Mix two drachms of the filings of iron with one ounce of concentrated spirit of vitriol in a strong bottle that holds about a quarter of a pint; stop it close, and in a few moments shake the bottle; then taking out the cork, put a lighted candle near its mouth which should be a little inclined, and you will soon observe an inflammation arise from the bottle, attended with a loud explosion.

To guard against the danger of the bottle bursting, the best way would be to bury it in the ground and apply the light to the mouth by means of a taper fastened to the end of a long stick.