Sur la limite de visibilité de la fluorescence et sur la limite supérieure du poids absolu des atomes d'hydrogène

Spring, W. Bulletin de la Classe des Sciences, Academie Royale de Belgique (1905), 201-11; SciFinder (Chemical Abstracts Service: Columbus, OH); https://scifinder.cas.org (accessed July 8, 2010).

A solution of fluorescein in optically pure water was subjected to the action of a powerful beam of electric light, and the limit of dilution was observed at which a visible green fluorescence was produced. Assuming under these conditions that one cubic millimetre of the solution contained one molecule of fluorescein (C20H10O5K2 = 408), the value 2.5 × 10-21 grams is obtained for the superior limit of the weight of the atom of hydrogen, which is one-twenty-thousand-millionth part of the value 5 × 10-11 calculated by Annaheim (this Journal, 1877, i, 31), but is about seven thousand times as great as the value 3.45 × 10-25 calculated from the kinetic theory of gases.

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