I am pretty sure there are ways to distinguish between plastique and various
petrochems exploding.  They explode quite differently.  For example sewer gas
probably would not destroy the sewer cap... instead it would knock it up into
the air.  On the other hand c-4 would frag the sewer cap.

It's the speed of the explosive reaction and the distribution of force that
matters. Petrochemicals burn rather slow, while c-4 is faster (the nitrate
groups are what do it).

However, a methane explosion can shatter a sewer cap if the sewer cap was
secured to its mounting. It's outer edge would be secured while it's center
would be pushed outward. BAM! One shattered sewer cap. This is the reason
for pressure relief valves in high pressure systems like power plant
boilers and such. Overpressure in the system can cause the entire pipe to
shatter explosively.

On the other hand, if the sewer cap _wasn't_ secure and free to pop off
rather easily, and the c-4 charge was spread out over a good deal of the
cap's surface, then the sewer cap would knock it into the air. The uniform
force on the cap induces no stress, so the cap doesn't fail. This same
principle is what's used in anti-demolition disposal, where a bomb is
dropped in a big steel drum mounted on truck springs. The force of the
explosion is directed up, and the springs absorb the shock. If the drum
wasn't free to move, then it would be easily wrecked by a bomb.

A uniform force applied to an object just causes it to accelerate. It's
_differences_ in force that causes stuff to break.

As for potassium and chloride... explain to me again what makes that
special?  I
mean, sodium is a cation of the same family (group?  I forgot which it is
called) and chloride is well, chloride.  So why doesn't table salt kill us?

Because potassium cloride _isn't_ table salt. Just because two elements are
in the same group doesn't mean they have the same chemical activity.
Otherwise, the two elements can't be separated by chemical means, which can
be done with potassium and sodium. Elements in the same group share some of
the same chemical properties, but are chemically distinct.

The reason why potassium chloride is poisonous is because it messes up the
electrical equalibrium of the heart, causing it to fibrillate. A
fibrillating heart doesn't pump blood.

 I
am more knowledgeable about explosives than poisons.  And just because
such and
such ion exists in the body already doesn't mean it can't be detected as a
poison!  The body has CN- (cyanide) ions, as well as trace amounts of gold
and
other random crud.  If someone found a half kilo of gold in someone's blood
stream people would probably notice...

A half-kilo of gold in the body is glaringly obvious, as gold isn't
absorbed by the digestive system anyhow. However, the effect of a half-kilo
of gold would be physiological, namely embolisms and strokes. And it
doesn't _take_ a half-kilo of gold to kill someone. A mere fleck is good
enough, enough to cause a nasty and fatal stroke or heart attack.

On the other hand, poisons normally work by chemically interfering with
natural body processes. Curare, for instance, works by blocking
aceteocholine receptors, parylizing muscles including the diaphram. Botulin
interferes with nerve transmissions, causing all muscles to lock up.
Potassium cyanide knocks out a rare and important enzyme that mediates the
intake of oxygen into cells. Arsenic binds to sulphur-containing protiens
and interfering with their function.

However, cyanogen (CN-) in the body is normally bound up with other
chemicals; the ion isn't going anywhere. Sulphurous protiens are very
common in the body, so it takes a large amount of arsenic (a trace mineral)
to really interfere with function. Cyanide causes a rather obvious effect
on the body; it turns the victim cherry red (oxygenated hemoglobin).

On the other hand, potassium chloride breaks down as it does its work. It
breaks down into potassium ions (found naturally within the body in
reasonable abundance) and chloride ions (also found naturally within the
body in reasonable abundance). It also causes the heart to fibrillate and
fail, which is pretty much identical to a cardiac arrest. Potassium and
chloride ions disperse quickly into the body tissues as well. That's why
its, if not untracable, very hard to detect.

Also, if potassium chloride's used in the right kind of victim, say one
with preexisting heart disease or renal failure, then you case a reaction
that wouldn't be unexpected in such people. The heart disease victims die
of heart failure, but what do you expect with a patient with heart disease?
The renal failure victims die of an electrolyte imbalance, but what do you
expect from a patient with renal failure?

I have heard of several drugs that induce heart attacks, and while the CIA
might
know otherwise, all the ones I am familiar with are traceable.

They're traceable because they aren't normally found in the body. Potassium
and chloride ions are, so potassium chloride poisoning is more difficult to
trace. The poisons used by the CIA work by wontonly interfering with normal
body function. Potassium chloride poisoning works by upsetting electrolyte
balance, which is just as deadly but harder to distinguish from disease.
Injection with some carbolic acid causes the victim to die of acitosis. E.
coli and Staphylococcus cause sepsis. Cocaine? Murder or overdose?

My father is a pathologist, and used to do autopsies... out of curiousity
I used
to ask him what chemicals one could use to kill someone without it being
traceable as an actual intentional poisoning rather than an accidental
one.  He
said it is pretty difficult, as techniques are sophisticated these days.

Like I said, if the victim is right (heart or renal disease) then no one
will think twice about it.

Traceability isn't so much the problem, as is making it look accidental or
like a disease. That's hard to do with forgien poisons but much easier with
sensitive chemical balances and nasty infections. (Ebola, anyone? <wg>)


                           ---------------------
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##   ##   ###   ###   ## ##   ## of UT      <wyrm@mail.utexas.edu>
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