38 On the Salt Works of the [Jan. 



being an oblong square of fifteen feet by five, and not more tban nine 

 inches in depth. They are built with the stiff kankar clay, with the 

 stalks of sugar-cane laid crosswise, to form the bottom of the filter, in- 

 stead of bamboos and mats used to form the bottom of the saltpetre fil- 

 ters. A few which I saw had a layer of jungle grass laid over the canes, 

 which rendered the filtering process more effective. 



About fifty maunds of the saline earth is operated upon, at each charge. 

 This raw material being laid on the bottom of the filter, so as to form an 

 uniform thickness of about five inches, and trodden down to the desired 

 hardness by the feet of the operator. Water, from a well close by, is 

 then poured upon the earth to the depth of three or four inches, and the 

 whole suffered to remain tranquil for the space of several hours, during 

 which time, the fluid finds its way through the earthy bed, and dissolv- 

 ing the salt in its passage, runs off in the form of a weak brine, by 

 means of a spout into an earthen vessel used for a receiver. 



The brine thus obtained is more or less charged with a colouring 

 matter from decomposed vegetable matter and oxide of iron which the 

 kankar soil contains. On a subsequent examination of the brine from 

 several filters, I found the average to give a specific gravity of 1.095. 



The brine obtained in the above manner next undergoes a subsequent 

 process, as follows : — on the surface of the ground, near to the filters, eva- 

 porating beds are constructed of about twenty feet square, and not more 

 than four inches in depth. The bottom is formed of the nodules of 

 kankar limestone, plastered over with a cement of the same material, 

 similar to the roof of a pucka built house. These pan-like squares are 

 for the purpose of solar evaporation. A thin layer of cow-dung is spread 

 over the surface of this evaporatory, and the ras (as the natives term 

 the brine) is poured over, till the dung is saturated. The evaporation 

 goes on, and when the mixture is sufficiently dry, the saturated dung is 

 collected into a large heap, in order to be burned, or calcined, in the 

 same way that khiira Ion earth is burnt in Tirhoot, except that the cow- 

 dung serves instead of rice-straw for fuel. 



The calcined saline mixture is then removed to a filter (formed of clay), 

 of smaller dimensions than the one above, which I have attempted to 

 describe, (being only about five feet long, three broad, and two deep,) 

 when it is again subjected to the process of filtration. But in this se- 

 cond process, no more water is used than is necessary to dissolve the 

 common salt (which is known to be more soluble than most other salts) 

 contained in the calcined mixture ; consequently a very strong solution 

 of brine is obtained from this second operation. By the process of burn- 

 ing, the colouring matter is in some measure destroyed, so that the brine 

 from this second operation is less coloured than that resulting from the 



