M1-:TIH'|)> 



ANALYSIS. 



27 



acids of various oils as determined in this laboratory and as found in 

 the literature on the subject are given in Table XVI I I. ~\^^ 



T \UI.K XVIII. M'ltiixj finiiit l' t'<tlt>/ 



SOLID FATTY Acms. 



By >olid fatty acids arc meant those whose lead salts arc insoluble 

 in ether. The method of determination used was that described in the, 

 Provisional Methods for Food Analysis." From these rcsult>. calcula- 

 ting the average total fatty acids present as 1C).:) per cent.''' the percent- 

 age of liquid fatty acids can be, obtained. As the latter are the unsatu- 

 rated fatty acids and alone absorb the iodin, the percentage of these 

 acids and their iodin value irives a fair idea of the nature of the oil 

 under consideration. Some of the oils of Tunis must contain fatty 

 acids more unsaturated than oleic to give the high iodin number, and 

 also the high per cent of solid fatty acids found by Milliau, Bertain- 

 chand. and Malet/ 



The iodin number of the oil multiplied by !<>(> and divided by the 

 per cent of liquid fatty acids will give their iodin number, providing 

 the solid fatty acids are saturated. The calculated results agree fairly 

 well with thoM> obtained by experiment. These results show that in 

 olive oils the unsaturated fatty acids are variable in their composition 

 and can not be considered as pure oleic acid. 



From Table XXXIII it is seen that in lard oil the unsaturated fatty 

 acids have practically the same iodin number as the unsaturated acid> 

 of olive oil. Rape-seed oil does not differ much in this respect from 

 olive oil. Mixtures of lard and cotton-seed oils which would give a 

 normal iodin number for olive oil would have a much higher iodin num- 

 ber for the liquid acids. The relations between the solid fatty acids, 

 the iodin number of the oil. and the liquid fatty acids, are of great 

 value in identifying an oil of unknown origin. These factor- for vari- 

 ous oils are given in Table XIX. It can be seen from this table that 

 the mixing of these oils with olive oil will change the figure* on the 

 mixture in -a number of ways. An addition of maixe oil would 

 increase the iodin number of both the oil and the liquid fatty acids, but 



U. S. Pept, Agr., l.urcau ..!' ( 'licniislry I'.ul. IM. p. 

 "Rapport sur k-s huiU-s d'olive de Tunisie, 1900. 



