Cherokee,
The process of Chelation (from the wikipedia) is a generic chemistry term used to describe the action that certain types of protein molecules go through when they are exposed to different environments.

For example, a very important protein molecule in everyones body is hemoglobin. Hemoglobin is the protein in your red blood cells that bind to oxygen and allow it to transport to the distant parts of your body. Hemoglobin chelates oxygen in your lungs, and dechelates (releases) that oxygen at your toes or fingers, allowing your tissues to breathe.

A simple analogy for chelation is a rat trap that only reacts to a specific type of rat. Imagine a tiny spring mousetrap (like the ones you see in the cartoons, with the arm that snaps shut on the fingers) floating around your body, but unlike the cartoons, these mousetraps only spring when they come into contact with blue rats with purple stripes. Nothing else will make the trap spring. When a blue rat with purple strips comes along, the trap "senses" it and snaps around it and makes it part of itself. Both rat and trap are now inseparable. Now the Trap/Rat combination can be safely removed from your body.

The act of the trap springing is chelation. I know that is a crude analogy, but it gets the point across (I hope?).

Where Chelation Therapy comes into it is by adding the chelation chemical into the patient (where the mercury is trapped and being harmful) and allowing it to rat-trap the mercury (and other heavy metals) and then get eliminated, removing the toxic mercury and elimating (we hope) the underlying cause of the autisic symptoms.

My wife and I are in the process of preparing to perform Chelation Therapy as the next step of the road to recovery on our 5yr HFA son.

Jarrett
Father to Connor, 5yr HFA Boy
(Disclaimer: I have a BS in Biological Sciences, with a focus on Human Anatomy and Physiology, but its been a while since I have had to use the detailed knowledge.)