What’s Inside: Tear Gas

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• Charcoal
  Usually made of wood heated until it’s almost pure carbon. Pull the pin, and the fuse will set it smoldering: When combined with potassium nitrate, charcoal is easy to ignite.
• Potassium nitrate
  Aka saltpeter, it gives off great quantities of oxygen when it burns, feeding the fire. Plants need potassium and nitrogen, so KNO₃ has been used in fertilizer for centuries. The stuff used to come from bat poop or livestock pee, but today it can be made from ammonia.
• Silicon
  As the potassium nitrate and charcoal burn, elemental silicon is converted into tiny droplets of 2,500-degree silicon dioxide (aka superhot glass), which then spatters onto the other ingredients and ignites them.
• Sucrose
  Fuel for the fire. Sugar melts at 370 degrees Fahrenheit, a relatively low temperature that heats and vaporizes the tear-making chemical without destroying it. An oxidizer will help keep combustion going.
• Potassium chlorate
  An oxidizer. When heated, KClO₃ releases copious amounts of pure oxygen. It also breaks down into potassium chloride, which makes up some of the smoke from the grenade.
• Magnesium carbonate
  Potassium chlorate does not get along with acid (the mixture is explosive). This stuff, found in laxatives, fire extinguishers, and pool cue chalk, keeps pH levels slightly basic, neutralizing any acidic content caused by chemical impurities or moisture. When heated, it gives off CO₂, further dispersing the tear gas.
• O-Chlorobenzalmalononitrile
  A lachrymator, meaning it produces tears. It also causes that burning sensation in the nose and throat and on the skin. As little as 4 milligrams per cubic meter will disperse unruly crowds. It’s believed that a lethal dose is around 25 grams per cubic meter.
• Nitrocellulose
  Some grades of nitrocellulose, like guncotton, are explosives. Others are lacquers that might provide the finish on, say, a vintage guitar. Here, low-nitrogen NC is used as a sticky binder to keep all the other ingredients homogeneously blended.