VELOCITY OF REACTION. HOMOGENEOUS SYSTEMS 75 



present if no calcium chloride is added. 1 Chlorides of 

 barium and magnesium exert a similar influence to that 

 of calcium ; the less ionised magnesium sulphate has an 

 analogous but weaker action. 



In another series of experiments the concentration of 

 the casein was changed. The solvent by means of which 

 the attenuation was accomplished was milk freed of casein, 

 i.e. whey. The experimental values are given below ; the 

 quantity of rennet present was always the same, I c.c. of a 

 given solution. 



The calculated values for the time of coagulation (/) 

 are found by means of the empirical formula : 



10 M 



t 21.6= 1.75- 



M 



1 As the authors assert, this supposition assumes that only about 15 per 

 cent of the calcium salts present in milk are in ionic state. 



