The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1886-07-24
Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.
THE FLOW OF METALS.

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THE FLOW OF METALS.
In one of his recent interesting lectures in Lon
don, Prof. Roberts Austen spoke of eight promi-
neut points of resemblance between metals and
fluids which have long been known. They are
the rejection of impurities on solidifcation, SUI
fusion, flow under pressure, changes due to CON-
preston, absorption of gases, absorption ofiquids
vaporization, and surface tension. Of these prop
critics perhaps the most astonishing are those ex-
hibited by metals when compressed. Placing
cold, powdered metals in powerful press, Prof.
W. Spring, of Liege, caused lead to weld into
solid mass by a pressure of IL tons per square
inch zinc, by 10 tons; tin, 81 tons; an
timony, 3S tons; aluminium, 80 tons; bismutn,
SO tons "copper" So tons. At SO tons per square
inch lead actually began to flow, and at Al tons
tin showed the same phenomenon. When pres
sure of more than so tons to the square inch was
given the metals under experiment flowed through
the fine cracks of the comprising chamber like
SO much treacle. Prof. Spring also proved that
the crystalline structure of metals may be changed
by pressure as by fusion; and that it is possible
even to build up alloys by pressure.
MYSTERY EXPLAINED.
Profs Ayrton and Perry the English electricians,
have accidentally observed that on amalgamation,
or coating with quicksilver, brass expands, so
that if one side only is amalgamated plate OF
brass becomes curved. They imagine that this
may be the primary cause of the phenomena OF
the Japanese "magic Mirror" which has cast on
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polished face, yet is mysteriously distinct in the
patch of light reflected by the mirrorupon screen.
Amalgamation would affect the thinner parts made
by the pattern more than the rest of the plate,
giving the mirror the imperceptible unevenness
that becomes plainly apparent in the reflected
image.
THE WASTE OF LIFE.
An English naturalist remarks that it is sad
reflection that while the turbot lays 100000
eggs, not more than one an average, ever lives
to reach maturity. In fish generally it takes
yearly at least hundred thousand eggs for each
individual to keep up the average of the species.
In frogs and amphibians few hundred are amply
sufficient. Reptiles often lay only much smaller
number. In birds, which hatch their own eggs
and feed their young, from ten to two eggs per an
mum are quite sufficient to replenish the earth
Among mammals three or four at a birth is a rare
number, and many of the larger sorts produce one
calf or foal at a time only. In the human race at
large, total of FIVE or six children for each mar
ried couple during whole lifetime makes up suf-
ciently for infant mortality and all other
of loss though among savages far higher rate
is usually necessary. In England an average OF
four and a-half children per family suces to keep
the population stationary.
FROGS SKIN ON MAN.
Skin from the back of frog has been used by
DR.. O. Petersen for fastening the healing OF
wounds. Crafts of the size of the thumb nail
were caused to firmly adhere in two days, and in
two days more the fermentation of the transplan.
ted skin had almost disappeared. The resulting
cicatrix is of great softness and elasticity Some
of the London hospitals now beginning to
employ frogs skin gratis in place of other skin
TREE-AGEs.
The researches of the Chief Forester of Prussia
have convinced him that no tree in the German
forests ever reaches so great age as 1000 years
He finds that the limit of sound life in the trees o.
Central Europe is as follows Pines, $40 years
the white fir, 429 years; the larch, 274 years the
mountain maple, 224 years the birch, 100 to 2O(
years; the ash ITO years the elm, 130 years
and the aspen, PIG years. famous linden in
Wurtemberg is said to be over 700 years old, but
it is withered ruin, and can hardly be regarded
as alive.
CLOUDS DEPENDENT UPON DUST.
Investigations by DIR. R. Won Helmvoltz, de-
scribed to the Berlin Royal Society, confirm the
statements that the formation of cloud in saturated
air is induced solely by particles of dust, and that
the finer and sparser the dust particles the
more slowly is the cloud formed. These results
are also conirmatory of Prof Tyndals expana-
ton that the blue color of the sky is due to float
ing dust.
MISCELLANEOUS
remarkably brilliant meteor was lately seen
in England, and two hours and half later SIM
liar phenomenon was witnessed in India, over
5000 miles away. 1t is suspected tina. the two
observations we're of the same meteor, about the
usual speed of meteors being indicated.
German physicist argues that the polar seas
must be higher in summer than in winter, when
the accumulation of ice increases the sadness,
sequenty also the density, of the water.
Wonderful progress is being made in microscop-
ical Society recently pointing out that results are
now attained which mathematcians five years
ago declared to be impossible.
native white mushroom of Natal attains a
diameter of from eighteen inches to two feet. 1t
makes delicious dish when fried, and is greatly
relished by the natives, who refuse the common
edible mushroom of the same localities.
A thorough scientific examination of the people
and prospective resources of the Crimea is to be
made by representatives of the Russian Govern
ment.