Bitters are usually sold under the name of the substance which has been used to give them the predominant flavour, such as orange, angostura or peach bitters, &c. The alcoholic strength of bitters varies, but is generally in the neighbourhood of 40% of alcohol.
Some bitters, although possessing tonic properties, may be regarded as beverages pure and simple, notwithstanding the fact that they are seldom consumed in an undiluted state; others again, are obviously medicinal preparations and should be treated as such.
A clinical or therapeutical classification into such divisions as anaesthetics, expectorants, bitters, and so on, according to their practical applications, also leads to difficulties, as many drugs are employed for numerous purposes.
The aromatic bitters such as chamomile flowers, cascarilla bark, hops, orange peel and others contain in addition small quantities of essential oils which increase their local action.
The active principles in some of these bitters have been isolated pure, and have been found to be alkaloids or neutral compounds.
