The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1900-02-17
Correspondence Baltimore County Union.
SCIENTIFIC MIS- CELLANY.

SCIENTIFIC MIS- CELLANT.
Fire-Resisting Construction = @ pp r
Mines of 2, 900 Years Ago-Fungus De-
struction of Locusts-A Year in Radio
graphy-An Industrial Opening-Quick-
Growing Timber-Life History of Hoist
ing Ropes-Water-Solu Mercury
Mans Muscle.
report by the British Fire Prevention Com
mittee gives interesting results of recent test
of ireproofed floor and ceiling. The floor was
Of 9-inch wooden beams, close-bedded, the joints
being stopped with fire-clay, and this was sub
jected for one hour to fierce fire, reaching a
temperature of 1862 F., with no damage be-
yond the charring of the under surface of the
beams to a depth of two inches. The ceiling
was heated to 5O0o f. for half an hour, then the
temperature was slowly raised to 1,5OO' F. The
materials-laths and asbestic-were but little
injured, and were not damaged by the water
used for putting out the fire, while no portion
fell. The surface was cracked, however, while
some of the laths were little charred
Ruins of the most ancient mines in history
still exist. These arc the copper mines of Sinai,
which were worked from about 5000 to 1900 OF
1900 b. c., and whose adits are still preserved,
with remains of the furnaces, crucibes and huts
and tools of the miners. The scepter of Pepi
of the Sixth Dynasty, now preserved in the
British Museum, was made of pure copper from
these mines. Three ores-turquois, copper hy-
drosilicate, and sandstone impregnated with
copper-are found, and some of the tools con-
tain arsenic. which the Greek and Egyptian
alchemists used for hardening copper.
-
Infection of locusts with disease fungus is
producing a marked effect in the districts of
Cape Colony where it is being tried. In one
case the freeing of hundred inoculated locusts
set up an epidemic which caused large numbers
of dead lucusts to appear on the sand dunes on
the next morning and the following days; and
in another case the immersion of young locusts
in water containing the fungus was followed
some days after by finding of heaps of the dead
three miles away.
whistle to be heard forty miles consists of
three whistles-the two smaller with mouths
turned downward-between two steel discs.
Ine steam passes through openings in the discs.
So
Reviewing the past years work with Roentgen
rays, DIR. G. M. Moulin finds that no branch of
medicine or surgery has failed to give evidence
OF the improvements made. The f1uorescent
screen has now reached such perfection that the
miDutest movement of heart and lungs and the
least change in the action of the diaphragm can
be studied at leisure and there is scarcely any
irregularity or disease of heart, lungs or great
blood-vessels that cannot be seen and photo
graphed. So great has been the advance with
the microscope, in fact, that examination of a
patients chest will doubtless ere long become
as much matter of routine in all doubtful
cases as examination with the stethoscope is at
present. In surgery the results have been quite
50In1sy On Wnerner fracture is properly set or
dislocstion completely reduced. Perhaps the
most remarkable of recent achievements has
been the detection of renal calculi. The pres
ence of these can now be determined with great
certainty. and negative evidence can be relied
upon to show that operation is unnecessary.
"a
The manufacture of lithicum salts is a supces-
ted new American industry. Lithium is usually
regarded as a very rare metal, but it occurs in
considerable quantities in the spcdumene and
ledidolte of New England, the Black Hills, and
California, the most important source of sup
ply now known being the lepidolite deposit of
San Diego Co.. Cal. This deposit is estimated at
l5O0OOO tons. the lithia being estimated at three
to five per cent. The lithium carbonate used
in the United States for making artificial lithia
water is variously estimated at 10000 to 100000
pounds annually, and this all comes from Ger
many, the value of the salt in New York being
> $500 or more pound
"a
The blue gum and other eucalypti of Australia
are being planted in the neighborhood of Johan-
nesburg and Pretoria to overcome the scarcity
of mining timber. So rapidly do these trees
grow, Notwithstanding the poor red loan form
ing the soil and the elevation of $500 to 6OO0 feet
that a twelve-year-old plantation is yielding
good timber sticks up to forty feet in length.
"a
Abnormal sense of hunger, due to disease, is
now relieved by water charged with carbonic
acid gas-that is, "soda;water."
ga
An accurate record of the performance of all
mining ropes used in the Dortmund mine in
spection district, in Germany, has been kept
since 1872. During the q years to the close of
1898, the proportion of breakages of winding
ropes has gradually become reduced from 1913 to
054 per cent. of the whole number. Out of the
1859 ropes renewed at the 116 colieries last year,
316 were round and So fiat, all being of cast steel
wire, the material exclusively used since 1895.
Two OF the ropes broke suddenly, one after
raising net load of 35,510000 tons in 1S7 days,
the other after raising a net load of 13,2S00OO
tons in 246 days. The reasons for taking out
ropes were breakage of individual wires in 200
cases, general wear in TO- changed conditions of
winding in 49, too great reduction of length in
%, weakness as shown by testing piece cut
from the end in q, and alteration of form in IA.
Of the ordinary round ropes, 8 have been in use
more than LOGO days.
"a
The following is a recently patented method
for making metallic mercury soluble in water ::
Mercurous nitrate is brought into 10 per cent.
solution with the aid of very little nitric acid.
this solution is slowly stirred into a solution of
stannous oxide in nitric acid, and the resulting
dark-colored liquid is mixed with concentrated
solution of ammonium citrate. The metallic
mercury is precipitated as black mass. The
LIQUID is neutralized with ammonia and decant-
ed, and the residue is dried, yielding firm black
fragments that form with waters dark, strongly
fiuorescent solution.
IS
The muscular strength of man has been
studied by a German physician with a special
dynamometer. From 10000 separate expert
ments, he finds that the average man in good
health reaches his maximum strength at tho
age of about 81 years that at17 he can lit with
out difficulty 277 pounds; at 20, S17 pounds; at
81, 400 pounds; at 40. 339 pounds; at so, S2S
pounds, and at 20, 246 pounds Further expert
ments show that-contrary to general belief
negroes have nearly the strength of whites.
"a
A jar of wheat at Wisbech, Eng, is known to
have been sealed for sixty years. 1t is in good
condition, and portion is to be sowed to test
its vitality, the remainder being again sealed up
to wait the lapse of another long period.
-0p cATE