VELOCITY OF REACTIONS 29 



solution). The quantity coagulated in unit time is 

 proportional to the quantity of egg-white in solution 

 and, further, nearly proportional to the acidity of 

 the solution. Now the quantity of acid diminishes 

 when the egg-white becomes coagulated. Within 

 certain limits the quantity of acid is nearly pro- 

 portional to the quantity of egg-white remaining in 

 the solution during the process. It therefore looks 

 as if the quantity coagulated in unit time should be 

 proportional to the square of the concentration of 

 the egg-white, which is characteristic of a so-called 

 bimolecular chemical process. If the acidity is 

 kept constant the process is, as we have seen 

 above, monomolecular, i.e. the logarithm of the 

 concentration is a linear function of time. 



Even the diluting water itself may interact with 

 the preparation. It is well known that in most 

 cases the preparations of organic origin resist de- 

 composition much better when in a dried state than 

 when dissolved. On this ground the anti-diphtheric 

 serum used for standardizing diphtheria-poison is 

 dried with phosphoric anhydride in a vacuum and 

 also kept at a low temperature. Very instructive 

 in this respect are the experiments of Madsen and 

 Walbum regarding the stability of different solutions 

 of rennet. 



They found the following reaction constants K 

 at 46-15° C. for different concentrations : 



Concentration 7 5 3 2 1 0-25 0-125 0-063 



Rate of Decom- 

 position . . 0-0037 0*0049 0-0154 0-021 0-028 0-039 0- o6o 0-073 



