Chap. 19.3 Regtilus of Arjenk. \i\ 



is a calx of arfenic, by heating it with one-tenth of its 

 weight of charcoal, or of any unctuous matter. The 

 mixture is put into a tall veffel, and a gradual and 

 gentle heat applied to the lower part of it, while the; 

 upper is kept cool by the air. The arfenic, when 

 nearly ret hot, parts with its oxygen, and rifes to the 

 upper part of the vefiel, where it is condenfed in the 

 metallic form. To give it, however, its perfect me- 

 tallic fplendour and opacity, the fublimation mi)ft be 

 repeated. 



The regulus of arfenic is of a bright yellowim white 

 colour, very ponderous and friable, and fubject to 

 tarnifh'and become black on expofure to air. If heat 

 is applied to the regulus in contact with air, it is 

 volatilized before it melts, and is at the fame time 

 imperfectly calcined. The fumes are dangerous, and 

 have a ftrong and offenlive fmell, refembljng that o,f 

 garlic. 



The white calx of arfenic is fo far in a faline (late 

 as to be foluble in eighty times its weight of cold, or 

 fifteen times that of boiling water. When diftilled 

 with the nitrous acid, it decompofes that fluid by de- 

 priving it of part of its oxygen. The arfenic, by this 

 addition of oxygen, is reduced to the ftate of an acid 

 lefs volatile than either the regulus or calx, but retain- 

 ing the form of a white concrete fubftance. The oxy- 

 genated muriatic gas likewife reduces arfenic to the 

 Jtate of an acid. 



Arfenic readily melts with other fubftances fo as 

 to form glafs, and even promotes their fufion. At 

 firft it always renders the glafs milky, but by a con- 

 tinuation of heat the arfenic evaporates, and the glafs 

 becomes quite tranfparent. It is an ingredient in the 

 white enamel dial-platts j and it forms thofe white 

 Spirals which are common in the flalks of wine- 

 gla/Tes, 



Sulphur 



