STERILIZATION OF OILS 57 



of the twenty-four hour period, 1 cc. samples of the broth were 

 plated out in beef infusion agar. While this increased the 

 chance of contamination somewhat, it afforded a much more 

 delicate test of sterility. The effectiveness of the mercury lamp 

 when operating at higher voltages in causing sterility is indicated 

 by the fact that twenty tests of B. sublilis suspended in olive 

 oil in the quartz tube for four minutes (voltage 140 in ten tests, 

 150 in the other ten) showed no growth in any case after twenty- 

 four hours incubation in broth and twenty-four hours cultiva- 

 tion on the plate, although control plates were crowded with 

 colonies. The same result was obtained in another series of 

 seven tests made by four minute exposure to 150 volts and of 

 five tests made by two minute exposure to only 130 volts. 



These and subsequent experiments have amply demonstrated 

 that oils of the nature described can be sterilized at the rate of 

 1^ liters an hour with a small ultra violet ray equipment. 



THE ACTION OF ULTRA VIOLET RAYS ON LIPASE 



In connection with the action of ultra violet rays on bacteria 

 it is of interest to note also their effect on the lipolytic enzymes 

 present in raw vegetable oils. The presence of lipases in oil 

 used in the preparation of lipo vaccines would be somewhat 

 objectionable owing to the more rapid formation of free fatty 

 acids after injection. As an instance of this phenomenon, raw 

 cotton seed oil which had been incubated at 37° for eighteen 

 hours showed an increase in acid value from 0.11 to 0.78. 



That ultra violet rays definitely affect enzymes has been 

 shown in a number of cases. Agulhon (1912) found that sucrase, 

 amylase, catalase, lactase, and peroxidase were all rendered in- 

 active by these radiations. Mazouc found that the inacti- 

 vation due to ultra violet light rays is extremely rapid at the 

 beginning upon amylase and invert in. In a mixture of the two, 

 the amylase, because of its greater sensitiveness to the rays, is 

 weakened much more rapidly than the invertin. Bruge, Fischer 

 and Weill (1916) found that secretin, pepsin, trypsin, ptyalin, 

 amylopsin and trypsinogen were destroyed by exposure to ultra 

 violet radiation, the rate of destruction being proportional to 



