64 THE BUTYRIC ACID GROUP. 



ether, and, when treated with potassium, yields cyanide of potas- 

 sium, hydrogen, and carbo-hydrogens. 



Valeral, C 10 H 10 O 2 , is produced by the dry distillation of 

 valerianate of baryta ; it is a very fluid inflammable oil, which, on 

 exposure to the air, soon becomes converted into valerianic acid. 



Preparation. This acid occurs preformed in certain plants; 

 it is, however, like the preceding acids, a not unfrequent product 

 of decomposition both of vegetable and animal substances : it is 

 obtained from fusel-oil (hydrated oxide of amyl) in precisely the 

 same manner as acetic acid is obtained from alcohol (hydrated 

 oxide of ethyl), and from oil of valerian by simple oxidation by 

 means of an alkali ; it is formed, together with other acids of this 

 group, from the fats by oxidising them with fuming nitric acid 

 (Redtenbacher*) ; from animal nitrogenous matters, both by putre- 

 faction (Iljenko and Laskowskif), and on decomposing them by 

 strong oxidising agents (Schlieper,t Guckelberger, Liebig||) ; and 

 finally, if leucine be treated with caustic potash, or allowed to 

 putrefy, it becomes converted into valerianic and no other acid, 

 ammonia and hydrogen being evolved. 



It is most easily obtained in a state of purity by the action of 

 spongy platinum and atmospheric air on potato fusel-oil. 



Tests. In most of the ways in which valerianic acid is formed, 

 it occurs mixed with other acids of this group ; and it is as impos- 

 sible in this case, as in that of the homologous acids, to detect it in 

 a mixture by any special reagent; it must, therefore, be separated 

 from these acids before it can be accurately examined. As its 

 boiling point is so high, it can readily be separated from the first- 

 described acids of this group by fractional distillation ; it may still 

 remain contaminated with butyric acid, from which it can be tole- 

 rably well separated by crystallisation of the baryta-salts, the vale- 

 rianate and butyrate of baryta assuming different forms. But an 

 elementary analysis, or a determination of the atomic weight must 

 be made with the valerianate thus obtained, since mistakes may 

 very easily arise between the salts of valerianic acid and those of 

 certain acids afterwards to be described. 



[Liebig^f has recently published a paper on the separation of 

 valerianic, acetic, and butyric acids, to which we may refer the 

 reader. G. E. D.] 



* Ann. d. Ch. u. Pharm. Bd. 59, S. 41-57. 



f Ibid. Bd. 55, S. 78-95, and Bd. 63, S. 264-273. 



J Ibid. Bd. 59, S. 375-378. 



Ibid. Bd. 64, S. 50. 



|| Ibid. Bd. 57, S. 127-129. 



If Ibid. Bd. 71 ,S. 355. 



