246 



REPORT — 1901. 



Inversion of Cane Sugar. — It is well known that the inversion of cane 

 sugar is brought about by the addition of acid to its aqueous solution, and 

 that the reaction can be followed by means of the polarimeter. The 

 velocity of the inversion is proportional to the amount of acid added, and 

 it is evident that this is a method which can be applied to the estimation 

 of the acid which is hydrolytically set free from the salts of weak bases. 



The first application of this method appeal's to have been made by 

 Bruner in 1893. He measured the hydrolysis of a number of inorganic 

 chlorides, nitrates, and sulphates at 40°. His work was, however, very 

 much overlooked, through having been only published in a Polish journal. 

 In 1900 he republished it in the ' Zeitschrift fiir phys. Chem.' (32, 133). 



Meanwhile Walker and Aston > had determined the hydrolysis of a 

 number of hydrochlorides of weak organic bases, and a few inorganic 

 nitrates by the same method at 60°. Ley extended this work on 

 inorganic salts at 100°.''^ It is impossible to directly compare these 

 results with one another, as they were all obtained at different tem- 

 peratures. The temperature has been shown to have a very great in- 

 fluence on the hydi-olysis, as the dissociation constant of pure water rises 

 aonormally rapidly with rise of temperature. 



The inversion is a monomolecular reaction, and the calculations are 

 vei'y similar to those of the catalysis of esters. Ley points out that this 

 method is somewhat limited in its applicability. Some salts which react 

 acid to litmus act as neutral tov/ards cane sugar, and conversely some 

 neutral salts bring about inversion of the sugar. Even potassium 

 chloride brought about inversion of the sugar at 100°, but gave very 

 irregular results. A disadvantage of working at such a high temperature 

 is that the results may be vitiated by impurities dissolved from the glass, 

 and it is probable that something of this sort occurred in the determina- 

 tions on potassium chloride, &c., for Ley found similar irregularities on 

 making experiments with extremely dilute solutions of hydrochloric acid. 

 The inversion seems also to be considerably influenced by dissolved salts. 

 Ley considered the limit of accuracy to be about 0-5 per cent, in y-J-^ 

 normal solution. 



The following tables contain a number of results obtained by the 

 abovcmentioned observers for the hydi'olysis of organic and inorganic 

 chlorides : — 



III. — Hydrolysis of the hydrochlorides of organic bases as determined 

 by the inversion of cane sugar. 



Ternj)erature = 60°. 



