294 Dr. WitTHerine’s Experiments and Obfervations 
Profeflor Bercman, in his Sciagraphia Regni Mineralis, 
publithed laft year at Leipfic, conjectures (§ 58.), with his 
ufual fagacity, *¢ Terra ponderofa nitrata forte alicubi hativa 
“\oocurrit,, a, neming tamen adhuc inventa, quod etiam valet 
“¢ de aerata.” 
- Iwas much delighted by ae dcreangn of a ieee eh 
promifes to be of very confiderable utility in chemical inquiries, 
and more fo when I found it to be a native of this country ; 
for itis not improbable, that it may be met with in many other 
mines, befides that at Alfton-Moor. 
Mr. Bourton, with his ufual benevolence, prefented me 
with a piece of it, part of which accompanies this paper, for 
the infpe@tiion of the Members of the Royal Society. 
\ 
_ 
More obvious Properties. 
Its general appearance is not much unlike that of a lump of 
alum; but, upon clofer infpe@ion, it {eems to, be compofed of, 
flender {piculz in clofe contaét, but more or lefs diverging. .. It 
may be cut with,a knife. , Its pari Bray is from 4, 300: 
to.44338. | (| : dp 
vor 
It effervefces idle panes toa pees ey! the. blow-pipes 
though not wery readily, Placed ina covered crucible, ina hot 
parlour fire, it loft its tranfparency. | Pe 
‘ 
After expofure to a moderate heat: in a melting furnace, it 
adhered, to, the crucible, and exhibited figns of fufion ; but 
was ‘not) diminifhed in weight, did not feel cauftic when ap- 
plied)to the tengue, nor had it loft its property of effarvelean 
with acids, 
* ake 
