OF ARTS AND SCIENCES. 



69 



" The first modification of the experiment was in the extent of sur- 

 face of lead. 



" Table III. — Experiments with Two Bars of Lead. — In all 

 other respects the conditions were the same as in the foregoing exper- 

 iments. 



" Table IV. 

 same as before. 



Experiments with TJiree Bars. — Other conditions 



" From the foregoing experiments it was deducible, — 



" 1st. That the action upon lead was most energetic during the first 

 few days of exposure. 



"2d. That the differences between the action on one, two, and three 

 bars, the volume of water remaining the same, being inconsiderable, 

 the action could not be dependent upon the surface of lead exposed, 

 but upon some other constant condition. 



" The observation, that, where the bar touched the containing tube, the 

 action seemed most vigorous, suggested an explanation of the want of 



