Alchemy

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…will be no result, but if a touch of some acid be added, it will oxidize. The explanation is that "the acid provokes oxidation of the metal because it has an affinity for the oxide which tends to form." - a material fact most metaphysical in its production, and only explicable thereby. He concluded his argument with an appeal for tolerance towards the medieval alchemists, whose work is underrated because it is not properly understood.