118 



J. E. MAYER, ESQ. ON THE WATER 



we have here urged to particular views relative to modes of 

 action, or to forms of Apparatus, we think, with reference 

 to the manufacture of filter beds for Towns, &c„ that Table 

 Y. shews undeniably that the natural magnetic oxide of iron 

 holds a high place as a filtering agent. By its means nearly 

 34 per cent of organic matter were separated : it is superior 

 to finely divided mica, and inferior only to the artificial 

 magnetic oxide, and to Swedish filter paper ; both which 

 are inapplicable for all but Table or Laboratory experi- 

 ments. 



If the statements made at page 110 by Dr. Parkes (noted by 

 us in a former part of this paper) have been held in mind, it 

 will be observed that we have not been able to confirm them. 

 The utmost amount of organic matter that we have been 

 able to separate by filtration is less than 40 per cent, and 

 differs widely from 88 per cent, as stated in the work above 

 mentioned. 



With reference to the ready procurability of the natural 

 magnetic oxide in various parts of India, we beg to submit 

 such information as we have been able to obtain. 



Inquiries at the Government Central Museum have shewn 

 that magnetic iron ore is to be found at many places in the 

 Vellore Taluq, &c. — Vide page 25 of the Catalogue of Articles 

 contributed by Madras to the International Exhibition of 

 Works of Industry and Art, held in London, 1862. 



By reference to the Catalogue of the iron ores of Southern 

 India, it will be found that the following are named as loca- 

 lities from which iron ores can be obtained, viz., in numerous 

 villages in the Northern Division of Arcot ; in some places 

 in the Bellary District ; in many places in the Canara District? 

 in several localities in the Chingleput District ; in several 

 places in the Cuddapah District; in some places in Guntoor 

 and Kurnool ; from one place in Madura ; from twelve different 



