Nouvelles Recherches sur les Lois des Proportions chimiques, sur les Poids atomiques et leurs Rapports mutuels.

1866. Paris, Victor Masson et Fils, 1866. 8vo. Contemp. hcalf, raised bands, gilt spine. Light wear along edges. Wear to top of spine. Small stamps on verso of titlepage. In "Annales de Chimie et de Physique", 4ieme Series - Tome IX. 528 pp., 2 folded plates. (The entire volume offered). Stas' paper: pp. 215-243. Internally clean and fine. First French printing of Stas's importent (first) paper in which he demonstrates the incommensurability of the atomic weights, proving that atomic weights are not whole numbers or multiples of halv or a quarter of the atomic weight of hydrogen."Stas demonstrated that the values of the atomic weights he had determined were neither multiples of unity, nor of one half, as Marignac believed, nor of one quarter, as Dumas maintained. This publication led Marignac to doubt the universality of the law of definite proportions. In three papers collectively entitled "Nouvelles recherches sur les lois des proportions chimiques, sur les poids atomiques et leurs rapports mutuels" (1865), Stas presented the results of an extensive series of experiments devoted to the new demonstration. By painstaking and accurate measurements he established that atomic weights were incommensurable, thereby disproving the facile conclusion that discrepancies with whole-number values were due merely to experimental errors. Prout’s hypothesis was thus discredited."(DSB).