‎"HESS, (GERMAIN HENRY). - ANNOUNCING ""THE LAW OF HEAT FORMATION""‎
‎Recherches sur les quantités de chaleur dégagées dans les combinaisons chimiques. Lettre de M. Hess à M. Arago.‎

‎(Paris, Bachelier), 1840. 4to. No wrappers. In: ""Comptes Rendus Hebdomadaires des Séances de L'Academie des Sciences"", Tome X, No. 19. Pp. (721-) 775 (entire issue offered). Hess' paper: pp. 759-763. A few scattered brownspots.‎

Reference : 48828

‎First apperance of the announcement of Hess' newly discovered law, known as Hess's Law, in form of a letter to Arago. ""Here thermochemistry received its first importent advance at the hands of Germain Hess, who showed that the heat evolved in a reaction is the same regardless of whether the reaction is carried out directly or in a number of steps..."" (Leicester & Klickstein ""A Source Book in Chemistry"", pp. 329-332). This announcement preceded the larger paper published the same year in ""Annales de Chimie et de Physique"" and the original (and larger) paper in ""Bulletin scientifique, Academie impériale des Sciences (St. Petersbourg)"". Parkinson ""Breakthroughs"" 1840 C.‎