Rutherford kept a mouse in a jar with confined quantity of air until it died. He then burned a candle in what was left until the candle went out. He then burned phosphorus in what was left after that, until the phosphorus burned no more. Next, the air was passed through a solution that allowed air to absorb carbon dioxide. The air remaining now would not support combustion, a mouse would not live in it, and a candle would not burn.