258 
The crystals are more dull 
en the superficies, and have 
an opaline lustre. 
The longitudinal fracture 
is laminar, the transverse is 
unequal and vitreous. 
Nitric acid takes up 50 in 
the 100. 
Sp. gr. 2.3. 
With phosphoric salts, in 
just proportions, before the 
a milky, 
With soda it melts imper- 
fectly into an opaque enamel, 
Account of some new Vesuvien Minerals. 
The crystals are always 
splendent. 
The fracture is vitreous 
conchoidal, and a little splen- 
dent in all directions. 
Nitric acid takes up the 
smallest possible quantity. 
re 3s 
In the same salts yields a 
pearl of transparent glass, 
which becomes opaline om 
cooling. 
into a glass with- 
out colour. 
Finally, the chemical composition is totally different. It 
is known from the mezo Haity, because its natural joints 
haracters. sp. gr. of Davina is 2.03; that 
of pseudo-Nepheline is 2.18. fore the blowpipe, the latter 
melts with extreme difficu ty, the former very easil itric 
a = 
