The Growth of Metal

In 1674 Robert Boyle published his Hidden Qualities of the Air in which he demonstrated the existence of said hidden qualities  with the example of metals which had been extracted from mines and exposed to the air, and which had grown, or multiplied. Boyle does not argue the point adroitly, but instead prefers to include several testimonials (what he calls observations) from people who have seen metals multiplying in the air. The first is this:

Observations about the growth of tin

AN ancient Owner of Mines, being asked by me, Whether he could, otherwise than upon the Conjectures of vulgar Tradition, prove, that Minerals grow even after the Veins have been dug? Answer’d affirmatively; and being desired to let me know his proofs, he gave me these that follow.

He told me, that not far from his House there was a Tin-Mine, which the old Diggers affirm’d to have been left off, some said eighty, some an hundred & twenty years ago, because they had by their washing and vanning separated all the Ore from the rest of the Earth, and yet of late years they found it so richly impregnated with Metalline Particles, that it was wrought over again with very good profit, and preferr’d to some other Mines that were actually wrought, and had never been so robb’d. And when I objected, that probably this might proceed from the laziness and unskilfulness of Workmen in those times, who left in the Earth the Tin that was lately separated, and might then have been so; I was answer’d, that ’twas a known thing in the Country, that in those times the Mine-men were more careful and laborious to separate the Metalline part from the rest of the Ore, than now they are.

He also affirmed to me, that in his own time some Tenants and Neighbours of his (imploy’d by him) having got all the Ore they could out of a great quantity of stuff, dug out of a Tin-Mine, they laid the remains in great heaps expos’d to the Air, and within twenty and thirty years after, found them so richly impregnated, that they wrought them over again with good benefit.

And lastly he assured me, that, in a Work of his own, wherein he had exercis’d his skill and experience, (which is said to be very great) to separate all the particles of the Tin from the Terrestrial substances, that were dug up with it out of the Vein, he caus’d Dams to be made to stop the Earthy Substance, which the Stream washed away from the Ore, giving passage to the water after it had let fall this Substance, which lying in heaps expos’d to the Air, within ten or twelve years, and sometimes much less, he examin’d this or that heap, and found it to contain such store of Metalline particles, as invited him to work it again and do it with profit. And yet this Gentleman was so dexterous at separating the Metalline from the other parts of Tin-Ore, that I could (not without wonder) see what small Corpuscles he would, to satisfie my Curiosity, sever from vast quantities (in proportion) of Earthy and other Mineral stuff.

Relations agreeable to these, I received from another very ingenious Gentleman that was conversant with Tin-Mines, and lived not far from more than one of them. (pp.3-6)

Boyle continues through lead, iron, silver and gold, mixing testimony from unnamed ingenious gentlemen conversant with metal mining with books and travel reports. There is an article discussing Boyle’s sources online here

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