DESCRIPTION OF A NEW PROCESS OF REFINING. 73 



fected, he decants the nitrate of filver, and wafhes the gold 

 until the water from the warnings will no longer decompofe 

 muriate of foda. 



The gold is not yet freed from all alloy, he therefore adds to 

 it fome nitric acid of the fame ftrength, and brings the mixture 

 to ebullition, he then decants the nitrate of filver, wafhes the 

 gold, and adding to it nitric acid of 40°, he replaces the veflfel 

 on the fand-bath. When it has been fufficiently boiled, he 

 feparates the gold from the acid, and wafhes it with great care, 

 dries it by a gentle heat, melts it and forms it into ingots, the 

 purity of which, as I have faid above, does not generally ex- 

 ceed .998, and is even often below .995, which is the limit 

 fixed by law. In the latter cafe, the refiner is obliged to pro- 

 ceed to a new quartation and a new parting ; his expencesare 

 then doubled and may be even trebled, if in the fecond ope- 

 ration, he does not furmount the inconveniencies which caufed 

 the firft to fail. 



This is the department of refining which I have brought Improved pro- 

 neareft to perfection, as will be feen in the defcription of my 

 procefs. 



I mix, as in the old operation, the ingots of commerce, in Quartation and 

 fuch a manner, that when they are melted together, the gold ^eTunlredS^ 

 in the alloy fhall bear proportion of one to four parts of filver. part of nitre. 

 I melt the ingots thus prepared, and when the matter is very 

 liquid, I project thereon about 200 grammes of nitrate of potafli 

 for every 20 kilogrammes of the alloy. This fmall quantity 

 O.f faltpetre is fufficient, as I have remarked, to oxidate the 

 tin, which is always combined in greater or lefs quantity with 

 the ingots of commerce. It is effential to feparate this tin, 

 becaufe in the operation of parting it becomes oxidated and 

 mixed with the gold, and at the time of that metal being 

 melted, it may perhaps be partly reduced and render it harfh 

 and of lefs purity. 



When the whole is in perfect fufion, I immediately granu- Granulation, 

 late and diftribute it, as in the former method, into pots. 

 There I add to it the fame quantity of nitrid acid of the fame 

 ftrength, following exactly the fame manipulations as thofe I Parting as 

 have defcribed above : in one word I obferve the antient pro- 

 cefs to the moment, when the gold, after having been well 

 warned, is put into the crucible : I collect the gold in this ftate The parted gold 



into as fmall a veflel as poffible, and add to it as much fu!phu-?^ /ft/ . wi '* 

 '' * ™ Julpbuncacidi 



ric 



