312 Proceedings of the Asiatic Society. [No. 3. 



side of the lode, which no doubt was of a kind of ore which they found 

 easier to smelt, or less mixed with silex than this which they have left. 



Examination of a Sulphuret of Copper from the Barragunda Copper 

 Mine, sent by Mr. Mackenzie. 

 This ore is imbedded in a clear quartz matrix, and, unless the dressing 

 be very carefully attended to, a heavy loss will always arise, either from 

 the quantity of ore rejected in small fragments by the dressers on the one 

 hand, or by the quantity of silex which will find its way into the furnace 

 as ore on the other. At least 10 per cent, should on this account be struck 

 off from my actual results, which were of course from a lot of picked 

 fragments of pure ore, as free as possible from matrix. There is also a 

 considerable mixture of iron pyrites with it, which will in practice deterio- 

 rate much from its value, for the two are constantly mixed in the dressing. 

 I find that this ore contains in 100 parts as follows : 



Silex, °- 50 



Sulphur, 31.42 



Iron (Perox. 48.55) Metallic, 33.98 



Copper Metallic, 34.10 



100.00 



The iron and copper being both in the state of bisulphurets. 

 In the smelting of this ore on the large scale it must be taken into 

 account that the 34 per cent, of copper will be reduced in practice as 

 follows : 



Silex with the ore, from veins and bad dressing,. ... 10 per cent. 



Sulphuret of iron mixed with it at least, 10 „ 



Waste in smelting at least 10 to 15 „ 



35 per cent. 

 or say one-third ; so that the 34 parts of copper will be reduced to 34 less 

 11 or 23 per cent, of the ore as sent to the furnace : and if this is obtained, 

 it will be by very good management. 



H. PlDDINGTON, 



Cur. Mus. Econ. Geology. 



March \\th, 1853. 



I have next to announce a discovery which may be of importance, being 

 that of a fine variety of coal in the neighbourhood of Darjeeling, in the 

 Chawa JSuddee, about a coss from its junction with the Teesta. 





