What gas is in Dulce et decorum est?

What gas is in Dulce et decorum est? Later the mustard gas, which is described in Dulce et Decorum Est, was delivered by artillery shell, the Five-Nines (so called because they were 5. 9 inches or 150 mm long) which Owen used in an earlier draft of line 8. What is the green gas in … Continue reading What gas is in Dulce et decorum est?