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CHAPTER 9°
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X—RAYS
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9—1.
Introduction.—In 1893,'Lenard announced his discovery
of ari invisible radiation produced in a discharge tube and capable
of passing through a thin
”opaque to ordinary
light; a radiation now called Lenard rays, or electrons. This was
Ï
followed by a systematic search by Roentgen for penetrating
…
radiations in the vicinity of
Crookes” tubes.
He prepared a
_
platino-_barium-cyanide or uorescent screen, covered his _dis—
charge tube With black paper
to avoid the light from the trace of
gas in the tube and was making preliminary adjustments Of the
interrupter on the induction coil used to excite the tube when he ‘
,
noticed that the screen was ‘occasionally emitting light. In the
sense that
before he
his discovery, Was
_
an _“ accident.” He found that the radiation which was produced
by the tube and which caused
could not be
«
deected by
with Lenard-rays and
that it
He …aînnounced thé diScOvery
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of these unknown
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“
,
’
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He soon found that X—rayswere capable not Only of causing
.œrtain
and aff‘eCt'—{ -
»
_
Ling photographœplatesTheyœuldn0tbereectedoefracœd
:
Weight
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ÎpreducedThexraysmayehkenedt0theswndwmsf°- ; _