A HISTORY OF SCIENCE 



air. These four elements were accountable for every 

 substance in nature. Some of the experiments to 

 prove this were so illusive, and yet apparently so sim- 

 ple, that one is not surprised that it took centuries to 

 disprove them. That water was composed of earth 

 and air seemed easily proven by the simple process of 

 boiling it in a tea-kettle, for the residue left was ob- 

 viously an earthy substance, whereas the steam driven 

 off was supposed to be air. The fact that pure water 

 leaves no residue was not demonstrated until after 

 alchemy had practically ceased to exist. It was pos- 

 sible also to demonstrate that water could be turned 

 into fire by thrusting a red-hot poker under a bell- 

 glass containing a dish of water. Not only did the 

 quantity of water diminish, but, if a lighted candle 

 was thrust under the glass, the contents ignited and 

 burned, proving, apparently, that water had been con- 

 verted into fire. These, and scores of other similar 

 experiments, seemed so easily explained, and to ac- 

 cord so well with the "four elements" theory, that 

 they were seldom questioned until a later age of in- 

 ductive science. 



But there was one experiment to which the alche- 

 mist pinned his faith in showing that metals could be 

 "killed" and "revived," when proper means were em- 

 ployed. It had been known for many centuries that 

 if any metal, other than gold or silver, were calcined 

 in an open crucible, it turned, after a time, into a pe- 

 culiar kind of ash. This ash was thought by the al- 

 chemist to represent the death of the metal. But if 

 to this same ash a few grains of wheat were added 

 and heat again applied to the crucible, the metal was 



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