228 SOILS OF JSDIA. 



1 



built on black cotton ground, or forming the rich mould of 

 gardens, as in many parts of the Northern Circars. In such 

 situations, from the begiiming of the dry season in Feb- 

 ruary till the rains commence again in May and June, the 

 streets, and particularly the lower parts of the mud walls 

 with which the houses are built, or the yard surrounded, 

 appear wet and black in the morning, and crumble down 

 into a fine soft mould. What collects in a heap under the 

 walls is gathered every other day by sweeping. It contains 

 about one-fifth of its weight of crude saltpetre. The na- 

 tives observe that this substance is produced abundantly in 

 those years in which the preceding monsoon-rains have 

 been strongest, and accompanied by a great deal of thun- 

 der and lightning. A heavy thunderstorm in April or May 

 is likewise reckoned very favourable for the manufacture. 

 When the saltpetre has been extracted from this earth, it is 

 thrown in heaps, and spread out when the monsoon is over. 

 After lying a year or two it is swept every day, and is again 

 found to yield, by sweeping it every other day, saltpetre 

 earth fit for the manufacture ; for no potash is added, so 

 that the saltpetre seems to be ready formed in the soil. 



The manufacture of saltpetre hardly extends lower than 

 the eastern limits 6i Bahar, and it is said that the produc- 

 tion of nitre is greatest during the prevalence of the hot 

 winds. These winds blow from the west, and formerly did 

 not extend eastward beyond Bahar ; but from the change 

 of seasons within these forty years their influence is now 

 felt in Bengal ; in which province, on that account, the ex- 

 tensive manufacture of saltpetre might be attempted with 

 success. 



Saltpetre grounds are frequent in Bengal. The tendency 

 of the soil to reproduce saltpetre is very troublesome to the 

 builders and the occupants of houses. " It can scarcely," 

 says Heber, " be prevented from encroaching, in a few years, 

 on the walls and floors of all lower rooms, so as to render 

 them unwholesome, and eventually uninhabitable." Half 

 the houses in Calcutta are in this predicament, and their 

 ground-floors useless. Cellars are unknown in this part of 

 India. 



In Tirhoot, one of the principal districts in India for the 

 manufacture of saltpetre, the soil, according to Tytler, is 

 everywhere thoroughly impregnated with this substance. 



