The Third Part of the Prosperity of Germany

of animals. When you have proceeded correctly, you will be able to procure for yourself a great quantity of saltpeter in a very short time, at little expense and almost no labor. The lime and ashes from which the saltpeter has been extracted can be mixed again with new lime and new ashes, and from them other vaults can be made, into which, as we have taught before, urine must be continuously poured, so that by the work of fire and air they may be animated into saltpeter. But if fresh lime and ashes are always at hand, it is better to construct vaults from them in place of the destroyed ones, and to commit those from which the salt has already been extracted to lean soil that is very moist, so that it may serve as manure for the soil, since it is impossible to separate all the salt entirely so that none of it remains.

I make this common to all, but I reserve for my friends the method by which, with the help of other waters that cost nothing and can be had in any place, a much larger quantity of saltpeter can be prepared from the said vaults in an even shorter time than by the benefit of human or animal urine. There are also certain waters which we have observed to coagulate into burning saltpeter in the space of eight days, a secret which can certainly be directed toward practice with the greatest profit in any part of the world that enjoys the presence of men.

Besides those mentioned, many other subjects offer themselves, obvious to all, from which vaults can