46 



HATCH t THE KOLAR GOLD-FIELD. 



Reef mill. The following table summarizes the milling practice at 

 the Kolar mines : — 



Name of Mine. 



u- 6 

 o « 



U.S 



z-2 



*^ CO 



«_ 10 



°£ 



C 



"— 10 



J- Q. 



Average stamp 

 duty per diem 

 (24 hours). 



CO 



<u 



-e 

 



.5 



a, 

 

 u 



Q 



u 



a) 



a, 

 <u 



"S a 



v 'a 



a. c 



to 



'3 

 © 



-F. *- 



Q 



Mesh of screen- 

 ing (number 

 of holes per 

 square inch.) 



Nature of 

 screening. 



Mysore Mine . 



f 120 



I 3o 



1,050") 

 75o) 



2*27 



8 



85 



7 



1,600 



Woven wire. 



Champion Keef . . 



150 



850 



2*00 



7 



90 



6 



900-1,200 



ditto. 



Ooregum . . 



no 



850 



2*26 



7-8 



70-90 



5 



1,000-1,200 



ditto. 



Nundydroog . . 



40 



goo 



2*62 



8 



90 



2 



No. 6 needle= 

 900. 



Punched 

 copper. 



Balaghat . 



15 



1,050 



270 



8* 



85 



2 



No. 6needle= 

 900. 



ditto. 



Tank Block . 



3o 



95o 



2'6o 



7 



8S 



J| 



840 



Woven wire 



Coromandel . . 



40 



95o 



2"20 



1\ 



S5 



3 



900-1,200 



ditto. 



Nine Reefs 



20 



95o 



i*8o 



1\ 



85 



3 





Punched iron. 



Road Block 



20 



1,050 



2*02 



7i 



85 



3 



No. 6 needle = 

 900. 



ditto. 



The mercury consumed per ton of ore crushed varies from '37 ounce 

 to 2 ounces (avoirdupois), the latter extraordinarily large amount 

 being the result of the use of Wheeler pans. Challenge feeders are 

 in use in all the mills except in two at Champion Reef and those of 

 the Ooregum company where hand-feeding is still practised. Hand- 

 feeding is theoretically good, but with native labour, requiring most 

 constant and watchful supervision, does not give in practice as 

 good results as automatic feeding. No concentration is practised, 

 except to a very small extent on the Ooregum Mine where black sands 

 and pyritic material are collected on riffle-strakes below the amalga- 

 mating plates. These are ground with mercury in Wheeler pans. 



The striking feature of the milling practice on the field is the 

 multiplicity of small mills on some of the properties. Thus the 

 Champion Reef company has three independent mills each of 50 

 stamps. The Ooregum company has also three mills, two of forty 



