1833.] On the Manufacture of Saltpetre. 23 
Il.—On the Manufacture of Saltpetre, as practised by the Natives of 
Tirhtt. By Mr. J. Stevenson, Supt. H. C.’s Saltpetre Factories in 
Behar. 
The soil of Tirhoot almost every where contains a large proportion 
of saline matter, such as nitrate of potass (saltpetre), nitrate of lime, 
sulphate, and muriate of soda, &c.* but in general the sulphate of soda 
is most abundant. The saltpetre (as well as the other salts) lies in 
patches as it were, some parts being more productive than others, ac- 
cording as carbonate of lime and sand alternately predominate. By 
analyzing the different soils, I have found those places most productive 
of nitre to contain a redundancy of the former; and on the contrary, 
where the soil was unproductive, I found a redundancy of the latter 
substance. I am therefore naturally: led to the conclusion, that carbo- 
nate of lime is one of the principal agents in the formation of this arti- 
cle. This will also account for the district of Tirhit being more pro- 
ductive of nitre than any other place in India, for almost half of its soil 
is calcareous; an average sample of it, collected from various places 
where saltpetre abounds, and carefully analyzed, gave me the composi- 
tion as follows. 100 parts being operated upon. 
Matter insolubleinthethree mineralacids, Silex, .............. 50.0 
Matter soluble in ditto, ............ Carbonate of Lime,.... 44.3 
Sulphate of Soda,...... 2.7 
; Muriate of do......... 1.4 
Matter soluble in water,.......... Fulci et capes tac sis 0.9 
Nitrate of Potass,...... 0.7 
100.0 
This analysis does not agree with Dr. John Davy’s, but be it remem- 
bered, that scientific gentleman operated upon saltpetre earth from 
the factories, which of course contains more saline matter than the 
general soil. 
In the month of November, the Joneahs or native manufacturers of 
saltpetre commence their operations, by scraping the surface off from 
old mud heaps, mud buildings, waste grounds, &c. where the saltpetre 
has developed itself in a thin white efflorescence, resembling frost rind. 
This saline earth being collected at the factories, the operator first sub- 
jects it to the processes of solution and filtration. This is effected by 
* T have not been able to ascertain whether the sajji mati (native carbonate of 
soda) is found in this district ; as far as my own observations have extended, it does 
not form a part of the composition of the soil. I also could not detect any alumina, 
though it is likely some parts may contain it. 
