448 
NITRE. 
several villages on the banks of the Nile, where the 
inhabitants are chiefly employed in making salt- 
petre.” 
The Americans collect a considerable quantity of 
the saltpetre, with which they make their gunpow- 
der, from caverns in the mountainous parts of Ken- 
tucky. These grottos are met with on the sides of 
calcareous hills, and the earth which they contain 
is very full of nitre. 
Besides the places which we have enumerated, 
nitre is found in Persia, in India, in Arabia ; espe- 
cially in a valley between mount Sinai and Suez. 
In Africa, to the south of the cape of Good Hope, 
on the sandy Karroo desert; and in South America, 
where the dry pastures near Lima are covered with 
a nitrous efflorescence. 
The three circumstances mentioned by naturalists 
as principally conducive to the formation of nitre 
are these : first, the presence of chalk, or some cal- 
careous substance ; in this manner, according to 
Fourcroy, the nitre is formed which appears on the 
surface of old walls covered with plaster, and from 
this circumstance great quantities of nitre are usually 
found in the remains of old buildings. We have 
already noticed, that in nature this substance is 
chiefly found in calcareous situations ; and we may 
add, as a further confirmation, that the Duke de la 
Rochefoucault has obtained it in the proportion of 
an ounce to a pound from the chalk of Roche- 
Guyon. 
