AVOGADRO (Amedeo). Remarks on the law of the elastic force of air in relation to its density in the case of compression without loss of heat, and on that of the specific heat of air in relation to temperature and pressure. [Turin, Stamperia reale, 1828]. Extract from Memorie della reale accademia delle scienze di Torino, tom. XXXIII, pp. 237-274. In-4, bradel marbled boards, untrimmed, dummy cover (Modern binding). Extremely rare first edition of this important article by the Italian physicist and chemist Amedeo Avogadro (1776-1856), famous for the law that bears his name (two equal volumes of different gases, under the same conditions of temperature and pressure, contain an identical number of molecules), and for Avogadro's number (the constant that defines the mole). A copy given by the author to François Arago (1786-1853) with an autograph dispatch "À M. Arago, membre de l'Acad[émi]e R[oyal]e des Sciences, l'auteur" on the first blank page.