± 1 $ 
MINERALOGY. 
likewife into oftoedral criftals of a metallic 
^pearance, whofe fpecific gravity is 8,308^ 
i. The calx of atfenic, which always, on ac-^ 
count of its volatility, mull be got as a 
fublimation^ is white, and eafily melts to 
a giafs, whofe fpecific gravity is 5,oobi 
When fulphur is blehded in thi^ calx, it be- 
comes of a yellow, orange, or red colour 5 
and according to the degrees of colour is 
called Orpiment or yellow arfenic, Sanda- 
rach. Realgar or red arfenic, and alfo Ru^ 
hinus At fenki, 
f. This calx and glafs are difibluble in water,’ 
and in all liquids ; though not in all with 
the fame facility. In this circumftance ar- 
fenic refembles the fairs, for which reafon 
it alfo might be ranked in that clafs. Sedt^ 
cxix. 
g. The regulus of arfenic difiblveS in fpirit of 
nitre; but as it is very difficult to have it 
perfedly free from other metals, it is yet 
very little examined in various metiftrua. 
h. It is poifonous, efpecially in form of a 
pure calx or glafs : But probably it is lefs 
dangerous when mixed with fulphur, fmce 
it is proved by experience, that the men at 
mineral works are not fo much affedled by 
the fmoak of this mixture, as by the fm oak 
of lead ; and that ' ibme certain nations 
make ufe of the red arfenic in fmall dofes 
as a medicine. 
/. It unites with all metak^ and is likervife 
much ufed by nature itfelf to diiTolve, or, 
as we term it, to mineralife the metals, to 
which its volatility, and diffoliibility in 
water^ miifi: greatly contribute. It is like- 
Wile moft generally mixed with fulphur. 
' L It 
