MANGANESE IN GOLD DEPOSITS 



diagram shows that D, which was twice as concentrated as A , dis- 

 solved about 12 times as much gold. 



9. Richard Pearce 1 placed native gold in a flask containing 

 hydrated manganese dioxide with 40 gm. of salt and 5 or 6 drops 

 of ELSO4. After heating for 12 hours appreciable gold had been 

 dissolved. 



10. T. A. Richard 2 extracted 99.9 per cent of the gold from 

 manganiferous ore with a solution of ferric sulphate, common salt, 

 and a little H 2 S0 4 . 



n. Don 3 found that 1 part of HC1 in 1,250 parts of H 2 0, in 

 the presence of Mn0 2 , dissolves appreciable gold. 



100 



TIME, HOURS 



Fig. 2. — Diagram Showing the Solubility of Gold in Concentrated Solutions of Hydro- 

 chloric Acid and Cupric Chloride. (Illustrating Experiment 8, by McCaughey.) 



A number of experiments on the solubility of gold in cold dilute 

 solutions were made by A. D. Brokaw. 4 The nature of these 

 experiments is shown by the following statements, in which (a) 

 and .(b) represent duplicate tests: 



12. Fe 2 (S0 4 ) 3 +H 2 S0 4 -f-Au. 



(a) no weighable loss. (34 days.) 



(b) no weighable loss. 



13. Fe 2 (S0 4 ) 3 +H 2 S0 4 +Mn0 2 +Au. 



(a) no weighable loss. (34 days.) 



(b) 0.00017 gm. loss. 5 



1 Trans., XXII, 739 (1893). 



2 Trans., XXVI, 978 (1896). 3 Trans., XXVII, 599 (1897). 

 * Journal of Geology, XVIII, No. 4, 321-26 (May- June, 1910). 



5 This duplicate was found to contain a trace of CI, which probably accounts for 

 the loss. 



