523 



«-sugar -\- H3O ^ 113 d rate ^ /?-siigar + H^O 

 great rotation small rotation. 



The equilibrium J sets in with great velocity, whereas equilibrium 

 2 does so slowl}', so that the mutarotation lies in the second 

 equilibrium process. 



2. Experimental part. 



a. Inqulrij into the stability of the occurring solid phases; deter- 

 mination of the transformation point Hydrate — {i-anhydride -\- solution. 



This was the state of affairs when we began our examination of 

 the milksugar, which examination was very attractive, because here 

 a very slow establishment of the internal equilibrium was found, 

 which opened the possibility to get to know something about the 

 relation between the pseudo-system and the setting in of the internal 

 equilibrium. 



In the first place we had to examine what was the stability of 

 the solid phases, hydrate, /i-anhydride, and <^f-anhydride in the 

 system water-milksugar. It appears clearly from the method of 

 preparation and the investigation of Hudson that the hydrate is 

 stable below 93°; accordingly both the /i-ahydride and the «-anhydride 

 always yielded the hydrate below 93° in contact with water. 



It further appeared again both from the method of preparation 

 and from Hudson's investigation that above 93°, /J-anhydride is the 

 stable solid phase; accordingly the hydrate gave the ^-anhydride 

 above this temperature in contact with the saturate solntion, and 

 the «-anhydride always gave the p^-modification under these circum- 

 stances. 



It followed, therefore, from this that the a-form is metastable not only 

 below 93°, but also above it. 



The question is now whether there exists a transition point 

 between the a and /i-modification at higher temperatures. For this 

 purpose the final solubility was first determined from 93° to 200°, 

 both starting from the ,?-and from the «-modification. 



The result was that the «-form was always first visibly converted 

 into the ji-forra, and that the found points lay without exception on 

 the solubility curve of the f?-modification. 



These determinations could now be made to fit in with Hudson's 

 results about the hydrate, as the 7',.i'-figures 1 and 2 express. 



F'rom the graphical representation in fig. 3, in which loy .r is 



1 

 represented as function of —10*, follows the temperature 93°, 5 for 



