GALVANIC ELECTRICITY. 375 



Cortona, inscriptions engraved on plates of pure 

 lead in a perfect state of preservation ; while in 

 the Gallery of Florence, he found that medals 

 composed of lead and tin, or lead and some 

 other metal, were entirely reduced to a white 

 powder, though carefully wrapped up in paper, 

 and preserved from the atmosphere in drawers. 

 He had further noticed, when in England, that 

 the iron nails then employed in fastening to- 

 gether the copper sheathing of ships, caused so 

 much corrosion of the copper, that the holes made 

 by them were sometimes larger than the heads 

 of the nails all of which he referred to chemical 

 action produced by the mutual contact of different 

 metals exposed to moisture, atmospheric air, &c. 

 That this was the case in the experiment of 

 Sultzer, he thought was proved by the fact, that 

 when the tongue was wiped dry, scarcely any 

 perceptible sensation was excited. 



In another set of experiments, Fabroni put 

 different metals in vessels filled with water, two 

 and two, in contact, when he found that the 

 most ox id able metal was visibly oxidized at the 

 moment of contact. A month afterwards, the 

 connected metals had acquired so strong a 

 degree of cohesion as to require a considerable 

 force to separate them. Not only were the 

 metals oxidized, but covered over with small 

 crystals of various forms, which had been de- 

 posited from a state of solution. (Traite de 



