86 NOMOS. 



points the eye of the philosopher, no less than the 

 eye of the mariner, to the star by which he can 

 direct his course. It is of a truth the Philosopher's 

 stone a stone, not turning everything it touches 

 into gold, but effecting a far higher transmutation 

 than this that of ignorance into knowledge. 



But we are not yet at the end of the inquiry 

 which can furnish an answer to the question what 

 is electricity, though we have approached suffi- 

 ciently near to this end to be able to conjecture 

 what the nature of this answer must be. We have, 

 indeed, still to consider the phenomena of electrical 

 light and heat ; and first with regard to the light. 



The various arguments which connect the several 

 forms of luminous "discharge" and "conduction" 

 with ordinary "conduction" prepare us to expect 

 that electrical light must be referred to chemical 

 Electrical action. The arguments are so complete 

 light must be that others are scarcely necessary; but 



referred to , . ,, - , . 



chemical ac- there is one of great beauty which has not 

 been mentioned, and which ought not to 

 be overlooked. This is to be found in the following 

 experiment: A wheel, with a written inscription 

 upon one of its spokes, is placed upon an axle in the 

 focus of a photographic camera, and arrangements 

 are made for illuminating it when necessary with an 

 electric spark. Having darkened the room, the wheel 

 is then set in motion, and when the motion has at- 



