VELOCITY OF REACTION. HETEROGENEOUS SYSTEMS 127 



some observations regarding the influence of the quantity 

 of enzyme. With 0.5 g. of Ricinus seed were emulsified 

 5, 10, 15, 20, 25, or 50 g. of Ricinus oil and the same 

 quantities of 2 per cent acetic acid. The results are 

 indicated in the table below. The calculated figures are 

 found under the assumption that the acting mass of the 

 enzyme is proportional to its quantity. The agreement be- 

 tween calculated and observed values is very satisfactory, 

 except for the greatest quantities. The constant for two 

 days is, within the errors of observation, double that for 

 one day. The concentration in the presence of 50 g. 

 oil and 50 g. acid is taken as unit. 



ACTION OF 0.5 G. RICINUS SEEDS ON DIFFERENT QUANTITIES OF RICINUS 



OIL 



In this case the presence of a certain quantity of free 

 acid, about 4 c.c. of a 0.2 normal solution, the same 

 quantity for all acids, weak or strong, is necessary. This 

 circumstance resembles very closely the action of acids 

 in peptic digestion. If no acid is added, the acid in the 

 seeds acts, and new acid is procured by the process. 



A lipolytic process, which probably should be regarded 

 as occurring in a homogeneous system, is that studied by 



