XXIV 

 AMADEO AVOGADRO 



1776-1856 



Avogadro, who continued the researches of Dalton and Gay-Lussac, 

 was born in Tiirin, Italy, June p, ^^77^- In 1796, after receiving 

 the doctor's degree in lazv from the University of Turin, he was em- 

 ployed by the government for the following ten years. He began 

 his work in science in 1806 and three years later was made pro- 

 fessor of physics at Vercelli. In 181 1 he announced his famous law. 

 According to Merz, since the time of Boyle ^'it had been known that 

 equal volumes of different gases under equal pressure change their 

 volumes equally if the pressure is varied equally, and it was also 

 known that equal volumes of different gases under equal pressure 

 change their volumes equally zmth equal rise of temperature. These 

 facts suggested to Avogadro, and almost simultaneously to Ampere, 

 the very simple assumption that this is owing to the fact that equal 

 volumes of different gases contain an equal number of the smallest 

 independent particles of matter. This is Avogadro' s celebrated hy- 

 pothesis. It was the first step in the direct pJiysical verification of 

 the atomic view of matter." 



In 1820 Avogadro becanw professor of physics at Turin Uni- 

 versity, where he remained for many years. He died Jidy p, 18^6. 



THE MOLECULES IN GASES PROPORTIONAL TO THE 



VOLUMES * 



I. 



M. Gay-Lussac has shown in an interesting Memoir (Mcmoires de 

 la Societe d'Arcueil, Tome II.) that gases always unite in a very 



* Translated from Essai d'une maniere de determiner les masses relatives 

 des molecules elementaires des corps, et les proportions selon Icsquelles elles 

 entrent dans les combinaisons — Journal de Physique, (181 1). 



177 



