The herald., 1896-03-11
ROENTGEN RAYS DISCUSSED
An Interesting Meeting of the
Science Association
PROF. ROENTGEN'S LECTURE
A Translation Of the Original Read by
Mr.. S. G. Marschutz
4 Series Of Experiments Illustrating the Ca.
thode Rays Given by Prof. VIM. Lund.
berg-A Scientific Discussion

The regular monthly meeting of the Sou
thern California Science association in the
assembly room at the chamber of COM
merce last evening was devoted to discus
sion of the latest great discovery in science,
the Roentgen rays. by which dense, opaque
substances are penetrated and pictures
taken. The general interest in this SUBJ
ject, " hich has occupied SO much space in
the public press within the lsst few
weeks, was evidenced by the large attend
ance. The seating capacity of the room
was taxed to it's full capacity; there was
not vacant seat and quite number were
compelled to stand during the entire even
ing.
President William H. Knight presided,
and Secretary Baumgartner and the other
officers of the association were present.
The first thing on the program was a
number of interesting experiments by
Prof. William Lundhorg, producing the
famous cathode rays in series of CroolSe' g
vacuum tubes. The experiments were a
success and were thoroughly enjoyed by
the lay as we'll as the scientific element in
attendance.
S. G.Marschutz then read translation of
the original lecture of Prof, Wilhelm Kon-
rad Roentgen. delivered before the Wurz-
burg Physic Medico society in December,
1895, announcing the discovery of the Y
rays that have since made the gentleman
famous. Owing to the general interest in
this great discovery, and the eXaggeration
and misrepresentation that has followed,
the authentic announcement of the discov-
90, ,fc ia1 Mt tit,,o
and hence the lecture is given in full as
follows:
PROF. RoENTGEN's LECTURE
If we allow the discharge of a larger
Ruhmkorf coil to pass through Hittorf
vacuum tube, or Crooke's or similar tube,
sufficiently exhausted and cover the tube
with close fitting jacket made of black
pasteboard, holding opposite the same a
screen, that we had covered with Barium-
Platinum-Cyanide,w we will see upon the
screen luminous rays in the perfectly
darkened operating room. These rays APP
pear with every discharge. no matter
whether the painted part of the screen, or
the reverse is exposed to the apparatus.
This fluorescence appears even at dis
lance of two meters, or six and one-half
feet.
1t is at once apparent that the cause of
this fluorescence originates from the dis
charge apparatus or tube and from no
other source.
What appears the most striking in this
experiment is that no visible rays, nor
ultraviolet rays of the sun or electric rays
of light, can pass through the black jacket,
yet some agent passes through it, which
causes remarkable brilliant fluorescence.
And we therefore first investigate if other
bodies are affected also in a similar man.
ner.
We soon find that all bodies allow of the
passing of such agent. but in very different
degrees. will illustrate a few examples:
Behind bound volume of 1000 pages l
observed the aforementioned fiuorescent
screen still illuminated; the printers ink
offered no visible resistance to the passage
of the mysterious rays.
/ also observed fiourescence behind a
double deck of cards; single card be-
tween apparatus and screen is hardly no.
ticeable to the eye.
A single sheet of tin foil is hardly notice.
able. Only after several thicknesses are
used, then are their shadows strongly
visible on the screen. Thick wood blocks
arc still transparent; two or three en-
thick boards of pine absorb the rays very
little. An aluminium sheet about 5 NM.
thick weakened the effect considerably,
but did not cause q total disappearance Of
the tiourescence. Several CM. thick discs
of hard rubber still allow the rays to pass.
Glass plates of equal thickness act diff
ferently; those that contain more lead
don't allow the rays to pass as freely as
those that have less lead. IL we hold the
hand between the discharge apparatus and
the screen, we see the dark shadows of the
bones in the hand, in the only slightly
darkened slladowgraph of the hand. Water,
sulphite of carbon and Other liquids, show
that they allow the rays to pass very
freely. / could not find that hydrogen is
more easily penetrated than air. Behind
plates of copper, silver, lead. gold, plat
mum, the tiuorescence is still distinctly
visible if the plates are not too thick.
Platinum at 2-1O MN. is still penetrated,
Lead at ~ NM. thickness is practically
opaque, and for that reason was
frequently used. A square rod of
wood, one side Of which was
emily. according to the way it is held be-
tween the apparatus and tee screen.
If the rays pass parallel with the painted
side, il offers almost no obstruction, how
ever, if they pass through the painted side
il throws dense shadow. These eXperi-
ments lead me to the conclusion that the
different substances pass these rays ac-
cording to their densities, presuming all of
equal thickness. No other quality is in
such a high degree noticeable. The follow
ing experiments, however, prove that the
density alone, does not govern the passage
of the rays. l examined for percolation
almost equal thick plates of glass, alu-
minum, crystallized carbonite of lime and
quartz. The density of these plates
proved to be about the same, still it was
evident that crystallized carbonite OF lime
is less subject to the percolation, as the
other substances which have about equal
relation to the other. ] could not observe
any exceedingly strong huorescence of
crystallized carbonite OF lime especially
compared with glass. With increasing
In order to find any connection between
percolation and density of layers, made
photographs of partly covered dry plates.
These dry plates covered with tinfoiI. in
creasing the tinfoil layers in steplike
manner. | will photo metric tests of the
same shortly, as soon as the suitable pho
tometer will be ready for me.
The fluorescence of barium platinum
cyanide is not the only visible effect of the
TX" rays.
will now mention that other bodies arc
also tluorescent, for instance those as
phosphor known calcium compounds
Uranium glass, ordinary glass, crystal
lized carbonite of lime, furthermore uran
rock salt, etc. Most remarkable in many
ways is the fact that Photographic dry
plates have proven themselves sensitive to
the az rays. II enables us to fix various
experiments whereby mistakes are easier
excluded, and l have controlled every
more important observation and expert
ment on the fiuorescent screen, whenever
possible, by photograph of the same. In
that case the action of the rays to pass
almost unchecked through thin wood, pa
per or tin foil layers is very acceptable and
u-k- l.