The Colours Of White Light
Hypothesis: Colours are added when white light passes through a prism.
Experiment: Newton (1665) blocked all colours except one, then passed it through a second prism.
Result: The single colour was unchanged by the second prism.
Conclusion: This proved that prisms did not add colours.
Newton thus proved that white light comprises colours “mixed” together, and that the prism merely separates them.