Van Helmont's Experiment: How Plants Grow A Willow Tree

On August 17, 1771 Jan Baptist Van Helmont a Dutch scientist did an experiment that he soon discovered how plants grew. Van Helmont used a willow tree for his experiment here are his measures:
Hypothesis: If you grow a willow tree and put soil and water in with the tree then it will grow.
Independent variable: The soil is the independent variable.
Dependent Variable: The plants depend on the water and the soil.
Controlled Variable: In this experiment the controlled variable is the soil and the pot.
Conclusion: He was wrong about his experiment the soil stayed the same way and the bark grew from water only.
Flaws of the experiment: Instead of the bark growing by soil it grew by the water. (1)

Joseph Priestly- mint jar

Joseph Priestly is another scientist who discovered photosynthesis when he does the mint in a jar experiment he soon discovered oxygen her are his measurements: Hypothesis: if I put a candle in a jar with a leaf of mint in it then it will burn until it runs out. Independent Variable: The jar doesn’t depend on anything.
Dependent Variable: The candle depends on the oxygen to stay lit.
Controlled Variable: The air is the controlled.