355 



May 13. 1918 Stability of Olive Oil 



PLAN OF THE EXPERIMENT 



The object of the investigation primarily was to ascertain the nature 

 and extent of the action of the several agents upon the oil as determined 

 by changes in physical characteristics and chemical composition; and 

 secondarily to deduce, if possible, from the results obtained a practical 

 method for handling commercial oils. The experiment was platmed to 

 demonstrate the effect of air, light, and moisture, singly and in com^bi- 

 nation, which, together with control (the basis for comparison) and 

 enzym-free samples, required nine series of tests, as follows: 



Condition of the 

 Series. experiment. 



A Control. 



B Enzym-free. 



C Air. 



D Light. 



E Moisture. 



Condition of the 

 .Series. experiment. 



F Air-light. 



G Air-moisture. 



H Light- moisture. 



I Air-light- moisture. 



As the change in the oil in most cases would be comparatively slow, 

 six years were believed necessary to obtain the maximum effect desired. 

 The previous experiment having demonstrated that analysis oftener than 

 once a year did not compensate for the extra labor involved, only i 

 sample was alloted for each year, or 6 for each series, making a total of 54 

 samples. Six ounces of oil were taken for each sample which was insuf- 

 ficient for some physical tests, but ample for most chemical. Round 

 flint-glass bottles of 6-ounce capacity with glass stoppers were used as 

 containers after being carefully cleaned and dried. 



Five c. c. of distilled water were pipetted into each bottle of series 

 E, G, H, and I, after which all the bottles, with the exception of series B, 

 were filled with the oil as received, after it was thoroughly mixed to in- 

 sure uniformity. Another portion of the oil, used for series B, was 

 heated to 70° C. on two successive days for approximately 60 minutes 

 on the first day and 30 on the second, to destroy enz\Tiis, if any were 

 present. All bottles were filled to the shoulder. Where air was not a fac- 

 tor, the bottles were closed with glass stoppers and carefully sealed with 

 wax. Such treatment failed as a control measure, as a small amount of 

 air remained in the bottles; but this appeared unavoidable under the 

 circumstances. Each series of tests was inclosed in an 8-inch Fruehling 

 and Schultz desiccator after the porcelain plate had been removed. The 

 bottles in an upright position were arranged in a circle and well spaced. 



To exclude the action of moisture (series A, B, C, D, and F) sulphuric 

 acid, previously heated in most cases to 212° C, or higher, was poured 

 into the desiccators to absorb any water that might gain access. To 

 secure a saturated atmosphere (series E, G, H, and I), distilled water was 

 poured into the desiccators, in addition to the water in the bottles. 



To exclude air (series A, B, D, E, and H), the desiccators were rarefied 

 by means of a vacuum pump, and a small U-shaped manometer was sus- 

 pended from the hook of the stopcock to indicate the rarefaction and its 



