The Redwood gazette. [volume] (Redwood Falls, Minn.) 1873-1940, 1873-05-08
CarbOnic Acid i'm the Soil.

1t is we'll known to every one, that plants
derive much of their subsistence from the
air about them, and that their principal
articles of food are carbonic acid and
water. The presence of large quantities of
the former in the atmosphere during the
carboniferous period of geological history,
caused the plants of that time to attain
great luxuriance and enormous size. But
plants find also supply of carbonic acid
under the earth's surface, the solid earth
being in fact porous and permeated with
gas, of which the quantity increases with
the depth of soil. DIR. Pcttenkofer has
made some interesting experiments on this
subject in Munich. He first dug a pit
fourteen feet deep, and in this he placed
fine lead pipes of one fourth inch diameter,
and ending at different depths. The first
reached to the bottom of the pit; a second
went to depth of ten feet; a third about
eight feet; fourth five feet, and a fifth
two and one-fourth feet. The upper ends
of the tubes were carried into the labora-
tory, and connected with aspirators. After
filling the pit with the earth taken out,
and pounding it firmly down, it was found
that air could be drawn through all the
tubes just as easily as if the tubes were
suspended in the open air. In the course
of from two and one-half to three hours,
from thirteen to sixteen quarts of air were
drawn through the tubes; and the amount
of carbonic acid was determined by alb
sorbing it in baryta water. Observations
were made at all seasons of the year
and the quantity of carbonic acid was
found to be greatest in August and Sep
TENDER, when from fourteen to sixteen
parts of this gas were found in one thou
sand parts air from depth of fourteen
feet. The smallest quantity found at this
depth was Sin January, when three and
forty-six one-hundreth volumes of gas
were found in one thousand volumes of
air. The air nearer the surface contained
much less of the gas, except in the months
of June and July. The experimentor
thinks that this carbonic acid may he pro-
duced by organic processes in the soil,
being given off by living organisms of a
very low order. The fact that the amount
decreases as we come nearer the surface is
attributed to the diffusion of it into the
air, ventilation being less perfect in sum-
mer than in winter, as is the case in a
dwelling or elsewhere. Nearly the whole
amount of carbonic acid present in the
atmosphere, he thinks, comes from the
soil. 1t was noticed, by Schultze, in 1871,
that when the wind blew from the sea, the
percentage of this gas in the air was less
than when the wind had travelled over the
continent. Roscoe established the unex-
pected fact that all the furnaces and chin
neys in busy Manchester did not percept-
IDLY increase the amount of carbonic acid
in the atmosphere of the city; much less
could the manufactures scattered over the
continent explain the phenomenon OBJ.
served by Schultze. The supposition that
it is everywhere given off from the soil is
the only plausible explanation of it. We
hope to hear of the experiments being
repeated in different parts of our own
country, so that the results Of different
observers may he compared.-Scient!fc
Americ0n.