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826. Saltpetre is manufactured largely in Bihar and to 

 a certain extent in several districts of the N.-W. Provinces, 

 the Punjab, Bombay, Madras and Burma. More than two- 

 thirds of the saltpetre exported from Calcutta comes from 

 Tirhut, Saran and Champaran. The climate best suited for 

 the production of nitre is where dry weather follows the rains 

 and thus by evaporation allows the salt to effloresce on the 

 surface. Presence of carbonate of lime in abundance is help- 

 ful to the generation of nitre and this accounts for the district 

 of Tirhut being so fruitful in the production of nitre, for almost 

 half of its soil is calcareous. The manufacture in Bihar is in 

 the hands of a caste called the Nuniahs, who revel in old 

 village sites and mud walls. They make piles of loose earth 

 after the rains are over and build mud walls round them that 

 the precious stuff may not be washed away. This earth is 

 obtained by scraping off an inch or two of the bed chosen and 

 made into conical heaps 2 to 4 ft. high. By March or April 

 when a large number of these heaps have been collected, 

 the processes of solution and filtration begin. The best 

 temperature for nitrification is 98 F. and if this and mois- 

 ture can be given artificially in presence of lime and 

 organic matter, nitre-beds and heaps should give the best 

 results. Kalsies are placed on tripods, each kalsi having 

 a hole at its bottom. A layer of straw is put at the 

 bottom, over it ashes from indigo refuse, and then the 

 vessel is nearly filled with the saline earth, in a loose 

 manner. Under each kalsi filled with saline earth is placed 

 an empty kalsi and above it one filled with water having an 

 orifice at the bottom in the manner in which an ordinary 

 kalsi filter is arranged. A series of these stands are erected 

 side by side, and the liquid from the bottom kalsies is removed 

 from time to time and boiled until the liquor comes out so 

 free from salt that it is not worth boiling. The liquor obtain 

 ed contains 2 to 5 % of saltpetre. Oval iron pans from i to 

 3 ft, in diameter and 6 to 9 inches in depth are used for boiling 



