'After the Salt-peter is extracted, if the Earth be laid wet in the same place again, it will be twenty Years e'er any considerable quantity grow there of it; but if the Earth be well dryed, it will come in twelve or fourteen: and if they mingle with the dryed Earth store of Pigeons-dung, and mellow Horse-dung, and then temper it with Urine (as was usual before we were supplyed with Peter from India) it will be fit to dig again in five or six Years. He that shall cast Water upon a Ground fit to dig for Peter, will only sink the Mineral deeper into the Earth; but he that throws Soap-suds on it, will quite destroy the Peter (as the Workmen have a Tradition) and it very well deserves a further Enquiry.
'That Salt-peter, and the way of drawing it out of the Earth, now in use, was a modern Invention, is generally concluded by all Authors; but whether we owe it to chance, or the sagacity of some great Wit, is as unknown, as the time when it was first discovered.
'It seems to have many Years preceeded the Invention of Gun-powder, which by Germans is ascribed to Constantine Autlitzer, or Berthold Schwertz, a Monk of Friburgh, and was, in all probability, not long discovered, when the Inventor (Polydore Virgil tells us) taught the use of Guns to the Venetians, at the Battel of Fossa Claudia, when they obtain'd that notable Victory over the Genoueses, Anno 1380. For there is mention made, both of Salt-peter and Aqua-fortis, in the Writings of Geber, a Spanish Moor, and an Alchymist; but at what time he lived, is unknown, though it be certain, some hundreds of Years before Raimund Lully, who
