> What kind of gas S02 ???? Is it a powder that you mix with water ???
>
> Moe

Moe - The powder that is normally used with wines is either potassium
meta-bisulfite, or sodium meta-bisulfite. Either can be used to
sanitize equipment, etc., but generally pot. meta. is preferred if
adding directly to the wine. The active component is sulfite (S03, I
believe), but it is usually referred to in winemaking circles as SO2.
SO2 by itself is a gas, if I recall correctly from high-school
chemistry, but SO2 gas is not used in winemaking (as far as I have ever
heard, anyway). Rather, small amounts of meta-bisulfite are used, to
provide the necessary sulfite level to discourage wild yeast and
bacteria, and to prevent oxidation of the wine.

Doug