BOOK VII. 243 



Mix one part of this ore, when it has been roasted, crushed, and washed, with 

 ihree parts ol some powder conipoiuid wliich melts ore, and six parts of lead. 

 Put the charye into the triangular crucible, place it in the iron hoop to which 

 the double bellows reaches, and heat hrst in a slow lire, and afterward 

 gradually in a herccr hre, till it melts and Hows hke water. If the ore does 

 not melt, add to it a httle more of these Huxes, mixed with an equal portion 

 ui yellow litharge, and stir it with a hot iron rod until it all melts. Then 

 tai<.e tiic crucible out of the hoop, shake off the button when it has cooled, 

 and when it has been cleansed, melt hrst in the scorilier and afterward in 

 the cupel, l^'mally, rub the gold which has settled in the bottom of the cupel, 

 after it has been taken out and cooled, on the touchstone, in order to find out 

 what proportion of silver it contains. Another method is to put a centum- 

 pondium (of the lesser weights) of gofd ore into the triangular crucible, and 

 add to it a drachma (of the larger weights) of glass-galls. If it resists melting, 

 add half a drachma of roasted argol, and if even then it resists, add the 

 same quantity of roasted lees of vinegar, or lees of the aqua which separates 

 gold from silver, and the button wiU settle in the bottom of the crucible. 

 Melt tliis button again in the scori&er and a third time in the cupel. 



We determine in the following way, before it is melted in the muffle 

 furnace, whether pyrites contains gold in it or not : if, after being three times 

 roasted and three times quenched in sharp vinegar, it has not broken nor 

 changed its colour, there is gold in it. The vinegar by which it is quenched 

 should be mixed with salt that is put in it, and frequently stirred and dissolved 

 for three days. Nor is pyrites devoid of gold, when, after being roasted and 

 then rubbed on the touchstone, it colours the touchstone in the same way that 

 it coloured it when rubbed ui its crude state. Nor is gold lacking in that, 

 whose concentrates from washing, when heated in the fire, easily melt, giving 

 forth little smeh and remaining bright ; such concentrates are heated in the 

 fire in a hollowed piece of charcoal covered over with another charcoal. 



We also assay gold ore without fire, but more often its sand or the con- 

 centrates which have been made by washing, or the dust gathered up by 

 some other means. A httle of it is shghtly moistened with water and heated 

 until it begins to exhale an odour, and then to one portion of ore are placed 

 two portions of quicksilver^* in a wooden dish as deep as a basin. They are 

 mixed together vnth a httle brine, and are then ground with a wooden pestle 

 for the space of two hours, imtil the mixture becomes of the thickness of dough, 

 and the quicksilver can no longer be distinguished from the concentrates 

 made by the washing, nor the concentrates from the quicksilver. Warm, or 

 at least tepid, water is poured into the dish and the material is washed until 

 the water runs out clear. Afterward cold water is poured into the same dish, 

 and soon the quicksilver, which has absorbed aU the gold, runs together 

 into a separate place away from the rest of the concentrates made by 

 washing. The quicksilver is afterward separated from the gold by means 

 of a pot covered with soft leather, or with canvas made of woven 

 threads of cotton ; the amalgam is poured into the middle of the cloth or 



'"The amalgamation of gold ores is fully discussed in note 12, p. 297. 



