280 Correspondence. 



Extract of a report of Captain Campbell, Assistant Surveyor General, 

 Madras, addressed to the Coal and Mineral Committee. 



I have not long ago forwarded, through the head of the survey 

 department, a report upon the mineral carbonate of soda, afforded by 

 lixiviating certain soils in the Barramahal. 



I shall here only remark, that there are several uses to which this 

 soda may be put besides becoming an article of export ; for instance, 

 in saturating with it the common country vinegar made from sugar, 

 or by manufacturing the vinegar from the destructive distillation of 

 wood. The acetate of soda thus made, might probably pay as an 

 article of import into England, for the purpose of making acetic acid. 



Regarding the kaolin earth, which is found in great quantities in My- 

 sore, I have also forwarded a report, which will probably reach the 

 Committee. 



A very fine clay of this kind, which burns of a fine white, is found 

 somewhere about Arcot ; but I have never had an opportunity of visiting 

 the spot. A manufactory of goglets is established at the place, and 

 are an article of trade to many parts of South India. A mixture of this 

 clay, ground up with the Mysore kaolin, would afford a material for 

 the manufacture of the very finest kinds of pottery. 



About five miles north of Salem, carbonate of magnesia occurs in very 

 great profusion as dykes and veins injected into an argillaceous tuffa, 

 which is associated with hornblendic rocks. The. magnesia has evidently 

 been injected in a state of pasty fusion, for the dykes and veins shew 

 on their side the most indisputable evidence of having been squeezed 

 through narrow fissures, and is often found in every variety of mi- 

 neral composition, from pure magnesia through all the varieties of 

 actynolite and amianthus. As magnesian clays have been used with 

 success in the manufacture of porcelain, it is not improbable that this 

 mineral might be valuable in the manufacture of improved kinds of 

 pottery. 



Iron is made in very numerous places in the Salem district, by 

 smelting iron sand. The mode of manufacture is exactly t the same 

 as has been described by Buchanan, (Journey in Mysore.) The iron 

 sand is derived from the disintegration of the softer parts of the granite 

 hills, and not from trap rocks, as has been very generally asserted, and 

 there are several different kinds ; but how many, I am not yet able 

 to state. The varieties can be readily distinguished by the colour, 

 which in some is a deep coal black, and in others a lead coloured 

 black. I cannot at present state the chemical composition of all the 

 varieties ; but a black kind which I have analyzed yielded titanium 

 and magnetic oxide of iron. 



