Some Experiments in the Gold Bullion Assay. 7 



RESULTS. 



Parting Proportions. — The alloy containing 15 per 

 cent, of gold (or 1 of gold to 5f silver) went to pieces, the 

 minuteness of division increasing as the percentage of gold 

 decreased. 



The alloy containing 17 1 per cent, of gold (or 1 of gold 

 to 4 7-lOth silver) did not go to pieces, nor did the alloys 

 with higher percentages of gold. 



When the ratio of the gold to the silver was 1 gold to 

 4 7-lOths silver, or 1 gold to 2 J silver, or between these, the 

 cornet parted well. 



Surcharge. — With the alloy containing 15 per cent, 

 gold (1 gold to 5f silver) and those with more silver^ there 

 was negative surcharge. 



With the alloy containing 17|- per cent, gold (1 gold to 

 4 7-lOths silver), and those with less silver, there was posi- 

 tive surcharge. 



Between the alloys containing 35 per cent, gold (1 gold 

 to 1 9-lOths silver) and 40 per cent, gold (1 gold to IJ 

 silver) there was a sudden great rise in surcharge exhibited^ 

 the maximum being near the alloy containing 45 per cent, 

 gold (1 of gold to 1-22 silver). 



In Diagram I. these relations are made visible. 



Colour. — Buttons. — Beginning the examination with No. 

 1, and passing downwards, the gold could be detected iii'st 

 in the button containing 50 per cent, of gold ("500) by the 

 faint gTeen tinge it exhibited ; this coloui' increased in 

 depth with the percentage of gold until the button con- 

 taining 70 per cent, of gold ('700) was reached, at which 

 point the warm colour of gold appeared. This again kept 

 deepening until the last, in which the gold was tinged by 

 the residual copper. 



Cornets. — After coming fi-'om the acids — 



Nos. 6 to 13, inclusive, were dark ; 

 Nos. 14 to 19 bright ; 20 golden. 



After annealing — 4 to 12 bright yellow. 

 13 greenish yellow. 

 Increasing to 15. 

 16 — 19 silvery gTeen increasing. 

 20 coppery. 



