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cola, one of the most earnest and truthful of investigators, still 

 adheres to the belief that these gases in mines are manifestations 

 of devils, and specifies two classes — one of malignant imps, who 

 blow out the miners' lamps, and the other of friendly imps, who 

 simply tease the workmen in various ways. He goes so far as to 

 tell us that one of these spirits in the Saxon mine of Annaberg 

 destroyed twelve workmen at once by the power of his breath. 



At the end of the sixteenth century we find a writer on min- 

 eralogy complaining that the mines in France and Germany had 

 been in large part abandoned on account of the " evil spirits of 

 metals which had taken possession of them." 



But at various periods glimpses of the truth had been gained. 

 The ancient view had not been entirely forgotten; and as far 

 back as the first part of the thirteenth century Albert the Great 

 suggested a natural cause in the possibility of exhalations from 

 minerals causing a " corruption of the air " ; but he, as we have 

 seen, was driven or dragged off into theological studies, and the 

 world relapsed into the theological view. 



Toward the end of the fifteenth century there came a great 

 genius laden with important truths in chemistry, but for whom 

 the world was not ready — Basil Valentine. His discoveries an- 

 ticipated much that has brought fame and fortune to chemists 

 since, yet so fearful of danger was he that his work was carefully 

 concealed. Not until after his death was his treatise on alchemy 

 found, and even then it was for a long time not known where and 

 when he lived. The papal bull, Spondent pariter, and the various 

 prohibitions it bred, forcing other alchemists to conceal their 

 laboratories, led him to let himself be known during his life at 

 Erfurt simply as an apothecary, and to wait until after his death 

 to make a revelation of truth, which during his lifetime might 

 have cost him dear. Among the legacies of this greatest of the 

 alchemists was the doctrine that the air which asphyxiates work- 

 ers in mines is similar to that which is produced by fermen- 

 tation of malt, and a recommendation that in order to drive away 

 the evil and to prevent serious accidents, fires be lighted and jets 

 of steam used to ventilate the mines, laying stress especially upon 

 the idea that the danger in the mines is produced by " exhalations 

 of metals." 



Thanks to men like Valentine, this idea of the interference of 

 Satan and his minions with the mining industry was gradually 

 weakened, and the working of the deserted mines was resumed ; 

 yet, even at a comparatively recent period, we find it still linger- 

 ing, and among leading divines in the very heart of Protestant 

 Germany. In 1715 a cellar-digger having been stifled at Jena, 

 the medical faculty of the university decided that the cause was 

 not the direct action of the devil, but a deadly gas. Thereupon 



