Studies on Enzyme Action. 181 



Table VI. — Hydrolysis of Fat in Presence of one Molecular Proportion 



of Glycerol. 



Time. 



Acidity of system in c.c. 

 normal alkali. 



Percentage of 

 acid liberated. 



hours. 







2 



3 -54 3 -52 



20 -6 



4 



4-98 5-08 



29 "4 



8 



6 -05 6 -13 



35 6 



17 



7 -06 7 -42 



42 -3 



30 



7 -73 7 -38 



44-3 



50 



7-73 



45 -3 



70 



7 -70 7 -64 



44 -9 



When more glycerol is present hydrolysis takes place to a reduced extent, 

 and still proceeds slowly even after 70 hours. 



Glycerol, molecular 



Percentage of acid 



Percentage of acid 



proportions. 



after 50 hours. 



after 70 hours. 



2 



29 -8 



30 -9 



4 



11 



12 -6 



The results of the experiments described are summarised in Graphs 1, 2 

 and 3, the synthetic observations in Graph 1, the hydrolytic in Graph 2, the 

 parallel series of observations in the two opposite directions in Graph 3. 

 The manner in which water affects both the rate of the change and the 

 extent to which this takes place in one or the other direction is brought 

 out in a very striking manner in these diagrams : it will be noticed 

 especially how much less rapid is the approach, both from the hydrolytic 

 and the synthetic side, to an eqiiilibriuni as the amount of water present 

 is increased. Whilst the retardation of the hydrolytic change must be 

 ascribed to a direct interference of the water, which presumably prevents 

 the enzyme and the oil from coming into effective contact, the retardation 

 of change in the opposite direction, especially the diminution of the extent 

 to which synthesis takes place, must be ascribed rather to the withdrawal 

 of glycerol from the system through its dissolution in the water : in this 

 connexion, it is remarkable that synthesis is not entirely prevented even 

 by the presence of thirty molecular proportions of water to one of glycerol, 

 whilst in absence of an excess of water, an excess of glycerol beyond two 

 molecular proportions has but little effect in increasing the proportion of fat 

 synthesised. 



