38 



Nernst's law of partition cannot be applied here uni-eservedly, as 

 the fat phase consists chiefly of triglyceride at the beginning of 

 the saponification and chiefly of fatty acid at the end. The "constant" 

 of partition C can, therefore, not be constant in this case. We can, 

 however, draw a conclusion from equation (1) as to the probability 

 or improbability of the supposition that the saponification takes place 

 in the water pliase. For at any rate there appears from it that if 

 the said supposition is valid, the extent of the surface of contact 

 betvA^een fat particles and water particles plays no part. But then 

 the action of the Twitchell reagent must chiefly rest on this that 

 it causes an increase of C, in other words, increases the solubility 

 of the fat in the water phase. This is in itself very well possible, 

 but seeing that the saponification without reagent practically does 

 not take place, and obtains an etïicient velocity on addition of not 

 quite half a percentage to the emulsion, it is very improbable indeed, 

 that increase of the solubility of the fat in the water phase should 

 be the cause of it. 



As will appear in § 4, the action of the Twitchell reagent can 

 be quite plausibly accounted for by the supposition that the saponi- 

 fication takes place on the boundary of fat and water. 



There is, however, another phenomenon that points to this. It 

 appears namely, that, when triglycerides which contain little or no 

 free fatty acid, are saponified, the reaction velocity is very small at 

 first, then it increases and reaches a maximum. Wegscheider '), 

 who assumes the reaction in the aqueous solution, wants to explain 

 this by taking the concentration of the triglyceride in the water- 

 phase constant. The increase of the reaction velocity would then be 

 caused by the presence of lower glycerides in the waterphase. On 

 this assumption Wegscheider comes to the following equation of 

 velocity for the splitting off of fatty acid : 



— — ^k.C~^k.C.e-^^ (2) 



dt 



In this C represents the not changing concentration of the tri- 

 glyceride in the aqueous solution, k is a constant of velocity. 



Equation (2) would really be able to explain the increase of the 

 velocity of saponification, if it could be applied to the saponification 

 of fat in this form. Now it is clear that (2) can only hold for the 

 saponification by means of bases, as only in this case the fat phase 

 which is in contact with the aqueous solution, consists practically 

 exclusively of triglycerides, because of which the concentration of 



1) Kais. Ak. d. Wissensch. Wien 116, II b. 1325 (1907). 



