Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1882-06-03


soil itself second, that generated during
the chemical processo of oxidation and decay,
and third, the heating effects of the suns
RAYS. It is an undoubted fact that the
earth was at one time mass OF molten
matter, and that the exterior crust was
formed by gradual cooling from the sur
face inward. That this heat still exists IN
the mass of the earth cannot be doubted.
Molten volcanic lava, emissions OF steam
from the interior Of the earth, and the hot
springs and geysers all point TO the general
conclusion that there is still great heat
locked up IN the inner reCesses Of the earth.
1t is held By scientists that the evapora-
ton Of heat from the surface of the earth IS
so great that the whole surface would be
constantly frozen were 1t not Tor the heat
derived from the sun. Most Of the per
ceptible heat Of the earth's surface is d.
rectly owing to the heat absorbed by the
earth from the suns rays. As we all know,
the temperature of the earth's surface varies
with the season. and these, in turn, depend
upon the distance between, and the relative
positions of the earth and the sun. The
point OF unvarying temperature ID that
loss of heat from the interior is compen-
stated by that gained from the sun, so that
the changes are reduced to a minimum. 1t
is u noticeable fact that the temperature OF
the earth's crust perceptibly increases as
we proceed toward the center. This fact
is made most unmistakably apparent at a
depth OF only few thousand feet below the
surface. The heat arising from the oxlda-
ton and
DECAY or VEGETABLE AND OTHER ORGANIC
MATTER
Is directly proportional TO the amount Of
such matter in the soil. The heat evolved
by decaying vegetation is considerable, but
it seems probable that, inasmuch as decay
cannot proceed except the temperature be
high enough to conduce tovegetable growth,
the heat generated by such decay is not
directly effective in the soil, and therefore
that the main source OF heat in the soil is
the sun. This being the case, 1t must read
lily be perceived that the amount OF heat
accumulated in the soil depends upon the
absorptive capacity of the ingredients Of
the surface soil. The effect of the suns
rays is very different on different objects.
For instance, it's heating effects on the up
per surface of water, and by radiation
through the atmosphere, are comparatively
small, while many solids not only readily
absorb heat, but also accumulate it to such
an extent as to burn the hand when applied
to them. During the constant evaporation
of water from the soil surface large amount
OF heat is rendered latent /; that is, is alb
sorbed during the conversion of the liquid
into the vapor of water. This result of
evaporation is one which, while of the ut
most Importance, isnot generally understood
by the farmer; and, in fact, is hardly guessed
by the average husbandman. 1t IS a well
known chemical phenomenon that ice the
solid form of water-absorbs or renders
latent $40 thermal units Of heat in passing
from the solid into the liquid state Ia
thermal unit is the heat required to raise
a given body through one degree Of TEN.
perature in one minute and that in passing
from the liquid to the gaseous state 972
thermal units are absorbed. To illustrate ::
if piece of ice which is at temperature
Of 80 Fahrenheit be placed over lamp so
regulated as to raise the temperature one
degree every minute, the ice would con-
Of which time it would all have been
liquifed, and in so doing would have alb
sorbed the 40 units of heat given off by
the lamp during the time-l40 minutes. If
the same increase Of temperature had been
kept up for 972 minutes longer, the water
would have all been converted into steam
with the docking up" of 972 thermal
units OF heat. The conversion of steam
into liquid, and water into ice, are followed
by freeing OF the heat rendered latent
during the reverse processes. We may
easily apply this principle to the
EVAPORATION,
Which is almost continually going on from
the surface OF the soil. Since, as we nave
seen, in converting liquids into gases heat
is rendered latent, or neutralized, an al
most incredible amount of heat must be
distracted from the soil by the evapora-
ton of liquid water. Were it not for the
constant extraction OF heat by the evapora-
ton continually taking place during the
hot season the soil would literally become
an oven, and all plants would be scorched
to death. We can apply the same explana-
quired to produce sunstroke in different
localities. The difference in the effects OF
the same temperature in different localities
iB owing entirely to the amount of
moisture in the atmosphere. 1t is well
known that in a dry atmosphere men will
successfully Withstand five to ten degrees
higher temperature than they could in
localities where the atmosphere is
more or less humid, and where much
lower temperatures are often fol-
lowed by sunstrokes. This is owing
to the fact that in dry atmosphere evap-
grafton goes on rapidly from the surface of
the body, and the heat, which is rendered
latent during this operation and which is
virtually extracted from the body, reduces
the temperature so low as to precluded the
possibility OF sunstroke. In the case of a
humid atmosphere, evaporation, owing
to the amount of moisture already in the
atmosphere, can not take place to any ex-
tent, and therefore the heat, instead Of
being extracted from the body accumu-
lates and to such extent as to render man
and horse alike very susceptible to sun
stroke. This also accounts for the fact
that we of the interior and dry localities OF
CaulOTnla Will Haruly reuaIh aDOut LeiH-
perature which in the Eastern States is Of
ten accompanied by sunstrokes. The in
portance to the agriculturist of the alb
sorption and freeing of heat during evap-
Grafton and condensation, can hardly be
overestimated. He can utilize the knowl-
edge in the spring as well as IN the summer.
IN THE SPRING,
When it is OF the greatest importance that
the soil should become warm so az to start
the seed, it is necessary that the evapors.
ton be reduced to minimum, in order
that the heat may accumulate in the soil
instead of becoming latent. Bat the farmer
says. ~ must have my land dried, and how
can dry it without surface evaporation ?"
The way to do it is to under-drain thor
oughly, 80 that the water will never stand
any longer on the surface of the ground in
spring than can be helped. By this means
the surface evaporation will be reduced and
the escape of heat prevented. We will
have occasion to speak again of this subject
when we come to consider drainage. In
IL L