Note:  Do not rely on this information. It is very old.

Prouts Law

Prout's Law. It was assumed in 1815 by the chemist Prout that all the supposed elementary substances arose out of the condensation of a primordial matter or "protyle." This substance was supposed to be identical with hydrogen, and as each of the other atoms was formed by the condensation of a definite number of hydrogen atoms, it followed that the atomic weights of all the elements should be integral multiples of that of hydrogen. This is what is usually meant by Prout's hypothesis or Prout's law. At first the data at the disposal of chemists were insufficient to adequately test this; but, as fresh and accurate determinations of atomic weights were made, it became evident that it could not be held as valid. In spite of some alterations made to account for certain discrepancies - such as halving the hydrogen atom - the law at present is not sufficiently supported, although the number of elements whose atomic weights do approach very nearly to integral values is a remarkable fact. [Atomic Theory.]