Structure of Simpler Organic Compounds. 93 



mercial processes with sodium carbonate ; on concentration 

 of the solutions thus produced, the hydrated salt separates 

 out in crystals. The anhydrous salt can be obtained by 

 fusing these crystals. 



Glacial acetic acid has a sharp pungent taste, and exerts 

 a corroding action on animal tissues. It is miscible with 

 water, alcohol, and ether in all proportions. It is largely 

 used in the preparation of various drugs, dyes, and other 

 chemicals, and also as a solvent in the laboratory. Some 

 of the salts are of importance. 



Sodium acetate, C 2 H 3 O 2 Na 3H 2 0, is largely used as 

 a laboratory reagent. 



Lead acetate, (C 2 H 3 2 ) 2 Pb 3H 2 0, and basic lead acetate 

 are both largely used as precipitants ; the former is pre- 

 pared by dissolving litharge in acetic acid solutions and 

 concentrating the product ; the basic salt is obtained by 

 dissolving litharge in solutions of the ordinary acetate. 



Various copper acetates are known, of which one of 

 the basic ones is known as verdigris. 



Of the other fatty acids, propionic acid occurs amongst 

 the products of destructive distillation of wood ; normal 

 butyric acid occurs in butter (as a glyceride), and is pro- 

 duced as a product of various fermentation processes. The 

 valeric acids occur in various plants. The higher fatty 

 acids will be referred to in detail later in the discussion of 

 the chemistry of fats. 



The chemisfoy of the fatty acids may be summarized 

 as follows : They can be represented by the general formula 

 R COOH, the residue CO OH being known as the 

 carboxyl group, and contained in the majority of organic 

 acids. It contains one hydrogen replaceable by a metal, 

 and a hydroxyl group replaceable by chlorine when the acid 

 is treated with phosphorus pentachloride. The genetic re- 

 lationship of the acids to the substances already discussed 



