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 higher parts in the Country about it. And for the River Nile, there must needs be less scruple concerning it, if we call to mind that once in a year, it sweeps with an impetuous overflow the burnt and barren Desarts of Africa under the Torrid Zone; where, by the relation of Travellers, those Sands are visibly full of Nitre, and those few Springs and Wells that are to be found there, are by that reason so bitter, that the Moors and their Camels are forced to make a hard shift with them in their long journeys.

'But when he comes to describe the Aphronitrum, he comes more home, both to the name and nature of our Salt-peter, in these words, Proxima ætas Medicorum tradidit, Aphronitrum in Asia Colligi in speluncis & molibus distillans, dein sole siccant. And Scaliger speaking of Salt-peter, says, Eft quædam Nitri species inhærens Rupibus, in quibus insolatur, ac propterea Salpetra dicitur. And, I my self, for my own satisfaction in the point, have drawn very good Rock-peter out of those Stiriæ, which are usually found hanging like Icycles in arched Cellars and Vaults; and have been told, that a Physician in Shropshire did perform great Cures by vertue of Sal-prunellæ, which he made only of Flower of Brimstone and those Stiriæ.

'But to steer more directly upon our immediate subject Salt-peter; tho' be likely, that the Air is every where full of a volatile kind of Nitre, which is frequently to be seen coagulated into fine white Salt, like Flower of Wheat (but by the very taste may be easily known to be Peter) sticking to the sides of Plaistered-walls, and in Brick-walls to the Mortar between the Bricks, (in dry Rh