HISTORY OF GALVANISM. 65 



gative." As a proof and illustration of this pro- 

 perty, the author informs us, that " if one finger 

 be applied to the wire of the positive pole, and 

 another finger wetted to the soap, no shock is felt, 

 and the electrometers do not show the least change 

 in their respective divergencies. But if the experi- 

 ment be repeated, by establishing a communication 

 between the positive pole and the soap, with both 

 fingers wetted, a very perceptible shock will be 

 felt, and the two electrometers will arrive at an 

 equal, and a very weak degree of intensity." He 

 proposes the following nomenclature for thes"e Erman's 

 five classes of bodies : 1st, Insulators ; 2d, Per- 

 feet conductors ; 3d, Bipolar imperfect conductors ; 

 4th, Positive unipolar ; and 5th, Negative unipolar 

 bodies.* Although, as we shall afterwards find, 

 Mr. Brande explains the facts upon rather a 

 different principle, yet they are highly impor- 

 tant, and Erman is entitled to much commendation 

 for the skill with which he conducted his ex- 

 periments. 



Morveau suggested an idea, which appears suffi- Morveau's 

 ciently plausible, that the action of galvanism 

 may affect the formation of metallic oxides, and 

 even cause them to assume the particular forms 

 which they occasionally exhibit.f Bucholtz de- 

 tailed a series of experiments which he performed, uigmetai- 

 where a metallic oxide, held in solution by an llc oxides * 



acid, was precipitated in the metallic state by the 







* Journ, de Phys. Ixiv. 121. f Ann. de Chim. Ixiii. 113. 



F 



