372 
Records of the Geological Survey of huliu. 
[vot. Sill. 
ordinary dung heaps may produce plentiful supplies of ammonia, but no nitric 
acid. Indeed, nitric acid, if present, is changed by the reducing action of the 
decomposing organic matter to ammonia. If wood ashes containing carbonato 
of potash or lime be mixed with the heap, tlio acid becomes fixed. Artificial 
nitre beds, called nitrieres, or nitre plantations, were first inti’oduced by the 
chemists of France to supply nitre for gunpowder during the wars of the 
Revolution, when the ports of France were blockaded by the English and 
imports prevented. Animal manure is mixed with carbonate of lime and wood 
ashes and frccpiently watered with urine, which produces much ammonia. This 
is cultivated for two or three years. In tro 2 iical countries the production of 
nitrates is more jdontiful and rajiid. A manure of a valuable quality could 
probably be made by municipalities or by the zamindars themselves by 
mixing jiounded kankar, or even marly soil, with manure and moistening it 
frequently during one or two hot seasons. If it wore moistened with liquid 
sewage, which would tend to pi’oduce more ammonia, the production would 
be increased. This artificial production is an exact imitation of what take.s 
place naturally in soils in which nitre is produced. In the Punjab nitrates 
elfioresce near villages where the soil becomes impregnated with animal sewage, 
which undei’goes nitrification in presence of the carbonate of lime and alkaline 
carbonate in the soil. The most plentiful sujijily is in the soil on the mounds 
that indicate the sites of old villages. This is the main source of the manufac¬ 
ture of saltpetre in the Punjab. Similarly, near buffalo ponds and watering- 
places for cattle, where dung is trodden into the soil, nitrates effloresce and are 
swept up) by the zamindars as manure. A similar process no doubt takes place 
when a field is well manured with animal refuse. The conditions of the pDroduc- 
tion of nitrate of lime in the soil are piresent, and this may account to some 
extent for the reclamation of alkali soils by manuring alone. For this puiqiose 
animal manures would be far superior to vegetable. In plants there is com¬ 
paratively little nitrogenous matter, which alone can generate nitrates or ammonia. 
In Utah a favourite manure is the refuse of slaughter-houses, which would be 
capable of sujqjlying large amounts of ammonia and nitrates. 
33. As regards the uses to which the alkali efflorescence might be put. 
Uses of reb sulphate of soda can easily be separated by evaporation 
and forms a useful pmrgative. It might bo piossible to 
utilize those more rich in alkaline suljohate for the manufacture of carbonate of 
soda for glass or soapi work. The average mixture of sodium chloride and 
sodium sulpdiate resembles the product of the first stepi of manufacture of this 
carbonate, which is done by the addition of sulpihuric acid to common salt. By 
evaporation the sulphate which crystallizes out first in saturated solutions made 
from efflorescence containing excess of sulpihate, can be freed from most of the 
common salt, and this would resemble the salt cake. The materials for the fur¬ 
ther reduction, charcoal and lime, would be readily available, the latter from the 
kankar beds. Certain 'soils contain carbonate of soda in such quantities that it 
can readily bo separated by the crystallization pu'ocess. At one time an enquiry 
was made as to whether the nitre manufacturers defrauded the revenue to any 
extent by disposing of the alimentary salt left in the refuse saltpetre earth after 
