374 



GIBBS AND AGCAOIL] 



Table II. 





Fat. 



Oxygen 

 equiv- 

 alent. 



Butyrin 



196.7 

 287.8 

 289.6 

 293.0 

 121.6 





Olein - - 



Stearin - 







The oxidation as carried out by the previouslj' described method does 



not go this far. If the 0.1 per cent solution of the products of the 



N 

 saponification are oxidized with zr^ potassium permanganate by the usual 



method of titration, the oxidation stops far short of complete production 

 of carbon dioxide and water. A number of fats were treated by the 

 following method: 



To 25 cubic centimeters of the 0.1 per cent solution after saponification, were 



added 25 cubic centimeters of 50 per cent sulphuric acid solution. The mixture was 



N 

 kept at the boiling temperature and — potassium permanganate added gradually, 



until the pink color remained permanent for three minvites. The evaporated water 

 was replaced from time to time. An excess of permanganate was always indicated 

 by a small quantity of suspended particles of the oxides of manganese. 



Fairly concordant results were obtained. In the following table the 

 averages of a number of determinations, and for comparison the iodine 

 numbers, are given. 



Table III. 



No. 



Sample. 



Permanga- 

 nate,cc.N. 



Oxygen 

 equivalent. 



Iodine 1^ 

 numbers 

 (Ha.nus) . 



6 



32 



55157 



54452 



25 



28 



13 



2 



27 



3 



31 



29 



Refined coconut oil 



7.8 

 7.5 

 12.4 

 11.7 

 12.8 

 15.0 

 15.6 

 15.4 

 21.8 

 24.4 

 29.9 

 28.0 



24.96 

 24,00 

 39. 68 

 37.44 

 40.96 

 48.00 

 49.92 

 49.28 

 69.76 

 78.08 

 95.78 

 89.6 



1 8.-9.0 



1 26.-38 



32.-41 



59.8 



62.6 



67.4 



83.-85 



79.-88 



173.-180 



Coconut oil 



Butter 





Cacao butter 



Pili-nutoil _ _ 



Lard 



__ _ do . 



Castor oil 



Olive oil 





Glycerol— 





'' The iodine numbers are taken from Lewkowitsch, "Oils, Fats, and Waxes," 

 and from Leach, "Food Inspection and Analysis," except the pili-nut oil and the 

 lards Avhich are our own determinations. 



