84 



Lord Kelvin on 



is brought from a distance into the neighbourhood, and that 

 a glass rod rubbed with silk increases the divergence. Hence 

 we conclude that in the separation of two discs of copper and 

 zinc the copper carries away resinous electricity and the zinc 

 vitreous electricity. 



§ 2. Experiment 2. — The same apparatus as in Experi- 

 ment 1, except that the polished zinc and copper discs have 

 their opposed faces varnished with shellac, and are provided 

 with wires soldered to them for making metallic connexion 

 between them when the upper rests on the lower, as shown 

 in Fig. 2. All operations are the same as in Experiment 1, 



Fisr. 2. 



but now with this addition — when the upper disc rests on 

 the lower, make and break metallic contact by hand as shown 

 in the diagram. The results are the same as those of Experi- 

 ment 1, except that the quantity of electrification given to 

 the gold leaves by a single cycle of operations is generally 

 greater than in Experiment 1, for this reason : In Experi- 

 ment 1 at the instant of breaking contact between the zinc 



