NITROGEN. 169 



substance possessed of an excessive appetite, or affinity, 

 for oxygen. A small portion of it in a wine cask, will 

 seize on what little oxygen finds admission, and so 

 prevent the deterioration of the wine. It destroys it- 

 self in this act of protection, and is converted into sul- 

 puric acid. 



How is sul- ^' ^ SE 1N SUGAR MANUFACTURING. 



phurous acid The oxygen of the air so modifies the 



employed in . . ~ ,, .. . . , , 



manufactur- juice of the sugar-cane, that it cannot be 

 ing sugar ? made to yield its due proportion of sugar. 

 Sulphurous acid, by appropriating the oxygen to itself, 

 prevents this effect, and is said to double the product. 

 It is generally used in the form of its lime compound, 

 called sulphite of lime. The objection to its use con- 

 sists in the slight sulphurous taste which it imparts to 

 the sugar. But this is said to be removed by clarifi- 

 cation, at a loss of ten per cent., leaving still a large 

 gain from the employment of the process. The bleach- 

 ing effects of sulphurous acid have already been illus- 

 trated. 



NITROGEN. 



411. DESCRIPTION. Nitrogen is a trans- 

 trogen ? parent gas, without taste or odor. It forms 



Where is it about f our _fif t h s of the air we breathe. It 



found ? 



occurs also in combination with other ele- 

 ments in a solid form. One-fifth of the weight of the 

 dried flesh of animals is nitrogen. It also enters into 

 the composition of nitre and other salts. 



