Lesson xxi.] ELECTRICITY. 123 



whatever bodies they reside, or to whatever bodies 

 they may be communicated. 



If a tube of glass, an inch and an half in diame- 

 ter and about three feet long, be rubbed, by re- 

 peatedly drawing the hand, or a piece of leather, 

 from one end to the other, it will become electric ; 

 so that small flashes of divergent flame, ramified 

 somewhat like trees bare of leaves, will dart into 

 the air ; from many parts of the surface of the tube, 

 to the distance of six or eight inches, attended with 

 a crackling noise ; and sometimes spafrks will fly 

 along the tube to the rubber at more than a foot 

 distant. This luminous matter is called the Elec- 

 tric Matter or Fluid, and all bodies that we are 

 acquainted with have more or less of it in them j 

 though it seems to lie dormant till it be put in 

 action by rubbing, and then (in a dark room) it 

 appears, like fire. 



Some bodies freely admit this fluid, and let U 

 pass through th,eir pores ; others do not. The 

 former- of these are called, Non-electrtts, or Con- 

 ductors : of this sort are all metals, living-creatures, 

 water, and moist wood ; but metals. are found to 

 be the best conductors. The latter, which do not 

 allow the Electric Fluid to pass through their 

 pores, are called Electrics, or Non-conductors : of 

 this kind are glass, wax, rosin, dry glue, baked 

 wood, and silk. But if either of these be wetted 

 with water, the water that adheres to it will render 

 it a conductor ; consequently, when any body is to 

 be used as a non-conductor, it should be well wiped 

 G 2 with 



