The citizen. (Frederick City, Md.) 1895-1923, 1899-06-23
Written for the Citizen

w TlIUeH lOT GDe OlIlEen.
Even window washing is now
subject of scientific study. For
Ave years a German chemist has
been Investigating the action of
nnre water and dilute acids upon
plate glass and he has prepared
tables showing exactly how much
Of the glass is dissolved by each
reagent. From these and other
results, Mr.. W. l.. ScOville con-
eludes that windows shonld be
cleaned with weak ammonia water
and polished with dilute hydro
cOric acid and friction. The
ammonia, though sufficiently SOL
vent to suspend some of the silica
and streak the glass, has less eff
feet than soda or potash, and the
acid neutralizes the ammonia and
the alkali in the glass, forming
some soluble chlorideS that aid in
the polishing. The final opera
tion is drying and polishing with
b clean cloth. To avoid damage
TO paint and arnish, not more
than half an ounce of concentra-
TED ammonia water should be
used in a pa full of water, and
the usual two or three ounces of
strong acid to the pail full should
be lessened if the window frames
aTe of metal.
Though the fuorescent screen
is very family luminous, Rev.
Alexander MOffat finds if the
ROentgen rays were continuous
instead of intermittent, they
would exert an effect 500 times
greater than sunlight falling per-
pendicularly upon a surface.
Only A per cent. of the energy
impinging upon the screen is rep
resented by the visible traditions,
while the interval between two
X-ray discharges is about 1000
times the period covered by the
discharge itself. A Georgia in
ventor, it may be noted, has pro-
duced Roentgen-ray lamp,
which is claimed to yield an in
tense light from the bOmbardment
of a covered magnet core by the
cathode rays.
The reducing property of cath
ode rays has been shown by M.
Willard to be due to hydrogen,
the conclusion being reached,
moreover, that the rays from the
cathode are formed entirely of
hydrogen. This suggests the
novel plan of restoring exhausted
vacuum tubes by passing gas
through a heated platinum plate
in the tube wall-such diffusion
having been shown by Deville to
take place rapidly
From a description of the tor
pedO- controlling devices of Wal
ter Jameson and John Trotter,
it appears that very satisfactory
arrangement for steering by
Hertz waves is obtained by means
of two solenoids, or wire spiraIs,
the right or left one-accOrding
to the direction of the current re-
ceived-being made to act as a
drawing in an iron core
and giving IA corresponding turn
to the Tudder attached. The
waves are sent out from the con
trolling ship by manipulating the
switch of an induction coil. They
are received by two rods project
ing from the torpedo above the
water, pass to cOherer of special
type and by leSsening the resist
ance of the metal power of this
coherer close the secondary cir
cult of relay, causing an cleo
trio current to flow through a
selection" to the proper solenOid,
which sucks in its core and keeps
the helm turned until the de-
sired course is attained, when the
operator opens the induction coil
switch and the waves cease. The
helm then flies back to the mid
ship position.
The production of photographs
in relief is the promising new art
of M. Lemac, who has used his
process for fine medallions from
living persons. Two successive
film negatives are made, the
model being in exactly the same
with the light-from
concentrated source like a mag
nesium cartridge-applied to OPP
posite sides, thus bringing out in
intense black the most salient
points of the face. A print is
made from the two negatives ex-
actly superposed. The print is
retouched to bring out hair and
drapery, and any lettering desired
Is drnmn u,ith InIin inl if To hn