Genever was the original spirit used as a cocktail mixer, starting with the first golden age of the cocktail in the mid-1800s. Several grains are malted like whiskey, then triple distilled. Clear and very mild, like a vodka but with traces of fine botanicals.
Learned all about this at Drink in Boston the other day, when the Bols Master Distiller came over from Holland with the original 1820s recipe book he uses for the new release of Bols 1820 Genever.
I think they’ll be in David Wondrich’s book.