The Art of Making Whiskey:

The art of extracting wine from the juice of the grape, not being the object of this book, I shall confine myself to what is necessary and useful to the distillers of whiskey; it is therefore of the vinous liquor extracted from grains, that I am going to speak.
The formation of that kind of liquor is founded upon a faculty peculiar to grains, which the learned chymist, Fourcroy, has called saccharine fermentation. Sugar itself does not exist in gramineous substances; they only contain its elements, or first principles, which produce it. The saccharine fermentation converts those elements into sugar, or at least into a saccharine matter; and when this is developed, it yields the eminent principle of fermentation, without which there exists no wine, and consequently no spirit…