rjz Of the Arsenic 



a real ftone, or ore, and put to the like ufe ; tho* 

 the fublimed neither fhews like, nor contains any 

 thing referable to the nature of a ftone. And 

 here the difference between native and factitious 

 fly ftone is carefully to be obferved, which you 

 have, when the experiments exhibited therewith 

 happen not to coincide ; in regard the native, on 

 the fcore of its incidental admixture, proves, at 

 times, to be fomething different. 



In a powdery form arfenic is of iiich a degree of 

 tendernefs, or fubtlety, as therein not to be ex- 

 ceeded by the moft impalpable powders ; and of 

 different colours, as, black, yeliowifh, grey, and 

 white ; yet, moft frequently, of the white grey. 

 When it appears white, like a beautiful meal, or 

 flour, which happens to it in the fining, it proves 

 right pure •, and by how much the whiter, fo 

 much the lefs is it fullied with foreign admixture ; 

 if grey, it contains fomething of a footy, inflam- 

 mable, nay, a metallic earth ; as appears from the 

 grey poifon-meal, often collected from the vents of 

 the tall furnace ', with fome lead, and a little filver 

 amongft it ; if black, it contains ftill more of fuch 

 a coaly earth, to which colour it never arrives in 

 a large and open, but only in a clofe, fmall, and 

 fudden or brifk fire ; if yeliowifh, which colour 

 commonly runs to an orange, it has then fome ful- 

 phur along with it. 



Thefe various incidental colours proceed chiefly 

 from the incidental ores along with it, as well in 

 regard to thefe ores xhemfelves, as their various 

 admixtures, which may be either accidental, or 

 procured by defign : where, for inftance, the ful- 

 phur, when lodged in an ore, and rifing toge- 

 ther with the ar-fenic, muft needs make it of an 



orange 





