1S6 Of the Arsenic 



firft, native, reguline, femi-metallic flate, fo as to 

 prove more beaiui f Y«] than it originally was ; as thus : 

 take finely pounded white cryftalline arfenic, and 

 mix it, either with the black flux, or with fah- 

 petre and tartar, in the ufual manner of making 

 regulus of antimony, and letting it duly run in the 

 wind-furnace, you then procure a compleat, beau- 

 tiful regulus of arfenic \ yet, little or none at all,Jif 

 either you let the crucible ftand too long, or give 

 too brifk a fire : but if you mifcarry in this, take 

 iron in aid, and proceed in the ufual method of 

 preparing the martial regulus of antimony, and the 

 arfenic will be fufficiently fixed. Only, by this laft 

 method it proves impure, from having fwallowed 

 up a-great deal of iron, as appears from the analy- 

 fis; it is, however, the greateft part arfenic, which 

 may eafily again be made to fume from it. It ge- 

 nerally appears like a fpeife 9 with which it alfo 

 greatly agrees, and, upon adding fome copper to 

 it, it turns of a reddiih caft, nay, becomes the very 

 mixtion of the above defcribed kupffer-leg, nay, 

 even kupffer-nkkel. 



I fhall further only fuggeft, that hut-fume cor- 

 rodes the very window-panes of the huts, turning 

 them of a milk-colour, and rendering them dim and 

 opake, and thus it finds, as it were, a magnet in 

 them. Again, that with lead it vitrifies exceed- 

 ingly eafy ; and the glafs thus procured proves ex- 

 tremely ufeful in incotlions, as it forces ftubborn 

 and unkindly ores, with this circumflance attend- 

 ing, that this highefl of combinations, which is even 

 performable in clofe vefTels, is an uncommon and 

 almoft incredible inftance in the bufinefs of vitrifi- 

 cation : and this, in my opinion, affords, if not the 

 principal, yet not the leaft confiderable reafon, why 

 miffpickeU when its arfenic^ in the operation of 



crude- 



