This week we welcomed Don Napper on back to this time to present an interesting presentation on the science behind gas warfare in WWI. Science can of course be used both for good and evil – to nourish life and to destroy it. The career of the German chemist, Fritz Haber, well exemplifies this truism. Haber showed in 1909 how the nitrogen in the air could be converted into fertilizer for food production which led to an exponential increase in the supply of food and avoided worldwide famine. For this, Haber was controversially awarded the 1918 Nobel Prize for Chemistry. ‘Controversially’ because it was he who in 1915 also introduced poisonous gas warfare onto the Western Front, where some 12,000 Australian soldiers were gassed including Don’s Uncle Frank. Fortunately, Allied chemists were rapidly able to provide effective protection against the various gases deployed so that less than 5% of all battlefield deaths resulted from the effects of gas. Gas warfare, nonetheless, was exploited as a psychological terror weapon by both sides and sadly serves the same purpose even today.