246 BOOK VII. 



in the middle of it. As soon as the borax crackles and the lead-stone melts, 

 which soon occurs, remove the coal from the crucible, and the lead wiU settle 

 to the bottom of it ; weigh it out, and take account of that portion of it 

 which the fire has consumed. If you also wish to know what portion of silver 

 is contained in the lead, melt the lead in the cupel until all of it exhales. 



Another way is to roast the lead ore, of whatsoever quaUty it be, wash 

 it, and put into the crucible one centumpondium of the concentrates, together 

 with three centumpondia of the powdei"ed compound which melts ore, mixed 

 together, and place it in the iron hoop that it may melt ; when it has cooled, 

 cleanse it of its slag, and complete the test as I have already said. Another way is 

 to take two ««aae of prepared ore, five drachmae ol roasted copper, one uncia of 

 glass, or glass-galls reduced to powder, a semi-uncia of salt, and mix them. Put 

 the mixture into the triangular crucible, and heat it over a gentle fire to 

 prevent it from breaking ; when the mixture has melted, blow the fire 

 vigorously with the bellows ; then take the crucible off the Hve coals and 

 let it cool in the open air ; do not pour water on it, lest the lead button being 

 acted upon by the excessive cold should become mixed with the slag, and the 

 assay in this way be erroneous. When the crucible has cooled, you will find 

 in the bottom of it the lead button. Another way is to take two unciae of 

 ore, a semi-uncia of htharge, two drachmae of Venetian glass and a semi-uncia 

 of saltpetre. If there is difficulty in melting the ore, add to it iron filings, 

 which, since they increase the heat, easily separate the waste from lead and 

 other metals. By the last way, lead ore properly prepared is placed in the 

 crucible, and there is added to it only the sand made from stones which easily 

 melt, or iron fihngs, and then the assay is completed as formerly. 



You can assay tin ore by the foUowing method. First roast it, then 

 crush, and afterward wash it ; the concentrates are again roasted, crushed, 

 and washed. Mix one and a half centumpondia of this with one centum- 

 pondium of the chrysocolla which they call borax ; from the mixture, 

 when it has been moistened with water, make a lump. Afterwards, 

 perforate a large round piece of charcoal, making this opening a palm deep, 

 three digits wide on the upper side and narrower on the lower side ; when 

 the charcoal is put in its place the latter should be on the bottom and the 

 former uppermost. Let it be placed in a crucible, and let glowing coal be 

 put round it on all sides ; when the perforated piece of coal begins to burn, 

 the lump is placed in the upper part of the opening, and it is covered with a 

 wide piece of glowing coal, and after many pieces of coal have been put round 

 it, a hot fire is blown up with the bellows, until all the tin has run out 

 of the lower opening of the charcoal into the crucible. Another way is to 

 take a large piece of charcoal, hollow it out, and smear it with lute, that the 

 ore may not leap out when white hot. Next, make a small hole through the 

 middle of it, then fill up the large opening with small charcoal, and put the 

 ore upon this ; put fire in the small hole and blow the fire with the nozzle of 

 a hand bellows ; place the piece of charcoal in a small crucible, smeared 

 with lute, in which, when the melting is finished, you will find a button 

 of tin. 



