Describe very briefly the contribution of the following scientists :

(1) Jan Ingcnhousz

(2) C.B. Van Niel

(3) Joseph Priestly

(1) Jan Ingenhousz showed that sunlight is essential to the plants process that somehow purifies the air.

(2) C.B. Van Niel, proposed  that the oxygen produced during the photosynthesis comes from water and not carbon dioxide. 

(3) Joseph Priestly  reported that green plants purify the air and restore to the air whateever the burning of candle or breathing animals remove from the air.