296 EXPERIMENTS ON VARIOUS ALLOYS OF GOLD. 



Moreover, that gold alloyed with lead only loft three grains> 

 chiefly by vitrification. 



That gold alloyed with iron loft 12 grains, which formed 

 fcoria. 



That gold alloyed with bifmuth alfo loft 12 grains chiefly by 

 vitrification. 



That gold alloyed wilh antimony loft the fame quantity, 

 partly by volatilization, and partly by vitrification. 



That gold alloyed with zinc loft one pennyweight, by vola- 

 tilization. And, 



That gold alloyed with arfenic, not only loft the whole 

 quantity of alloy, but alfo two grains of the gold, which were 

 carried off in confequence of the rapid volatilization of the 

 arfenic. 



Lewis, (Phil. Comm. of Arts, p. 88,) however, aflertsthat 

 * gold is more volatilized by antimony than by arfenic or zinc ; 

 •1 but to produce this effect the fire muft be vehement, the 

 H crucible (hallow, and the air ftrongly impelled." Thefecir- 

 cumftances, according to their variations, muft undoubtedly 

 » very much influence the refults of fuch experiments ; and 



therefore, although the reverfe was found to take place in the 

 experiments here ftated, it does not follow that certain changes 

 Ihould not be produced by different degrees of heat, by the 

 figure of the veffels, and by a current of air more or lefs ftrong. 

 Silver and cop- The wno ^ e of the experiments of this fection tend to prove, 

 per only are fit that (agreeably to general practice and opinion) only two of 

 for the alloy of ^ metals are proper for the alloy of gold coin, namely, filver 

 and copper ; as all the others either confiderably alter the co? 

 lour, or diminith the ductility of gold. In refpect to the latter 

 quality, the different metallic fubftances which have been em- 

 ployed in the prefent experiments, appear to affect gold nearly 

 in the following decreafing order. 

 Order of efTeft J# BifmUth. 2. Lead. 3. Antimony. (Thefe are nearly 

 equal in effect.) 4. Arfenic. 5. Zinc. 6. Cobalt. 7. Man- 

 ganefe. 8. Nickel. 9. Tin. 10. Iron. U. Platina*. 

 12. Copper. 13. Silver. 



* Had the platina been quite pure, the compound metal would 

 probably have poffeffed more du&ilityj I cannot therefore take upon 

 me to aflert pofitively, that the place here affigned to platina, is pre* 

 cifely that which it ought to occupy. 



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