METHODS OK ANALYSIS, 



results obtained on Califoinia oils. From these result* ii would M-CIU 

 that the raiiii'e of iodiu numbers on ( 'ali fornia oil> i- from 7s to '.*". a 

 little wiiler than that found on French oils, hut about the vnnr ;i- <ui 

 Italian and Algerian oils. 



Table XI trives the ranev of iodin values found in this laboratory 



and by other analysts on various oils of known purity. With all these 



oils this raiiMV is extremely wide, and for this reason the determina- 

 tion of the iodin value is by itself of little value MS a inean^ of detect- 

 ing adulteration. Only in cases of trross adulteration could it be 

 conclusive. By a careful selection of the oils to be used in making 

 the mixture, lar^e proportions of either lard or peanut oil could be 

 used without producing an abnormal iodin value. A- i- -hown in 

 Table XVII, pa^e '2*>. the iodin value increases as the solid fatly acids 

 and the melting point of the fatty acids decrease. It is only when 

 this factor is determined. i:i connection with these other factors and 

 with the iodin value of the liquid fatty acids, that it may serve a< a 

 valuable indication of the purity of an oil. 



TABLE XI. Tlif Unlil number of various i/*. 



The Htibl method has never been considered entirely satisfactory, 

 owing- to the poor keeping <juality and the slowness of reaction of the 

 iodin solution used. Recently two new solutions have been proposed afl 

 substitutes, both of which, it is claimed, remain practically unchanged 

 for .several months" and are more rapid in their reaction than the 

 Hi'ibl solution. The Wijs'' solution consists of iodin mono-chlorid di^- 

 solved in glacial acetic acid: the other, proposed later by Ilanus/ is a 

 solution of iodin mono-bromid in glacial acetic acid. Comparative 

 testfi of these two solutions with the Hubl solution, made upon a.lar^'e 

 number of olive and other oils, verify the claims made for these new 

 solutions both as regards their keeping qualities and their rapidity of 

 action. A comparison of these methods is -riven in 'Fable XII. 



"Tolnian and Munson, Jour. Anicr. Chcm. Soc., 1'to:;, '2~>: 1!44. 

 6Ber. 1898, 81: 752. 



. Nahr. u. Genussm., 1901, 4: 91H. 



