about the Year 1333, published some of his Books, wherein he treats of Salt-peter and Aqua-fortis. It is no ill conjecture of Maierus, that the foresaid Monk, being a skilful Alchymist, had a design to draw a higher Spirit from Peter than the common Aqua-fortis; and that he might better open the Body of Peter, he ground it with Sulphur, and Charcoal, by which Composure he soon became the Inventor of Gun-powder.
The Manner of making
SALT-PETER.
IN the first place you must be provided of eight or ten Tubs, so large, that they may be able to contain about ten Barrows full of Earth each of them. These Tubs must be all open at the top; but in the bottom of every one of them, you must make a hole near to that side you intend to place outermost, which hole you must fit very well with a Tap and Spigot on the outside downward. On the inside of the Tub, near the Tap-hole, you must carefully place a large wad of straw, and upon that a short piece of board, which is all to keep the earth from stopping up the Tap-hole. When you have placed your Tubs on their stands, at such a distance one from the other, that you may come with ease between them, then fill them up with such Peter-earth as you have chosen for your work, leaving only void about a span's breadth between the earth and the edge of the Tub; then lay on the top of
