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NECESSITY OF A KNOWLEDGE OF CHEMICAL PRINCIPLES TO A FARMER. 
NECESSITY OF A KNOWLEDGE OF CHEMI¬ 
CAL PRINCIPLES TO A FARMER. 
It will be my object, in the few brief remarks I 
intend to make in this paper, to illustrate, by some 
familiar - examples, the absolute necessity of a 
knowledge of the principles of chemistry, to every 
one who expects to carry on the operations of the 
farm, or even domestic affairs successfully. 
Heat is one of the great agents of nature in ef¬ 
fecting her changes, and modifying her results. 
What heat is, whether matter, or some effect or 
result of matter, is yet unknown. Great heat is 
always attended with light, and it is probable that, in 
all its degrees, it is inseparable from electricity, and 
perhaps is identical with it. But it is my present 
object simply to show, by some practicable exam¬ 
ples of every day occurrence, some of the laws by 
which it acts. 
Heat expands, with some slight exceptions, all 
the objects into which it enters. Thus, a cold 
hand is shrivelled ; but warmed, it is more plump 
and full. Every one knows that a boot or shoe 
that is too tight for summer use, can be comforta¬ 
bly worn in the cold of winter. An ordinary me¬ 
tallic pendulum that keeps correct time in summer, 
by its contraction, will beat too quick, and conse¬ 
quently produce fast time in winter. An iron bolt, 
when fastened while hot, will contract on becom¬ 
ing cold, and close up a seam, which the power of 
man, with the lever and screw, could not effect. 
The blacksmith sets his iron on the wagon wheels 
while red hot, and immediately cooling it, he sinks 
it sometimes half an inch on every side in the 
wood. The common thermometer is another illus¬ 
tration of this principle. 
Fluids partake largely of this expansibility by 
heat. But its effects are more strikingly 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 asunder, and 
they feel the influence of heat in a wonderful de¬ 
gree. A cubic inch of water when converted into 
steam occupies 1700 times its original space, even 
when nearly of the same temperature. The princi¬ 
ple on which all steam engines are propelled, is 
solely that of the expansive power of -water and 
vapor by the application of heat. Thus, the heat 
yielded by a handful of wood, passing through a 
half-inch iron boiler into water, and then expanded 
into steam, will produce an effect that the combined 
strength of 100 horses could not accomplish. 
Heat produces nearly all the changes of weather, 
by the rarefaction (or expansion) of the air, and 
the consequent currents of that fluid which necessa¬ 
rily follow; for as the heated air becomes neces¬ 
sarily lighter by expansion, and rises, heavier air 
rushes in, frequently from an immense distance, to 
supply its place, and hence storms and sometimes 
hurricanes, whose violence is proportionate to their 
cause ; and so if the air suddenly loses its heat, the 
neighboring warmer air hurries to supply the par¬ 
tial vacuum. 
Heat (another form of electricity perhaps, or in 
all cases associated with it), 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 cotyledons burst from the 
germ ; nor is its vivifying influence withheld for a ^ 
moment from the growing plant, till the entire work 
of reproduction is accomplished, and the seed is 
fully matured which i^to perpetuate other genera¬ 
tions through the whole course of time. 
The most striking, exceptions to the expansive 
effects of heat, are in clay, and water below a cer¬ 
tain temperature. The former contracts through the 
highest known temperature that can be given to it; 
and a thermometer for furnaces, called, from the 
name of its inventor, Wedgwood, has been con¬ 
structed from this material, which is not injured 
by the most intense heat known. Water con¬ 
tinues to contract till it reaches a temperature of 
39° Fahrenheit, when by a merciful exception 
to the general law, it begins to expand, and con¬ 
tinues till it reaches 32°, the freezing point, 
when it congeals. This keeps the cold water on 
the surface till it freezes, and this change of 
the liquid into a solid still farther diminishes 
the density, thus keeping the whole body of 
water in lakes and rivers beneath, in a 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. A rough surface 
imbibes heat much quicker than a smooth one 
when exposed to the rays of the sun or a fire ; and 
when at a higher temperature than the surrounding 
atmosphere, parts with its surplus heat more 
readily than such as are smooth. The color oi 
bodies has much to do with receiving and repel¬ 
ling heat, and retaining or parting with it. A black 
surface, when exposed to a high temperature,, soon 
becomes hot, while such as are white require a 
much longer time, under similar exposure, to reach 
the same temperature. Many substances of nearly 
equal density conduct heat with much greater faci¬ 
lity than others. L,et us consider for a moment some 
beautiful examples of the application of these laws. 
Animals and birds inhabiting the arctic regions, 
where the cold is intense, are not only covered with 
thick fur and down, both of which are the best 
known conductors of heat, but on the approach of 
winter most of these change to a white color, 
which of all others is the worst conductor. Du^ 
ring a great portion of an arctic winter, there is ab¬ 
solutely no sun, and for the remaining portion but 
a mere glimmering of his rays. All the warmth of 
living things in that region, therefore, is generated 
within the covering of fur or feathers, by the com¬ 
bination 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 Arctic 
ocean, whales, porpoises, seals, walruses, &c., &c., 
are not les«s protected than those on land, though in 
a different manner. Fur or feathers, if constantly 
immersed in water, would after a time admit it 
next the body, when a rapid lowering of its tem¬ 
perature would take place. Almighty wisdom has 
guarded the animals which live in that element in 
a manner totally different, yet equally effectual with 
such as live in the air. They have a smooth, 
