The emigrant aid journal of Minnesota. [volume] (Nininger City, Minn. Terr. [i.e. Minn.]) 1856-1858, 1858-03-24
For the Emisrant Aid Journal.
Curtosi(ies Of Science.-NO. 8.

Expansion If LoRits IL is in the nature Of all ma
serial things to expand by heat, and with one or two
exceptions to contract BY cold. Heat must be opposed
10 cohesion for when it enters into any body il re-
moves the PARTICLES TO = greater distance from each
other, rs proved b the fact that = heated body occupies
more space than before. If heat therefore is opposed
70 cohesion, those substances expand the most in which
the influence Of cohesion is felt the least and accord
ingly we find that 20 be the case. n solids the least
expaa>;ou-in liquids greater than It sollds--ln gaseous
substances the greatest.
Observation-Disclosures & bolt, and a ring in which the
bolt will exactly fit when cold. When the bolt IS heat
ed, it will no. pass through the ring. Then heat the
ring, sud !. will again pass through. The boiling
down Of liquids is but s vulg gar term for evaporation
or expansion Of them. The expansion of the air Is
shown in two ways. A cubic foot Of air IN winter
weighs heavier than in summer Or i'll winter q great
err amount Of oxygen may be obtained from a certain
quantity than in summer.
applications. This properly Of expansion and con-
traction of bodies has been applied to useful purposes
in the arts. The walls of Il building in Paris had bu!ged
out, ana were made 80 assume their upright position by
an application Of this principle. Holes were made in
opposite walls. and iron bars thrown across having
screws for large screw.nuts. The rods we're then heat
80 'N
ed by means Of argand lamps, and the nuts screwed
tight to the outer sides Of the walls. Being then al
lowed to cool, the walls were brought towards each other
by the invisible but irresistible power Of contraction,
or, what is the same, cohe ion. A repetition of this
same operation finally brought the wall to a perpendicu-
lar. The rivets for steam boilers are put in when hot,
that they may hold the parts more firmly together when
cold. The very common method Of fastening on wagon
tires is an application Of this principle. The tire IL
made smaller than the circumference Of the wheel, but
when heated it has expanded sufficiently to be slipped
On easily. To proven; burning the wood, it is rolled
through water, which also suddenly contracts the iron
band to its original diameter; Tightening, by its un'
Welding grasp, the ioosened wheel, and therefore axes
itself firmly upon it.
Water expands when heated in the form Of vapor,
and if the heat be continued, it will entirely disappear
Cold also contracts the vapor, and it becomes water
again. The contraction is continued with the fall of the
temperature to near the freezing point $500 Of Fahren-
belts scale) when it begins again to expand, and in the
form of ice has expanded l-ll,h Of its volume. This
is an exception to the general law; for it follows the
Law until near the freezing point, and then fortunately
for all animate creation, it begins to expand
There is G wise exhibition of Providence in all this
and we, whether able or unable to explain the cause
rnust admit it when we consider the important phenome
non. If contraction and therefore the density of water
continued until it became q solid-as all other liquid.
ao-the specific gravity of ice, therefore, being create.
than water, it would sink to the bottom in a succession
Of layers, until every pond and lake and river and sea
would become solid. The earth, now the abode of sen
tient and happy beings, would be quite uninhabitable
would become 4 dread waste and every living plan,
and animal would become forever extinct But it il
ordered otherwise, "a striking example, says Silliman
scf the wisdom Of that Being who though he has mad.
great laws for the government Of matter, can make ex
ccpticns TO them when The welfare Of His creatures re
quire it. l.. N. CoCNTRrMAN.
Ninirger, March god, 1855.