174 Of the Arsenic 



Now where it cannot thus, on account of the 

 reafons mentioned, arrive to its proper femi-metal- 

 lic form, but, according to the particular method 

 of operation, happens to be difperfed, it proves 

 no other than an earth, an alh, or a calx of a me- 

 tallic body, whofe metalleity may be deflroyed, 

 and again reftored. 



Thus it rifes in the operation of roafting in the 

 tall furnaces, and copper-furnaces, and fettles 

 wherefoever it finds the firfl cool and quiet retreat ; 

 in the tall furnaces, indeed, it feeks the higher! ; 

 and where the air has once taken due hold of it, it 

 is thereby diflipated to a confiderable diftance ; 

 and this, at the mines and huts, is called hut-fume \ 

 however, this, which is a pure arfenic meaJ, is 

 not to be confounded with calamy, though they 

 are not unlike in colour; but the former fettles 

 lower down, whereas the other is by the fire driven 

 much higher up. 



Arfenic alfo lodges in zink and calamy flowers, 

 in fublimates and cadmia fornacum^ though in a 

 very fmall quantity : thefe are either entirely pow- 

 dery, or in tolerably compact lumps and marTes, 

 neither firm nor hard, but tender and crumbly, 

 and eafily pulverable, though in themfelves not a 

 powder, but naturally like a baked earth. Their 

 colour is commonly a dark-grey underneath, over 

 that a whitifh grey, and the uppermoft of all a 

 yellowifli white -, their particles are generally quite 

 clear, or flakey, like a tender glimmer \ their tex- 

 ture very porous, fpongey, and loofe, confequent- 

 ly are extreamly light ; to the touch they feel 

 rough, ftubborn, and gritty, though rubbed to a 

 tolerably fine powder. 



They 



