AUSCHWITZ:                         Technique and Operation                             of the Gas Chambers ©    Back   Contents Page 18 Home Page  Forward         In order to give a better understanding of the texts referring to Zyklon B, the units used, the concentrations for disinfestation and its toxicity, here are some data concerning its principal active agent, HCN (hydrocyanic or prussic acid):      • Molecular weight: 27.   • Weight per liter: 1.20g  • 1% by volume represents 12g /m³  • 1g/m³ represents 0.083% by volume.   • 1% by volume represents 10,000ppm (parts per million).  • 1ppm represents 0.0012g/m³ or 1.2 mg /m³  • With air, it constitutes mixtures whose lower and upper limits of combustion are respectively 5.6 % (67.2g/m3) and 40% (480g/ m³).  • Olfactory threshold: 2 to 5ppm (2.4 to 12mg/m³).  • Maximum threshold used in work places: 10ppm (12mg/m³)  • Exposure without a mask to a content of 100 to 200ppm (120 to 240mg/m³) for 30 to 60 minutes may result in death. The lowest lethal dose known for man by inhalation: 120mg/m³ in one hour and 200mg/m³ in ten minutes.  • Immediately mortal concentration: 300mg/m3 or 0.3g/m3.  • A concentration equal to or greater than 12gm/m³ (1%) would not tolerable even for a man wearing a mask except in case of necessity and not for more than a minute  • A concentration of 24g/m³ (2%) may bring loss of consciousness in ten minutes for a man with a mask.  • Concentration used in homicidal gassing in Birkenau: 12g/m³ (1%), or 40 times the lethal (or mortal) dose.    Concentrations in g/m³ and contact times recommended in disinfestation:    • Mosquitos: 0.25 for 30 minutes.    • Bugs: 2.5 for 1 hour.    • Fleas: 1.25 for 2 hours.    • Lice: 5 for 2 hours.     • Cockroaches: 5 for 2 hours.     • Destruction of all insects: 5 for 6 hours.     • Rats and mice: 2.5 for 2 hours.  (Or according to Degesch: 2-4g/m³ for 4 hours). Concentration used for disinfecting mills according to Degesch: 10g/m³ This level, close to 1%, does not prevent Degesch operators from distributing Zyklon-B disks with bare hands and apparently without ill effects [Photos 7 and 8]. A concentration of 15 to 30g/cm³ can be reached in restoration work (in the case of wooden works of art [statues] Infested by death watch beetles).       Faurisson has succeeded in his writings in presenting prussic acid as a dragon breathing fire, scarcely to be approached and with clawed feet clinging strongly to the ground even when dead. This apocalyptic picture has but little to do with actual practice. If HCN was like that, the staff of Degesch would long have been unemployed. After the world war, the Germans acquired greater experience than other nations in the handling of gases. Thus, they were the only people to have perfect mastery of the use of gas lighter than air (hydrogen) in their Zeppelin airships while the Americans who filled their airships with a non inflammable gas (helium) suffered one setback after another. Just as the Hindenburg "accident" put an end to this supremacy and to the reign of lighter than air craft, the fraudulent use of Zyklon B to exterminate Jews "stopped" the spread of gaseous disinfestation -- although this technique is of incontestable value.    [Editorial note: Photo 13 is incorrectly labeled Photo 12 in the original publication.] Photo 13: [PMO neg. no. 1196] Label of a Degesch packing case for Zyklon-B cans sent to Auschwitz on 24th April 1944. Guaranteed shelf-life: three months from the date of dispatch.    Document 5: [which can be consulted in German at the Paris CDJC under reference CLIX a21]   TRANSLATION OF DOC. NO. NI 9912 Office of Chief of Counsel for War Crimes     DIRECTIVES FOR THE USE OF PRUSSIC ACID (ZYKLON FOR THE DESTRUCTION OF VERMIN (DISINFESTATION)    I.  Properties of prussic acid (hydrocyanic acid)    Prussic acid is a gas which is generated by evaporation. Boiling point 25 degrees Centigrade Freezing point -15 degrees Centigrade Specific gravity 0.69 Steam density 0.97 (Air 1.0) The liquid evaporates easily Liquid: Transparent, colourless Smell: Peculiar, repulsively sweet Extraordinarily great penetrative powers Prussic acid is soluble in water         Danger of explosion        At 75 g prussic acid per m3 air. (Normal application approx. 8 10 g per m3, therefore not explosive.) Prussic acid may not be brought into contact with an open flame, glowing wires etc., because then burns up slowly and loses all its effectiveness (carbonic acid, water and nitrogen are formed)         Toxic effects on warm blooded animals         Since prussic acid has practically no indicative irritant effect it is highly toxic and very dangerous. Prussic acid is one of the most powerful poisons. 1mg per kg of body weight is sufficient to kill a human being. Women and children are generally more susceptible than men. Very small amounts of prussic acid do not harm the human body, even if breathed continuously. Birds and fishes are particularly susceptible to prussic acid.         Toxic effects on insects         The effects of prussic acid on insects do not depend on the temperature to the same extent as that of other gases, that is, it is also effective at low temperatures (even at 5 degrees Cent.) The eggs of many insects, particularly of bugs and lice, are more susceptible than the full grown insects.         Toxic effects on plants         The degree of toxicity depends on the type of vegetation on the plants. Plants with thick leaves are less susceptible than those with thin ones. Mildew and dry rot are not killed by prussic acid. Prussic acid does not destroy bacteria.       II  Method of using prussic acid         ZYKLON is the absorption of a mixture of prussic acid and an irritant by a carrier. Wood fiber discs, a reddish brown granular mass (Diagriess Dia gravel) or small blue cubes (Erco) are used as carriers.       Apart from serving its purpose as an indicator, this irritant also has the advantage of stimulating the respiration of insects. Prussic acid and the irritant are generated through simple evaporation. Zyklon will keep for 3 months. Use damaged cans first. The contents of a can must be used up at once. Liquid prussic acid damages polish, lacquer, paint etc. Gaseous prussic acid is harmless. The toxicity of the prussic acid remains unchanged by the addition of the irritant; the danger connected with it is however considerably decreased.         Zyklon can be rendered [harmless] by combustion.      III  Possible poisoning       1.  Slight poisoning Dizziness headache, vomiting, general feeling of sickness, etc,. All these symptoms pass if one immediately gets out into the fresh air. Alcohol reduces resistance to prussic acid gassing, therefore do not drink alcohol before fumigation. Prescribe 1 tablet Cardiazol or Veriazol in order to prevent heart disorders, if necessary repeat after 2-3 hours.      2.  Severe poisoning   The affected person will collapse suddenly and faint First aid: fresh air, remove gas mask, loosen clothing, apply artificial respiration. Lobelin, intramuscular 0.01g. Do not give camphor injections.        3. Poisoning through the skin Symptoms as for 1. Treat in the same way.      4. Stomach poisoning Treat with Lobelin intramuscular 0.01 g Ferrous sulfate Burnt magnesia.      IV   Protection against gas When fumigating with Zyklon use only special filters, e.g the filter insert "J" (blue brown) of the Auergesellschaft Berlin or of the Draegewerke, Luebeck. Should gas seep through the mask, leave the building immediately and change filters after also checking the mask and its fit to see whether they are tight  . AUSCHWITZ: Technique and operation of the gas chambers Jean-Claude Pressac © 1989, The Beate Klarsfeld Foundation  Back Page 18 Forward
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