USE OF THE ELECTROSCOPE. 



569 



The instrument serves for detecting the presence and 

 determining the kind of electricity in any body, and as 

 for both purposes only the metal parts come under con- 

 sideration, the remaining parts of the instrument are 

 left out in the following figures. 



A 







7) 







FIG. 308. 



In the ordinary state the electroscope contains equal 

 quantities of positive and negative electricity, as repre- 

 sented at A in fig. 308. When a body charged, say, 

 with positive electricity, is brought near it, electrical 

 separation is effected, the negative electricity being 

 attracted to the knob r the positive electricity being 

 repelled to the further extremity, that is, to the gold 

 leaves. These are now electric, and being both charged 

 with the same electricity, they repel each other, that is, 

 being flexible, they diverge, as at B. When the in- 



