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SMITH'S INTERMEDIATE CHEMISTRY 



The compounds with oxygen, such as NO and HNOs, and with 

 hydrogen such as NH 3 , are of immense commercial value, but, 

 not being very stable, they are formed only in traces by direct 

 union of the elements. The processes for utilizing these tenden- 

 cies to union, feeble as they are, for manufacturing purposes, will 

 be described under the compounds themselves. 



THE ATMOSPHERE 



The components of the air may be conveniently divided into 

 regular components and accidental components. The regular 

 components, again, consist of three which are present in practi- 

 cally the same proportions in all samples, and three (namely 

 water, carbon dioxide and dust) which vary markedly in quan- 

 tity. 



Components Present in Constant Proportions. The 



components whose proportions are practically invariable are 

 nitrogen, oxygen, and the group of inert gases. When the vari- 

 able components are removed, the proportions of the constant 

 ones are as follows : 



The inert gases, excepting argon, are present in traces only. 



The Water Vapor. The proportion of water vapor in the 

 air is exceedingly variable. When air becomes cool, the moisture 

 separates in cloud and fog, which are composed of minute drops of 

 liquid water. When much moisture is condensed, the drops are 

 larger and fall as rain. When they fall through a cold region, 

 they freeze to hail. When condensation takes place in air already 



