68 THE BUTYRIC ACID GROUP. 



CAPRYLIC ACID. C 16 H 15 O 3 .HO. 



Chemical Relations. 



Properties. At the ordinary temperature this acid forms a soft, 

 semifluid mass, which crystallises in needles below + 10, boils at 

 236, has a sweat-like odour, an acid and acrid taste, is difficult of 

 solution in water, and is inflammable. 



Composition. According to the above formula it consists of: 



Carbon 16 atoms .... 66-667 



Hydrogen 15 .... 10-416 



Oxygen 3 .... 19-667 



Water J 1 .... 6-250 



100-000 



The atomic weight of the anhydrous acid = 1687'5, and 

 its saturating capacity = 5*926. Its rational formula is 

 C 14 H 15 .C 2 3 .HO. 



Combinations. The salts of this acid are more difficult of solu- 

 tion than the corresponding salts of the acids already described. 

 Its baryta-salt crystallises in white granules of the size of poppy 

 seeds, is anhydrous, resists the action of the atmosphere, and does 

 not fuse at 100. The silver-salt is white and almost insoluble. 

 The lead-salt is also very difficult of solution. 



Caprylone, C 15 H 15 O, was discovered by Guckelberger* among 

 the products of the dry distillation of caprylate of baryta ; it crys- 

 tallises in fine needles of a silky lustre, but when fused resembles 

 Chinese wax ; it is perfectly white, fuses at 40, solidifies at 38, 

 and boils at 178, is devoid of taste, has a waxy smell, is lighter 

 than water and insoluble in it, but dissolves readily in strong 

 alcohol, in ether, and in ethereal as well as fatty oils. With nitric 

 acid of 1 '4 specific gravity it yields an acid nitrogenous oil (nitro- 

 capry Ionic acid?). 



Preparation. We have become acquainted with this acid as a 

 product of the saponification of butter, and as a product of the 

 oxidation of oleic acid when acted on by nitric acid ; as in the latter 

 case it is mixed with several substances, it is best obtained by the 

 recrystallisation of the baryta- salts of the volatile acids of butter. 

 In the observations on caproic acid it was mentioned that the dry 

 mass of the baryta-salts of all four acids, when treated with five or six 

 parts of water, separates into a soluble portion containing the buty- 



* Ann. d. Ch. u. Pharm. Bd. 69, S. 201-6. 



