Re: Question about Cyanide Gas (for a good cause :-)

In your letter dated Fri, 16 Oct 92 10:23:01 BST, you wrote:
>
> > Much too steep.
>
> Yeah. It looks that way. I got my original info from a chem-major
> and former player of mine, but I thought the area of effect sounded
> way off. You basically confirmed that.
>
> Thank you very much for the detailed reply. It's exactly what I needed
> to nuke the idea of using HCN in the story (now I have to find something
> even nastier :-)

Well, I'd refigure some numbers to be sure, but it doesn't look very practical.
Depends on how much of the ship you really need to contaminate, and how fast
you think the crew could respond.  For comparison, I looked up the lethal
dose (LCt50) of Sarin, a common nerve gas invented in World War II, and rather
than being 2000-4500 mg-min/m**3 for HCN, it's more like _70_mg-min/m**3.
Almost 30 times more lethal...so instead of a few tons you'd only need
about 9.45 kilograms to deliver a lethal dose in one minute.  Air mixing
and filters, of course, remain a problem.  Now, some biotoxins are _much_
more toxic than Sarin--something like poison arrow frog venom from South
America is 10,000 times more lethal than Sarin, but it is usually delivered
by injection.  I see a note that says that mixing it with scorpion venom
increases its toxicity by a factor of 20...

Given an SF universe, you could probably come up with something almost
arbitrarily lethal, although imposing severe handling precautions would
be in  order!

Rob Dean

(Additional note: HCN is lighter than air at room temperature, so given some
warning, you could engage in defensive measures like dropping to the floor and
cranking the grav-plates up to 2-Gs to encourage it to concentrate at the
ceiling, and it's also very soluble in water, meaning that a wet rag over the
breathing orifices would probably provide _some_ filtering effect.)