COPPER. 11., 



the larger pieces have been broken up, the material goes to the 

 sorting tables, each of which finds employment for 8 or LU women 

 and girls, who are very skilful at their work. The rich pieces 

 arc picked out and placed in baskets. The remainder goes to the 

 dumps. The latter consist of the gangue and also of the low-grade 

 ores, disseminated sulphides and carbonates. The water percolat- 

 ing through the dumps was of a bright blue colour and appeared 

 to bear an appreciable quantity of copper salts in solution. 



The rich picked ores, consisting chiefly of erubescite and chal- 



copynte are carried down to the smelters, 



Ore treatment. V, - . ' 



which are situated in the village. They are 



first of all roasted in large quadrangular kilns for three days with 

 ironstone, charcoal and wood. The caked masses from this opera- 

 lion go into the large blast furnaces ; the smalls and dust are washed, 

 the heavier portions kept, and smelted in a special furnace of 

 smaller dimensions. The preliminary calcination appears to drive 

 off volatile impurities, to reduce the ores to a certain extent and 

 to prepare a hard porous cake in good condition for the final opera- 

 tion in the blast furnace. Three sizes of blast furnace are made 

 use of generally in benches of six. The largest are from 20 to 

 25 feet high with a covered-in chimney, but with a long 

 opening in front, above the wall of the actual reaction chamber 

 which is of course much smaller. The other furnaces are about 

 15 feet high, and there is also a still smaller type. The smelting 

 operation takes three days to complete in the biggest furnaces, 

 working day and night, and twelve hours in the smallest type. 

 The blast is supplied from large cylindrical blowers worked bv 

 relays of coolies. The molten metal is not tapped, but when the 

 reaction is completed the front of the furnace is broken in, leaving 

 a bath of molten metal at the bottom in the hemispherical-based 

 crucible. This is allowed to cool, and the cooling process is hastened 

 by spraying rice water on the hot surface, which as it solidities is 

 removed in plates. The charges for the largest sized furnaces are 

 said to be as follows : — 



Calcined ore ..... 



Iron ore ..... 



Charcoal ..... 



Limestone ..... 



The amount of copper produced, according to my Chinese infor- 

 mant, may be anything from ; t to | ton. 



40 loads, 



say 



3 tons. 



20 „ 



»» 



n „ 



40 „ 



i) 



; > >, 



- f o „ 





n ,. 



