specific Gravity , and comparative JVear of Gold. 65 
As soon as the fine metals are in fusion, the manganese floats 
upon the surface of the lead, is gradually vitrified, and is ab- 
sorbed by the cupel, which becomes tinged with a dark blackish- 
brown colour throughout the whole of its substance ; and it must 
be observed, that this tinge is very different from that afforded 
by any other metal with which gold may be alloyed. 
The cupels on which the manganese has been separated from 
gold by lead, are corroded in deep holes, by the compound of 
manganese and lead ; an effect which is never observed when 
copper, or any other of the alloys of gold are destroyed by lead. 
The mixture of gold and manganese is more difficult of 
fusion than gold alone ; yet, when the heat is continued with 
access of air, the whole of the manganese becomes oxidized, and 
remains on the surface ; and, when the mass is cold, it may be 
separated from the pure gold which is underneath, by the blow 
of a hammer. 
24 carats of the mixed metal, which had acquired of its 
weight by the absorption of oxygen, was reduced in close 
vessels, by fusing it with charcoal and oil, as already described. 
The manganese again became metallized, and was again com- 
bined with the gold, to which it communicated the gray colour 
and brittleness of the original metal ; and the button weighed 
nearly as at first, viz. 24 carats. 
The solution of the mixed metal in nitro-muriatic acid, when 
evaporated to dryness, leaves a light or pale orange -coloured 
spongy mass, not so readily deliquescent as the evaporated solu- 
tions of pure gold, which are also of a much deeper colour. 
The solution of the mixed metal affords, by ammonia, a 
mixed precipitate, composed of yellow and white particles ; but 
MDCCCIJI. K 
