert by the supply it niav obtain by the 

 contact of its surface with the particles floating in the at- 

 mosphere? 



2. The transitions from the negaiive to the positive states, 

 and^i'i'ce versa, are so rapid, that they can hardly be recon- 

 ciled to the opportunities of supply or abstraction offered by 

 a dry atmosphere. 



In the first case, a moist state of the weather, or a room 

 abounding with dust, will, in fact, rapidly destroy the etlt-ct 

 ef excitation : in a dry atmosphere it may be supposed that 

 the uniform dlfiusion of the fluid is so much disturbed by 

 friction that the interior particles are a long time before the. 

 equilibrium is restored, in consequence of the verv slow and 

 difRcult transmission of the fl^uid through the pores of elec- 

 tric substances. 



In the second case, these transitions may be tfl'cctcd wiJi- 

 out any material alteration in the absolute quantity of the 

 fluid brought into action by a change of capacity or Attrac- 

 tive force only. 



I confide in the experienced candor and indulgence of 

 the society to excuse the imperfections they will undoubt- 

 tdly detect; but, as my object is the attainment of truth, 

 I shall be satisfied with the hope, that if my paper does not 

 produce conviction it will e.xcite inquiry. 



LIV. A IrUf 



