Making Homemade Wine and Beer

Brix scale from Answers.com

A system of measurement, given in degrees, of the amount of sugar present in grape juice. Similar systems are used in different countries, eg. the Balling, Baumé and Oechsle scales, all providing sugar content measurements that can be used to approximate the final alcohol content of wine being produced. See also must weight.  

Another definiton from Onlineconversion.com 

Balling: The name of a density scale for measuring sugar content in water base solutions. Since grape juice is primarily sugar and water, the balling scale was used for a quick and easy “sugar analysis” of juice. The Balling scale contained a slight inaccuracy however, and it was corrected by Dr Brix. Today the Brix scale is in actual use, but the terms Balling and Brix often are used interchangeably. 

The Balling (Brix) scale is simplicity itself: Each degree is equivalent to 1 percent of sugar in the juice. For example, grape juice which measures 15.5 degrees on the Balling or Brix scale contains about 15.5% sugar. 

Now that you know the Brix of your juice, you can easily fiqure out how much alcohol your juice will make by using this formula: 

Brix count x .575 

So if your brix count is 23, take 23 x .575, which equals 13.23.  Your wine should be slightly over 13% alcohol content whenever it is done fermenting.