212 
THE CULTIVATOR. 
July. 
Foreign Correspondence. 
NITROGEN. 
Munich, Bavaria, May, 1854. 
Messrs. Editors —The nature of the sources of the 
food of vegetables is a topic of deep interest to the 
farmer who is intelligent in the study and pursuit of 
his profession. But a very few years have elapsed 
since this subject began to excite the altention of those 
capable of subjecting it to a successful examination, 
and to-day we are in the midst of an era which is oc¬ 
cupied with solving the problem. Already so much is 
known with regard to this matter as to furnish one of 
the most interesting chapters in physical science. 
Yet from year to year the formerly received principles 
require extension and correction from the results ox 
new researches. 
The farmer knows that the muscle which sustains 
his labor, and the nerve which impels and guides it, 
contain as an invariable and essential ingredient, a 
substance called azote, or nitrogen. lie knows that it 
must be contained in his food in order that it support 
life, and of course also must be obtainable by the 
vegetable which is the only ultimate source of animal 
nutrition. It is assumed as a general thing that the 
chief hindrance to perfect vegetable development is a 
deficiency of this body, or at least a deficiency of those 
forms of it which are capable of giving it to the 
plant. 
Chemistry teaches that there occur in nature, but 
three bodies which can directly supply the vegetable 
kingdom with the nitrogen needful for its growth. 
These are, 1st, the free nitrogen of the atmosphere; 2d, 
ammonia, existing in air, in water and in the soil; and 
3d, nitric acid in union with ammonia, potash, soda, or 
lime, in the atmosphere, in water or in soils. 
It is proposed in this paper briefly to review the 
facts and doctrines hitherto received concerning the 
availability of each of these bodies us sources of vege¬ 
table nutrition, and to bring forward the interesting 
results of recent investigations. 
1. To what extent is atmospheric nitrogen directly 
assimilable by plants ? 
Four-fifths of the air which constantly bathes the 
leaves of plants is nitrogen.* *The result of nearly 
every one of the earlier investigations was, however, 
that this nitrogen does not contribute directly to vege¬ 
table growth, and accordingly in the standard treatises 
on the chemistry of vegetation it is accepted as a fact 
that nitrogen is acquired by the plant from other 
sources. Boussingault, indeed, was led by some of his 
grand trials to suppose that atmospheric nitrogen 
might be directly absorbable, but hi3 results have been 
usually explained in another way. Very recently in- 
* The mixture known as atmospheric air, is coipposed, 
under almost all circumstances, quite uniformly as follows : 
In 10,000 parts, 
Nitrogen,..A 7012 
Oxygen,.2080 
Carbonic acid,... 4 
Carburetled hydrogen,. 4 
Ammonia,. trace. 
vestigations have led to the fact that the 1 nitrogen of 
common air is actually absorbed and assimilated by 
plants. Dr. Knop of Leipzig, in a series of experi¬ 
ments upon aquatic plants, found that shoots of the 
common “■cat-tail,” when brought into glass vessels, 
inverted in water and partly filled with an air consist¬ 
ing | of nitrogen and h of oxygen' (in such proportions 
are oxygen and nitrogen found in the air which is dis¬ 
solved in spring water) in a short time completely ab¬ 
sorbed it. During the last twoseasons Ville, a French 
chemist, has experimented with tobacco, the sunflower, 
and wheat, in the following manner. He sowed seeds 
of these plants in soil tree from all nitrogen, viz., pure 
sand mixed with the ashes of the plant experimented 
with, and contained in a glass chamber, the air of 
which was statedly renewed. He determined accurate¬ 
ly the small quantity of nitrogen which the imprison¬ 
ed plants could receive from the ammonia of the air 
admitted to them; be also found how much the seeds 
sown originally contained : the sum of these two, how¬ 
ever, in every case fell short of the amount of nitrogen 
existing in the piants at the conclusion of the experi¬ 
ment. The difference so far as can be seen must have 
been furnished by the atmospheric nitrogen. 
The only report of his experiments that I have seen 
does not afford any data for ascertaining what plants 
assimilate the nitrogen most readily, and therefore 
stand least in need of artificial nitrogenous manures; 
but we may hope before long to learn many facts of 
practical importance from the prosecution of similar 
but more extended inquiries. 
2. What part does ammonia and its compounds play 
in vegetable development 2 
By whatever natural process animal and vegetable 
matters containing nitrogen are destroyed, whether by 
undergoing the changes that accompany animal nutri¬ 
tion, by burning, or by decay, their nitrogen is con¬ 
verted into the compound called ammonia. In nature 
ammonia always is found in the state of carbonate 
(salts of hartshorn, smelling salts) which as well known 
is so volatile as to diffuse itself rapidly through the 
air, and as nitrate which is highly soluble in water 
but not volatile. Ammonia itself is a compound of 
nitrogen and hydrogen. According to Mulder, the 
humus, or vegetable matter of the soil devoid of nir 
trogen, in its decay evolves free hydrogen, which at 
the moment, unites with atmospheric nitrogen, pro¬ 
ducing ammonia. The animal kingdom furnishes in¬ 
directly a large share of the ammonia that occurs in 
nature. The muscles, nerves, and other tissues of an 
animal, as is well known, are constantly wasting as a 
result of their use, and as constantly being renewed 
frprn the materials of the food. In the animal as well 
as vegetable, the carbon, hydrogen and oxygen of the 
food are mostly reduced to bodies of very simple con- 
stitution, as carbonic acid and water, and in these 
shapes separated from the system through the lungs, 
(leaves) or by the perspiratory process through the 
skin. In the animal, however, the used-up nitrogen is 
not excreted as gaseous 'ammonia, for that would be 
10,000 
