THE IMPORTANCE OF OXYGEN. 70 



the relations of aethereal and ponderable matter. 

 All the waters of the earth are composed of oxy- 

 gen and hydrogen, in the proportions of 8 to 1 

 by weight. When converted into vapour by solar 

 caloric, and diffused through the atmosphere, 

 water is connected with all the phenomena of 

 metereology. As a mechanical agent, running 

 water is perpetually wearing down mountains, 

 hills, and elevated plains, and transporting them 

 to valleys, lakes, and seas. 



As a chemical agent, water is slowly but con- 

 stantly dissolving rocks, salts, and metals, which 

 are again precipitated in the crystalline or solid 

 state. It forms a large proportion of all animal 

 and vegetable bodies ; also, of many salts arid 

 rocks. As a constituent of the atmosphere, oxy- 

 gen is indispensable to all the phenomena of vi- 

 tality. It enters largely into the composition of 

 nearly all acids, alkalies, native ores, or metallic 

 bases ; and constitutes about \ of the earth's crust. 



The importance of carbon is not less manifest; 

 forming, as it does, the basis of all organic matter. 

 In combination with hydrogen, it constitutes the 

 principal portion of the food by which we are 

 nourished, and of the fuel by which we are 

 warmed, and kept alive during winter. Accord- 

 ing to the analysis of Gay-Lussac, and of Dr. 

 Prout, it forms about one half of lignin, or per- 

 fectly dried woody fibre. It is the chief ingre- 

 dient in those immense subterranean forests of 



