64 LAWRENCE T. FAIRHALL AND PAUL M. BATES 



It was found that oil exposed in the open air to ultra violet 

 light acquires the property of liberating iodine when shaken with 

 an aqueous solution of potassium iodide. This is probably due 

 to the presence of a small quantity of an ozonide of oleic acid 

 formed during the exposure. According to Molinari one 

 molecule of ozone is assimilated with the formation of oleic acid 

 ozonide, Ci 8 H 34 5 , when ozone or ozonized air is passed through 

 oleic acid. Experiments were carried out in which oils were ex- 

 posed in an atmosphere of carbon dioxide in a small sealed tube 

 of transparent quartz surrounded by a larger quartz tube through 

 which ice water was flowed. Oil so exposed showed no greater 

 oxidizing power than the raw oil. That this substance (oleic 

 acid ozonide) plays no important r6le in the sterilization of the 

 oil was proved by exposing samples of the oil under an atmosphere 

 of carbon dioxide in a quartz tube and testing for sterility. The 

 oil so exposed was readily sterilized indicating that the specific 

 effect is produced by the ultra violet rays alone. 



The chemical changes produced in oils exposed to ultra violet 

 rays for long periods of time have been studied in a few cases. 

 Lesure (1910) found that olive oil was bleached but not notice- 

 ably changed in exposures of less than one half hour. Exposure 

 of olive oil to the rays for an hour caused an increase of more than 

 5 per cent in acidity (Lesure), 1910. Romer and Sames (1910) 

 found that butter fat when exposed to ultra violet rays for one 

 and three fourths hours showed a decrease of 7 in its iodine 

 number. 



A number of determinations of the change in acid value of olive 

 oil following relatively long periods of exposure was made with a 

 view of estimating the magnitude of this effect. Samples of oil 

 exposed for the same period of time both in the open air and in 

 an atmosphere of carbon dioxide showed no significant variation 

 in acid content. The results of these experiments are shown 

 graphically in figure 4. It will be noted that the oil does increase 

 in acidity with exposure and that this increase is directly propor- 

 tional to the length of time. In curve (1) the oil was 4 cm. dis- 

 tant from the lamp, while in curve (2) the distance was 1 cm. only. 

 In the latter case the fat splitting property is more pronounced 



