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Absorption Spectra, Molecular Weights, and Visual Purple


HOUSTON1 has shown that, in the case of absorbing media, the number p of electrons per molecule of solute giving rise to an absorption band with a maximum at the wave-length λm is given by where e and m are the electronic charge and mass respectively, mH the mass of the hydrogen atom, n the refractive index of the solution at λm, km the absorption coefficient at λm, s the concentration in gram-molecules per c.c., and λ' the wave-length at which the absorption index is half the value km. Houston calculated p for some thirty substances, and found values between 0·1 and 1 in eighteen cases ; between 1 and 2·7 in four cases ; and considerably less than unity in the remaining cases.

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WEALE, R. Absorption Spectra, Molecular Weights, and Visual Purple. Nature 163, 916–917 (1949).

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