Hope this works this time..........

Ooops...Nope. With the alcohol gone, seems I would have to
add 3 points to the difference in order to get the best
estimates when using the "old" formulas (a la CJJ Berry).
(eg. to compensate for the 3 point allowance for acid used
in the BRIX calculation). These "old" formulas were based
on the assumption that the acid and alcohol would cancel
eachother which of course isn't true or we would never
get readings below 1.000.

FWIW - For dry ferments, no calculation is required because
the original PA already tells us how much alcohol the wine
will have when (if) all of the sugar gets converted. So - the
only time we need to calculate is for RS wines/musts. With
sugar, alcohol, and acid all present when the post pitch
reading is taken, it is then a matter of sorting out how much
influence each one has on the single SG reading we have to
work with.

I no longer have my books and my memory sure ain't what
it used to be, so I think I better shut up and let you guys
figure this out...........HTH

Frederick



"frederick ploegman" wrote in message
...
Steve, Pp, et al

Why not try that "boil off the alcohol" procedure that someone
mentioned here earlier. With the alcohol gone and the "before
and after" readings restored to direct comparability, any of the
old formulas that ignored alcohol completely should then work.

Never tried this myself. Just found it easier to compensate for
the alcohol numerically. HTH

Frederick


"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

PS - The news reader at my ISP only allows me to read the
last 60 days worth of posts. If you are posting replies to
threads older than this, I can't read them. Since I think
others may be having the same problem, it might be nice if
you would start new threads instead. TIA

Frederick


"