184 Of the Arse nic 



darach\ yet, under a proper encheirefis, or treat- 

 ment, it often turns out as beautifully tranfparent 

 as any ruby, only its rednefs inclines more to an 

 orange, whence it is ibmetimes called fulphur-ruby *. 

 If it degenerates to a brown-red, it has either (tood 

 too long in the fire, or got fome foreign admix- 

 ture along with it, either by accident, or with de- 

 sign, as may be feen from the lapis de trihus, where 

 the metallic, antimonial portion muft needs fully 

 it; yet this brown-red tint is often no impediment 

 to its tranfparency, when held to the light in thin 

 pieces. 



It is brought over, like fulphur, by a dift illa- 

 tion, from retorts into receivers, rather than by a 

 fublimation, and this is the very reafon of its opa- 

 city ; for, if you force off only a little of it again 

 in a glafs body by a ftrong fand-heat, fo as to melt 

 in the neck, it runs down in clear drops, appearing 

 like a red glafs. It is certain, arfenic greatly af- 

 fects the fulphur found here, and muft therefore 

 impart the colour ; and no way has hitherto been 

 hit on, I will not fay, of feparating it entirely, 

 which is impofilble, but of feparating even the 

 g reateft part of it -, and yet fome of it muft go off, 

 partly of itfelf, by the fofteft degree of fire, for 

 fulphur mounts eafier than arfenic, though this fuc- 

 ceeds not with the yellow cryftalline arfenic \ partly 

 through the addition of a feparating medium, or 

 matter, which fulphur more affects, for inftance, 

 quickfilver: when the arfenic happens to rife white 

 icparately, and fettle higher up, the quickfilver, 

 which cannot rife fo high, fettling iower down, as 

 a grey fublimatc along with the fulphur, 



More- 



v Rufcinws. fulplmrif., Ic?m. Tuhinua aKaiici. 



