102 CHEMICAL EQUILIBRIA 



de Chimie, y ser., 9, pp. 104, 155, and 230, 1914). 

 They investigated two different glucosides of methyl 

 or ethyl, called a-glucosides and /3-glucosides. The 

 first are decomposed by a glucosidase contained in 

 air-dried under-yeast, the second by emulsin (from 

 almonds). The equilibrium was reached from both 

 sides, when 76-6 per cent of the a-glucoside or 67-4 

 per cent of the /3-glucoside were decomposed into 

 glucose and alcohol (in this case ethyl alcohol). The 

 progress of the decomposition or synthesis may be 

 followed by means of a polarimeter (a is for a- 

 glucoside + 150-6°, for /3-glucoside — 35*8°, and for 

 glucose 52-5° at 20° C). 



Here we have a quite regular and characteristic 

 case. Each glucoside is only attacked or synthe- 

 sised by its specific ferment. The degree of decom- 

 position is different in the two cases, but does not, 

 as in most cases investigated, lie so near to 100 per 

 cent that the equilibrium cannot be determined. 

 And further, just as with common katalysers, the 

 equilibrium may be reached from both sides, whether 

 we let the ferment act upon the glucoside or upon 

 a mixture of alcohol and glucose. The authors let 

 the equilibrium be reached at room temperature — 

 one month was sufficient for it — and then disturbed 

 it by adding one of the acting substances. The end 

 result always agreed with the calculations according 

 to the figures given above. 



By far the simplest equilibrium occurs in the 

 partition of a substance between two phases. If 

 the. substance retains the same molecular weight in 



