These know-your-chemical-weapon posters were produced by the Medical Training Replacement Center at Camp Barkeley near Abilene, Texas as training materials for soldiers being sent to fight in WWII. They're a weird mix of cheerfulness and atrocity:
Four WWII Posters That Taught Soldiers to Identify Chemical Weapons by Smell (via Kadrey)
Of the four chemicals mentioned here—phosgene, lewisite, mustard gas, and chlorpicrin—three were used in World War I. (Lewisite was produced beginning in 1918, but the war ended before it could be used.) Phosgene, which irritates the lungs and mucus membranes and causes a person to choke to death, caused the largest number of deaths among people killed by chemical weapons in the First World War. (Elsewhere on Slate: A firsthand account of what it felt like to be hit by mustard gas.)
The smells that these posters warn soldiers-in-training to be wary of are the everyday scents of home: flypaper, musty hay, green corn, geraniums, garlic. The choice of analogies seems particularly appropriate for soldiers raised on farms—a population that would become increasingly small in every war to follow.
(Images: National Museum of Health and Medicine)