43 



§ 6. Before proceeding to the derivation of an equation tf' (2,5) = 0, 

 we must first discnss the question what is to be expected in the 

 saponification of fats in which dijferent fatty acids are present. 



The natural fats are, namely, mixtures of diff"erent triglycerides 

 and in a molecule of triglyceride there are often found two, some- 

 times three different groups of fatty acid. Now it is first of all 

 conceivable that e. g. the oleic acid group is more easily separated 

 from a molecule of oleo-dipalmitine than a palmitinic acid group. 

 Secondly, however, the possibility exists e. g. for a mixture of 

 trioleine and tripalmitine that the surface tension of one of these 

 glycerides in contact with the water surroundings with which the 

 saponification is carried out, is lower than that of the other. The 

 consequence of this would be that the triglyceride, which has 

 the lowest surface tension in contact with the water phase, was 

 adsorbed at the common surface, and was consequently more rapidly 

 saponified. 



Of this, however, nothing has ever appeared. 



It has been shown by Thum ^) that in the saponification with 

 bases as well as when palm oil and olive oil become rancid, the 

 iodine value of the split off fatty acids agrees with that of the fatty 

 acids that are still combined to glycerine. 



Stiepel ') finds for autoclaved tallow fatty acids that the still 

 combined fatty acids exhibit a somewhat higher iodine value than 

 the split off ones ; for the autoclavation of cocoanut oil and palm 

 kernel oil he arrives, however, at the conclusion that the split off 

 and the combined fatty acids have the same composition. Stiepei. 

 finds a corroboration of this ^) in the fact that on distillation of 

 partially saponified cocoanut and palm kernel oil the distillate 

 presents the same acid values as that on second distillation of the 

 fat mass that had first remained behind in the kettle, after this 

 mass had been saponified anew, and now entirely. 



It follows from this that a difference in saponifiability between 

 ester groups of different fatty acids may in general be neglected, 

 and further that the surface tensions of the glycerides occurring in 

 the fats examined by Thum and Stiepel in contact with the saponi- 

 fying surroundings can be only little divergent. 



CoNNSTEiN, HoYER and Wartenberg ^) have found that the fermen- 

 tative saponification with the ricinus seed ferment proceeds more 



1) Z. f. angew. Ghem. 3 482 (1890). 



2) Seifens. Ztg. 31 937, 965, 986, 1006, 1026 (1904), 36, 788, (1909J. 



3) Seifens. Ztg. 35 1359 (1908). 

 *y Ber. 35. 3988. (1902). 



