Chap. 33 .] Amalgam cf Tin and Mercury. 213- 



*)f evaporation, remains attached to the furface of the 

 copper, and undergoing the operations of burnifhing, 

 &c. the latter is gilded* or gilt. This method of 

 gilding copper, by means of gold and qutckfilver, was 

 known to the Romans. The furface of iron cannot 

 be covered in the fame way with gold ; but the iron, 

 by being moiftened with a Iblution of blue vitriol, as in 

 the procefs for browning firelocks, and being thus co- 

 vered with a lamina of copper, becomes as fulceptible 

 of being gilded as if its whole fubftance was copper. 



It is this property which quickfilver has of uniting 

 with the precious metals, and dififolving them, which 

 has rendered it lo ferviceable in the extraction of them 

 from the earth with which they are mixed. The earth 

 or ftones, in which gold and (ilyer arc con timed, being 

 reduced to powder, are mixed with quickfilver, which 

 difiblves every particle of the precious metals without 

 contracting the lead union with the other matters - t the 

 quickfilver is then driven off by heat, and, being con- 

 denfed in the receiver, is again employed in the fame 

 procefs. The gold and filver are feparated from each 

 pther by proceffes, which will be defcribed in treating 

 of thofe metals. Since the difcovery of the American 

 gold mines, the confumption of quickfilver has been 

 much increafed. Hoffman concludes, from calcula- 

 tion, that fifty times as much gold as quickfilver is 

 annually extracted from the bowels of the earth. 



Looking glafles are covered on one fide with an 

 amalgam of tin and mercury. Tin, being beaten into 

 thin leaves, is called tin foil ; on tin foil, evenly dif- 

 pofed on a flat ftone, quickfilver is poured, and fpread 

 with a feather until its union has brightened every part 

 pf it j a plate of glafs is then cautioufly (lid upon the 

 tin foil, in fuch a manner as to fweep off the redundant 

 quickfilver which is not united to the tin j weights are 

 F 3 <!,cn 



