VALERIC ACIDS. 95 



(p. 68). A liquid very similar to butyric acid ; is, how- 

 ever, more difficultly soluble in water (in 3 parts at the 

 ordinary temperature) ; boils at 153-154. 



Calcium isobutyrate, (C 4 H 7 2 ) 2 Ca+5H 2 0, crystal- 

 lizes in long prisms, and is much more easily soluble 

 in hot than in cold water. 



Silver isobutyrate, C 4 H 7 2 Ag, crystallizes from 

 hot water in lustrous laminae. 



Monobromisobutyric acid, C 4 H 7 Br0 2 



CBr.CO.OH. By heating isobutyric acid with bro- 

 mine to 140. Colorless crystals, fusing at 45, not 

 volatile without decomposition. Becomes oily on 

 being mixed with water; over sulphuric acid in a 

 vacuum, it congeals again. But slightly soluble in 

 cold water, soluble in every proportion in hot water. 



5. Valeric Acids. 

 C 5 H 10 2 = C 4 H 9 .CO.OH. 



Of the four acids of this composition, which are 

 theoretically possible, only two are well known. 



1. Normal valeric acid, C1P.CH 2 .CH 2 .CH 2 .CO.OH. 

 Is prepared from butyl cyanide like propionic acid. 

 Is also obtained by the oxidation of the mixture of 

 alcohols from the amyl hydrides of petroleum. Color- 

 less liquid, with an odor like that of butyric acid. 

 Boiling point, 184-185; specific gravity at 0, 

 0.9577. 



The barium salt (C 5 H 9 2 ) 2 Ba crystallizes in small 

 anhydrous laminae. 



2. Ordinary valeric acid (Isopropylacetic acid), 

 I CH.CH 2 .CO.OH. Is contained in the root of 



Valeriana and Angelica qfficinalis and of Athamanta 

 oreoselinum ; in the berries and bark of Viburnum 



