MONOBASIC FATTY ACIDS. 503 



Analytical reactions. 

 (Sodium acetate, NaC 2 H 3 O 2 , may be used.) 



1. Any acetate heated with sulphuric acid evolves acetic acid, 

 which may be recognized by its odor. 



2. Acetic acid or acetates heated with sulphuric acid and alcohol 

 give a characteristic odor of acetic ether. 



3. A solution containing acetic acid, or an acetate carefully neutral- 

 ized, turns deep red on the addition of solution of ferric chloride, 

 and forms, on boiling, a reddish-brown precipitate of an oxyacetate 

 of iroa 



Potassium acetate, Potassii acetas, KC 2 H 3 O 2 = 97.44. Sodium 

 acetate, Sodii acetas, NaC 2 H 3 O 2 .3H 2 O === 135.1. Zinc acetate, 

 Zinci acetas, Zn (C 2 H 3 O 2 ) 2 .2H 2 O = 217.82. These three salts may 

 be obtained by neutralizing the respective carbonates with acetic acid 

 and evaporating the solution ; they are white salts, easily soluble in 

 water. 



Ammonium acetate, NH 4 C 2 H 3 O 2 , is official in the form of a 7 

 per cent, solution, which is known as Spirit of Mindererus. 



Iron acetates. Both the ferrous acetate, Fe(C 2 H 3 O 2 ) 2 .4H 2 0, and the ferric 

 acetate, Fe(C 2 H 3 O 2 ) 3 , are known. The latter is formed by adding sodium ace- 

 tate to the solution of a ferric salt, as is indicated by the deep-red color which 

 the solution assumes. As stated above in reaction 3, on boiling, decomposition 

 of the salt takes place. The separation of manganese and some other metals 

 from iron depends on this reaction. 



Lead acetate, Plumbi acetas, Pb(C 2 H 3 O 2 ) 2 3H 2 O = 376.15 (Sugar 

 of lead), is made by dissolving lead oxide in diluted acetic acid. It 

 forms colorless, shining, transparent crystals, easily soluble in water; 

 on heating, it melts and then loses water of crystallization ; at yet 

 higher temperatures it is decomposed ; it has a sweetish, astringent, 

 afterward metallic taste. Commercial sugar of lead contains often an 

 excess of lead oxide in the form of basic salts ; such an article when 

 dissolved in spring water gives generally a turbid solution, in conse- 

 quence of the formation of lead carbonate ; the addition of a few 

 drops of acetic acid renders the liquid clear by dissolving the pre- 

 cipitate. 



When a mixture of lead acetate and lead oxide is digested or boiled 

 frith water, the acetate combines with the oxide, forming a basic lead 



