Dr. von Hayek thanked the speaker in the name of those 

 present for his interesting address, and referred to a passage 

 in the writings of his own former master in occult science, 

 Cardano: "Alchemy," he wrote, "contains several admirable 

 things, several useless, several doubtful, several desirable, but 

 none salutary, none efficacious, none of great hope, none of 

 peril, none of which to boast." He thereupon stated that in 

 his long experience as Director of the laboratories of the 

 Imperial court and as examiner of those who claimed to be 

 adepts in transmutation, he had detected many kinds of frauds 

 and he proposed to give a summary of them to put his friends 

 on their guard. Some imposters used double-bottomed 

 crucibles, the false bottom being made of powdered crucible- 

 earth mixed with wax, gold-filings being concealed in the 

 space between. Others devised hollow rods for stirring the 

 molten ingredients, the ends being stopped with wax which 

 melted easily, and thus gold-powder secreted in the rods was 

 introduced into the crucibles. Another adept was detected in 

 dropping into the crucible a piece of charcoal in which gold- 

 leaf had been hidden ; one well versed in the chemical art had 

 steeped a bit of charcoal in a solution of gold and when 

 busy about the furnace-fire he slily threw it into the crucible. 

 Those who pretended to make gold and silver without fire, 

 coals, crucibles and metallurgical accessories, resorted to other 

 ' ingenious schemes; one used aqua fortis in which silver had 

 . been secretly dissolved ; another had a knife-blade made of 

 two metals soldered together, the golden half painted black 

 with a varnish soluble in alcohol, and the removal of the 

 coating from the gold by immersion in spirits of wine effected 

 the deception. A more unusual trick was to bleach copper 

 with a preparation of arsenic, but the most common of all 

 consisted in using a compound of gold and mercury known 

 as amalgam; when this amalgam is heated to the third 



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