96 



retard the rapidity of inversion of sucrose by hydrochloric acid. 



5. The behaviour of glycine and alanine deserves special attention 

 because these compounds behave by the usual way of titi-ation as 

 practically neutral. 



The number of cm\ alcali necessary for colouring pink a solution 

 of glycine or alanine, which contains phenolphtalein, is insignificant 

 if coinpared with the quantity of alkali which would be necessary 

 when both compounds should behave in this case as one-basic acids. 

 The same holds for phenol (Compare 7°). 



6. The destructive influence of sodium-hydroxide on monosac- 

 charids and the inversion of sucrose by hydrochloric acid can be 

 used for the edificalion of two sensible methods, which enable us 

 to judge in another w^ay than was usual up to now, whether a 

 compound has acidic or basic properties ^). 



7. Remarkable too is the behaviour of phenol in alkalic solution. 

 Phenol acts then as about a one-basic acid, whilst this compound 

 practically has no influence on the inversion of sucrose by hydro- 

 chloric acid. 



8. The pure amphoter behaviour of glycine in alkalic and in 

 acidic solution, together with the behaviour of betain, which com- 

 pound in alkalic solution is practically neutral and in acidic solution 

 acts as one-acidic basic substance, make it probable that glycine 

 as well as alanine possess in alkalic and acidic solution the open 

 formula of constitution. In entirely neutral solution the ring formula 

 is sufficient. To betain the ring-formula must be granted in neutral 

 and alkalic solution, in acidic solution the open constitution-formula. 



This research will be continued in different directions in order 

 to study the acidic and basic character of the substances and at 

 the same time to determine how far their usual constitution-formula 

 corresponds with this chai-acter. 



Dordrecht, February 1917. 



^) These methods can only be used if we know with certainty that the sub- 

 stance to be examined is not destroyed in acidic or alkalic solution and has for 

 the rest no disturbing influence. 



