There are many different designs for gas chambers, depending on who made them and their intended purpose. In the United States, gas chambers used to carry out capital punishment basically work like this:
- The executioner places cyanide pellets in a box under the chair in the gas chamber.
- The condemned is strapped into the chair.
- The door is sealed.
- The executioner pours sulfuric acid down a tube that goes into the box containing the cyanide pellets.
- The sulfuric acid reacts with the cyanide and forms hydrogen cyanide (HCN) gas.
- After the condemned loses consciousness and stops moving, the gas is vented from the room.