Mr. Majfey on Saltpetre. 209 
only allowing that thele allies may fometimes be 
accidentally introduced to an earth of this kind, 
to Ihew us how a true faltpetre earth may natu¬ 
rally be formed ; and if the ftreets of the city of 
Paris, or their dunghills upon which they throw 
their wood-allies, fometimes exhibit a true falt¬ 
petre earth, it can be no great rarity. 
It can fcarcely be conceived that the Englifh 
have been ignorant of the method of making 
faltpetre in France and Germany, where this 
bufinefs has been long carried on, in the moll 
public and open manner. But that fome points 
of no fmall importance may have efcaped their 
obfervation, may eafily be credited, from the ill . 
fuccefs with which their attempts have always 
been attended ; and none more likely than their 
cuftom of waiting till the materials, they lay 
together, for this purpofe, are found fit to anfwer 
their end. 
The author of this ElTay once formed a 
nitre bed with great care and exa&nefs; and, at 
the end of a year, expeded to have reaped the 
fruits of his labour; but herein was totally difap- 
pointed. The leys, that he drew from thele earths, 
afforded him no cryllals of this fait; upon which 
they were thrown afide as ufelefs; till, a year or 
two after, he took it into his head to make a 
fecond trial of them, and now found they an- 
fwered his purpofe extremely well; which he 
could only attribute to their being more per- 
Vol, I. P fe&ly 
