41 



As Nic],oux states ^) that the quantity of glycerine split off after 

 a certain time corresponds to the split off quantity of fatty acid, 

 the latter ratio must be correct. Tn the experiments of M. Nicloux 

 triglj'ceride seems to have split off practically directly into fatty acid 

 and glycerine. 



In the saponification by means of bases the fineness of the emul- 

 sion does certainly not remain constant. For here the soap that is 

 formed gives rise to a lowering of the surface tension between fat 

 and aqueous solution, hence the fineness of the emulsion will increase 

 during the saponification. The same thing holds, at least for the 

 beginning of the reaction, for the autoclave saponification with zinc 

 oxide and likewise for the saponification with lime. Nor does the 

 fineness of the emulsion remain the same in the course of the 

 TvviTCHELL process. As can be shown with the aid of Donnan's 

 pipette the surface tension between e.g. linseed oil fatty acid and 

 water is smaller than between linseed oil and water. Here too the 

 surface of contact between fat and water phase vvill therefore 

 become larger in the course of the reaction. 



It is clear that in these cases measurements of velocity are of 

 little use. The constant of velocity will always present a course, 

 and then there is no criterion whether the equations of velocity that 

 have been drawn up, are correct or not. We shall have to adopt 

 another course here. 



When we draw up equations of velocity for the splitting off of 

 fatty acid in the saponification of triglyceride, and when there occurs 

 in them only one constant k, which is dependent on the extent of 

 the surface of contact of fat- and waterphase, and which there- 

 fore from the beginning of the saponification may be considered 

 really constant only during a small period C\t^ we arrive after inte- 

 gration of the drawn up equations between the limits and A^^ at 

 a relation between the number of molecules of fatty acid {z) split 

 off after the time Lt^ and k and Lt^. Let this function be: 



z=f{kX^t,) (3) 



For stagewise saponification a second equation denotes : the number 

 of molecules of glycerine (s) split off after the time ht^ as function 

 of k and A^i- Let this function be : 



s = ff{/cX^ti) (4) 



If we now can eliminate k X ^^i from the two equations (3) and 

 (4), we find a relation : 



ip(^,«) = (5) 



I) 1. c. 52. 



