View Here : Jan Ingenhousz Photosynthesis Experiment
Jan Ingenhousz concluded that sunlight is essential for plant processes that purify the air. He discovered that the green parts of plants release oxygen during photosynthesis. During his experiment he placed an aquatic plant submerged in transparent jar in sunlight. He found that bubbles (gases) were formed on the lower surface of the leaves.
Through those experiments Ingenhousz discovered that a candle would burn longer, and a mouse would be revived by having a plant in the jar… only if the plant was exposed to direct sunlight. What this proved was that plants did something to air- but only with the help of the sun.