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

Expansion Of Jo9its Ii is in the nature Of all ma
terial things to expand by heat, and with one or two
exceptions to contract By cold. Heat must be opposed
TO cohesion ; for when it enters into any body i. re-
moves the particles to L greater distance from each
other, as proved By the fact that a heated body occupies
more space than before. If heat therefore is opposed
TO cohesion, those substances expand the most in which
the influence of cohesion is felt the least and accord
ingly We find that 10 be the case. In solids the least
expan>;ou-in liquids greater than IL solids--in gaseous
substances the greatest.
Mus'rations.-Take Il 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, and !. will again pass through. The 'bo:iing
down of liquid, is but s vulgar 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 in winter q great
err amount Of oxygen may be obtained from a certain
quantity than in summer.
Appicctoas.--This property Of expansion and con-
traction of bodies has been applied to useful purposes
in the arts. The walls of a building in Paris had bulged
out, and were made 20 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 were then heat
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 iion. 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 ID
made smaller than the circumference Of the wheel, but
when heated it has expanded sufficiently to be slipped
on easily. To prevent 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 locsened wheel, and therefore fixes
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-
heit's 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,
must admit it when we consider the important phenome-
non. If contraction and therefore the density of water
continued until it Il became a solid-as all other LIQUIDS
do-the specific gravity of ice, therefore, being greater
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 plant
and animal would become forever extinct |! But it is
ordered otherwise, "a striking example, says Silliman,
'cf the wisdom of that Being who though he has made
great laws for the government Of matter, can make ex-
ceptions to them when the welfare Of His creatures re-
quire it, L. N. CoCNTRrMAN.
Niniuger, March god, 1858.