ON THE NITROGEN OF PLANTS. 
235 
tained a quantity decidedly greater than those which formed 
the surface. 
It is worthy of observation, that the ammonia contained in 
rain and snow water, possessed an offensive smell of perspira- 
tion, and animal excrement, — a fact which leaves no doubt 
respecting its origin. 
Hunefeld has proved, that all the springs in Greifswalde, 
Wick, Eldena, and Kostenhagen, contain carbonate and ni- 
trate of ammonia. Ammoniacal salts have been discovered 
in many mineral springs in Kissingen and other places. 
The ammonia of these salts can only arise from the atmos- 
phere. 
Any one may satisfy himself of the presence of ammonia 
in rain, by simply adding a little sulphuric or muriatic acid 
to a quantity of rain-water, and evaporating this nearly to 
dryness in a clean porcelain basin. The ammonia remains in 
the residue, in combination with the acid employed ; and 
may be detected either by the addition of a little chloride of 
platinum, or more simply by a little powdered lime, 
which separates the ammonia, and thus renders its peculiar 
pungent smell sensible. The sensation which is perceived 
upon moistening the hand with rain-water, so different from 
that produced by pure distilled water, and to which the term 
softness is vulgarly applied, is also due to the carbonate of 
ammonia contained in the former. 
The ammonia, which is removed from the atmosphere by 
rain and other causes, is as constantly replaced by the putre- 
faction of animal and vegetable matters. A certain portion of 
that which falls with the rain, evaporates again with the water; 
but another is, we suppose, taken up by the roots of plants, 
and, entering into new combinations in the different organs 
of assimilation, produces albumen, gluten, quinine, morphia, 
cyanogen, and a number of other compounds containing ni- 
trogen. The chemical characters of ammonia render it capa- 
ble of entering into such combinations, and of undergoing 
