ar 
* * : ¥ nah at % - 
4 subterranean voyage for twelve” hours. * He stated that the 
course of the eave after proceeding some way to the southwest, 
_ became south ; and southeast by south, the remaining dist ce, 
7. 
Natural Nitre. ¢ 
The sides of the principal excavation present a few a 
ments which are interesting, principally because they furn 
large quantities of the earth from which the nitrate of potash 
is obtained. This is a circumstance very common to the caves 
of the western country. In that at Nicojack, it abounds, and 
is found covering the surfaces of fallen rocks, but in more 
abundance beneath them. ‘There are inds, one is called 
the “clay dirt,” the other the “ black dirt ; ” the last is much 
more strongly impregnated than the first. For several years 
there has been a considerable manufacture of saltpetre from 
this earth. The process is by lixiviation alld crystallization, 
and is very simple. The earth is thrown into a hopper, and 
the fluid obtained, passed through another of ashes, the alkali 
of which decomposes the earthy nitrate, and uniting with its 
acid, which contains chiefly nitrate of lime, turns it into nitrate 
of potash. The precipitated lime gives the mass a whitish co- 
lor, and the consistence of curdled milk. By allowing it to 
stand in a large trough, the precipitate, which is principally 
lime, subsides, and the superincumbent fluid, now an alkaline, 
. 
¥ 
instead of earthy nitrate, is carefully removed and boiled for 
some time in iron kettles, till it is ready to crystallize. It is 
then removed again to a large trough, in which it shoots into 
crystals, It is now called ‘rough shot-petre.” In this state 
it is sent to market, and sells usually for sixteen dollars per 
hundred weight. Sometimes it is disolved in water, reboiled 
and recrystallized, when it is called refined, and sells for twenty 
ollars per hundred. One bushel of the clay dirt yields from 
3 to 5ibs. and the black dirt 7 to 10lbs. of the rough shot- 
Petre. The same dirt, if returned to the cave, and scattered on 
the rocks, or mingled with the new earth, becomes impreg~ 
nated with the nitrate again, and in a few months may be thrown 
into the hopper, and be subjected to anew process. 
a 
ee ee ne via 
Gg ty Condi aE 
* 
