Ethanol, a fuel made primarily from corn, has often been touted as a solution to a fossil-fuel shortage. This type of fuel, a mixture of 85 percent ethanol and 15 percent gasoline, is used in flex-fuel cars; regular vehicles don't require ethanol to run. With an ethanol-gasoline blend, drivers may find they can drive fewer miles per gallon before their tank is empty again. If you want to find out if ethanol is in your gas, a test can be performed with only a bottle or test tube.
Use a permanent marker to draw a horizontal line on the container. Make the line two inches from the bottom.
Pour water into the container until it reaches the line you have drawn. Fill the container the rest of the way with the gasoline you want to test.
Cover the container with a cloth or paper towel. Lightly shake or tap on the container, then set it aside for several minutes.
Observe the water level in the container. The gasoline remains on top of the water in the container. If the water level has noticeably increased past the line you have drawn, the gasoline contains ethanol. Bubbles floating downward are also an indicator of ethanol.
This water level increase occurs because the water super-saturates the gasoline, causing the ethanol to precipitate out of it.
