AVOGADRO, Amadeo (1776-1856) - Fisica de' corpi ponderabili ossia trattato della costituzione generale de'corpi del cavaliere. Turin: Stamperia Reale, 1837. First volume of the first edition of Avogradro's major treatise containing his famous hypothesis that the number of integral molecules in any gas is always the same for equal volumes, or always proportional to the volumes. In this first volume Avogradro covers the structure of matter at a given temperature setting out his ideas concerning molecular structure and discussing mathematical and mechanical problems involving the equilibrium of molecular forces with external forces. 8vo (237 x 162mm). Half-title, 9 folding plates at end (some light occasional soiling). Original printed wrappers (text divided into two block).