Orange bitters are an unsweetened, strong alcohol infusion made from dried Seville orange peel, soaked in an alcohol to let the flavour go into the alcohol. The alcohol used is often either gin or pure alcohol.
The two most common brands are one made by Chateau Thierry and by Fee’s. The Fee’s brand, called Fee’s West Indian Orange Bitters, contains alcohol, glycerine, oil of bitter orange (“terpeneless”), and water, as well as “other natural flavours.”
If you have tried Angostura bitters, you will find that Orange Bitters, as their name would imply, have a fruitier taste.
Used mostly in cocktails.
Orange bitters used to be very popular. There was a time when it was very fashionable to put a drop of orange bitters into a martini.