THE RUDOLF REPORT

6. FORMATION AND STABILITY OF IRON BLUEWhen writing the initial versions of this expert report intended tobe presented at German courts of law, I was extremely anxious not tomake any errors, because I knew that the topic was extremely controversial.As a consequence, I over-examined several chemical aspectsinvolved, some of which can be understood only by chemical experts.Others aspects are not really necessary for an understanding of the coreissue. In order to have a complete English version of my expert report,I nevertheless decided to include all the material I accumulated overthe years. Those sections, however, which are considered of marginalinterest or of interest to experts only, I have given headlines alwaysstarting with “Excursus”. For some readers it might be advisable toskip these chapters. They will most likely not miss anything. 319But first a short description of the starting substance, hydrogencyanide.6.3. Properties of Hydrogen Cyanide, HCNHydrogen cyanide, a colorless liquid, is similar, in many of itsphysical properties, to water. 320 This similarity also explains the limitlesssolubility of HCN in water and its strong tendency towardsabsorption (dissolution) in water. The equilibrium concentration 321 ofhydrogen cyanide in water is investigated in more detail in chapter6.5.3.The opinion is often expressed that, because gaseous hydrogencyanide is approximately 5% lighter than air, it must separate from airand rise. Hydrogen cyanide gas is, however, only slightly lighter thanair and does not separate, because of the thermal movement of everygas particle. To clarify this, reference must be made to the principalcomponents of air: The main component of air, nitrogen, 78% by volume,is 8% heavier than hydrogen cyanide gas. If a separation tookplace between hydrogen cyanide gas and nitrogen, it would all themore occur between the two main components of air, since oxygen(21% of air by volume) is 15% heavier than nitrogen. This would have319 I also want to point out that I did not include all this academic, self-serving ivory tower chatterin order to impress people. I was simply advised by many friends, supporters, and adversariesto include all my material since back-references to my German original is no help to mostEnglish language speakers, of whom only a tiny fraction can read German.320 High polarity, low molecular mass, possibility of formation of hydrogen bonds.321 Concentration is the number of parts per volume.155