222 Mr. Majfey on Saltpetrei 
•when a large quantity is collected it may be 
elixiviated leparately. 
Inftead of ufing pot-afh in fubftance, it may 
be dilTolved in a given quantity of water; for 
inftance, one pound of pot-afh in two pounds of 
water, and three pounds of this liquor ufed in 
the room of one pound of pot afh. 
The French miniftry are fo defirous of bring¬ 
ing pot-afh into ufe, being fenfible of the great 
advantages that mud refult from it, that they 
have ordered the Regiftres des poudres , to furnifh 
the faltpetre makers, and others who may be 
inclined to take up this bufinefs with this arti¬ 
cle, and to take care that it is of the beft qua¬ 
lity. Thus far the authors, who have fet their 
names to this little piece, who are no other than 
Mefirs. Macquer, Lavoifier, D’Arey, Cadet, and 
Sage. 
It is certain, that by percolating a fixt alkaline 
folution through a nitrous earth, duly matured\ 
the fame kind of ley may be obtained with that 
in common ufe among the faltpetre makers; 
and that a folution of pot-afh, of fome kinds, 
if not of all, may anfwer this end; but we can¬ 
not approve of ufing it in fubftance, as is here 
recommended. By diflblving it in water, and 
weighing it, we can know the exadt quantity of 
fixt alkali we employ, and may with great eafe 
increafe q~ diminifh it, as we fee occafion. 
The 
