4 tbsp. bluing
4 tbsp. water
Piece of coal, brick, sponge or broken clay pot, dampened
Drops of any food coloring
4 tbsp. ammonia
Salt

Place dampened coal (or any of the above pieces) in an old bowl, pouring liquids over coal. Sprinkle with salt to cover generously. Put a few drops of food coloring here and there on top of salt. This was a 2nd grade school class project. Mr. Abercrombie gave us the pieces of coal.