62 LECTURES ON IMMUNITY 



view, which seems to be the best expression of our pres- 

 ent knowledge. 



A very prominent place in this connection is held by 

 the rule of Schiitz, according to which some processes, 

 especially the peptic digestion, proceeds through a certain 

 time nearly proportionally to the square root of the time 

 and thereafter more slowly. 



To understand the meaning of this rule, we at first 

 examine a very well-known process, the saponification of 

 ethyl-acetate by means of ammonia, on which I have 

 carried out some experiments. A mixture was made of 

 1 8 c.c. distilled water and I c.c. ( = 0.91 grammes) of 

 ethyl-acetate, in a vessel used for determining conductivi- 

 ties, held at a constant temperature (16 C.). At a certain 

 moment I c.c. of a 0.02 normal solution of ammonia was 

 added and the vessel shaken. Afterwards the resistance 

 was determined. It decreased at first rapidly, then slowly, 

 indicating that the well-conducting acetate of ammonia 

 was formed from the less-conducting ammonia, according 

 to the equation : 



NH 3 + CH 3 COO C 2 H 5 + H 2 O = NH 4 CH 3 COO + C 2 H 5 OH. 



By means of the conductivity the progress of the chem- 

 ical process was determined. If we take the quantity of 

 ammonia at the beginning, like 1000, then the following 

 quantities of ammonium-acetate, ;r oba ., were observed at the 

 given times (t in minutes). 



The table contains two calculated values of x, viz. ^ calc< , 

 found by means of a formula given below, and ;r calc< 2 , 

 deduced by means of Schiitz's rule. At ^=14 the latter 

 quantity exceeds 1000, which is evidently impossible. 



