LAWS OF CHEMICAL COMBINATION. 



43 



1 volume of hydrogen combines with 1 volume of chlorine, 

 forming 2 volumes of hydrochloric acid gas ; 2 volumes of hydro- 

 gen combine with 1 volume of oxygen, forming 2 volumes of 

 water-vapor; 3 volumes of hydrogen combine with 1 volume 

 of nitrogen, forming 2 volumes of ammonia. 



If the different combining volumes of the gases mentioned 

 are weighed, it will be found that there exists a simple relation 

 between these volumes and the atomic or molecular weights of 

 the elements. 



For instance : Equal volumes of hydrogen and chlorine com- 

 bine, and the weights of these volumes are as 1 : 35.5, which 

 numbers also represent the atomic weights of the two elements. 

 Two volumes of hydrogen combine with one volume of oxygen 

 and the weights of the volumes are as 1 : 8 or 2 : 16, the latter 

 being the atomic weight of oxygen. 



1 Volume 1 Volume 



Hydrogen f Chlorine 

 Weight =1 Weight=35.5 



'i Vol umes 

 Hydrochloric Acid 



1 Volume 1 Volume ; 1 Volume 



Hydrogen + Hydrogen + Oxygen 



W = l W = l W = 16 



2 Volumes 

 Water-vapor 



2 Voliumes 



Amm onia 



The above table shows the simple relation which exists be- 

 tween combining volumes, atomic and molecular weights, and 

 that such a relation exists is not surprising, if we remember the 



