
Orange bitters is a concentrated cocktail bitters flavored with orange peel — often bitter Seville orange — over a base of spices like cardamom, coriander and caraway.
Citrus peel in front is the whole job, and a bitters without it seasons the drink but does not brighten it. Any bottle that leads with orange swaps dash for dash; anything that leads with warm spice is a different seasoning.
Aromatic bitters (e.g. Angostura)
Both are dashing bitters at similar strength, but they are two different seasonings rather than variants of one, and most classic specs name which they want. Dash aromatic where orange is called for and the drink turns warm and spiced instead of bright.
Regan’s No. 6 against Fee Brothers West Indian
The two standard bottles and they are not the same seasoning: Regan’s leads with cardamom and reads dry and spiced, Fee’s is softer and candied. A Martini specced on one tastes sweeter on the other, so pick by the drink and keep the dash count.
This is the bitters that does not keep indefinitely, because the working part is citrus oil and citrus oil oxidizes. A year-old bottle still seasons a drink; it seasons it with something duller and slightly resinous. Buy the small bottle unless the bar goes through orange bitters quickly.

Bijou Cocktail
London dry gin

Dry Martini 7:1
London dry gin

Maple Old Fashioned
Bourbon

Martinez – IBA
London dry gin, Rosso vermouth

Martinez (gin version)
London dry gin

Mezcal Margarita
Mezcal

Singapore Sling (Old Tom Gin)
Old Tom gin

Coffee Old Fashioned
Rye whiskey

Corpse Reviver No. 1 (Savoy recipe)
Cognac

Dry Martini 15:1 Montgomery’s
London dry gin

Dry Martini 4:1
London dry gin

Irish Old Fashioned
Irish whiskey

Pomegranate Negroni
London dry gin

Screwdriver
Vodka

Dry Martini 2:1
London dry gin

Dry Martini 3:1
London dry gin

Negroni Frappé
London dry gin, Amaro, Rosso vermouth

Pomegranate Cosmopolitan
Vodka

Dickens Dry Martini
London dry gin

Grand Cosmopolitan
Vodka, Cognac orange liqueur (e.g., Grand Marnier)

Harvey Wallbanger
Vodka

Perfect Martini
London dry gin

Adonis
Fino sherry

Celebration
Cognac, Rosso vermouth, Red bitter