178 BIOGRAPHIES OF SCIENTIFIC MEN 



the Ecole Polytechnique. Much to his credit, the greatest 

 military genius the world has ever seen was always in- 

 terested in the work of men of science, and greatly esteemed 

 their talents. It was through the influence of Napoleon 

 (then First Consul) that Alexander Volta was awarded 

 a gold medal, 1 a prize of 6000 francs (both of the 

 Acade*mie des Sciences), and the Cross of the Legion 

 d'Honneur, for his electrical researches. 



In the year (1809) that Napoleon defeated the 

 Austrians at Wagram, and annexed Tuscany and the 

 Papal States, Gay-Lussac announced his discovery of the 

 law of volume. This all-important law is generally stated, 

 in these days, in the following words : When gases or 

 vapours, either elementary or compound, unite together 

 to form a new product, the resulting product always 

 occupies two volumes. Occasionally the resulting volume 

 is the sum of the constituent volumes, but usually there 

 is condensation. The following examples illustrate the 

 law of Gay-Lussac : 



H + C1 = HC1 



Volumes 1 + 1=2 



2H + = H 2 (steam) 

 Volumes 2 + 1=2 



3H 



Volumes 1+3 =2 



NH 4 C1 



(vapour) 

 Volumes 2 + 2 =2 



The resulting volume is always two. 



1 The medal bore the following inscription : " A Volta, se'ance du 

 II Frimaire an IX." Frimaire was the third month of the calendar of 

 the first French Republic from 21st November to 20th December. 



