From time to time, I have seen posts asking if there is a way to determine the ABV of a wine without knowing the original SG. There is if one is so disposed to do the work and I will list the method here. This was developed by William Honeyman, BS, PhD and was published in The Art of Mking Wine by Stanley Anderson and Raymond Hull. (I have paraphrased and listed metric units as well as English units.)
1. Measure the SG of the finished wine. This will be SG1.
2. Measure out exactly one pint (or 500 ml) of the wine. This is the "Sample."
3. In an enameled or glass pan, boil the sample until it is exactly 1/2 its original volume, i.e. 1/2 pint (or 250 ml). What had been reduced in this process is some of the water and ALL of the alcohol, because alcohol boils at a lower temperature than water, about 173 degress F (78 degrees C) for alcohol vs. 212 degrees F (100 degrees C) for water.
4. Using distilled water make the sample back to the original volume, i.e. 1 pint (or 500 ml).
5. Cool the sample to the temperatrue for which your hydrometer is calibrated and measure the SG of the sample now. You should get a higher reading (now that all the alcohol is gone). This will be SG2.
6. Find the difference between the SG2 and SG1, which we will call the "spirit indication" and read the ABV from the following where the first number is the difference in SG (spirit indication) and the second is ABV:
1.5=1%, 2=1.3%, 3=2%, 4=2.7%, 5=3.4%, 6=4.1%, 7=4.9%, 8=5.6%, 9=6.4%, 10=7.2%, 11=8.0%, 12=8.8%, 13=9.7%, 14=10.5%, 15=11.4%, 16=12.3%, 17=13.2%, 18=14.1%, 19= 15.1%, 20=16%, 21=17%., 22=18%, 23=19%, 24=20%, 25=21%, 26=22%
1. Measure the SG of the finished wine. This will be SG1.
2. Measure out exactly one pint (or 500 ml) of the wine. This is the "Sample."
3. In an enameled or glass pan, boil the sample until it is exactly 1/2 its original volume, i.e. 1/2 pint (or 250 ml). What had been reduced in this process is some of the water and ALL of the alcohol, because alcohol boils at a lower temperature than water, about 173 degress F (78 degrees C) for alcohol vs. 212 degrees F (100 degrees C) for water.
4. Using distilled water make the sample back to the original volume, i.e. 1 pint (or 500 ml).
5. Cool the sample to the temperatrue for which your hydrometer is calibrated and measure the SG of the sample now. You should get a higher reading (now that all the alcohol is gone). This will be SG2.
6. Find the difference between the SG2 and SG1, which we will call the "spirit indication" and read the ABV from the following where the first number is the difference in SG (spirit indication) and the second is ABV:
1.5=1%, 2=1.3%, 3=2%, 4=2.7%, 5=3.4%, 6=4.1%, 7=4.9%, 8=5.6%, 9=6.4%, 10=7.2%, 11=8.0%, 12=8.8%, 13=9.7%, 14=10.5%, 15=11.4%, 16=12.3%, 17=13.2%, 18=14.1%, 19= 15.1%, 20=16%, 21=17%., 22=18%, 23=19%, 24=20%, 25=21%, 26=22%
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