EXPERIMENTS ON VARIOUS ALLOYS OF GOLD. 295' 



GOLD ALLOYED WITH SILVER. 



-Gold alloyed with pure filver, in ftandard proportion, is fo Gold and Giver. 

 generally known, that it would be needlefs here to fay more, 

 than that it approaches the neareft to the ductility of fine gold, 

 and that the fpecific gravity of this mixture differs but very 

 little from that which, according to calculation, would refult 

 from the relative proportions of the two metals. 



From the foregoing experiments it is evident, that many of General remarks 

 the metallic fubftances with which gold may be alloyed, are on alloys of gold * 

 more or lefs liable to be feparated from it during fufion, in 

 confequence of their relative affinities with caloric, with oxygen, 

 or with both ; and that thefe affinities become modified, by thofe 

 which prevail between the various metallic fubftances and gold. 

 Moreover, it is evident, that even the molt oxidable metals 

 have this property much.diminimed or checked by being united 

 with gold, which appears fo to envelope and retain their parti- 

 cles, as to impede the ufual influence of heat, as well as the 

 natural exertion of their affinities with the oxigen of the at- 

 mofphere. The following experiment was therefore made, to 

 afcertain the comparative lofs caufed by the volatilization, or 

 by theoxidizeraent of various metallic fubftances, when added 

 to gold during a given period of fufion, and under fimilar cirr 

 cumftances. 



Experiment. 



Ten four-inch crucibles, which had been previoufly made Experiment on 

 red-hot, were put into as many twelve-inch crucibles, which 5k e jj£ s ky^ e * t- 

 were placed in wind furnaces of fimilar conftruclion, and heat- ent alloys. 

 ed as equally as poffible. Each of the fmall crucibles contain^ 

 ed five ounces ten pennyweights and fourteen grains of gold, 

 %:3 car. 3| grs. fine, which being completely melted, nine pen- 

 nyweights and ten grains of the feveral metals were added, 

 and mixed in the ufual manner, after which, the fufion was 

 continued in the open vefTels during one hour 



The different maffes, when cold, were weighed^ but, pre- 

 vious to this, the fcoria or glafs which had been formed on 

 fome of them was gently removed. 



It appears, that fine gold, gold alloyed with filver, gold al- Refults of loft 

 loyed with copper, and gold alloyed with tin, did not fuffer b ? ftron S heat# 

 any lofs during the experiment. 



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