The works of the Honourable Robert Boyle, Esq., epitomiz'd by Richard Boulton ... ; illustrated with copper plates.

CHAP. IX. Observations of the growth and increase of Metals.

* 1.1I am told by the Master of a Tin Mine, that after a Tin Mine had been quite drained of its Ore, by washing and vanning about 120 years after, it yielded rich Ore again, and that a good quantity of stuff being quire drained of its Ore, and laid on a heap in the Air, in thirty years it afforded Metal again. And the same Gentleman told me, that having caused the Water which washes the Earth away from the Ore, to lay down that Earth, by stopping the current of it, till its own weight made it sub∣side, that Earth being twelve years exposed to the Air, yielded a good quantity of Metal. And Relations agreeable to these I have received from another.

* 1.2It hath been observed, that Lead Ore clear∣ed of its Metal, and laid in heaps for some years yields Metal a second time. And J. Gerhard in Decade questionum p. m. 22. says, Fessula∣rum mons in Hetruria Florentiae civitati imminens, lapides Plumbarios habet, qui si excidantur brevi temporis spatio novis incrementis instaurantur. And Agricola, speaking of the growth of Mines in general, testifies the same; but I am told, that this happens not in all Mines. And tho' it be believed that the Reason why the passa∣ges into some Mines grow narrower, is to be attributed to the growth of the Metal, yet I am apt to believe, that it may be caused by the powerful expansion of some frozen Water in the Earth, that encompasses those passages; and whereas it is urged as an Argument of the growth of Metals, that Lead increases its weight by being exposed to the Air on the tops of Churches, yet I am inclined to believe, that it rather proceeds from a Cerusse formed by corro∣sive Parts, uniting with the Parts of the corro∣ded Metal, and chiefly for this Reason, viz. Because I have observed, that the Wood which lyes about that Lead abounds with an Acid Spi∣rit, capable of corroding Lead, and that when they have been long exposed to this Acid, a white Lead may be scraped off better than the common Cerusse, and this is found on that side the Lead which is next the Wood, and not on that exposed to the outward Air. And I have observed, that even Alablaster and white Mar∣ble will yield an Acid Spirit, so that we que∣stion whether Lead fixed to the feet of Statues,

may not by the help of that acquire a greater bulk, and increase of weight.

* 1.3We are told, not only by Pliny and Srabo, but Fallopius and Caessalpinus, that in the Island of Elva not far from the coast of Tuscany, Iron hath been observed to grow; and Agricola at∣tests the like to be observed in Germany. And Johan. Gerherd. tells us, that he was informed, that not far from Amberga, the Ore exposed to the Air for some time in heaps requires Metal∣line Parts.

* 1.4I have been told, that Silver grows in the form of Vegetables, and in a Voyage to Pern I find the following relation, viz. That in the Mines of Potosi it is observed, that Earth that was dug out of the Grooves and Shafts, and thrown aside, hath such a propensity to the Production of Metals, that after some years it would yield Metal.

* 1.5Tho' there is no Gold to be found on the coast of Guyny in Congo, and other Parts of Africk, where Writers mention it to be found, yet I am told, that in Hungary, the Master of that famous Gold Mine of Cremnitz hath observed, that the whole Mountain abounds with Particles of Gold, and that when they have cleared a great deal of the Soil in one Place of its Metalline Parts, they throw it into the hole again, and observe, that in a little time it will yield Gold as before; and Johan. Gerherd. gives us an In∣stance of the growth of Gold in Germany.

Postscript

Dr. Brown tells us, that he observed the pas∣sages in several Mines grown up, especially in moist places, and that the yellow Soil near Cremnitz yields some Gold.

Whether the increase of Metals depends on the influence of the Air, or some other cause, till further and more strict Observations have been made, I shall not undertake to determine; but shall only add, that a Marchasite having been shut up in Vacuo, it acquired a Vitriolate Efforescence betwixt blue and green.

Notes

• * 1.1

  About the growth of Tin.
• * 1.2

  Of the growth of Lead.
• * 1.3

  Of the growth of Iron.
• * 1.4

  Of the growth of Silver.
• * 1.5

  Of the growth of Gold.