YOU do the mathematics.

You see: I am in France, a country with similar legislation to the one leading to an infamous decision in Ratisbonn. I have no 10.000 € to spend. I will quote only one defender* of the public thesis that Mgr Williamson said he disbelieved in. And wikipedia. And make a few remarks.

While it is true that hydrogen cyanide (HCN) is a highly poisonous gas. it is also true that it follows all of the laws of physics pertaining to gases. Hydrogen cyanide has a very low molecular weight (27.02), a high vapor pressure of 630mm Hg at 20° C, and a low density of .90 (i.e. lighter than air).

Sure of those temperatures?

Wikipedia says:

Boiling point 25.6 °C, 299 K, 78 °F
Solubility in water completely miscible

or in Portuguese, just to test that English version is not tampered with:

Ponto de ebulição 26 °C (299,15 K)
Solubilidade em água Completamente miscível.

So at ordinary room temperature, like 17° C, is it a gas - or a liquid?

Moreover, was Cyclon B pure Prussic Acid or dissolved into something?

Hydrogen cyanide absorbed into a carrier for use as a pesticide (under IG Farben's brand name Cyclone B, or in German Zyklon B, with the B standing for Blausäure)[23] was most infamously employed by Nazi Germany in the mid-20th century in concentration and death camps. The same product is currently made in the Czech Republic under the trademark "Uragan D1." [still quoting wiki]

Back to the responses to Mgr Williamson:

In keeping with the gas laws it would disperse almost instantly when released in a closed space. The concentration would be uniform in every corner of any space where it is released within seconds. Clothing is porous to gas. According to Graham's Law of Diffusion (or Effusion):

Gases under no change of pressure that either diffuse in all directions from an original concentration or effuse through a small hole move into mixture at a rate that is inversely proportional to the square root of the formula weight of the gas particle.

Yes, that goes for gases. So, is Hydrogen Cyanure a gas or a liquid in room temperature?

Perhaps Leuchter and Bishop Williamson are confusing the physical characteristics of hydrogen cyanide gas with those of a product known as "mustard gas." For the record, mustard gas is not really a gas, but a dense, oily liquid:

Mustard gas is a clear amber colored oily liquid with a faint odor of mustard/garlic. It is not readily combustible. Its vapors are heavier than air, are very toxic, and can be absorbed through the skin. The effects from exposure to the material include blindness which may be delayed. Prolonged exposure of the container to fire or intense heat may cause it to violently rupture and rocket. Mustard gas is also known as dichlorodiethyl sulfide.

National Oceanic and Atmospheric Administration.

While mustard gas might appear to be a "gas" it is not governed by the Gas Laws. In use it is a finely dispersed heavier-than-air liquid. Like all aerosols it is affected by gravity (which gases are not) and tends to slowly drop to earth. It boils at 215.5°C, and is dispersed as a fog.

J. Bebie, Manual of Explosives, Military Pyrotechnics and Chemical Warfare Agents (Boulder, CO: Paladin Press, 1942)

Something about time scale with use:

From Henley's Formulas for Home and Workshop (pp. 419-420): Originally published as Henley’s Twentieth Century Formulas, Recipes and Processes © 1907

The Use of Hydrocyanic Gas for Exterminating Household Insects. Recent successful applications of hydrocyanic gas for the extermination of insects infecting greenhouse plants have suggested the use of the same remedy for household pests. It is now an established fact that 1-½ grains of 98 percent pure cyanide of potassium volatilized in a cubic foot of space will, if allowed to remain for a period of not less than 3 hours kill all roaches and similar insects.

My underscore.

Quote within quote goes on to say:

At the end of the time required for fumigation, the windows and doors should be opened from the outside and the gas allowed to escape before anyone enters the building.

Quote within quote does not state for how long.

OK

A concentration needed to kill all roaches, is it smaller or lesser than one needed to kill men woman and children all packed in a room?

Or is it greater? But why, if so, use somthing more lethal to men than to roaches?

Furthermore: a concentration killing in three hours, is it greater or smaller than one killing in half an hour, multiply that by the nature of victims?

Or maybe part of idea with three hours is for prussic acid to cool down to liquid state so it evaporates too slowly to kill, except by direct contact with too much in liquid state?

After a greater concentration, is a longer or shorter ventilation required for ventilation, before it is safe to enter the room?

You do the mathematics. I have stated why. Feel welcome to comment. Especially if you are not in France or Germany.

Hans-Georg Lundahl
Bibl. Château d'Eau, Paris X
21/IV/2010

*Harry Mazal at http://www.holocaust-history.org/williamson/williamson.shtml with a back up at http://www.webcitation.org/5p9oXae9q