COMBINING PROPORTIONS. 



107 



COMBINING PROPORTIONS. 



* 



All analyses prove that the composition of bodies is fixed 

 and invariable : 100 parts of water are uniformly composed of 

 11.1 parts by weight of hydrogen, and 88.9 parts of oxygen, 

 its constituents never varying either in nature or proportion. 

 This and other substances may exist in an impure condition, 

 from an admixture of foreign matter, but their own composition 

 remains the same in all circumstances. It is this constancy in 

 the composition of bodies which gives to chemical analyses all 

 their value, and rewards the vast care necessarily bestowed 

 upon their execution. 



An examination of the composition of any class of bodies 

 containing an element in common, such as the oxides, shows 

 that any one element unites with very different quantities of the 

 other elements. Thus in each of the five oxides, of which the 

 composition is given below, the oxygen and other constituent 

 appear in a different relation to each other. 



Composition of Oxides. 



But the relation between the oxygen and the other consti- 

 tuent in these oxides will be seen more distinctly by stating 

 their composition in such a way as to have the oxygen expressed 

 by the same number in every case, or made equal to 100 parts. 

 Thus, 



From which it follows, that 



12.5 parts of hydrogen, 

 396 parts of copper, 

 403 parts of zinc, 

 1294 parts of lead, 

 1 352 parts of silver, 

 combine with 100 parts of oxygen. 



