57 

 Testing of the Derived Formulae. 



§ 18. Measurements for the purpose of a comparison of the split 

 off quantity of glycerine with the split off quantity of fatty acid 

 have been carried out by Kellner^), who determined free fatty 

 acid and combined glycerine") of partially saponified palmkernel oil 

 by different methods of saponification. 



Let us first examine how T and g are to be found from Keli.ner's 

 observations. For the calculation of the percentage of split off fatty 

 acid the procedure is always as follows: The acid value is determined 

 of a sample of the fat (which has first been washed with water 

 and then dried), this is divided by the acid value of the esterfree 

 fatty acid, and multiplied by 100. The value obtained (we shall 

 call this 100 T') now indicates how much free fatty acid the sample 

 contains in percentages, but only in approximation what percentage 

 of the total fatty acid present occurs as free fatty acid (100 T). 

 The acid value of the esterfree fatty acid indicates how many mgr. 

 K H is required to neutralize 1 gramme of this fatty acid. If of a 

 sample of partially saponified fat we want to determine what per- 

 centage of total fattj acid present occurs as free fatty acid, we 

 must know, not the number of mgr. K H {a), required to neutralise 

 the free fatty acid of 1 gramme of fat, but the number of mgr. K OH 

 {h) required for a quantity of fat which contains the same quantity 

 of total fatty acid as 1 gramme of esterfree fatty acid. The value of 

 saponification being a measure for the total fatty acid present, 

 we get : 



b saponification value of the esterfree fatty acid 

 a saponification value of the fat to be examined * 



It is clear that in consequence of the glycerine content of the 

 partially saponified fat, always b'^ a. To find, therefore, T from 

 T' , we multiply by bja. 



To calculate g we multiply the glycerine content of every sample 

 again by bja, and thus find the number of grammes of glycerine present 

 in a quantity of the sample, which contains 100 grammes of total fatty 

 acid. If we now also know the glycerine content of the triglyceride, 

 hence also the quantity of glycerine present in so much triglyceride 

 as contains 100 grammes of fatty acid, (/ can be directly determined. 



§ 19. Let us now discuss Kellner's results. 



1) Ghemiker Ztg. 33, 458, 661, 993, (1909). 



2) According to the oxidationmethod. 



