126 CIMICIC ACID, ETC. 



5. Cimicic Acid. 

 C i5 H 28 2 ^ C 14 H 27 .CO.OH. 



Occurs in a leaf bug, Rhapigaster punctipennis. 

 Yellowish, crystalline mass. Fusing point, 44. 



6. Hypogceic Acid. 



C 15 H 29 .CO.OH. 



In the form of the glycerin ether in ground-nut oil 

 (the oil of the fruit of Arachis hypogcea). Colorless, 

 needly crystals, fusing at 33, which become yellow in 

 the air. Combines with bromine to form the clibro- 

 mide C^H^Bi^O 2 (solid, uncrystalline mass, fusing at 

 29), which, when treated with alcoholic potassa at 

 100 yields monobromhypogmc acid C 16 H 29 Br0 2 . When 

 carefully heated with nitric acid, hypogseic acid is 

 converted into an acid of the same composition, gaidic 

 acid. Crystals, fusing at 39. 



7. Oleic Acid (Ela'ic Acid). 

 Ci*H 34 2 = C 17 H 33 .CO.OH. 



Contained in nearly all fats as glycerin ethers 

 (elain) ; in the largest proportion in the liquid fats, for 

 instance, olive oil, oil of almonds, whale and seal oils. 

 In order to prepare it from these, the liquid fat is 

 digested with lead oxide, the lead salts washed, and 

 from these the lead oleate extracted with ether, and 

 the ethereal solution decomposed with hydrochloric 

 acid. The solution, poured off from lead chloride, leaves 

 impure oleic acid behind when evaporated. It is 

 dissolved in ammonia, barium oleate precipitated by 

 adding barium chloride, and the salt, after having 

 been repeatedly recrystallized from alcohol, is decom- 

 posed by means of tartaric acid. 



Colorless oil, congeals at 4 and fuses at 14 ; inodor- 

 ous and tasteless. Alone, it cannot be distilled, the 

 distillation can, however, be effected by means of over- 

 heated vapor of water at 250. In a pure condition 

 pretty stable; in an impure condition it takes up 



