The Dakota chief. (Gann Valley, Buffalo County, S.D.) 18??-1913, 1896-03-12

and rom which they are thrown with 4
power apparently greater than their strik-
ing force, are as open gates for the y
rays. On this point H~ocntgen, the pioneer.
says:
III" most striking feature of this plenom-
eiIon is mat an influence capable of exciting
brilliant fuoreSCencc is able to pass through
thc black cardboard cover. which transmits
none Of the ultraviolet rays of the sun or
OF the electric are. and one immediately in
CURES whether other bodies possess this
property. Ii is soon discovered that all bodies
are transparent to this influence, but in
very different degrees. A few examples will
suffice. Paper is very transparent. The
fiuorcscent screen held behind Il bound vol
ulnc or l,0oD pages still lighted up brightly;
the printers ink offered no pcrceptible OBJ
Stacle. FIuoreScence was also noted behind
TWO packs OF cards: Il few cards held be-
tween apparatus and screen made no per-
cr"ptible difference. A single sheet Of tin
foil Is scarcely noticeable; only after several
layers have been laid on top of each other
Is a shadow clearly visible on the screen.
Ihlck blocks of wood are also Transparent;
nr planks two or three ccntimcterS thick
are but slightly Opaque. A film of aluminium
about fifteen miiimeterS thick weakens the
effect very considerably. though 1t does not
entirely destroy the 1luorescence. Several
ocntinnetcrS of Vlilcanized India rubber let
the rays through. Glass plates of the salne
thickness behave in a different way. accord
Ing AZ they contain lead ttlint glass, or not;
INV dlN iiItI ItNS transparent IlHll
The latter. If the hand is held between the
discharge tube and the screen the dark
shadow of the bones is visible within the
slightly dark shadow of the hand. Water.
biSulphide of carbon and various other
liquids behave in this respect as if they We're
very transparent. was not able To deter
mine whether water was more transparent
than air. l;chind plates of copper. silver.
lead, gold. platinum. tluorcsccnce is still
clearly visible. but only when the plates are
not too thick. Platinum o. ~millimeters
thick is transparent: silver and copper
sheets may be decidedly thicker. Lead 10
millimeters thick Is as good as Opaque, and
was on this account often made use of. \
wooden rod Of 2OX2o millimeters cross see
lion. painted white. with lead paint on one
side. behaves in Il peculiar manner. When
it is intcrposed between apparatus and
screen ii has almost no effect when the y
rays go through the rod parallel to the
painted side. but it throws a dark shadow
If the rays have to traverse the paint. Very
similar To the metals themselves are their
salts, whether solid or in solution.
The reports OF Prof. Roentgen's eX-
periments produced a great activity
among students everywhere. Newspa-
pers and scientific journals were filled
with reports of the labors and new discov-
cries made. There is not an institution
of learning or Il laboratory worthy the
name in America where the Roentgen
method of photography has not been put
10 practical test. One remarkable dis
covery was made incidental to some eX-
periments in New York. Prof. Max Os-
tenberg, of Columbia College. desiring to
photograph the framework of a mouse,
drowned the creature in a bucket of water.
The animal remained under water fifteen
minutes after it had ceased to struggle.
1t had been effectually dead more than an
hour when the apparatus was hnally ar
ranged. 1t was laid upon the plate and
subjected to the powerful rays from the
Crookes' tubes. and after an hour of eX-