American citizen., 1880-03-27
USEFUL AND SCIENTIFIC.

many artistic and industrial purposes,
has been recently announced in England.
The substance belongs the class known
as the thiates or sulphur sulphides.
Nearly year ago Mr.. J. Berger Spence
discovered that sulphides of metals
combined with molten sulphur formed
a liquid. This liquid on cooling became
solid homogeneous mass, possessing
great tenacity, and having peculiarly
dark gray, almost black color. 1t has
a comparatively low melting point, viz:
$50 degrees Fahr., or rather more than
100 degrees above the temperature of
boiling water. 1t would thus require
only small amount of fuel to reduce
or to melt it. The new compound also
expands on cooling-a property not
shared by the majority of other metals
or metallic compounds. For such pur-
poses as joining gas or water pipes this
expansion is of great Importance. 1t is
also claimed that the new compound re-
sists favorably atmospheric or climatic
influences, as compared with bronze or
marble, and that its resistance to acids
is much superior to that of other metals
or metallic compounds. These qualities
if sustained by further experience, would
certainly render the new compound very
useful in many ways.-N. Y. Tribune
ABOUT MICRosCoPEs.-One of the
first questions asked by person who
looks at a microscope is, % What is its
powerP" and others ask, "What is the
highest power ever reachedP' OF sim
Pile microscopes, or hand-glasses, as
they may be termed, one sent to the
Royal Society of England, by Di Tarre,
of Naples, was said to magnify $500
diameters.s II was lent to Baker for trial,
but he could make nothing of it, and
states his sight was seriously injured by
trying to use it. With compound mi
croscopes the highest power ever
reached is 1O0,0 900 diameters. This was
obtained about ten years ago by DIR.
Dickinson, of New York City. Under
such q power q single blood corpuscle
would be over thirty-six inches in diam
eter, or the size of n small cart-wheel.
A human hair thus maghified would
rival the giant trees of California, for it
would be over forty feet in diameter. A
fly would appear as monster three.
quarters of a mile long, and a claw of a
honey-bee would stretch across the
widest street and clasp the houses on
both sides. OF course, in such case
the whole fly could not be seen under
the microscope, as small part of one
of the facets of its compound eye would
fill the whole field, SO that the "fly"
would not appear at all. This power
was obtained by artificial means, and all
sharp definition was lost; thus for real
work of any practical use such power
when obtained is worthless. The highest
recorded magnifying power of scientific
value was that obtained by DIR. Lionel
Beale, who obtained 10000 diameters
with a one-eightieth objective. He uses
long tube in preference to high eye
pieces, and no amplifier.
INGENIOUS RAT TRAPs.-Yankee ge-
MUS has invented an innumerable va
riety of traps for catching vermin, and
though no one seems to be permanently
successful, they do good service. A
rat that has once lost his foot in a trap
is sure not to put his foot in it again,
and he somehow seems to have the fac
ulty of communicating to his fellows its
dangerous character. A steel-trap is
very likely to catch two or three rats,
and then not secure another customer
for a month; but the very presence of a
trap, when its mission is understood by
the vermin, seems to drive them away.
They like to live where freedom reigns,
freedom to rove and pilfer without re-
oeA anu, SuCA dS tuCy uuu City ScWtIS
A very simple contrivance, which we
have used with great success, is to fill a
barrel third or half full of water, and
then cover the surface of the water thor
oughly with oats If board is placed
making an inclined place from the floor
to the top of the barrel, and few oats
sprinkled on it, the rats will be sure to
find their way up this plane and leap
into the barrel. With his fur soaked |
with water, rat can not escape to tell
the story to his companions, and they
follow on to the same wa
terry grave. A modification of,
and, perhaps, an improvement |
upon this trap we have recently noticed
recommended. This is, to tic thick |
paper as head to the barrel, and on
this place some oats, or, better still,
crumbs of cheese-renewing the bait |
every day for two or three days till the |
rats have become habituated to this |
dining table; then cut a couple of Sits
crosswise in the paper just long enough.
to let rat through easily when he
comes to his next dinner. The trouble |
with this and all such traps is that the |
vermin soon comprehend the strategy, |
and act on the principle of the business |
man who said: I" If a rogue cheats me |
once, he is to blame; if he cheats me |
twice. am to blame.'' Rats are too
cunning to be caught twice with the
same chaff. A neighbor overrun with
rats once tried this mode of getting rid |
of them, which proved very successful
Catching one of the largest, he stupe-
fed him with chloroform, and then,
tying little bell around his neck, let |
him run. The vermin left his premises
with perfect stampede, but his neigh
bOrs found sudden increase of depre-
dators in their houses We can not |