“And thus I saw the horses in the vision, and them that sat on them, having breastplates of fire, and of jacinth, and brimstone: and the heads of the horses were as the heads of lions; and out of their mouths issued fire and smoke and brimstone.”
King James Version (KJV)
Re 9:17 Having breastplates as of fire, and of jacinth, and brimstone. Or, bright red, blue and yellow. These are the colors observed. The heads of the horses [were] as the heads of lions. Strength and fierceness are implied. And out of their mouths issued fire and smoke and brimstone. This is a destroying power. It might well describe the use of gunpowder. One looking at a distance would see the flash of fire, and the smoke, apparently coming from the horses' heads, would smell the brimstone odor, and would see the destructive effect.