NITRE. 
451 
the bottoms of the vessels, while long regular cry- 
stals appear in the middle, which are called nitre in 
sticks , and in this state it is used in commerce. 
Since the invention of gunpowder the demand 
for nitre has exceedingly increased, this salt being 
the principal ingredient in that destructive com- 
position. 
2 g 2 
