Ok, I _think_ I found what you want. Principles and Practices of
Winemaking, by Boulton et al, Chapter 5, section 2 page 195. It's way
too deep to go into detail here, but it's exactly what you and Fred
are looking for. I have a copy and will sum up:

The French have done a ton of work on this and so have the
Californians since the 50's. The bottom line seems to be that PA is
nothing more than a ballpark value. The variety of wine must, area
grown in and seasonal weather variations all impact alcohol
conversion, not to mention fermentation practices.

Hera are a few formulas:
Dujardin: (They make a wonderful ebulliometer too by the way)
PA= 0.0595* [2.66*Oe- 31.8]





"Ray" > wrote in message om>...
> Responding to PP, Paul, and JEP above:
>
> PP,
>
> On your comments concerning the accuracy of the PA scale on the hydrometer.
> I think you will find that this is the same scale that is found in the
> common SG/Brix/Sugar/PA table that is published all over the place. Fred
> and I have been having an extended discussion of this off line. He has one
> view of it's meaning and I have another. Neither of us have found
> diffinative data showing which one is right. We are both looking for such
> now but it may take time. The data you include does bear on the discussion.
>
> Fred maintains that the PA values in the table represent the maximum
> possible alcohol yield and anyone who uses or supports a calculation that
> gives values higher than these is wrong by deffinition. He has not produced
> any data to directly support this. He has arguements that do but they have
> not convinced me. I will leave it to Fred to argue his point.
>
> If you look at many published accounts of the table the instructions suggest
> that if your SG drops below 1.000 you have to calculate the extra alcohol
> that is being generated. This suggests that the table is based on
> frementing, not to dryness, but to an ending SG of 1.000. This is the
> interpretation that I use. It is supported by other authors that look at
> the SG/PA relationship in different ways. But, in all honesty, I cannot say
> that I can prove my view any better than Fred can. All I have to go on is
> the comments of well respected authors who Fred discounts.
>
> The calculation I use is that published by Duncan and Acton in Progressive
> Winemaking.
> PA = (G begining - G ending) / F
> Where
> G = 1000 * (SG - 1) = gravity
> and
> F = 7.75 - 3*(G begining - 7) / 800
>
> The F term corrects for non-sugar solutes in the wine. Depending on the
> media you may need to adjust the value 7 up or down. It is interesting to
> note that Duncan and Action did not mension the common PA table at all but
> if you assume and ending SG of 1.000 you will get the values in the common
> table using thier equation. (See "The Unified Theory of Gravity" in
> April-May WineMaker Mag.)
>
> I have really not found any data that proves that this is true but you will
> typically get 1% higher calculated alcohol useing this meathod over just
> looking up PA in the table. The numbers you posted do seem to indicate that
> you can get numbers higher than found in the common table. That is
> interesting. But I am not going to say that they prove my side of the
> arguement. I want a bit more before I claim that.
>
> So, by Freds interpretation, he would say that the table is correct and the
> measurements you quote must be wrong. By my interpretation, I would expect
> you to get a higher alcohol level than given in the table if you ferement to
> dryness.
>
> -----------------------------
> Paul wrote: "I am wondering if the error might not be non linear and may in
> fact be opposite for lower Brix juice."
>
> IMHO:
> I suspect that the difference is linear as the other relations in the table
> are linear. What is probably not linear is error caused by using different
> yeast strains and differen media. Different yeast may be more or less
> efficient as converting sugar to alcohol and different media may have a
> different correction in the F term.
>
> ---------------
> JEP wrote "I would be careful about using data sheets like this too. Even
> wine
> labels can have an inacurate ABV listed on them. For all the crap the
> US government puts wine makers through concerning labels, they allow a
> pretty big margin of error when it comes to alcohol content."
>
> IMHO:
> Regardless of what is put on the labels, they do perform laboratory analysis
> on wines out west to determine the true alcohol level. This is for tax
> purposes. I have been in communication with a number of agencies, labs, and
> some wineries out there recently. The government is strict on them. Back
> east they seem to ignore the goverment requirements. One of these days the
> Feds are going to come down on them. I think the main reason for the
> difference in enforcment is that Cal. grapes are much higher sugar content
> and are at risk of making higher than 14% wines. The goverment taxes these
> at a higer level. East coast grapes are rarely in danger of having this
> problem.
>
> Ray