Another vaguely dangerous recipe
Want to make that classic hammer-horror "smoking beaker" effect in your own home, but can't get dry ice anywhere?

Acquire a soda-stream bottle (the big ones) and put a marble against the valve stem. Put a double-layer of tight cloth around the whole valve area and press the cylinder down hard on the marble, against a tabletop or suchlike. The cylinder must be valve-down to do this. Solid carbon dioxide will accumulate rapidly in the material and can be forced out in a lump (carefully, it can give you a nasty freeze burn). Drop this lump into someone's drink for that chilly, drifting fog effect. nb - since it's only carbon dipoxide it's not harmful, but don't let them swallow the dry ice).

(mind your fingers, wear thick gloves).
(Jack Rarebit ...We like chillies, Mon 4 Dec 2006, 0:38, Reply)