SALTPETRE 



POTASSIUM 

 NITRATE 



NITRE OR SALTPETRE 



Price. 



Uses. 



Gunpowder. 



Dyeing. 

 Medicine. 



Manure. 



Production. 



Trade. 



and set out to crystallise. " In from six to ten days the crystals are extracted 

 and the residual tor or mother-liquor is then available for future use." In thi.s 

 mother-liquor, crude saltpetre is dissolved and the solution concentrated by 

 boiling in large evaporating-pans. During the boiling a dirty white granular 

 substance (sitta) falls to the bottom of the pan and is removed as it forms. This 

 sitta is sometimes washed and the washing returned to the pan. In Bihar it is 

 mixed with the refinery earth. " It is composed for the greater part of common 

 salt mixed with other salts, earth and nitrogenous matter." Meanwhile the 

 evaporation of the liquid in the pan is continued at the temperature of boiling 

 water. The scum which forms on the surface (zag, zoga, mail or phain) may be 

 removed at this stage or after transfer to the settling- tank. "After boiling for 

 three hours, or until the liquid changes from a dark to a light yellow colour, the 

 concentration is considered complete." The clarified liquor is transferred into 

 one or more crystallising vats. " At the bottom of the settling-tanks is found 

 a substance called matiaree, which is a by-product containing nitrates, and is 

 accordingly carried off and mixed with the nitrous earth in the factory yard. 

 The crystallising- vats under the sheds are filled with nitre liquor to about six 

 inches from the top. In the United Provinces, on the surface of each is floated 

 a trellis-work made of interlaced bamboo sticks (called tattis in Cawnpore). This 

 device facilitates the formation of good crystals. After seven days the bamboo 

 frames are removed and the adhering nitre crystals are shaken or picked off, 

 and the crystals at the bottom and sides of the trough collected in a heap and 

 drained." 



" The damp saltpetre is contaminated with the mother-liquor adhering to it 

 and minute crystals of salt, and these must be removed by washing before the 

 salt is ready for market." " Bags containing the refined substance are placed 

 over an empty tub or vat, which is slightly tilted to allow the liquor to drain. 

 Cold water is sprinkled from time to time upon the saltpetre through the open 

 mouth of each bag. This water trickles slowly through the saltpetre crystals, 

 carrying with it inferior salts in solution. Some saltpetre is also dissolved, 

 but the loss is not great. After the washing, the refined saltpetre is spread out 

 and dried, and after remaining a few hours, is conveyed to the store godown" 

 (Hooper, I.e. 36). The price of refined nitre in 1904 is stated to have been Rs. 5-8 

 to Rs. 6 per maund in Bihar and Hissar, Rs. 8 in Cawnpore, and that of extra 

 good quality, Rs. 9. 



Uses. It is even still an important ingredient in gunpowder, owing 

 to the large volume of oxygen it contains, the ease with which it parts 

 with its oxygen, and the fact that it does not readily absorb moisture 

 from the air. On the other hand, sodium nitrate is preferred for the 

 manufacture of nitric acid because it is cheaper and yields about 7 per 

 cent, more acid. In India, saltpetre is used in association with certain 

 animal dyes, such as lac and cochineal. In MEDICINE it is sometimes 

 prescribed because of its diaphoretic properties. Its merits as an anti- 

 septic in preserving fish and meat are well known. As a MANURE it is 

 much appreciated, especially for wheat and tobacco (see p. 771 ; also 

 c./. Agri. Ledg., 1893, No. 10; 1897, No. 8, 171), and in India it is 

 sometimes used as a flux in glass-making. 



Production and Trade. According to Holland, the returns are so 

 imperfect, being considerably below the amounts of export, that 

 these must be taken as the only satisfactory index of the extent 

 of production. For the period which he reviews (1897-1903), the 

 average annual exports, including those across the frontier, amounted 

 to 382,353 cwt., valued at 262,592. He further states that a com- 

 parison with the figures returned for the past twenty years shows 

 that there has been only a slight reduction in the amount exported, 

 in spite of the discovery of large deposits of sodium nitrate (now being 

 extensively utilised in America), of variations in tariff, and of whole- 

 sale changes in the substances used for manures and in the manufacture 

 of explosives. For the six years 1878-1883 the average quantity of 



974 



