Massey on Saltpetre. 135 



contain many oily and mucilaginous parts, which, till they 

 are duly attenuated by putrefaction, will not suffer any 

 crystals to form in the leys that are drawn from these 

 earths ; and they are laid in these heaps for this event to 

 take place. 



' The ingenious author of the " Chemical Dictionary " has 

 told us, that the nitrous acid is nowhere found but in such 

 earths as are impregnated with the juices of vegetables and 

 animals, and where these juices have sustained the whole 

 putrefactive process. But having assigned no reason for it, 

 he seems to have been little regarded. 



' The common soil in some parts of India is naturally 

 nitrous, owing plainly to the fish and slime that is left upon 

 it by the inundations of the river Ganges, which soon 

 corrupt in that hot climate, and fill the earth with putrid 

 juices ; and here putrefaction, being carried on with the 

 greatest rapidity, is, of course, soon completed, and the 

 natives are, in a short time, furnished with a nitrous earth 

 perfectly matured. But it must not be forgotten, that their 

 strongest earths are found at the bottoms of their tanks or 

 shallow ponds of water, which, in this country, are often of 

 great extent, where, the water being evaporated by the 

 heat of the sun, large quantities of fish are left to corrupt, 

 which furnish a mud of the strongest nitrous quality. 



' In this manner are nitrous earths naturally formed in 

 these parts of the world, and might doubtless be formed 

 in others, though not perhaps so expeditiously, by throwing 

 into shallow ponds of water, natural or artificial, all sorts of 

 dung and carrion, with other putrid and putrefiable matters ; 

 where the water, being evaporated by the heat of our 



