MINERALOGY. 22^ 



Iikewife into octoedral criftals of a metallic 

 appearance, whole fpecific gravity is 8,308* 



e. The calx of arfenic, which always, on ac- 

 count of its volatility, mull be got as a 

 fublimation, is white, and eafily melts to 

 a glafs, whofe fpecific gravity is 5,000. 

 When fulphur is blended in this calx, it be- 

 comes cfa yellow, orange, cr red colour; 

 and according to the degrees of colour is 

 called Orpiment or yellow arfenic, Sanda- 

 Fach, Realgar or red arfenic, and alio Rm- 

 binus Arfenic 7. 



/. This calx and glafs are difToluble in water, 

 and in all liquids \ though not in all with 

 the fame facility. In this circumftance ar- 

 fenic refembles the falts, for which reafon 

 it alfo might be ranked in that clafs. SecSt. 

 cxix. 



g. The regulus of arfenic diflblves in fpirit of 

 nitre ; but as it is very difficult to have it 

 perfectly frtc from other metals, it is yet 

 very little examined in various menftrua. 



b. It is poifonous, efpecially in form of a 

 pure calx or glafs : But probably it is lefs 

 dangerous when mixed with fulphur, fince 

 it is proved by experience, that the men at 

 mineral works are not fo much affected by 

 the fmoak of this mixture, as by thefmoak 

 of lead i and that fpme certain nations 

 make uie of the red arfenic in fmall dofes 

 as a medicine. 



t. It unites with ?.1\ metals, and is Iikewife 

 much ufed by nature itfelf to diflblve, or, 

 as we term it, to mineraEffi the metals, to 

 which its volatility, and diliblubilit'y in 

 water, r e. 1 1 is like- 



wife moil gc : illy n frith fulphur. 



Q^ k. Is 



