Set the empty pot on its coals until it becomes hot and its copper glows. Then its impurity will melt within; its rust will be consumed.
KJV
Then set it empty upon the coals thereof, that the brass of it may be hot, and may burn, and [that] the filthiness of it may be molten in it, [that] the scum of it may be consumed.
ASV
Then set it empty upon the coals thereof, that it may be hot, and the brass thereof may burn, and that the filthiness of it may be molten in it, that the rust of it may be consumed.