The mirror. (Stillwater, Minn.) 1894-1925, 1916-09-14
o:-Wlll you please explain the of the barometer?

$1,000.
o:-W you please explain the use of the barometera-
A:-lhe discovery that air has weight announced by
an Italian, Torrcel in 1913 By tube which now
bears his name ne found that the the atmosphere Is
sufficient to support column of mercury 80 inches high
Subsequent study by other scientists revealed the
height of column varies weather that moist
air is lighter than dry air and the mercury rises therefore,
In dry air and falls the humidity of increases With
the discovery of this fact became possible by means of the
instrument the relative of moisture in the
and to determine the altitude above level any
given place for the reason that atmospheric pressure
at sea level and gradually dimnhes the altitude increases
lhe barometer is used considerable in making
weather forecasts rapidly rising barometer indicative of
unsetteded weather; gradual rise indicates settled condition
OF weather and rapid fall gives warning of stormy
he instrument consists essentially of glass tube about 80
inches long, closed at end 1t filled with mercury
open end is then immersed open vessel containing
curry The pressure of the atmosphere retains column of
mercury in the tube and determines the which rises
he weight OF the column in the tube is all times equal
that of similar column of air. extending from the level
open vessel to the top of the atmosphere.
Q:-An article stating that liquid air is being used for
mining came to attention recently. Would you kindly
publish in your "Ouery Column the method of EMPLOYING it
as baser for minng-E. H. A.
ALqud air has been used increasingly in Germany for
blasting since the outbreak of the and satisfactory
it been found that doubtless will more after the
One advantage that liquid air has other explosives
the safety with which it be handled. In blasting black
mouseke bags which called cartridges saturated with
liquid air and used charges. Though the cartridges
is powerful than ordinary charge of dynamite can be
amped under foot without danger Kissing sound like
escaping steam being the only noise produced. The miners
take several of these cartridges and with stick jam
hole that has been drilled into the rock Then
poson about to take place and the rocks about
hurled in direction, the miners hurry shelter. The
Oft
figures the liquid under present methods of
ture, about one half as much dynamite.
O:-Edito of Mirror: Would you kindly give solution to
these two problems, if is possible for you do
CD How many kilos of so degrees centigrade will
be required melt 20 ko of ice and bring quantity
of water to a temperature of 10 degrees centgrade.
(2 If two pounds of condenes in radiator and i'm
parts its heat the air Of Is II II feet many
degrees centigrade will the air be warmed?-T. J..
Al herewith toward you the the problems
which not answered in last ISSUE The party wishes
know how many kilos of 50 deg will 20
kos of ice and bring the total quantity temperature of 10
deg cent The however, fails give the temperature
of the ce which would be important for a solution
thus take for granted that he the of the
ice the melting point.
Soution:-
20 kilos = 20 900 grams the amount of heat-un
which required to melt the ice will be:
10000 so = $780, 900 caaories French unit of heaD
Dividing the temperature by the will give the
kios required melt the ice which in this will
1,6 $1,000: so = 81, 900 grams 80 kos.
In order to find the amount of so deg
qured bring the total quantity temperature of 10 deg.
it only necessary multiply the total quantity by 10
and divide the product by So which will be-
$4,000 & 20, 600 10 = 10. 400 grams 10. A kos.
so
Adding 30 kos and 1914 klo together gives the rough
answer. The thus is 49, klo at so
deg
In the second question he wishes know how many deg
will the air be warmed in Is - II by
densng pounds of radiator Again he fails
give the PRESSURE for he should bear in mind that
80 pounds gauge pressure will give than
lower pressure For this solution therefore take
atmospheric pressure Q4.7 pounds).
Solution:-
Specific heat of air = 02375. A IS II IL
900 cubic it, of air. The weight of this air will be
5000 08 2448 pounds, since air under ordinary condi
tions weighs .08 pounds per cubic foot.
SOL of Prob o.
during condensation 966 B. T. US 1882 B. T. US.
which in this will be 49, deg. Fahr In words, the
said will rise 49, deg. Fah the
amount if expressed in deg.
N. B. In this problem is taken of the heat
used up by fixtures etc.. which in actual experiments
would need to be considerable. c. L.
UNANSWERED QUERIES