Q^ OV THE ELECTRIC COLTJMN. 



mena produced by the latter, because it retains longer the 

 effect o{ friction; those produced by naked glass are of the 

 same nature, only reversed. 

 txp. 13. Ji.rp. 13. A ghiss rod covered with sealing icax must be 



rubbed so gently-, that, when applied to the column, it only 

 increases the divergence of the gold leaves at the negative 

 side, without any striking, else the effects would be confused : 

 vihen it produces the proper eifect, the phenomena are the 

 following. 



1. At the moment when the jod is placed, the divergence 

 increaKes at the negative side, and diminishes, or even ceases 

 at the positive side. The cause of these effects is, that the 

 expansive power of the electric Jiuid is lessened in the \Vhole 

 column, by part of its vector passing to the negative rod, 

 Vv here its quantity is less: and as however the equilibrium 

 of the electric jftuid in the column requires more electric mat- 

 ter on zinc th-axi on copper, the latter, at the first moment, 

 loses more of it, but not sufficiently to compensate the loss 

 of expansive poiver at the zinc side ; therefore less electric 



Jiuid passes into the gold leaves of the latter, which fall ia 

 consequence of this diminution. 



2. Within a little time, the positive divergence is renewed 

 at the zinc side, and the negative lessened at the copper side. 

 This effect is produced by the ambient air, which, during 

 the diminution (\( expansive power in the column, j'ields to it 

 some electric Jiuid, especially to the copper side which was 

 become strongly negative; and thus the former equilibrium 

 is restored in the column. 



3. The proof of the above explanations of the phenomena 

 observed, which embrace the whole system, both of the 

 motion of the electric Jiuid in the column, and of the iufllu- 

 tnice of the ambient air on this instrument, is obtained by 

 suddenly removing the rod: for the new quantity of electric 

 Jiuid <:ommunicated to the column by the air during the in- 

 jhence of the negative body malces both gold leaves strike 

 lit ouce on the zinc side by a very great divergence. 



F-.Tects of dif- Yhe last,object concerning the theory of the electric ef- 



size & lumibe*/^^^* '" ^^'^^ ^^^ column and the pile, which remains to b^ 



«f plates. considered, relates to the difference between the effects of 



the number ot groups and the size oi the ^;/afe^, considered 



under 



