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>light from a rising moon decanting away
>* 7 Yu Su drain a goblet crude saltpeter?
The Secrets of Alchemy – Discover the secret science! Alchemy began as a mixture of practical knowledge and speculation on the nature of matter. Over time it evolved into the science we know as chemistry.
>https://www.sciencehistory.org/distillations/magazine/the-secrets-of-alchemy
It might seem incongruous that a man so fervently committed to the ideal of poverty would also devote himself to finding the secret of making gold. Yet at the start of his ''Book of Light'', written about 1350, John states clearly why he studied chrysopoeia and why he decided to write about it.
same concern about the coming of the Antichrist lay behind much of what Roger Bacon—also a Franciscan friar—wrote to the pope about sixty years earlier: the church will need mathematical, scientific, technological, medical, and other knowledge to resist and survive the assault of the Antichrist. We are well familiar with the use of science and technology for national security; in the case of John and Roger, we find a medieval precedent that includes alchemy as a means of ecclesiastical security.
John describes a series of sublimations of mercury with vitriol and saltpeter, followed by digestions and distillations.
his book contains an annotation toward the end that notes how crude saltpeter ordinarily contains salt, and gives a method for purifying it by fractional crystallization.
The second possibility is that John intentionally left out the crucial ingredient as a way of preserving secrecy.
If this is the case, then it is significant that the end of his book includes a rather out-of-place paragraph describing the
general importance of table salt, its ubiquity, its use in purifying metals, and so forth, and then states that “the whole secret is in salt.”