To determine if ethanol is in the gas:
•On a test tube or olive bottle six or seven inches long, make a permanent line about two inches from the bottom.
•Fill with water to this line, then fill the tube to the top with gasoline.
•Cover the tube, agitate it, and let it stand.
The ethanol and water will mix and separate out together. If the water level appears to have increased, the fuel contains ethanol and should not be used. Ethanol percentages of less than 5% can sometimes give a reading below the line. Therefore, any deviation in the water line indicates the presence of ethanol and should serve as a basis for rejecting the fuel.
Hmmm. If you decant the gasoline off the water/alcohol mix is it OK to use now that the alcohol has been extracted?