Arfenic 'not eafily Soluble . 129 
Crydal, with a brownifh Hue ; but, after 
a few Days, it becomes opake, acquires a 
milky gloffy Whitenefs, and looks like 
white Enamel. When reduced to Powder it 
appears extremely white, and is frequently 
fold in the Shops by the Name of Ratjbane. 
Notwithdanding this Suhdance certainly 
abounds with Salts, as its crydaline Ap« 
- pearance and its caudic and corrofive Qua¬ 
lities fufliciently evince, they are fo fheathed 
or locked up (as the Chemids exprefs 
themfelves) in their Sulphurs, that they 
'are very difficult to be feparated and brought 
to View. Dr. Mead fays. White Arfenic 
• is entirely foluhle, if one Part of it be 
fufficiently boiled in fifteen Parts of di¬ 
ddled or Rain Water *, which (with what 
I fliall mention prefently) gives me Reafon 
to imagine there may be a Difference in 
Arfenic, from perhaps a different Way of 
preparing it; for notwithdanding I have 
boiled fmall Quantities, for a long while 
together, in much larger Proportions of 
Water, to the Confumption of the greateft 
Part, I always found mod of the Arfenic 
at the Bottom undiffolved.. Nor amongft 
the Chemids could 1 ever obtain any ^of 
its Salts, which I was greatly defirous to 
examine by the Microfcope 
Some- 
* Mead on Poifons, 3d Edit. pag. 217. 
t A Phyfician of great Eminence gave me once a fmall 
femi-tranfparent brown Mats, fact oat in Angles, which. 
Vql. II, R a Cheinift 
