This scientist placed a lit candle and a plant under a transparent jar. After the candle went out the first time, he covered the jar with a black cloth to prevent it from being exposed to light and found that the candle would not relight. He concluded that light was necessary for the plant to be able to change the composition of the air. He also did an experiment with little aquatic plants in transparent containers and noticed that in the light they produced little gas bubbles. In the dark, no gas bubbles appeared. This solidified his previous conclusion that light was necessary for plants to produce oxygen.
Who was this scientist?
Jan van Helmont