Prout's hypothesis

Etymology
Named after the English chemist William Prout.

Proper noun

 * 1)  An early 19th-century attempt to explain the existence of the various chemical elements: the hypothesis that, since the atomic weights for known elements appeared to be whole multiples of the atomic weight of hydrogen, the hydrogen atom was the only truly fundamental object, and the atoms of other elements were actually groupings of various numbers of hydrogen atoms.