A HISTORY OF SCIENCE 



although it took several generations completely to 

 overthrow a superstition that had been handed down 

 through several thousand years. In April of 1772 

 Monsieur Geoffroy made a report to the Royal Acad- 

 emy of Sciences, at Paris, on the alchemic cheats prin- 

 cipally of the sixteenth and seventeenth centuries. In 

 this report he explains many of the seemingly mar- 

 vellous feats of the unscrupulous alchemists. A very 

 common form of deception was the use of a double- 

 bottomed crucible. A copper or brass crucible was 

 covered on the inside with a layer of wax, cleverly 

 painted so as to resemble the ordinary metal. Be- 

 tween this layer of wax and the bottom of the crucible, 

 however, was a layer of gold dust or silver. When 

 the alchemist wished to demonstrate his power, he 

 had but to place some mercury or whatever substance 

 he chose in the crucible, heat it, throw in a grain or 

 two of some mysterious powder, pronounce a few equally 

 mysterious phrases to impress his audience, and, be- 

 hold, a lump of precious metal would be found in the 

 bottom of his pot. This was the favorite method of 

 mediocre performers, but was, of course, easily de- 

 tected. 



An equally successful but more difficult way was 

 to insert surreptitiously a lump of metal into the 

 mixture, using an ordinary crucible. This required 

 great dexterity, but was facilitated by the use of many 

 mysterious ceremonies on the part of the operator while 

 performing, just as the modern vaudeville performer 

 diverts the attention of the audience to his right hand 

 while his left is engaged in the trick. Such ceremonies 

 were not questioned, for it was the common belief 



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