Effervescent (fizzy) tablet or salt
This experiment can be repeated many times by simply dropping in more tablets/salt. However, when you do want to dispose of the oil, because of the chemicals dropped in you should wait for any remaining tablet to completely disolve away, screw the lid on tightly and throw it away. I wouldn't recommend trying to re-use the oil for cooking purposes. If any tablet/salt has not finished disolving before you screw on the lid the gas will build up inside the jar and if there is enough the jar could explode.