MANGANESE IN GOLD DEPOSITS 



27 



These results show that, in the presence of manganese dioxide, 

 free hydrochloric acid is more efficient than ferric chloride. The 

 same amount of chlorine was present in both solutions. 1 



2.0 



1.8 



1.0 



1.4 



< 0.8 -1 



'0.0 



0.4 



0.2 



0.04 0.08 0.15 0.16 0.20 



GRAMS Fe AS FERROUS SALT IN 125 cc. 



Q.2S 



Fig. 3.— Diagram Illustrating the Effect of Ferrous Sulphate in Suppressing the 

 Solubility of Gold in Ferric Sulphate Solutions, where Gold is Dissolved as 

 Chloride. (Illustrating Experiment 19.) 



19. McCaughey's experiments show the effect of very small 

 amounts of ferrous sulphate on solutions of gold in ferric sulphate. 

 To a solution, 125 cc, containing 1 gm. of iron as ferric, sulphate 

 and 25 cc of HC1, ferrous sulphate was added in quantities con- 

 taining from 0.01 to o. 25 gm. of ferrous iron. The solutions were 

 immersed in boiling water and subsequently 250 mg. of gold was 



1 Brokaw, Journal of Geology, XVIII, No. 4, 322-23 (May-June, 1910). 



