The wisdom of that time said if she were a Witch, the water, medium of Christian Baptism would reject her and she would float. Did not matter in most cases it was the old if you were accused, you were guilty. The results were the same. You were either drown, or killed. In the US, I believe the Witches were mostly hanged. In Europe they were burned alive, unless they were male Witches, then they were strangled then burned, they property confiscated and added to the holdings of the "Church." There were cases where they were already dead and buried and they were still accused, tried found guilty, their bones dug up and burned, and the property of their descendent's taken by the "Church" This was a 500 year reign of terror, another one of those "bright" spots on the History of the Christian Church.

BTW: Satan is a part of Christianity...the Pagans have no such member of their Divinity.