I have found no one who can definatively say which way is right. I include
the drop below 1.000 but have been in heated arguements with those who
disagree. You could calculate it both ways and report the results as a
range.

Ray

"Steve Gross" <gross**at**pdq**dot**net> wrote in message
...
> pp,
>
> Thanks for the discussion. I don't disagree with any of the points you
> make. I especially agree that there's no reason not to include final sg's
> that are under 1.0 in the alcohol content calculation. It seems to me
> that
> only by considering the total sg drop can you really estimate the overall
> compositional change during fermentation. But I know others out there
> disagree.
>
> Steve
>
>
> "pp" > wrote in message
> ups.com...
> Steve:
>
> No fight here. I noticed the 2 results closely correlate but that
> could just mean one formula could be derived from the other the real
> test is judging the computed results against measured values. The
> practical problem with this is we don't seem to have ready access to
> measured alcohol values so it's hard to support any result well.
>
> Some people discard D&A's work because they argue considering the
> final gravity is plain wrong because anything that goes under sg 1.0
> is just the effect of alcohol created from the sugar (which is
> captured by initial s.g. value). That would also apply to Balling's
> formula. This is more pronounced for wines where often the final s.g.
> can get to 0.990 for dry wines.
>
> Personally, I think that argument is faulty because it ignores how the
> formula was designed - it's just as easy to base the PA values solely
> on the initial s.g. as it is to base them on the difference between
> final and initial s.g. The latter does not artifically "add sugar
> that's not there", it just incorporates the fact that the sugar
> progressively changes into alcohol and bases the calculation on that.
> The results will not completely agree but it's just an estimate anyway
> because the actual alcohol depends on many factors that cannot really
> be measured in practice.
>
> That said, based on the s.g. values of the grapes and juice we
> routinely get from California these days, I think the D&A formula
> exagerates the PA values by about 0.5-1% of abv. Again, this is
> imprecise as it's based on taste comparisons of my wines with
> commercial wines with stated alcohol value, but it works for me and
> that's really what matters in the end .
>
> You might want to check out this page: http://www.brsquared.org/wine/
> in the Calcs/Info section, it has some other formulas from the
> literature. Actaully, given that you're already showing 2 different
> values anyway, it might be of real value to collect all the different
> formulas you can get hands on and add those to the applet, kind of
> like what Ben has in his table but more extensive. That would give
> people a full range of PA results comparison in one place; I think
> that'd be really useful.
>
> One final note on the subject of precision - I think all calculations
> should be round up to give the PA values in 0.5% increments. Anything
> more than that gives a false impression that the computed value is the
> exact amount of alcohol in the wine, which is at odds of what the
> formulas can really do.
>
> Sorry, I've made this longer than I wanted - I keep promising myself I
> won't get involved in these debates anymore but it doesn't seem to
> work...
>
> Pp
>
>
> On Feb 19, 6:17 pm, "Steve Gross" <gross**at**pdq**dot**net> wrote:
>> Okay, I didn't mean to start a fight! But in answer to Pp's comment
>> about
>> the Balling formula, yes, there don't seem to be any references to its
>> use
>> in the context of wine, at least on the web. But when I tested it, the
>> results were remakably similar to the Duncan & Acton formula. And when
>> you
>> compare equations (5) and (8) on my documentation page
>> (http://web2.airmail.net/sgross/fermc...c_alcohol.html) you'll
>> see
>> that both formulas have a very similar form. I found these comparisons
>> somewhat compelling, so I included both formulas in the calculator.
>>
>> Steve
>>
>
>