Extracts of two Letters, written by the Ingenious Mr. Adam Martindale to the Publisher from Rotherton in Cheshire, Novemb. 12. and Nov. 26. 1670. concerning the Discovery of a Rock of Natural Salt in that Country.

A GentlemanA gentleman of good account and reputation assures me, that in our Country there is lately found out a great rarity, viz. a Rock of Natural Salt, from which issues a vigorous sharp Brine, beyond any of the Springs made use(2016) of in our Salt-works; and this not nigh any River or great brook, as all our Salt-springs in this Country are, I should scarce have adventur'd to write this to you, had I not believed, that this discovery might perhaps prove usefull towards the filling up of some blank corner of a Page in the History of Nature. However I am perswaded, that such Ingenuity, as possesseth the R. Society, cannot but pardon my boldness, arising from a zeal to serve such Benefactors to Humane nature. And if you desire to know any more particulars concerning this matter, a Letter of yours directed  *  *  *  shall command me to view the place, and there to inquire after the circumsyances, and communicate them to you, &c.

This being so acceptable an offer, the Author of the Letter was desired accordingly, to give himself the trouble of viewing the place himself: Which desire he not only hath very obligingly complied with, but also imparted what he learned in that view, as follows;

I am just now return'd from visiting and viewing the Salt- work, and find things according to my Friends Relation: Only whereas I understood him, that no running water came near it, I now perceive, that he spoke of none that was considerable, or none that might annoy it. For there runs near it (at least in the Winter season) a small rindle (or gutter rather;) but it is wholly free from all danger of overflowing; which threatens all other Salt-pits in this County, every great shower, through the vicinity of Rivers.

The Rock of Salt, by the relation of the Work-men, is between 33, and 34. yards distant from the Surface of the Earth; about 30 whereof are already digged; and they hope to be at the Flagg, which covers the Salt-rock, about three weeks hence. I doubt, it will be several months, before I can accommodate you with a parcel of it; that which the auger brought up, being long since disposed of, and the work-men not daring to remove the Flagg, till the Frame be finish't and well setled for the securing of the work from the circumjacent earth. The Overseer hath promised to furnish me with a(2017) piece of the Rock for your use; as also to signifie to me the time, when they intend to uncover it; that, if possible, we may make some such Experiments, as you have intimated. That parcel of Natural Salt, which the instrument brought up, divers that saw it assure me, was as hard as Allom, and as pure; and when pulverized, became an Excellent, fine and sharp Salt. The first discoverer of it was one John Jackson of Halton, about Lady-day last, as he was searching for Coals on the behalf of the Lord of the Soil, William Marbury of Marbury Esquire. This is all I can at present serve you in; only I am consulting diligent and experienced persons concerning the practise of the Agriculture of this Country, and hope ere long to give you such an account as I can; though I cannot hope to discover any thing worth the notice of that truly Royal Society. It will be enough to satisfie my ambition, if I may but be continued in your thoughts as a Well-wisher to such Noble persons and designs. In confidence whereof I subscribe, &c.