I read that tests had been carried out on human subjects in Frankfurt and in one of the suburbs which no longer exists. Experiments were carried out on groups of five, groups of ten, on standardised groups – all men, all women and all children – and on mixed groups: families – father, mother, son, daughter, grandmother, even the maid if she was Jewish or a little soft in the head. The purpose of the experiments being to determine how much gas was needed in both cases to kill quickly and efficiently. Since lung capacity differed from one subject to another, it was possible to establish a correlation between the volume of air inhaled and the time taken before death ensued, taking into account natural disparities, such as the fact that though a baby inhales less air than an adult, being considerably weaker, it takes less gas to kill it. It’s the story of Galileo when, before an audience of stunned prelates, he demonstrated that, whether light or heavy, bodies in freefall fall at the identical speed which is, therefore, independent of their mass. An adult is resilient but inhales considerably more air than a baby, but the baby is physically weaker. In the end, death comes to both at the same time. These experiments demonstrated that people could be gassed in groups without regard to sex, age or physical condition. Whether by bullet, by rope or by gas chamber, they died just the same. There was no need to separate prisoners into groups, something of an advantage in a mass extermination. The problem, however, remained a complex one with many variables – the stress levels of the subject, the dosage, the shape and size of the gas chambers, the skill of those operating them, etc. There were fears that, though life and death are abstract concepts, the supernatural and the religious might produce unwelcome thoughts in the minds of those operating the chambers, there was talk of the rabbi’s curse, of avenging ghosts, of strange miracles. A production line process, they concluded, would put paid to such nonsense by giving each individual worker the impression that he was performing only the most innocuous task in the extermination process. Just as in a firing squad, every soldier is free to believe that he fired the blank. A production line approach was applied to every stage of the process, from the rounding up of the Jews, through their arrest and transportation to the burning of the bodies in the camps. The link does not know it is part of the chain. We are not all equal in the face of death, a breeze may be enough to kill one man, while another, no bigger, no stronger, no more intelligent, may survive an earthquake. It falls to the Machine to equalise our relationship with death. A means therefore had to be found to take into account the principal variables. Calculating devices were created to make the process easier for a workforce that was not especially bright. By turning a dial to the number of people packed into the chamber, and moving a slider to the volume of the chamber in cubic metres, it was possible to read off the quantity of Zyklon B necessary, this quantity was further refined by setting one slider to the temperature of the chamber and another to the initial figure for the quantity of Zyklon B. In warm weather, say 25ºC, death could be guaranteed for 95 per cent of the subjects in a thirty-minute period. In cold weather, however – below 5ºC – the mass of air is stationary, gas disperses poorly and productivity is negatively affected, making it necessary to repeat the procedure or increase the quantity of Zyklon B, either of which represented a waste of the Reich’s time and money. A loss of ten minutes and three Reichsmarks per subject may seem insignificant, but with some 10 million subjects marked out for death, the shortfall would amount to 100 million minutes and 30 million Reichsmarks, an unacceptable folly for a country already involved in an otherwise profitable world war.