Savannah morning news. [volume] (Savannah) 1868-1887, 1884-12-07
BITS OF SCIENCE.

According to the Complies Readres, bro
mide Of silver in contact with heat is an
explosive.
An optical telegraph was established on
LacroiX Peak, in Reunion, and Vert Peak,
in Mauritius, on the night of July 1913,
when messages were freely exchanged be-
tween the two islands.
From an extended series Of experiments
with rocks Mr.. p. r. Hay concludes that
the Indians must have used something
except round stones in the manufacture
of their various stone implements.
Water filtered through porous unglazed
porcelain is absolutely free from micro
bia. With a single such vessel. O.20 metre
long by 0.25 metre in diameter, Mr.. c..
Chamberlain obtained about 20 litres
day Of physiologicallv pure water.
Il. Poincaire contends that the attrac-
ton Of the moon mOdities the intensity of
gravitation. Hence at the equator the
clock is retarded by half a second yearly
by the combined attraction of the sun and
moon, and advanced a second at the poles.
Experiments with the albumenized pa
per of photographers show that light cam
not penetrate water to depth exceeding
some 900 feet; traces of light were dis
tinctly left on the plates at this depth, but
the plates employed were required to be
very sensitive.
In the Province of Viatka, Russia, there
are produced annually 100000 pounds
of tar, 5, 100000 pounds of pitch and 2, 160,-
600 pounds of turpentine oil. 1t is stated
that the annual product of birch oil
amounts to IA, 100000 pounds (4,000,000
pools }, an indication that the demand for
it is now great.
The eminent botanist De Candolle gave
the age of an elm at $50 years. The ages
IF no mi h0nr a frOr
600 to 700 years. that of an olive tree at
700 years, of plane tree at 720, of cedar
at 800 years, of an oak at 1000, of yeW
at 3, $3.50, of a taXOdlum at 1000, and of a
baObab tree at 5000.
A system of rails for street railways,
introduced by NJ. MarsillOn, is under trial
by the Campagnie des Omnibus, of Paris.
1t consists of an ordinary bridge rail and
counter rail of the same section bOlted to
an iron longitudinal sleeper. The absence
of wood makes the system a very durable
one, but it is very inelastic.
AS to the depth reached in sounding the
ocean, Lieut.. Bergman obtained bottom
at $50 fathoms a short distance south of
the Banks of Newfoundland. The depth
of the sea is commonly exaggerated. PeO-
pie used to think that it ranged from 1000
to 5000 fathOms. The average depth is
$500 fathoms in both the Atlantic and the
Pacific.
Cast iron if heated for several days to
about 900 to 1000 degrees neither melts
nor softens, but is converted into mallea-
BILE iron. Its surface is covered with a
graylsh efflorescence. The fracture is
sometimes of a uniform black, like that of
a lead pencil, and sometimes riddled with
large black points regularly distributed in
the metallic paste.
Until lately most of the supply of sugar
in Denmark was imported. Now the ma
terial for sugar is provided within the
boundaries of the kingdom. Six years
ago the Danes made 100000 pounds of
beet-root sugar, and four years later the
figures rose to 100000 pounds. The pro-
ductiOn of 1882 exceeded that of 1881 by
fully 100000 pounds.
Lead tanks which Tithstood sulphuric
acid perfectly, Mr.. S. p. Sharples reports,
were soon destroyed by hydrochloric acid.
In some recent experiments undertaken
to destroy cotton fibre by means of hot
hydrOchlOric acid it was found that lead
lined vessels were soon rendered useless
by it. Even the cold acid could not be
kept in wooden tanks lined with lead.
The skin or outer cover of the insect
consists OF the cuticle, not comparable
with any part Of the skin of vertebrate,
and underlying tissues. The cutiCle con-
sists of twovery distinct layers-One thick
and transparent, the other, in which also
pigment is developed, thin and Opaque.
The pigment is disposed in beautiful mi
crOscOpic markings, differing in different
species.
A composite pulley is among the recent
mechaical inventions. 1t is formed of
cast iron hub, a web or body made of pa
per, pasted and pressed into a solid block
of the thickness to insure the required
strength, and this web is surrounded by a
wrought or cast rim secured by knees or
tianges riveted through the rim and paper;
the rim, having thus uniform bearing
upon the paper body, is steadier and more
even than the iron pulley.