Foundations of the molecular theory / comprising papers and extracts by John Dalton, Joseph-Louis Gay-Lussac, and Amedeo Avogadro (1808-1811).

Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Foundations of the molecular theory / comprising papers and extracts by John Dalton, Joseph-Louis Gay-Lussac, and Amedeo Avogadro (1808-1811). Source: Wellcome Collection.

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    4. ESSAY ON A MANNER OF DETER- MINING THE RELATIVE MASSES OE THE ELEMENTARY MOLECULES OF BODIES, AND THE PROPORTIONS IN WHICH THEY ENTER INTO THESE COMPOUNDS. By A. AVOGADRO.* I. GAY-LUSSAC has shown in an interesting Memoir (Memoires de la Societe d’Arcueil, Tome II.) that gases always unite in a very simple pro- portion by volume, and that when the result of the union is a gas, its volume also is very simply related to those of its components. But the quantitative proportions of sub- stances in compounds seem only to depend on the rela- tive number of molecules t which combine, and on the number of composite molecules which result. It must then be admitted that very simple relations also exist between the volumes of gaseous substances and the numbers of simple or compound molecules which form * Journal de Physique, LXXIII. (1811), pp. 58-76. t [Avogadro has been accused of inconsistency in his use of the term “ molecule,” but a careful perusal of his paper will show that he uses it with its qualifying adjectives quite consistently, as follows:— MoUctde (translated “ molecule ”) without qualification means in modern chemical phraseology either atom or molecule. Mohkitle ititJgrante (translated “integral molecule”) means molecule in general, but is usually applied only to compounds. Molicule constiinante (translated “constituent molecule’’) is em- ployed to denote the molecule of an elementary substance. MoUcule ^li’mentaire (translated “elementary molecule ”) stands for the atom of an elementary substance.]