68 THE THEORY OF IONS 



hyde, C 4 H 7 N0 2 , by condensation. When in a free 

 state these acids have a neutral reaction. They can 

 form combinations with other acids, and also by 

 their carboxyl-end with bases. 



AMIDES, Acid-amines, or Aminic-acids. An 

 amido-acid can form other compounds with am- 

 monia, by substituting a radical in place of a 

 hydroxyl. The amides or aminic-acids are formed 

 by fixing ammonia to an acid at its carboxyl-end. 

 A molecule of water is eliminated by loss of H 

 from ammonia and OH from the carboxyl -group. 

 Thus Formic acid and ammonia = Formamide and 

 water ; or Acetic acid and ammonia = Acetamide 

 and water. Carbamic acid and ammonia = Urea 

 and water, thus : 



CH 3 N0 2 + NH 3 = CH 4 N 2 + H 2 

 or CO-1S T H 2 .OH + NH 3 . CO.NH 2 -NH 2 + H 2 0. 



Carbamic acid does not exist in a free state, and 

 unless it meets with other bodies to form carbamides 

 it splits into C0 2 and NH 3 . The acid may however 

 join any base, alcohol or another amide-group, by 

 displacing a hydroxyl ; it thus forms a salt, an 

 ether or an amide. Urea or carbamide is so formed 

 as the final decomposition product of the oxidation 

 of nitrogenous compounds such as albumin. 



If aspartic or amido-succinic acid be used the 

 ammonia ion displaces one of the hydroxyls, and 

 the resulting amide is Asparagine. If Benzoic acid 

 is used we get Benzamide ; and by joining the alkyl- 

 part of this to acetic acid we get Hippuric acid, 

 C 9 H 9 N0 3 , or Benzamide-acetic acid, which is looked 

 upon as benzoyl and glycocoll linked together. 



