Daly's Bartenders' Encyclopedia by Tim Daly (1903, p.83)

2 teaspoonfulspotassium bromide elixir — elixir bromide potassiumbase
1 teaspoonfulgentian tincture — tincture gentianbitter
water — Fill the glass half full with water.dilution
  1. Add the bromide elixir and gentian tincture to a whiskey glass.
  2. Fill the glass half full with water and serve.

This is a clear example of openly medicinal morning service surviving inside a bartenders' manual.

Its identity is entirely functional and restorative rather than convivial.

See also: Stomach Lining, Soda Cocktail