The Romance of Modern Chemistry
Forfatter: James C. Phillip
År: 1912
Forlag: Seeley, Service & Co. Limited
Sted: London
Sider: 347
UDK: 540 Phi
A Description in non-technical Language of the diverse and wonderful ways in which chemical forces are at work and of their manifold application in modern life.
With 29 illustrations & 15 diagrams.
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CHEMISTRY AND AGRICULTURE
in vegetable tissue only to a small extent, is an important
and indeed essential constituent. The reader might
suppose that the natural source of nitrogenous food for
the plant would be the atmosphere, with its vast stock of
nitrogen. It is conceivable that the leaves might take in
and assimilate the nitrogen of the air, just as they deal
with the carbon dioxide, which is so much more scarce.
There are some who have supposed that this really takes
place, but the bulk of the evidence shows that the leaves
of plants generally are unable to digest nitrogen when it
is presented to them in the form of the element itself.
Atmospheric nitrogen, however, does ultimately reach
the tissues of some plants, but by a very indirect road,
via the soil and the roots. Leguminous plants, such
as peas and vetches, are provided with exceptional
apparatus for assimilating nitrogen, in the shape of
swellings or “nodules11 on their roots. These nodules
contain micro-organisms which have the power of taking
in atmospheric nitrogen, and so manipulating it as to
render it suitable for use as food by the plant. The
majority of plants, however, are destitute of these para-
sitic attendants, and are unable to utilise atmospheric
nitrogen directly; they appear to find this element most
digestible when it is presented to them in the form of a
salt, such as a nitrate. Nitrates are readily taken up
from the soil by plants, and the nitrogen is subsequently
transformed into the complex nitrogenous constituents of
the plant tissues by various chemical processes which at
present are not within our knowledge, far less our power
of imitation. In comparison with the practical chemistry
which goes on in the cells of plants, the methods of the
chemist are elementary and crude, and he may well feel
humble in view of the complex and delicate processes
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