Early fire grenades were filled with salt water and a chemical called ammonium chloride. When tossed into a fire, the glass shattered and the liquid released fumes that were supposed to help smother the flames—though it didn’t always work as planned.

By the early 1900s, manufacturers upped the game with a more powerful chemical: carbon tetrachloride (CTC). When heated, CTC turned into a heavy gas that sank into the fire and cut off its oxygen supply. It worked well—but came with a dark side. CTC is extremely toxic. Breathing it in could damage your brain, liver, and kidneys—and long exposure could even cause cancer. And if that’s not alarming enough, at high temperatures it could create phosgene gas—a deadly chemical weapon used in World War I that killed over 85,000 people. So yes, fire grenades could put out a blaze... but they were a little terrifying too.