VELOCITY OF REACTION. HETEROGENEOUS SYSTEMS lot 



system. A series of experiments with 0.5 c.c. o.i n. NH 3 

 mixed with 10 c.c. 2.5 per cent suspensions of blood gave: 



Time (minutes) o 6 14 23 31 



Intact blood (per cent) 100 97 82 60 35 



Constant of reaction 0.00022 0.0062 0.0096 0.0147 



The "constant" increases very rapidly as the process 

 advances. This phenomenon depends evidently upon 

 something similar to the "time of induction," observed in 

 reactions in heterogeneous and sometimes also in homoge- 

 neous systems (action of light upon a mixture of chlorine 

 and hydrogen). In this case it is easy to understand that 

 a certain quantity of ammonia must diffuse into the erythro- 

 cytes and act there for some time before the haemoglobin 

 leaves the cells. According to different circumstances, 

 such as varying resisting power of the cells, distance from 

 the molecules of ammonia in the moment of mixing, the 

 different cells are attacked more or less slowly. 



Still it was possible to prove that the time necessary for 

 haemolysing a given number of erythrocytes is inversely 

 proportional to the strength of the haemolytic agent. Thus, 

 for instance, in experiments with solutions the dilutions 

 (inverse concentrations) of which were proportional to 

 1:0.44:0.23:0.133 the following times in minutes were 

 necessary for the haemolysis of 3, 10, 20, 30 and 40 per 

 cent respectively of the erythrocytes. In parentheses are 

 printed the calculated values obtained according to the 

 rule mentioned. 



Haemolysis 310 20 30 40 per cent. 



Dilution i 13 (13) 26 (26) 35 (35) 44 (44) 53 (53) min. 



Dilution 0.44 6 (5.7) 10 (11.5) 15 (15.4) 18 (19.4) 23 (23.3) min. 



Dilution 0.23 5.5(6.0) 9(8.0) 12 (10.1) 14 (12.2) min. 



Dilution 0.133 i-8 (3.5) 4(4-7) 6.2(5.9) 8(7.1) min. 



