THE BUTYRIC ACID GROUP. 39 



of atoms of hydrogen. Thus, these substances arrange themselves 

 in the following arithmetical proportion : 



Nitrile of formic acid = hydrocyanic acid = H . C 2 N. 



acetic acid ... = cyanide of methyl =C 2 H 3 . C 2 N. 



metacetonic acid = cyanide of ethyl =C 4 H 5 . C 2 N. 



Butyronitrile =C 6 H 7 . C 2 N. 



Valeronitrile =C 8 H 9 . C 2 N. 



While in the first three of these combinations the existence of 

 cyanogen may be regarded as established, Kolbe * believed that he 

 could recognise the existence of t such carbo-hydrogens as C 6 H 7 and 

 C 8 H 9 ; and, indeed, he fully proved their presence, by exposing to an 

 electric current the potash-salts of the acids corresponding to the 

 two last-named nitriles, namely, butyric acid and valerianic acid ; 

 besides other products, he then obtained the carbo-hydrogens 

 C 6 H 7 and C 8 H 9 . In further investigations^ by decomposing 

 cyanide of ethyl by potassium, he established the existence of the 

 radicals, methyl and ethyl, C 2 H 3 and C 4 H 5 . 



From these facts relating to the nitriles of these acids, we are 

 almost involuntarily led to Kolbe's original view, and to regard the 

 acids of this group as conjugated oxalic acids, that is to say, as acids 

 in which oxalic acid is so combined with one of the above-named 

 carbo-hydrogens =C n H n+1 , as not to affect the saturating capacity 

 of the acid. 



This view is supported by the following experimental evidence. 



Butyric and valerianic acids are decomposed under the influence 

 of the galvanic current ; assimilating an atom of oxygen, they yield 

 2 equivs. of carbonic acid and the corresponding carbo-hydrogen. 



Cyanogen with water becomes decomposed, as is well known, 

 into oxalic acid and ammonia (C 2 N-f 3HO=rH 3 N-r-C 2 O 3 ) ; 

 conversely, on heating oxalate of ammonia, cyanogen, together 

 with oxamide, is formed. The production and decomposition of 

 valeronitrile may hence be explained in the following manner : if 

 valerianic acid be an oxalic acid conjugated with the carbo- 

 hydrogen, #a/y/=C 8 H 9 , the latter is converted into cyanogen by 

 the metamorphosis of the ammonia-salt into nitrile; and the cya- 

 nogen combining with the adjunct C 8 H 9 , yields the empirical 

 formula for valeronitrile. If, however, the latter be regarded as 

 cyanide of valyl, and be decomposed by alkalies, the conjugated 

 cyanogen, just as if it were isolated, becomes converted into 

 ammonia and oxalic acid, which then remains in combination with 

 the conjugate C 8 H 9 . 



* Chem. Gaz. Vol. 5, p. 228. 



f Ann. d. Ch. u. Pharm. Bd. 65, S. 271-288. 



