The Third Part of the Prosperity of Germany

to establish, as was handed down above for knowing the quantity of saltpeter contained in them, does not succeed at all; because during calcination the saltpeter becomes volatile and departs into the air in its greatest part. Much less is it permitted to extract it with water from crude and non-calcined stones, for such stones exhibit no saltpeter at all unless they have been placed in the more moist air for the space of about half a year, whereby they fall into pieces by themselves. For when constituted in such a way, they most easily impart their saltiness to water poured over them, and thus exhibit saltpeter in abundance. And this is a most certain sign of this matter: namely, that if such stones lie hidden in some drier place, to which rain cannot reach, and we very often sprinkle them with common water, they are changed into powder or dust. If it happens otherwise, it is signified that very little saltpeter is found in them, and thus the labor is pronounced fruitless. But those that soften and collapse in the space of 6 or 8 months promise the greatest fruits of labor, namely a huge quantity of the desired salt. A hundredweight of such collapsed stones will easily give 10 lbs of saltpeter, more or less depending on the condition of the stone. The extraction of the lye is performed with common water, in a similar way to how lye is otherwise extracted from the earth that is dug up in animal stables. This method of extracting, coagulating, and perfecting saltpeter has been described clearly and sufficiently perfectly.