198 Mr. Majjey on Saltpetre. 
gardens, and other putrid and putrefiable matters, 
to which he added wood-afhes ; and by this 
means, in a courfe of time, obtained, not a mere 
nitrous , but a true Jaltpetre earth, that afforded 
him the cryftals of this fait, upon fimple elix- 
iviation and evaporation. 
It does not appear, that this celebrated Chemid 
had the lead idea, that thefe putrid matters were 
of any other ufe, than to draw the nitre, as he 
called it, from the air, in which the fixt fait of the 
wood-afhes might pofhbly afTift. In this date 
of ignorance, his followers, for the mod part, 
feem dill to remain ; having adopted, as far as 
we know, no other dodtrine; and having varied 
from this pradtice, only in difpofing thefe mate¬ 
rials above ground, indead of below, in order to 
expofe them the more to this element. 
It mud not be paffed over, that Glauber fome- 
times filled large wooden veffels with all kinds 
of dung, and, when they had completed their 
putrefadtion, he percolated a drong alkaline fo- 
lution, through them, drawn from lime and 
wood-afhes, which afforded him a ley of the fame 
kind and quality, with that drawn from the earth 
of his other nitre beds. 
A late writer has told us, that there are but 
three ways of obtaining nitrous earths. In walls , 
that is, by raifing clay walls, and expofing them 
to the air—In pits j by throwing all forts of 
' " putrid 
