20« 



REFINING OF Ll-A£». 



Procefs for re- 

 fining lead. 

 Cupels made of 

 afbes. 



Early obferva- 

 tion that the 

 oxide of lead 

 penetrates che- 

 mical vefTelsy 

 while filver, if 

 prefent, rexnains 

 aoetallic. 



X. 



A Memoir on the refining of Lead in the large Way, Containing 

 fame Re/le6Hons on the Inconvenienciesrefulting from Cupels 

 made of AJkes ; with a nexv and ceconomical Method of cort" 

 firuSiing tkofe Cupels, % Citizen Duhamel.* 



ALVERY one knows that in order to efFe€l the feparation of 

 filver from lead, a procefs called refining or cupellatiori is 

 made ufe of, which is efFeded in a bafon called a cupel ; and 

 it is like wife known that this bafon is formed of the afties or 

 incinerated remains of animal or vegetable fubftances, after 

 depriving them by wafliing of what faline matter they may 

 contain. 



The great quantity of wood afhes required for making thefe 

 cupels, and the difficulty of procuring it, have long ago in- 

 duced me to feek for a more fimple and lefs expenfive means 

 of forming thefe velTels. 



The es^rly chemifis having obferved that lead becomes ox- 

 ided and converted into what is called litharge, when it is ex- 



* This memoir is tranflated from the Memoirs of the French 

 National Inftltute, Vol. III. at the rcqueft of a conefpondent. 



pofed 



