I don't know if I can explain faith healing, but I have a theory which I'm sure is not unique.
I think that once your faith is put into motion you set into effect a positive reaction within your body. Because your mind believes it can happen, your body therefore responds, as well as sending out those positive brainwaives and feelings. Kind of tired right now so I don't know if it's making sense.
But thanks for the information, interesting.
By chemicals I don't mean man-made substances, but the natural molecular composition found within the substance. So basically H2O and some alcohol huh?