Furnaces were used for various purposes, as smelting the crude metal, and for crucibles to refine the metal; for lime and bricks; and as an oven. Genesis 19:28; Exodus 9:8,10; Proverbs 17:3 . The fiery furnace in Babylon must have been very large for four persons to have walkedtherein. It may have been the furnace they used for their bricks. Daniel 3:6-26 . The furnace is used figuratively for the oppression of Egypt, out of which God delivered the Israelites, Deuteronomy 4:20; and for the afflictions God afterwards brought them into to purify them from their idolatry and sin. Ezekiel 22:18,22 . In the N.T. the furnace of fire refers to the place of eternal punishment. Matthew 13:42,50 .