1909.] PUBLIC DOCUMENT — No. 31. 117 



neutralization number of the total fatty acids (n). The sub- 

 stitution of the latter value will not always hold true. 



A = - or .63 per cent. 

 n 



The percentage of fatty acids (N) and glycerol (G) in the 



neutral fat (F) can be calculated by similar formulae from the 



molecular weight (m) of the fatty acids of the neutral fats, or, 



less accurately, from the mean molecular weight of the total 



fatty acids. ^ 



N = FX.^ f-^ =95.07 per cent. 



3 m + C3H2 



The total fatty acids are equal to the sum of the fatty acids 

 in the neutral fat (95.07) and the free fatty acids (.63), or 

 95.70, the same result previously obtained. 



92 064 

 G = FX o r^TT or 10.42 per cent. 



3 m + C3H2 



The last three formula appear to have no greater merit than 

 those first given and are rather more difficult to apply. 



A direct determination of neutral fat and unsaponifiable 

 matter gave the same results as the calulated. 



Free fatty acids, .......... .63 



Neutral fat and unsaponifiable matter, ..... 99.37 



Unsaponifiable matter, ......... .03 



Neutral fat, 99.34 



Briefly, the process consisted of treating 2 grams of oil with 

 an excess of dry sodium carbonate in the presence of a small 

 quantity of alcohol, stirring thoroughly. After the evaporation 

 of the alcohol, quartz sand was added and the mixture trans- 

 ferred to an S. & S. capsule, extracted with dry ethyl ether in a 

 continuous extractor and the dried extract considered neutral fat 

 and unsaponifiable matter. The difference was free acids. The 

 unsaponifiable matter was determined by saponifying 10 grams 

 of oil with glycerol-soda, dissolving the resulting soap in warm 

 water, filtering and washing. The dried residue was extracted 



'& 



1 In tins case the molecular weights are the same, even to the second decimal, when the 

 unsaponiflable matter is included in the neutral fat. 



