The Baltimore County union. [volume] (Towsontown, Md.) 1865-1909, 1908-01-18
Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.

Correspondence Baltimore County Union.
SCIENTIFIC MISCELLANY.
A Substance of Philippine
Professionalism for Electrolyeis-
Injurious Dark Rays-A Bit Of Progress
Curious Balloon Danger-The City Fly
Even House Fires-Topography for
the Aeronaut.
Selenium, discovered by Berzelius in 1878, is
non metallic element closely related to sulphur
and tellurfum. In darkness it is practically
non-conductor Of electricity. but when lighted
1t passes current readily, and 1t is this unique
variability that gives to the substance great pos
sibilities of future importance. The curious
property has been applied experimentally in va
rious ways. 1t has given means of transmit
ting speech along a ray Of light, method Of
guiding and exploding torpedoes by light, and it
Is employed for sending pictures by wire. 1t
has been used also for measuring the Roentgen
rays applied in medicine. Selenium, now SELL
ing at 80 cents to $500 per ounce, is rare sub
stance In little demand, but in the United States
IL has been produced experimentaly from the
anode shines of the electrolytic refining of cop
per, and it is probable that moderate supply
can be obtained in this way.
~
Herbarium sheets already collected show 1,1O9
species of trees In the Philippine Islands, and it
Is expected that this number will be increased
to LOCO or 1900. The timber land is government
property. in care of the Bureau of Forestry.
The maps now In progress are designed In few
years to represent the different types of vegeta-
ton in the islands, the location and extent of
the different tracts of timber, and the habits of
the nearly 100 principal timber trees.
s*s
EIactrolvafa IF mines ia now nravenfad nv in
sulating from the ground. The pipes are cover
ed with a specially prepared asbestos paper,
coated with waterproof insulating compound,
and joints are made tight by strips and insula-
ting cement. The protection is claimed to be
permanently durable.
~
Our eyes need protection from the invisible
rays of our lamps, as shown by Drs. Schanz and
Stockhausen at the recent Congress of German
Naturalists and Physicists. DIR. Stockhausen
was made seriously Ill by the ultraviolet rays
from electric arcs, and investigation has proved
that with increasing intensity and temperature
our artificial illuminants have acquired great
ly increased percentage of such rays, although
sunlight itself is not very rich in them. In the
tests made, ordinary eyeglasses cut off only the
least active portion of these rays. The lens of
the eye protects the retina to large degree, but
reasons have been found for concluding that the
lens itself is slowly altered. while it is possible
that the cataract of old age is hastened by ultra
violet rays, and the front of the eye doubtless
irritated. An efficient safeguard seems to be
still lacking although an improved glass absorbs
an increased amount of ultra violet rays.
-.
Perhaps no industry has shown greater devel-
opment in the last year than the making of
chemical apparatus from Silica Evaporating
basins, beakers, crucibles, TASKS. retorts test
tubes and other vessels are now made wonder
fully clear and homogeneous, and the cost has
been reduced 70 per cent. The advantages of the
new utensils are really extraordinary. The yes
sells are thin. strong. tough and harder than or
binary glass, they are not cracked by the most
violent and sudden changes of temperature, they
will endure about the same temperature as plati-
mum without melting, and their expansion is
about seventeenth of that of platinum.
-
The bursting of balloon at Milan a year or
more ago has been traced by R. Namias to phos-
phoric and arsenic acids present in the impure
hydrogen used for imitation. Spots on the en-
velope showed where these acids had attacked
and weakened the fabric. which was strong else
where. This risk in ballooning can be avoided
by using pure materials for generating the gas.
.*s
The career of the housefy in cities like Liver
pool has been the subject of special investiga-
tion and report by R. Newstead, of the School of
Tropical Medicine. The chief breeding places
were found In pits for stable manure, ferment-
ing heaps of hop refuse, and ash-pits containing
fermenting vegetable matter. Infection was
about the same in closed as in open receptacles.
Ordinary disinfectants appeared to have little
effect in checking development, but the Of
the farm have great influence in reducing the
numbers of grubs and pup@. The period of de-
velopment, which may last three to five weeks,
may be reduced by the heat of fermentation to
minimum Of ten days, and this explains why
ash bins emptied weekly in summer produce no
lies. Continuing to empty all refuse every
seven days. and promptly removing fermentable
matter from streets and other public places, will
do much to lessen the fly pest.
.+s
City CRIME is not due to factory smoke alone.
In experiments lasting several months the chem
ist and analyst of Glasgow has shown that every
million cubic feet of chimney gases from an or
binary domestic fire contains "a pounds of heavy
oily hydrocarbons, which are black in color and
practically solid at ordinary temperature, but
when liquefed have the properties of very adj
herent heavy oil. This little considered source
of air pollution is important. The 10000 inhab-
tied houses of Glasgow have each one fire at least
twelve hours daily, and these fires must scatter
in the air each day 81 tons of the heavy oily ny
drocarbons.
-.
The mapping of airship harbors is new duty
of the British War Office. The map already
made shows chosen hollows in woods, at the foot
of sheltering hillsides and in deep gravel pits,
where balloon in distress may descend quickly
and lie protected from gales that may be sweep
ing over the exposed country