Vermont watchman and State journal. [volume] (Montpelier, Vt.) 1836-1883, 1846-05-07
From the American Agrculturist.
NECESSITY OF A KNOWLEDGE OF CHEM.
lCAL PRINCIPLES TO A FARMER

IL VIII be my object, in the few brief remarks I
intend to make in this paper, 10 illustrate BY some
FAMILIAR examples, The absolute necessity or n
knowledge of the principles of chemistry, 10 every
one who expects TO carry on the operations of The
iarm, or even domestic affairs successfully.
Hem Is one OF the great agents of nature in eff
iiectlng her changes, and modifying her results
What heat s, whether matter, some effect or re-.
suit OF matter, is yet unknown. Great heat ia nj
WAYS attended with light, and is probable that in
all ITS degrees, 1t inseparable from electricity and
perhaps is identical with it. But it is nv present
e6Ject simply to show, by some practicable exam.
pies OF every day occurrence, some of the laws by
which il acts.
Heat expands, with some slight exceptions, all
the objects into which it enters Thus n cold hand
is shriveed but warmed, it is more plnmn and
full. Every one knows that boot or shoe that is
100 tght Tor summer use, can be comfortably worn
IN the cold of winter. An ordinary metallic pendu
lum that Keeps correct time in summer, by its con-
traction, VIII beat too quick, and consequently pro.
duce fast time in winter An iron boil. when fas.
tened while hot will contract on becoming cold
and close up seam, which the power of man, with
the lever and screw, could not effect. The black
smith sets his iron on the wagon wheels while red
hot, and immediately cooling it, he sinks it some
times halt an inch on every side in the wood The
common thermometer Is another illustration of this
principle
Fluids partake largely of this expansibility BY
heat. But its effects more srikngy illustrated
IN air or gases, than In any other substances The
particles OF matter of which these are composed
are more easily separated and kept asnnder and
they feel the influence of heat in a wonderful de-
gree. A cubic inch of water when converted into
steam, occup es 100 times its original space even
when nearly of the same temperature. The nrin-
clple on which all steam engines propelled, is
solely mat OF the expansive power of water and
vapor by the application of heat Thus. the heat
yielded by handful OF wood, passing through
half inch iron boiler into water, and then expanded
into steam, will produce effect that the combined
strength Of 100 horses could not accomplish. Heat
produces nearly all the changes of weather. BY the
rarefactlon Tor expanslon OF the air, and the con-
sequent currents Of that fluid which necessarily
follow; for as the heated air becomes necessarily
lighter by expansion, and rises, heavier air PUSHES
In, frequently from an Immense distance, to supply
lis place, and hence storms and sometimes burri-
canes whose violence is proportiopatc TO their
cause; and so 1t the air suddenly loses its heat the
nelghborng warmer air hurries to supply the par-
tial vacuum
Heat (another form of electricity perhaps or in
all cases associated with l is also the great AGENT
of vegetable life, giving direction and effect to the
moisture and other elements of vegetables, when
the embryo plumules and cotycdons burst from the
germ; nor is It's vlvnying influence withheld for
moment from the growing plant till the entire work
OF reproduction Is accomplished, and the seed is
fully matured which is 10 perpetuate other genera
tons through the whole course of time.
The most striking exceptions TO the expansive
effects OF heat, are III clay and water below n GER
tam temperature. The former contracts through
the highest known temperature that can be given
to 1t; and a thermometer for furnaces called from
the name OF its inventor, Wedgwood has been con
structed from this material which is not injured bv
the most intense heat known. Water continues to
contract I'LL 1t reaches temperature of 80 deg.
Fahrenheit, when by merciiul exception to the
general law, It begins TO expand, and continues
TIL it reaches 81 deg, the freezing point when it
congeas. This keeps the cold water on the surface
till 1t freezes, and this change Of the liquid into a
solid, still farther dminlshes the density thus keep
ing the whole body Of water in lakes and rivers
beneath. IN condition to minister both SUPPORT to
its inhabitants, and the wants of man, and allow
the surplus water TO pass off towards the ocean.
The admission and retention of heat in bodies, is
much affected by their substance and surface A
dense body will receive and retain more heat than
such as are light and porous. rough surface i'm
blbes heat much quicker than Il smooth one, when
exposed 10 the rays of the sun or a fire and when
at higher temperature than the surrounding at.
mosphere, parts with its surplus heat more readily
than such as are smooth. The color of bodies has
much to do with receiving and repeing heat, and
retaining or parting with it. black surface, when
exposed to high temperature, soon becomes hot,
while such as are white, require much longer
time, under similar exposure, to reach the same
temperature. Many substances of neatly equal
density conduct heat with much greater facility than
others. Let us consider, for moment, some beau
titul examples of the application of these laws.
Animals and birds inhabtng the arctic regions.
where the cold is intense, not only covered with
thick fur and down, both OF which are the best
known conductors OF heat; but on the approach of
Writer most OF these changes TO a whIte color
which OF all others Is the worst conductor. During
great portion OF all artic winter, there is abso-
lutey no sun, and for the remaining portion but a
/ nj m of ic ~ Il
living things IN that region therefore, is generated
within the covering OF fur feathers by the COM
| bnation OF the carbon OF the blood derived from
their food, and the oxygen of the air inhaled into
| the lungs and all Of which heat is most economi-
cally husbanded for the comfort and preservation
of the living being.
The warm-blooded animals that live in the Arc
! tic ocean, whales, porpoises, SEALS walruses &c,
are not less protected than those on land though in
different manner. Fur or feathers, if constantly
| Immersed in water, would after time admit ii
| next the body, when rapid lowering of lis tenn
perature would take place. Almighty wisdom has
| guarded the animals which live IN that element in
manner totally different, yet equally effectual with
| such as live in the air. They have smooth ma
! ked skin, or sometimes covered with a thin hair
winch Is no impeachment to their rapid passage
through the water; and underneath is thick GOV.
erlng of fat, which, though vastly denser than fur
or feathers, is nearly equal in its non-conductng
Pi"PeItes' 90, 100, IN our own climate, the hog
which Is the only animal not sufficiently protected
against the rgors of winter by an external cover
ing, takes care to supply this deficiency effectuay,
| IL allowed TO indulge his gormandzins propensi.
ties, by loading the exterior of his carcass, imme.
dalely under his skin, with thick coating of fat
The temperature of the human being has to be
provided for, through the extremes of winter and
summer, by external clothing, though in extreme
hot weather. portion of this excessive heat is car
ried of by persplration, which involves another
beautiful principle OF chemistry, that we have moi
| time at present TO illustrate. Black is the warmesl