Describe the experiment of Priestley.

(N/A) Joseph Priestley $(1733-1804)$ performed a series of experiments in $1770$ that revealed the essential role of air in the growth of green plants.
- Priestley observed that a candle burning in a closed space (a bell jar) soon gets extinguished (Figure $a, b$).
- Similarly,a mouse kept in a closed space would soon suffocate.
- Based on these observations,he concluded that a burning candle or an animal that breathes the air,both somehow damage the air.
- However,when he placed a mint plant in the same bell jar,he found that the mouse stayed alive and the candle continued to burn (Figure $c, d$).
- Priestley hypothesized that plants restore to the air whatever breathing animals and burning candles remove.
- Later,in $1774$,Priestley discovered oxygen.