"Greg Cook" > wrote in message
s.com...
> On 5/7/04 10:06 AM, in article , "David C
> Breeden" > wrote:
>
> > seb ) wrote:
> >> (Ben Rotter) wrote in message
> >> . com>...
> >>
> >>> It means you'll get ~58% *total* SO2. Some of that will then become
> >>> free, and some will become bound (total = bound + free).
> >
> >> Ben, here a quote from the winemakermag :
> >
> >> "The key question now is: How much free SO2 is really added for any
> >> given amount of sulfite? Potassium metabisulfite and Campden tablets
> >> consist of approximately 57 percent and 48 percent SO2, respectively.
> >> This means that roughly half of the sulfite actually becomes free SO2
> >> when a solution is prepared and added to wine."
> >
> >> Thanks for your link, I had already read it and many more about SO2
> >> but I read different things about the 57% explanation. That's the
> >> only part i can't be sure of.
> >
> >> Séb
> >
> > Hi,
> >
> > It's easy enough to calculate for yourself. Meta is just K2S2O5,
> > and the molecular weights of K, S, and O are 39, 32, and 16,
> > repsectively. Find the total weight, and divide it into the weight
> > of the 2 SO2 molecules you get from each meta molecule.
> >
> > Voila! 57%.
> >
> > :-)
> >
> > Dave
> >
************************************************** **************************
> > Dave Breeden

>
>
> That's exactly right. But that would be TOTAL SO2 - not free SO2. Some
will
> still be bound as sulfite. The free SO2 will be dependant on the pH of the
> wine. So I guess 57% would be more like a "potential" SO2 rather than the
> actual free SO2 in solution.
> --
> Greg Cook
> http://homepage.mac.com/gregcook/Wine
> http://homepage.mac.com/gregcook/aws
>
> (remove spamblocker from my email)
>

It is only a measure of the chemical content of the medium. It is your
known starting point. As they say, "Settling may occur during shipment."
and the old standby, "Your results may vary." :-)