NATURE OF GLYCOCINE AND LEUCINE. 119 



0-Acids V-Amides 



C H (H0)0 3 Carbonic C H (H a N)0, Carbamic ? 



C, H 3 (HO) 3 Glycolic C a H 3 (H a N) 0, Glycocine 



C 3 H 5 (HO)0, Lactic C 3 H 5 (H 2 N)O a Alanine 



C 4 H 7 (HO)0, Bulatic C 4 H 7 (H Z N)0, Bulatine 



C 5 H 9 (HO) 0, Phocic C 3 H 9 (H,N) O a Phocine 



C 6 H n (HO)0, Leucic C 6 H XI (H,N)0, Leucine 



Excluding the mono-carbon compounds, whose behaviour in 

 other cases is frequently different from that of their more complex 

 homologues, we find that the /3-acids and y-amides may be obtained 

 from the corresponding fatty acids, through the intervention of 

 their a-chloro-derivatives, as above described. Excluding, again, 

 the mono-carbon compounds, we obtain the /3-acids by acting 

 upon the several y-amides with nitrous acid, whereas by acting on 

 them with an electro-negative chloride and water, we obtain the 

 a-chloro -acids, convertible into the normal acids by treatment 

 with nascent hydrogen. The relation, therefore, of glycocine to 

 the gly colic and chlor-acetic acids, and of leucine to the leucic 

 and chloro-caproic acids, is merely the relation of ammonia 

 H.H 2 N, to water H.HO, and to chlorhydric acid H.C1, as I 

 explained to you more fully in my first lecture. 



(128.) Glycocine I have referred to on several previous 

 occasions. It is produced, together with leucine and tyrosine, by 

 the action of acids or alkalies upon nitrogenous, and more par- 

 ticularly gelatigenous tissues, whence its original name of sugar 

 of gelatin. It exists as a constituent residue of sarcosine and 

 kreatine, as well as of the hippuric and glyco-cholic acids. The 

 next body, alanine, is obtainable from acet-aldehyd by treatment 

 with aqueous prussic acid in the same way that leucine is obtain- 

 able from valer-aldehyd, as mentioned also in my first lecture. 

 By analogy it should be called lactine, were not this appellation 

 otherwise appropriated namely, by milk-sugar CaH^Oe, whose 

 formula, you observe, is exactly twice that of lactic acid C 3 H6O 3 , 

 a compound to which this sugar is in some way or other very 

 closely related. It is curious that while lactic acid exists so 

 largely in flesh-juice, gastric juice, &c., alanine, which is 

 only an ammoniated form of lactic acid, should never have 



