326 



ALBERT D. BROKAW 



5. That the influence of ferrous salts in suppressing the solubility 

 of gold is negligible if manganese dioxide is present; 



6. That the solution of gold is practically limited to the oxidized 

 zone. 



In agreement with these experiments is the fact that manganiferous 

 lodes bearing pyrite, in areas of chloride waters, are leached to greater 

 depths than lodes that do not carry manganese. ' 



In conclusion, the writer wishes to thank Professor Emmons for 

 his suggestions and advice in the conduct of the work, and Messrs. 

 C. Russell and N. Sankowsky for placing at his disposal an unpublished 

 tabulation of mine waters which they have assembled. Six complete 

 analyses of vadose waters from their tables are appended : 



* U.S.G.S. Bull. 330, 547. 

 ^Ibid. 



tBtill. Univ. of Cal., IV, 192. 

 § Ihid., 189. 



H Beck, Nature of Ore Deposits (Weed) , II, 377. Analyses expressed in milligrams per liter. Where 

 necessary they have been recast. 



March, 1910 



I See W. H. Emmons, Min. and Sci. Press, December 11, 1909. 



