CHAP, iv.] ELECTRICITY AND MAGNETISM. 



251 



those shown in Fig. 109. The red lead settles down in 

 little red heaps and patches where the electrification is 

 negative. Fig. no shows the general appearance of 

 the Lichtenberg* s figure produced by holding the knob of 



Fig. no. 



the Leyden jar at the centre of a shellac plate that has 

 previously been rubbed with flannel, the negative elec- 

 trification being attracted upon all sides toward the 

 central positive charge. 



Powdered tourmaline, warmed and then sifted over a 

 sheet of glass previously electrified irregularly, will show 

 similar figures, though not so well defined. 



Breath-figures can be made by electrifying a coin or 

 other piece of metal laid upon a sheet of dry glass, 

 and then breathing upon the glass where the coin lay, 

 revealing a faint image of it on the surface of the glass. 



298. Production of Ozone. Whenever an elec- 

 tric machine is worked a peculiar odour is perceived. 

 This was formerly thought to be evidence of the existence 



