This has been mentioned before by
Post 91756 (missing)
(Dr. Joy: "Plentiful OTC source of Magnesium.", Chemicals & Equipment) back in '99.
Check this url:
http://www.experimentalchemie.de/versuch-045.htm
translation:
If one carefully looks around in his environment , then one will be astonished of how often pure chemical compounds can be found. An example is the
pencil sharpener, that apart from the variants from plastics, usually exists completely from magnesium. Magnesium belonged to the lightest metals (after beryllium) and exhibits some remarkable characteristics.
In this attempt the special characteristic is to be examined as strong reducing agent. Thus magnesium burns not only in air, but e.g. also in a CO
2, SO
2, NO
2 or water vapour atmosphere.
Devices:
Tigelzange (?), Bunsen burner or lighter, fibre glass, test tube (unfusable), glass tube with point, perforated plug, fibre glass, steel wool, burner, 2 candles, stand material
Chemicals:
Magnesium (either as a whole or in the form of splinters,
e.g. of a pencil sharpener), damp sand