VELOCITY OF REACTION. HETEROGENEOUS SYSTEMS 121 



dissolved egg-albumen. As will be seen, the latter formula 

 agrees very closely with the experiments, and much better 

 than the common formula for monomolecular reactions. 

 This indicates that the digestion follows the same laws in 

 both cases. 



In experiments on digestion there is often used a 

 method of including the coagulated albumen in short 

 capillary tubes, so-called tubes of Mett. By the aid of 

 this method Borissow found the rule of Schiitz to be 

 valid, if a solution of acid and pepsin diffused into the 

 tubes ; whereas Sawjalow, who mixed the pepsin with the 

 albumen, found then that the height of the digested albu- 

 men-pillar was proportional to the quantity of pepsin, and 

 not to the square root of it, as Borissow had found. 

 As is seen above, the results of Sjoqvist agree in the most 

 satisfactory manner with the values <2 calc . 2 , which for short 

 times coincide with values calculated from Schiitz's rule. 

 It should be emphasised that experiments with Mett's 

 tubes ought not to be used in investigating these questions. 

 For in them the rate of diffusion interferes with the chem- 

 ical reaction, and if it is the slower of these processes, 

 it causes the digestion to proceed proportionately to the 

 square root of the time and concentration. An analogous 

 experiment may be made with diffusion of alkali into a 

 Mett's tube filled with an acidulated jelly solution plus 

 phenolphthalein. At a given time (/) the concentration 

 of alkali in the Mett's tube surrounded by a solution of 

 the concentration 2 is at a given point double as great as 

 at the corresponding point in a Mett's tube surrounded by 

 an alkaline solution of the concentration i . Now the height 

 to which the alkali in a given concentration has reached 



