310 Mr. D. Forbes' s Researches in 



Gold 30-69 90-16 



Silver 3-15 9-26 



Copper and iron . . trace trace 



Quartz 0-11 0-32 



Loss in analysis . . 0*09 0"26 



34-04 100-00 



Another specimen of gold quartz from this lode was also 

 submitted to examination, the quartz fragments being pounded 

 for the purpose and washed in a batea by Mr. Melville Attwoocl. 

 The gold obtained was in irregular flakes, apparently somewhat 

 lighter in colour than the previously examined specimen, and 

 upon experiment its specific gravity was found to be 15*62, a 

 result evidently due to the gold flakes enclosing air-cavities. The 

 analysis of this specimen was conducted in precisely the same 

 manner as the other sample, and afforded when tabulated the 

 following results : — 



Gold 4-86 89-83 



Silver ...... 0-50 9'24 



Iron trace trace 



Quartz 0-04 074 



Loss on analysis . . 0*01 0-19 



^41 lOCKX) 



In this case no trace of copper was detected. 



The metals gold and silver are known to alloy with one another 

 in all proportions when fused, and, being both monometric in 

 crystallization, are doubtless isomorphic in their replacements. 

 It is interesting, however, to observe that the above analyses 

 closely agree with the formula Au 6 Ag, which, supposing the 

 equivalents of gold and silver to be respectively 196 and 108, 

 would on calculation require a percentage composition of 



A 6A Gold . . . 90-88 

 Au Ag Silver . . . 9-12 



100-00 



It may, however, be remarked that in some of the gold-speci- 

 mens shown to the author by Mr. Dean, there also appeared to 

 be another alloy of gold and silver occasionally present in the 

 quartz of this lode, which, as it is considerably lighter in colour, 

 would most probably on analysis be found to contain a larger 

 proportion of silver. 



The accessory minerals found in the Clogau quartz lode asso- 

 ciated with the gold were tetradymite, iron pyrites, chalcopyrite, 

 galena, chlorite, calcite, dolomite, ankerite (?), chalybite, and 



