400 



positive light was drawn out into strata. The needle of a galvano- 

 meter in circuit was violently deflected, and the polarity reversed, 

 settling at a deflection of 45. On heating the potassa, the dis- 

 charge again bursts into a sun-like flame, subsequently subsiding 

 into three or four large strata, of a cloud-like shape, but intensely 

 bright." 



On a subsequent occasion I found that the discharge did not pass 

 for about a minute after the circuit was completed, when a fine glow 

 appeared on the negative ball, fig. 1 A. Around the positive ball 



Fig. 1 A. 



there was a trifling glow, in a few seconds a momentary brilliant 

 flash, and the discharge ceased. The potash was then again heated ; 

 the large negative glow reappeared, followed almost instantly by a 

 remarkably brilliant stratified discharge, with intense chemical action 

 in the battery, denoted by the evolution of nitrous fumes ; at this 

 moment I separated the discs of the micrometer-electrometer, and thus 

 broke the circuit. 



I now arranged the apparatus by attaching gold-leaf electroscopes 

 to both terminals, and introduced the galvanometer, so as to enable 

 me to examine more carefully the action that would take place when 

 the potassa was heated. On heating the potassa, the fine negative 

 (fig. 1 A) was again developed ; the leaves of the electroscope did 

 not close ; but as the negative glow increased, the needle of the 

 galvanometer was suddenly deflected, immediately (although the glow 

 continued) returning to zero ; as more heat was applied a small globe 

 of light appeared on the positive (fig. 1 B), was visible, and the 



Fig. 1 B. 



needle gradually deflected 40 or 50. On withdrawing the lamp, 

 as the potash cooled, the positive glow disappeared, the needle of 



