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 workers in mines is similar to that which is produced by fermentation 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--stress being especially laid 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 lingering, 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 Prof.Loescher, of the University of Wittenberg, entered a solemn protest, declaring that the decision of the medical faculty was "only a proof of the lamentable license which has so taken possession of us, and which, if we are not earnestly on our guard, will finally turn away from us the blessing of God."(281) But denunciations of this kind could not hold back the little army of science; in spite of adverse influences, the evolution of physics and chemistry went on.

More and more there rose men bold enough to break away from theological methods and strong enough to resist ecclesiastical bribes and threats.

As alchemy in its first form, seeking for the philosopher's stone and the transmutation of metals, had given way to alchemy in its second form, seeking for the elixir of life and remedies more or less magical for disease, so now the latter yielded to the search for truth as truth.
More and more the "solemnly constituted impostors" were resisted in every field.

A great line of physicists and chemists began to appear.( 282) (281) For Loescher's protest, see Julian Schmidt, Geschichte des geistigen Lebens, etc., vol.i, p.