244 New Outl'mcs of Chemical Vhilosophy. 



tact with the zinc end of the cohiinn, it diverged to the sanie 

 angle, tlie wire of communication having been removed to the 

 otlier end. Hence it appears that the elements of electricity 

 came either from the earth or the tabic, through the wire which 

 formed a communicativon between the table and the column, and 

 that the two elements are of ecpial mechanical forces, for the two 

 electrometers were found to be in contrary electrical states. 

 That element which was received from the copper end of the 

 column was thcrmogen (positive electricity), the other electro- 

 meter recci\ed the contrary element from the zinc end *. 



Exp. 3. Having placed a silver-leaf electrometer in contact 

 with the co|)per end of an insulated electric column, and a com- 

 nnmication being made between the table and the zinc end, the 

 pendulums vibrated 140 times in a minute. These vibrations 

 were performed thus: As soon as the pendulum rq became 

 charged by the column, through the wire 7vr, it attracted and 

 charged the pendulum dp. The two pendulums being now 

 charged with the same element repelled each other; rg di- 

 verged to the right, dp to the left, and discharged its contents 

 into the wire at z, which conveyed it to the earth. The pen- 

 dulum dp being now reduced to its natural state, was again 

 attracted, charged, and repelled by the pendulum rq: thus the 

 vibrations of the two pendulums were continued. But as soon 

 as the wire of communication was removed from the zinc end 

 of the column, the pendulum ceased to vibrate : hence we may 

 conclude that the element which put the pendulums in motion 

 ascended up the wire at the zinc end, and passed through the 

 column to the copper end. 



The electrometer being placed at the zinc end of the column, 

 and the wire of communication against the copper end, the pen- 

 dulums performed the same number of vibrations in a given 

 time as before, but they ceased to vibrate as soon as the commu- 

 nication was cut off between the copper end and the tuble. The 

 ))endulums were put in motion at the copper end by thermogen, 

 the element of heat ; but at the zinc end, j)hotogen, the element 

 of light, produced an equal effect. 



Exp. 4, Two silver-leaf electrometers, whose pendulums were 

 of equal lengths, bt.ing j)laced in contact with an insulated elec- 

 tric column, one at each end, began to vibrate at the same time, 

 and the pendulums at the zinc end performed the same number 

 of vibrations in a given time, as those at the copper end. 



* Mr. Singer oliservrs, in Iiis Elements of Electricity, that " theelcctro- 

 intter connected with the zinc extremity of the cohnnn will be posilive, 

 that connected with the silver extremity will be negative." 



Mr. Singer was prolj.vhly led into this error by using Mr. Bennct's elcc- 

 trometir, which is a very iuiptrfcct instrument. 



Now 



