'Furnace' in the Bible

Yahweh said to Moses and to Aaron, "Take to you handfuls of ashes of the furnace, and let Moses sprinkle it toward the sky in the sight of Pharaoh.

They took ashes of the furnace, and stood before Pharaoh; and Moses sprinkled it up toward the sky; and it became a boil breaking forth with boils on man and on animal.

Mount Sinai, all it, smoked, because Yahweh descended on it in fire; and its smoke ascended like the smoke of a furnace, and the whole mountain quaked greatly.