[MUSIC]
Well, arsenic and thallium are well-known
in toxicology.
They've got a long track record of use in
poisoning,
so in a poisoning case, these are things
that people might look for.
But many other elements are also
poisonous,
but are not very well-known, and
therefore,
when there is such a case, no analysis is
done for these more exotic elements.
And one example would be the element
barium.
Barium poisoning is actually very, very
uncommon.
Partly because very few people actually
have access to compounds containing
barium.
One person who used barium poisoning was a
young lady
called Marie Robards, in the city of
Mansfield in Texas.
And presumably because of family problems,
she put some
barium acetate in her father's dinner, it
was Mexican food.
Whether she planned to kill him or not,
she probably didn't plan to kill
him, but she may have just used too much
barium acetate, and her father died.
It wasn't suspected that it was murder, so
he was buried, and Marie continued with
her life.
She went on to university and she took
some classes at university, and in
one of those classes, they were studying
the play by Shakespeare, Hamlet.
And it was actually William Shakespeare
that caught out Marie Robards.
Now, part of the play Hamlet, an
important part, concerns the murder of
Hamlet's father.
And this got to Marie, and she confessed
to one of her
friends that she had murdered her father
by putting something in his dinner.
And it was this friend who then went to
the police, and the investigation started.
So the victim was exhumed and analysis
showed,
sure enough, the presence of barium in his
body.
So Marie was convicted, she received a
jail sentence, and now
I understand she's been released and is
living under a new identity.
Barium, as I said, is not something that
anybody can find, and
it turns out that Marie had stolen it from
her school chemistry laboratory.
Now one use of barium is in medical
X-rays.
So you know very well that if you have a
broken arm or something like that, you
will be X-rayed, and the doctor can see a
picture of your bones very nicely.
A very important tool for diagnosis.
But suppose you have something wrong, for
instance, with your stomach or your
intestines, these are all soft tissues,
they don't show up on X-rays.
But a technique was developed so that the
intestines could be visualized by X-ray,
and this used what was called barium meal.
And barium meal contains barium, the
patient eats it
so their intestines are full of barium,
and that means
that when the patient is X-rayed, the
intestines will
show up nicely, and the doctor can do a
diagnosis.
So, why doesn't barium meal poison the
patient?
The reason is quite simple.
Barium meal uses barium sulfate.
Barium sulfate is highly insoluble in
water,
which means that even though your
intestines, in your intestines,
are stuffed full of it, it's not absorbed
into the body.
If it's not absorbed into the body,
it can't reach any target organs, and
therefore
no poisoning takes place, and the barium
is
ultimately excreted in the normal course
of events.
Marie Robards, on the other hand, she used
soluble barium acetate.
It's soluble, and therefore it's easily
absorbed.
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