Gold. 233 



lution, if calcareous, in nitrous acid, which 

 will diflblve the matrix, and leave the gold 

 at bottom untouched, or if gypfeous or fili- 

 ceous by digefting them in aqua regia, 

 as long as any metallic fubftance is taken up, 

 which the folution of tin, or phlogifticated 

 alkali will indicate, and then precipitating the 

 gold by a folution of vitriol of iron. 



6. Or by Amalgamation, with -,'- of their 

 w r eight of mercury, in a copper or iron veflel, 

 in which the mercury and pulverifed fand are 

 put together with water, which is kept con- 

 ftantly boiling, and the mercury after fome 

 time, abforbes the gold, from which it is fe- 

 perated by diftillation, Le e w. Com. 194. 

 or by heating the fand red hot, and quench- 

 ing it in water 3 or 4 times, then melting 

 it with twice its weight of litharge, then 

 reviving the litharge by charcoal, into lead, 

 which then feparates from the fand, and 

 laftly, freeing the gold from the lead by cup- 

 pellation. Lewisy Ibid. 



7. Native gold is feldom found perfectly 

 pure, being generaly alloyed with filver, or 

 copper, or iron, or all three. If fuch alloy 

 be diffolved in aqua regia, the filver will re- 

 main at the bottom in the form of horn filver, 

 If then a iblutk)n of vitriol of iron be drop- 

 ped into the folution of gold, this latter will 



be 



