256
'
11.
SPONTANEOUS DISINTEGRATÏON
of 3 to 10 minutes, remove the copper plate, without touch- '
ing its lower surface. Put the lid back in place. 7. Promptly, but
without haste take the plate to the electroscope and record the
activity every ve minutes for two hours. The natural leak
should be measured at hourly intervals, at least. 8. Correct the
observed rate of fall of the leaf of the electroscope for the natural
leak (average value) and plot the corrected activities as ordinates.
;
and the times, at the center of each activity reading, as abscissae.
9. If desired, the curve may be continued.
Activities may be'
measured every half hour from the two to the ve hour point and
every
hour or so from then on.
Determine the half period of
thorium B.
1ÿ‘ î‘ .
ÿL…‘;
»
.
EXPERIMENT 11—3
RATE OF DECAY OF THORIUM (:
The apparatus and procedure are the same as in the preceding
experiment, throughthe sixth step, except that a platinuih or a
’
tantalum plate should be used and the plate should be left at P
(gure 11—7) for at least one hour and
two hours.
While this is going on, place 3 cubic centimeters of concentrated,
.
hydrochloric acid in a watch glass over a small beaker containing
25 or more cubic centimeters of distilled water.
Heat carefully,
just to boiling, with a gentle ame. Keep hot but do not continue
the boiling.
…
‘
‘
7. After the plate has been exposed for one or two hours place
it in the hot HCl for three minutes (one to ve minutes).‘ Remove
with tweezers and Wash with‘approximately 25 cubic cent1meters
'
-
of — hot Water, * allowing the water to drain off the disc into the ac1d
Ÿ
“
‘
so
to dilùtethe acid to approximately…1.0 normal. 8Put
copper plate into the solution. Movethe
_
about vin: “the hot solution for three minutes.»
]
Fr0mr10Won, thezw0rk must becarnÏedon a: quickly asposszâl€
_' , ::'
and: record the time.
Th1$>lSth
; zer®t1me’Wash'theïÈflat€ véry. gent—ly in very hot water,theq
WlthafewdropsofË'alcoh0l.
the
e1eCtrosœpe(lnadlerentroom),placmg
on: a
ofuncontam1natedpapel”10Recordthet1meoffall of theleafovers
'
11.
SPONTANEOUS DISINTEGRATÏON
of 3 to 10 minutes, remove the copper plate, without touch- '
ing its lower surface. Put the lid back in place. 7. Promptly, but
without haste take the plate to the electroscope and record the
activity every ve minutes for two hours. The natural leak
should be measured at hourly intervals, at least. 8. Correct the
observed rate of fall of the leaf of the electroscope for the natural
leak (average value) and plot the corrected activities as ordinates.
;
and the times, at the center of each activity reading, as abscissae.
9. If desired, the curve may be continued.
Activities may be'
measured every half hour from the two to the ve hour point and
every
hour or so from then on.
Determine the half period of
thorium B.
1ÿ‘ î‘ .
ÿL…‘;
»
.
EXPERIMENT 11—3
RATE OF DECAY OF THORIUM (:
The apparatus and procedure are the same as in the preceding
experiment, throughthe sixth step, except that a platinuih or a
’
tantalum plate should be used and the plate should be left at P
(gure 11—7) for at least one hour and
two hours.
While this is going on, place 3 cubic centimeters of concentrated,
.
hydrochloric acid in a watch glass over a small beaker containing
25 or more cubic centimeters of distilled water.
Heat carefully,
just to boiling, with a gentle ame. Keep hot but do not continue
the boiling.
…
‘
‘
7. After the plate has been exposed for one or two hours place
it in the hot HCl for three minutes (one to ve minutes).‘ Remove
with tweezers and Wash with‘approximately 25 cubic cent1meters
'
-
of — hot Water, * allowing the water to drain off the disc into the ac1d
Ÿ
“
‘
so
to dilùtethe acid to approximately…1.0 normal. 8Put
copper plate into the solution. Movethe
_
about vin: “the hot solution for three minutes.»
]
Fr0mr10Won, thezw0rk must becarnÏedon a: quickly asposszâl€
_' , ::'
and: record the time.
Th1$>lSth
; zer®t1me’Wash'theïÈflat€ véry. gent—ly in very hot water,theq
WlthafewdropsofË'alcoh0l.
the
e1eCtrosœpe(lnadlerentroom),placmg
on: a
ofuncontam1natedpapel”10Recordthet1meoffall of theleafovers