578 Analysis of Nellore Copper ores. [Oct. 



the country ; but which cannot with propriety be entered upon in a 

 work devoted exclusively to literature and science. 



The ores now presented to me are from three different 'localities. 

 They differ considerably in quality one from the other, and all from 

 the former ore, which Dr. Thomson pronounced to be an anhydrous 

 carbonate, new to mineralogy. 



No. 1. A parcel, weighing 90 lbs. of roughly-picked and cleaned 

 ore, has a quartzose matrix, in some parts colored green, or appear- 

 ing so from the malachite beneath the transparent crystal. It con- 

 tains much iron, which, on solution in an acid, appears in the form of 

 a yellow ochre. Ten per cent, of quartz was separated from this 

 specimen on pounding it roughly, before setting it apart for analysis. 



No. 2. A parcel of the same weight is labelled " Bungeral Mettah," 

 and is the species stated to be found in clustered nodules in the 

 alluvium, of rounded exterior, as though they had been detached from 

 their original site, and reburied here. The ferruginous matrix of this 

 ore, on solution, assumes the appearance of a dark-red oxide. It is 

 the same probably as that of Dr. Thomson's specimen. The carbo- 

 nate of copper runs through it in veins, but the mixture of sulphuret 

 of iron and perhaps of copper with the oxide, gives the whole a dark 

 arenaceous texture. 



No. 3. The richest ore of the three is at the same time the most 

 abundant, and promises to yield the safest return, as it runs in unbroken 

 veins. This ore is a combination of carbonate and sulphuret, the 

 former intermixed with the latter, but readily distinguishable from 

 it, as the sulphuret is crystallized, and has the grey metallic lustre 

 of galena. The specific gravity of this ore is 3 - 77, being intermediate 

 between that of the carbonate, 32, and the sulphuret, 4 - 5. 



The analysis was conducted for the sake of expedition on separate 

 parcels of 100 grains each, in lieu of attempting the separation of the 

 ingredients from a single parcel. Some variation may thus be in- 

 duced from the irregularity of the ore ; but, on the whole, the results 

 ought to be more trust-worthy. Thus : the carbonic acid was estima- 

 ted by the loss of weight on digesting 100 grains, finely pounded, in 

 dilute nitric acid. The water, (for none of these ores was found to be 

 anhydrous,) by heating in a glass tube, removing the aqueous vapour 

 by bibulous paper, and ascertaining the loss. As the ore generally 

 lost its green colour by this operation, it is possible that a portion of 

 carbonic acid was also driven off. Calcination in an open dish, in the 

 muffle of an assay furnace, gave a loss, which was compounded of that 

 of the carbonic acid and the water. Calcination drives off the sulphur 

 also, but the equivalent of oxygen, which replaces it, being of precisely 



