152 



GEOLOGY OF TRICHINOPOLYj &C. 



[Chap. VIII. 



The extraction of the alkaline salts from white soil is carried on 



in various places by the following process. On or 

 Extraction of alkalies. . • n j o ■, -^ 



near the edge ot the more extensive flats of white 



soil may frequently be seen rudely conical mounds of soil, sometimes 



single, sometimes also in considerable number, which are employed in 



preparing the solution from which the salt is crystallized, the process 



being as follows : — 



On the tops of the heaps of earth are one or two basin-like hollows, 



from which subterranean channels lead down to another basin at the foot 



of the hillocks, as shown in the accompanying diagram, Fig. 7. The 



Fig. 7.— Plan and Section shewing mode of exteacting salts. 



m^^^w 



A, raised mound of earth, with fa), basins at top, connected by channels 



through the mound with the lower basin (i). 



B, shallow evaporating pans. 



upper basins are filled with the earth containing the salt, and on this 

 water is poured until the salt is supposed to be dissolved out. This liquor is 

 allowed to run by the channels into the lower basin, whence it is drawn 

 and poured into shallow pans made on a flat piece of ground close by, 

 and there allowed to evaporate. After the salt has been dissolved out of 

 the soil, the upper basin is cleared out and filled afresh, while the refuse 

 soil is thrown aside and increases the size of the mass. 



The manufacture of iron, which has long been carried on with 



^''°"- considerable success in parts of the district 



now referred to, has frequently been described by previous waiters, 



( 374 ) 



