388 



From Table 11^ it follows in an analogous way that 2 milligram- 

 molecules of leucin («-aminoiso-capmic acid) neutralizes the action of 

 ± IVs cm' of normal hydrochloric acid. In acidic solution leucine 

 behaves as ± 74 acidic alkali. 



Then I set myself to the examination of three more complicated 

 compounds viz. 



COOH . CH . (NHJ . CH, . CO(NH,) Asparagine 



Molecular weight m 132 (mono-amide of amino-succinic acid) 



COOH . CH(NH,) . CH, . CH, . COOH ' Glutamic acid 



Molecular weight =147 («-aminoglutaric acid) 



HO . C,H, . CH, . CH(NH,) . COOH Tyrosine 



Molecular weight := 181 (p. hydroxyphenylalanine] 



I observed that with my experiments acetamide CH, . CO (NHJ 

 and urea CO (NHJ, behaved in alkalic and in acidic solution as 

 practically neutral. 



From this appears again a contrast between the acid amides and 

 the amino acids; 1 observed before this contrast in another direction. ^) 



Furthermore it has been proved in a previous communication ') that in 

 alkalic solution phenol acts about as a one-basic acid, whilst this 

 compound practicall}' has no influence on tlie inversion of sucrose 

 by hydrochloric acid. 



In agreement with these results it could be expected that in 

 alkalic solution asparagine possessing the carboxyl group should 

 behave as a one basic acid. For the presence of the amijio group 

 asparagine should behave as monacidic alkali in acidic solutions. 



Glutamic acid, which compound possesses two carboxyl-groups in 

 presence of sodium hydroxide should act as a two-basic acid; in 

 acidic solution it should behave as monacidic alkali (NHj-group). 

 Finally tyrosine for the presence of the phenolic hydroxyl-group and 

 the carboxyl-group in alkalic solution should be two basic acid; in 

 acidic solution the (NHJ group should i-ender it monacidic alkali. 

 These predictions were confirmed by the experiments (Table HI'', 

 im and IV). 



From the experiments mentioned in Table IIF' it follows that 

 under the circumstances described asparagine acts as monobasic acid. 



1,06 milligrammolecule of asparagine neutralizes the action of about 

 J cm' 1,06 normal NaOH-solution, as results from the polarisation 

 after 37, hours. 



1) H. I. Waterman, Die Stickstoffnalirung der Presshefe, Folia microbiologica. 

 (Hollandische Beitrage zur gesamten Mikrobiologie) 2, 173 (1913). 



2) These Proceedings, Vol. XX, 88 (April '^7, 1917). 



