225 
CULTURAL CHEMISTRY. 
{Continued from page 204.) 
In the preceding number, an attempt was made to expose the mistake of that 
modern theory, which assumes that the leaves of plants absorb the gases that float in 
the air, and thus become the channels through which the organic substances that 
form their nutriment, are introduced into their tissues. Woody matter constitutes 
the bulk and strength of trees and shrubs ; and it is reasonable to suppose, that the 
ligneous principle is derived from carbonic acid. Wood is the origin of charcoal 
(carbon), so far as the works of man are concerned : whether — if reference be made to 
first causes — the order should be reversed, or not, does not belong to the present 
inquiry. For that, it need only be stated that there are two direct gaseous compounds 
of carbon with oxygen : — First, carbon the base, with one equivalent of oxygen, which 
combination produces carbonic oxide, a gas that abounds in all furnaces, where com- 
bustion proceeds slowly and at low temperatures, causing much waste and loss of 
fuel in all our forcing-houses. Second, carbon as the base, with two equivalents of 
oxygen, constituting carbonic acid — the product of perfect combustion — a gas de- 
structive of animal life, but congenial to vegetable nature, if applied in those due 
proportions which nature ever supplies, when man performs his part by the introduc- 
tion of decomposable manures into the body of the soil. Carbonic acid is always 
generated in large quantity, when organic matter undergoes fermentive decomposi- 
tion ; and its constant presence in the atmosphere, has induced the belief to which 
we have above referred. The other organic elements of organic structure are oxygen, 
the vitalising principle of atmospheric air ; nitrogen or azote, the qualifying or 
diluting principle (if the terms be allowed) of the air, by which, in all climates and 
in all situations, it is fitted to support the functions of breathing-life ; and hydrogen, 
the lightest of all gases, and the grand base of pure water. Three volumes of 
hydrogen gas and one volume of azote, condensed in bulk to two volumes, that is to 
one half, constitute ammoniacal gas, which is also, to a very limited extent, present 
in atmospheric air ; but this gas, and likewise carbonic acid gas, being very easily 
soluble in water, are brought down to the earth by mists, fogs, and every falling 
shower. With these facts, before the dismissal of farther inquiries connected with 
the organic constituents of vegetable structure, it will be just to the modern theory 
to state, that, among the many experiments which are inadmissible, there are others 
that appear to have been performed upon principles so correct to nature, as to have 
given fair sanction to the theory, that plants absorb gaseous elements through the 
porous system of their leaves. One of these has thus been cited in the French 
periodical " Illustration, Journal Universel," of September 30th : — " About five years 
since, an English agricultural teacher (agronome) put 100 kilogrammes (say 220 lbs.) 
of earth, previously dried in an oven, into an earthen vessel. The earth was 
VOL. XV. NO. CLXXVIII. G G 
