110 MAINE AGRICULTURAL EXPERIMENT STATION. 19OO. 



attempts of this kind, weighed filter blocks were used to absorb 

 the oil. By previous experiments the fuel value of these blocks 

 was found to be 4.130 calories per gram. For the iodine absorp- 

 tion number, Hubl's method,* as adopted by the Association of 

 Official Agricultural Chemists, was employed. The great 

 capacity of some of the oils for iodine made necessary the addi- 

 tion of large quantities of the iodine solution, as in the case of 

 the walnut oil, where /Occ were used. This fact is important 

 since the method is an arbitrary one, the amount of the absorp- 

 tion being to some extent affected by the excess of iodine 

 present. The results are not, therefore, so strictly comparable 

 as in the case of butters, where the absorption varies so little 

 that a constant amount of iodine can be used. 



So far as the writer is aware no study has been made of the 

 changes which these oils undergo through rancidity. They are 

 so susceptible to such changes that the age of the nut must to a 

 considerable extent affect the physical and chemical properties 

 of the oils. The work here reported was done during the sum- 

 mer months and the nuts must therefore have been nearly a year 

 old. 



As regards the changes which oils may undergo by heating, 

 attention may be called to the oils from the raw and roasted 

 peanuts (6225 and 6226). Although the roasting was carried 

 farther than usual, resulting in a decided darkening of the oil, 

 the constants so far as determined were practically the same. 

 It is probable that the drying oils, containing considerable 

 amounts of linolic, linolenic and isolinolenic acids, would have 

 undergone appreciable oxidation under the same conditions. 



The refractive index, the specific gravity, the idoine absorp- 

 tion number, and the calories per gram of the different nut oils 

 here reported are given in the table on the following page. 



* Wiley's Agricultural Analyses, vol. Ill, page 364. 



