Put three or four grains of iodine into a small clean Florence oil
flask, and close it with a cork. Warm the flask gently over a candle,
or before the fire, and the iodine will become converted into a
beautiful violet-coloured vapour, which condenses again into brilliant
metallic crystals, when the flask is suffered to become cold. The
experiment may be repeated with the same flask for any number of times.
Or, upon a small sheet of any metal, place a few grains of iodine, and
add a chip of dry phosphorous; when the latter will inflame, and the
iodine pass off in a violet vapour.