CHEMISTRY AXD ALCHEMY. 



183 



and England each produced almost simultaneously one of the most illustrious 

 representatives of what was called, in the language of the day, the great art ; 

 that is to say, the knowledge of the secrets of nature. Of these three 

 learned philosophers, Bacon possessed the highest abilities and the largest 

 powers of conception, and all three of them attracted numerous audiences to 

 their lectures, for they contrived to invest even the most common subject 

 with interest by their way of treating it. When Bacon described the motion 

 of the celestial sphere and the regular march of the planets ; when he expounded 

 his theory of the physical world, and set forth the laws which regulate the 

 matter and cause the transformation of substances, he was listened to with 



Fig. 130. The Alchemist Koger Bacon. After an Engraving by Vrieae. 



admiration and in complete silence, for he was himself convinced by the 

 proofs which he had obtained, and by the great problems which he believed 

 that he had settled, and he communicated his own convictions to his audience. 

 But, upon the other hand, experimental science often borrowed its proofs 

 from the most impudent imposture. Thus Arnauld de Villeneuve showed the 

 Parisians copper plates which he declared that he had just converted into 

 silver, and silver foil which he alleged he could convert into fine gold. The 

 people who witnessed these tricks looked upon them as so many miracles, little 

 knowing that a little nitric acid mixed with water would have destroyed the 

 illusion. 



