The volume of alcohol in a finished wine is directly related to how much fermentable sugar (by weight) the must contains.
A triple-scale hydrometer (with Specific Gravity, Potential Alcohol, and Brix/Balling scales) lets you read the predicted
value directly. Let’s say you have a juice that is 12 Brix and you want to add enough sugar to it to bring it up to 24 Brix.
You can make a sugar solution of known concentration(discussed in next month’s article) and determine how much
syrup to add. Of course, part of the sugar solution is water, which increases the must’s volume.