NITRE. 447 
nated with it that it bursts in many places, and 
forms white efflorescences and crusts resembling ca- 
nary sugar, mixed with gypsum on its surface : 
when these efflorescences are scraped off, more is 
generated in the space of about a month, but more 
quickly in summer than in winter. The nearly 
horizontal calcareous beds, whose edges appear in 
the interior of the Pulo, vary in thickness from half 
an inch to six feet. The stone of which they are 
composed is very compact, and abounds in marine 
bodies converted into calcareous spar. It is the 
thickest of these layers which are dug into the form 
of grottos, and the openings into these are said to 
be much smaller than the interior. Fortis tells us, 
that from those grottos where the entrance is so 
small as hardly to admit a child with a lanthorn in 
his hand, they collect the finest saltpetre. 
Van Egmont assures us, that nitre is not only 
found in all those parts of Egypt which are washed 
by the Nile, but also in several other places which 
are not influenced by the waters of that river. The 
earth containing this salt is sometimes known by its 
whitish surface, but it is often to be detected only 
b y its saltish taste. The saltpetre used all over 
Egypt is extracted from this earth, and the places 
where it is found are considered as mines belonging 
to the Grand Signor. They are worked on his ac- 
count, and therefore any person detected in em- 
bezzling the salt is sure to be severely punished. 
“ In going to Cairo,” says Van Egmont, “ there are 
