promise, is a Thing impossible both to Nature and Art, and therefore count them unworthy the Perusal of Philosophers, as well as undeserving of the Name. But it is a Maxim, That it is safer to credit an Artist in his own Art, than one that is an utter Stranger to it; and consequently it is rash to condemn what the Alchemists have defined to be possible; especially, since these Chemists openly declare, that their Writings are to be weighed in the Balance of the most certain Laws of Nature, which have been discovered with the greatest Evidence by the Events of Things; (that is, by exact and repeated Experiments) and they desire not to be credited, whenever they produce any Thing contrary to the Powers of Nature truly known by Experiments. Moreover they alledge, that they express themselves in such an obscure manner, only to keep profane Persons away from their Mysteries, which are unfolded to such as are initiated in them; and so that it was necessary that Things strange, obscure, and often false, should be mixed and interpolated with what is sincere, clear, and true in their Writings. For my part, upon looking into chemical Matters, and perusing the Writings of the Alchemists, I have found them all of the same Mind and Meaning as to the following Particulars: That Metals are naturally generated in their Veins, are nourished, grow, and multiply like other natural Things, each in their proper Place: That the Aliments or Nourishment of Metals, which before are of a foreign Nature to them, are, by the genital Power of the Metallic Seed, converted into a truly Metallic Nature; so that by this seminal Power alone they lose their former, and receive a new Property by the sole cherishing of the pregnant Warmth; for they will have all these Things to be effected entirely by the same Means: That as the Seeds of Animals and Plants change the Aliments they receive into their own Nourishment, so the vivificating Seed of growing Gold, having got a proper Food, in a fit Matrix, by the Help of a suitable and convenient Heat, digests the same into its own particular Nature: Therefore by that Means, according to a Law prescribed to subterraneous Things, they determine that true Gold is always produced by Length of Time out of a Matter of a different Nature from Gold: For having subdued its Aliment by its own Force, it grows, by vital Increase, into a Matter like to it, so long as those four Conditions that are absolutely required attend it. Upon pursuing their Researches into Nature with more Accuracy, they discovered that the Metals which are produced, and especially Gold, are very closely confined within a very solid and pure Stone, which is on every Side so very carefully closed up, that no Passage leading to or from the Metal can be discerned. The Matrix of the growing Metal is thick, hard, impenetrable, without Mixture, closed up on all Parts, and resembles Glass. There is nothing more hard to understand, than to discern the Manner how the