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HOW A LABORATORY
DATES SPECIMENS
SAMPLE EXAMINATION -
A sample to be dated is
identified, examined and cleaned in the first step of o
rodiocarbon dating laboratory's procedure. Tedious but
vital removal of foreign malter such os root hoirs from
charcool is vital. In the series of photos, the Humble Oil
ond Refinery Company laboratory in Houston, Texas is
pictured.
As port of the purification process, material -
in this
case charcoal - will receive o both and chemical treot–
ment with ocid.
After a thorough woshing, the sample will be dried in o
loboratory oven.
A PROCESS OF CONVERSION .
Somple, whether wood,
charcool, or other organic matter is then burned in com–
bustion apparotus. Fleme is hot enough to melt ordinory
glass. Ouring the fiery combustion process, somple is
converted into corbon dioxide gas. This is collected os
dry ice in frosty liquid nilrogen trop.
The carbon dioxide will then go through various other
purification procedures. Next, the gas will be re-collected
in a liquid nitrogen cold trap. Now the somple has moved
through the final step of purification. lt is then pumped
into the counter.
READY FOR MEASUREMENT.
Sample is now trapped in
one of three counters pictured in center of apparatus.
These ore ringed by twenty geiger counters and a 4,000-
pound lead-mercury shield.
ATOMS CLICK AWAY.
The scientist has wound up the
atomic clock by setting the high voltoge on counting
system. lt counts the click of the carbon-14 atoms as they
revert to nitrogen. Preliminary data are exomined as
they come in. Normal count is over a period of 1,000
minutes. This of course, varies with the laboratory and
individual specimen measurement. Automatic equipment
counts throughout the night.
Archaeology as well as geology benefit from the findings
of radiocorbon doting. lf proportion of radiocarbon to
ordinory carbon has remained steady - and no other
foctors hove upset the method - dating can reveal the
actual calendar years of a sample. Also, if properly
interpreted, radiocarbon dating con reveal flows in
archoeologicol ond geological estimates.
Humble
Oí/
ond Refinlng
Compony
Photos