Mr. Mafley on Saltpetre. 195 
where found, but in fuch earths, as are impreg¬ 
nated with the juices of vegetables and animals, 
and where thefe juices have Juftained the whole 
putrefactive procejs. But having affigned no reafon 
for it, he feems to have been little regarded. 
The obfervation is, however, certainly a very 
juft one, and had it been duly attended to, 
we imagine, might have prevented moft of thofe 
difappointments, which our countrymen have 
met with, in their attempts to make faltpetre; 
as we have reafon to think, they have been 
chiefly owing to their premature ufe of thefe 
earths. 
The common foil, in fome parts of India, is 
naturally nitrous, owing plainly to the fifh and 
flime that is left upon it by the inundations of 
the river Ganges, which foon corrupt in that hot 
climate, and fill the earth with putrid juices; 
and here putrefaction, being carried on with the 
created rapidity, is, of courfe, foon completed, 
and the natives are, in a fbort time, furnifhed 
with a nitrous earth perfectly matured. But it 
mull not be forgotten, that their ftrongeft earths 
are found at the bottoms of their tanks or fhallow 
ponds of water, which, in this country, are often 
of great extent, where, the water being evaporated 
by the heat of the fun, large quantities of fifh 
are left to corrupt, which furnifh a mud of the 
ftrongeft nitrous quality. 
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