538 SEC. 13. CHEMISTRY. 



273O. No. 7. Solution of Copper as drawn from the lixivia- 

 tors, containing, in addition to copper, &c., from three to four 

 grains of silver per gallon, with traces of gold. 



A quantity of iodide of potassium (or zinc) sufficient to precipi- 

 tate the silver present is added to this solution, and the precipitate 

 formed is allowed to subside and collect, the supernatant liquor 

 being passed into vessels in which the copper is precipitated by 

 means of metallic iron. 



ANALYSIS of COPPER SOLUTION of Sp. Gr. 1 -24. 



Contents per gallon. 



Grains. 



Sodium sulphate ----- 10,092 

 Sodium chloride - - 4,474 



Chlorine (combined with metals) - - 4,630 



Copper 



Zinc 



Lead 



Iron 



Lime 



Silver 



3,700 



480 



40 



32 



52 



3-06 



Arsenic, antimony, bismuth, &c. not estimated. 



Widnes Metal Company. 



2731. No. 8. Precipitate caused by addition of a soluble iodide 

 to solution of copper, &c. (Claudet's process), consisting of iodide 

 of silver mixed with various salts of lead, chiefly sulphate, 



Widnes Metal Company. 



2732. No. 8A. Silver Precipitate, obtained by the reduc- 

 tion of the iodide by means of metallic zinc. 



Silver 



Gold 



Lead 



Copper 



Zinc oxide 



Ferric , 



Lime 



Sulphuric anhydride 



Insoluble residue - * 



Oxygen and loss - 



100,000 

 Widnes Metal Company. 



2733. No. SB. Iodide of Zinc, obtained by reduction of 

 iodide of silver by metallic zinc, and used for the treatment of a 

 further quantity of argentiferous copper solution. 



Widnes Metal Company. 



