Hypothesis William Prout

William Prout s composite atoms hypothesis. G. Kirchhoff and R. Bunsen discover spectral analysis and significance of Fraunhofer lines Kirchhoff s law. 

Chemists still didn t know why there were so many different chemical elements or whether any patterns could be found in them. In 1815 the English physician William Prout had proposed the hypothesis that all of the elements were condensed hydrogen. For example, the atomic weight of oxygen was 16. According to Prout, this indicated that 16 volumes of hydrogen had condensed to form this element. Of course Prout s hypothesis was incorrect. However, during the nineteenth century there was no empirical evidence that either supported or contradicted the idea. Consequently, some chemists adopted the theory while many others opposed it. 

Marignac s life work, which, like that of Stas, consisted in making many precise determinations of atomic weights in order to test William Prout s hypothesis (71), won Berzelius sincerest praise, for he wrote ... 

While Dimitri Mendeleev had remained strongly opposed to any attempts to reduce, or explain, the periodic table in terms of atomic structure, Julius Lothar Meyer was not so averse to the reduction of the periodic system.The latter strongly believed in the existence of primary matter and also supported William Prout s hypothesis. Lothar Meyer did not hesitate to draw curves through the numerical properties of atoms, whereas Mendeleev beheved this to be a mistake, since it conflicted with his own behef in the individuahty of the elements. 

Such was the climate of opinion when, in 1816, William Prout (1785-1850) published his hypothesis that all matter is composed ultimately of hydrogen. Prout cited as evidence the fact that the specific gravities of gaseous elements appeared to be whole-number multiples of the value for hydrogen, and, on the equal volumes-equal numbers of atoms principle, the weights of the atoms of different elements would be whole-number multiples of the weight of the hydrogen atom. 

William Prout (1785-1850), English physician and chemist, formulated in 1815 the hypothesis that the atomic weights of all elements are integral multiples of that of hydrogen. Thus hydrogen should be the primary substance of which... 

The modern view of matter developed from John Dalton s theory which, for the first time, combined the abstractions of atom and element into a single practically useful concept, albeit at the cost of unwanted diversity. Resolution of the dilemma, by postulating hydrogen as the common building block of more complex atoms, was resisted so fiercely that the alleged author, William Prout, had to publish his proposal anonymously. The importance of number was at the heart of his hypothesis. Despite experimental evidence which contradicted the notion, Prout s hypothesis was not without support and remained alive until its final vindication in the discovery of isotopes and atomic number, which ironically also signalled the demise of atomic particle theory. 

William Prout (1815) proposed that all other atoms are built up of hydrogen atoms, suggesting that all elements should have integral atomic masses based on an atomic mass of one for hydrogen. This hypothesis appeared discredited by the discovery of atomic masses, such as 24.3 u for magnesium and 35.5 u for chlorine. In terms of modern knowledge, explain why Prout s hypothesis is actually quite reasonable. 

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