2 HOW CROPS FEED. 
of ammonia, which copiously escapes in the form of car- 
bonate, and may be separated by distillation. 
When bones are heated in close vessels, as in the manu- 
facture of bone-black or bone-char for sugar refining, the 
liquid product of the distillation is strongly charged with 
carbonate of ammonia. 
Commercial ammonia is mostly derived, at present, from 
the distillation of bituminous coal, and is a bye-product of 
the manufacture of illuminating gas. The gases and va- 
pors that issue from the gas-retort in which the coal is heat- 
ed to redness, are washed by passing through water. This 
wash water is always found to contain a small quantity of 
ammonia, which may be cheaply utilized 
The exhalations of volcanoes and fumeroles likewise 
contain ammonia, which is probably formed in a similar 
manner. 
In the processes of combustion and decay the elements 
of the organic matters are thrown into new groupings, 
which are mostly simpler in composition than the original 
substances. A portion of nitrogen and a corresponding 
portion of hydrogen then associate themselves to form am- 
monia. 
Ammonia is a Strong Alkaline Base.—Those bases 
which have in general the strongest affinity for acids, are 
potash, soda,and ammonia. These bodies are very similar 
in many of their most obvious characters, and are collec- 
tively denominated the alkalies. They are alike freely 
soluble in water, have a bitter, burning taste, alike corrode 
the skin and blister the tongue; and, united with acids, 
form the most permanent saline compounds, or salts. 
Carbonate of Ammonia,—If a bottle be filled with car. 
bonic acid, (by holding it inverted over a candle until the 
latter becomes extinguished when passed a little way into 
the bottle,) and its mouth be applied to that of a vessel 
containing ammonia gas, the two invisible airs at once 
