1824.] M. Labillarditre on the Lillebonne Statue. 103 



formed the Lillebonne statue of matter so friable as that of 

 winch it is now composed, -since a slight effort is sufficient ,to 

 break off pieces of it of considerable thickness : it is besides 

 impossible to admit that conclusion, for many parts of the statue 

 have been fixed by rivets ; neither can we imagine that the oxi- 

 dation of the metals, which in some parts is complete, and in 

 others partial, can have been occasioned by any accidental cal- 

 cination that the statue may have undergone. Theory and 

 experience prove that were the oxidation owing to the combined 

 action of heat and air, those parts completely oxida ted in which 

 the copper is found in the state of protoxide, ought to be in that 



° f Thesis a fact which deserves to be collated with the present 

 subiect Most bronze medallions found under the same circum- 

 stances as the statue, have suffered an analogous alteration 

 which we may attribute to their havmg also been gilded (as we 

 know they frequently were), for common medals which were not 

 gilt, though found likewise under similar circumstances, either 

 retain then metallic properties, or pass to the state of verdigris, 

 like copper utensils exposed to air and moisture. 



The oxidation of the metals of which the statue was originally 

 formed, is derived from a particular cause ascribab e to the 

 oalvanic effects produced by the contact of the gold leaf with 

 which one of its surfaces was covered, with the copper or bronze, 



which forms its basis. . . , 



We know that two dissimilar metals develope electric ty by 

 contact; that they assume different electrical states; and that in 

 the case of copper and gold, the gold becomes negative, and the 

 copper positive A voltaic pile constructed of those two metals, 

 and having its copper extremity, or positive pole, terminated by 

 a copper wire, and its gold extremity, or negative pole, termi- 

 nated by a gold wire ; if we place these two wires in a vessel of 

 water, and put the pile in action, the water is decomposed, its 

 oxygen goes to the positive pole, and combines with the copper 

 Wire, While the hydrogen, being incapable of combining with the 

 gold wire of the negative pole, to which it is determined, flies 

 uif in the form of gas. . • , ., 



The Lillebonne statue, formed chiefly of copper alloyed w.lli 

 a small quantity of tin, and covered with leaf gold, may be con- 

 sidered as a voltaic pile, capable of producing the same effecte 

 as a pile whose elements consist of gold and copper. 1 he statue 

 having been buried for twelve or fifteen centuries m moist earth, 

 determined the decomposition of the water by galvanic act.on, 

 like the pile in the preceding case. The oxygen of the decom- 

 posed water went to the copper and combined with it; the 

 hydrogen went to the gilded surface, and from thence escapee 

 into the atmosphere. The number of years that the statue laid 



