OR VOLTAIC ELECTRICITY. 391 



It is stated by Singer, Donne, and others, that 

 the energy of De Luc and Zamboni's columns* 

 is greatly augmented by an elevated tempe- 

 rature, and diminished by a reduction of tempe- 

 rature ; that they are more active during summer 

 than winter ; and in a warm than a cold room. 

 Dr. Jaegar found, that after the dry pile had 

 lost its energy, it was restored by a temperature 

 of from 104 to 140 F. That the energy of this 

 pile is owing to chemical action, like every other 

 form of the battery, is proved by the oxidation 

 which it undergoes, and by the total loss of its 

 power when perfectly dry. 



When isolated plates of zinc and copper are 

 immersed in dilute nitric acid, they are oxidized 

 and dissolved, when caloric is liberated as during 

 combustion; but when they are connected by 

 means of a metallic wire, galvanic electricity is 

 evolved. There can scarcely be a doubt that if 

 the caloric evolved by ordinary combustion could 

 be concentrated and conducted off like the gal- 

 vanic fluid, it would exhibit electrical pheno- 

 mena. Pouillet has actually shown that elec- 

 tricity is disengaged during nearly all combus- 

 tions, though in a slight degree, as had been 



* The first is formed of disks of writing paper, interposed be- 

 tween thin leaves of zinc and silver; while that of Zamboni was 

 composed of paper disks gilt or silvered on one side, and the 

 other side covered with a layer of black oxide of manganese 

 mixed with honey. 



