258 EXPERIMENTS ON VARIOUS ALLOYS OF GOLtf, 



By a full red heat, the arfenic rofe and combined with the 

 furface of the plate, producing a very fufible compound, 

 which ran down into the lower veflfel. The plate, which had 

 been ^ of an inch thick, was become as thin as paper ; but 

 was flilj pure gold. The fufed compound was extremely 

 brittle, and gray within. It contained a very large quantity o£ 

 arfenic, but how much is not ftated. 

 Experiment V. 

 Variation of Variation of the preceding experiment. The arfenic was 



fc*P« 4* introduced through a hole after the ignition, and the heat not 



kept up. The furface of the plate was impregnated with 

 arfenic ; but the heat not being fufficient to caufe it to flow 

 down, it adhered to the plate, and rendered it lefs flexible. 



GOLD ALLOYED WITH ANTIMONY, 



Experiment I. to VIII. 

 Gold and anti- Golds in various proportions and of different finenefs were 

 mony. combined with pure antimony by heat. Small proportions of 



the latter, produced a pale, dull, unmetallic colour, and 

 rendered the compound exceedingly brittle. Minute quan- 

 tities ftill impaired the metallic brilliancy, and caufed brittle- 

 nefs. Lefs than one quarter of a grain, in the ounce of gold, 

 were fuflicient to produce thefe effecls. The vapors of antimony 

 readily combine with gold in open as well as clofe veffels, and 

 afford the fame changes. 



GOLD ALLOYED WITH ZINC. 



Experiment I. to VI. 



Cold and einc By tne ^ e experiments, it was (hewn, that zinc is highly in- 

 jurious to the ductility of gold ; that a portion of it is eafily 

 feparated from gold by heat ; that, when a large quantity of 

 gold is alloyed with the flandard proportion of zinc, only part 

 of the latter is fpeedily volatilized, but, when fmall quantities 

 are treated, the whole of the zinc becomes feparated, and the 

 gold remains pure; that, if zinc is previoufly combined with 

 copper in the ftate of brafs, it is not fo eafily feparated by heat, 

 when added to melted gold ; and, laftly, that gold in fufion 

 abforbs and retains a portion of zinc, when expofed to the latter 

 metal in a volatilized (late, even in open veffels. 



GOLD 



5 



