THE RUDOLF REPORT

6. Formation and Stability of Iron Blue6.1. IntroductionHundreds of thousands of people are claimed to have been killedin the alleged Auschwitz ‘gas chambers’ by hydrogen cyanide in theform of the product Zyklon B ® . The question which now arises is thefollowing: could this poisonous gas leave chemical traces, which couldperhaps be detected in these alleged chemical slaughterhouses?If hydrogen cyanide (HCN), the reactive compound in Zyklon B,were only bound to the walls by adsorption (adhesion), 313 there wouldnot be any detectable residues today anymore, due to the volatility ofhydrogen cyanide (boiling point: 25.7°C); all the hydrogen cyanideinvolved would long since have evaporated.But if one assumes that the hydrogen cyanide, during fumigation,would combine with certain materials in the masonry to create other,considerably more stable compounds, then one might anticipate thepossible existence of chemical residues even today.The reaction products of interest to us in this respect are the saltsof hydrogen cyanide, called cyanides, 314 in particular, the iron cyanidegroup, formed by a compound of iron and cyanide. Iron occurs universallyin nature. It is iron which gives brick its red color, sand its ochrecolor, and clay its color ranging from yellowish to reddish-brown.More precisely, we are speaking of iron oxide, popularly known as‘rust’. Basically, all walls consist of at least 1% rust, as a result ofsand, gravel, clay, and cement, of which the wall is constructed.The iron cyanides have long been known for their extraordinarystability, one of them having achieved particular fame as one of themost commonly used blue pigments during the last three centuries:313 Absorption and Adsorption are not the same! Absorption is the incorporation (sometimes evenconsumption) of a matter into a medium (light is absorbed/consumed by a pigment, gas is absorbed/dissolvesinto a liquid), whereas Adsorption is the adhesion of matter onto a—usuallysolid—surface (dust on furniture, steam on windscreen, vapours on any solid surface...);Adsorption is further subdivided in chemisorption, in which the matter is bound to a surfaceby chemical bonds, and physisorption, in which the bonding is only a physical effect. Thetransition between both is fluent.314 For simplicity’s sake, ‘cyanide’ is frequently understood to mean only the anionic part of thecyanide salts, the cyanide ion, CN – .151