391 



Herewith the fact was in agreement that after 24 hours the liquid 

 of N". 6 (Via) did not possess any reducing power on Fkhling's 

 solution. 



A iodometrical determination of invert-sugar proved that less than 

 60 milligrams of inverl-sugar was present per 100 cm\ 



If the liquid of N". 6 (Via) after 24 hours is boiled for some 

 time the reducing power on Fehling's solution becomes greater. 

 Boiling with an extra quantity of strong hydrochloric acid gives a 

 liquid that after being neutralized with alkali possesses a strong 

 reducing action on Fehlfng's solution. 



From table Y\h it follows that 500 milligrams and 640 milligrams 

 of aniline compensate the action of respectively ± 5 cm', and 7 cm^ 

 of normal hydrochloric acid, which proves that in acidic solution 

 aniline behaves as monoacidic alkali. 



From table Vic it can further be concluded that 0.494 gr. of 

 pyridine compensates about 6 cm*, of normal hydrochloric acid, 

 pyridine acts therefore about as monacidic alkali in acidic solution. 



The basic and acidic character of the compounds described in the 

 above is in accordance with the constitution-formula, which nowadays 

 are assumed for these compounds. 



The method of research described can help to find a better con- 

 stitution-formula in cases where the said accordance does not exist ^). 



For the rest one may be astonished a little by the strong neutra- 

 lizing action against hydrochloric acid on the one hand, sodium- 

 hydroxide on the other hand of compounds being generally known 

 as feeble acids or basic substances. 



Frequently we can make good use of this neutralizing action of 

 substances with a but feebly acidic or basic character in watery solution 

 in order to compensate the influence of strong alkali or strong acid. 



In many experiments in the laboratory as well as in technical 

 processes we have often to struggle with the formation of strong 

 basic substances or strong acids. In such cases we can compensate 

 the action of the strong alkali or acid by the addition of efficient 

 amphoter or weak electrolytes. 



Dordrecht, June 1917. 



1) A first example of this was given in the preceding communication with the 

 betain. 



