Salty liquorice, also known as salmiakki or salmiak, is a variety of liquorice flavoured with ammonium chloride, common in the Nordic countries, Netherlands, Baltic States and Northern Germany. Ammonium chloride gives salty liquorice an astringent, salty taste (hence the name), which has been described as "tongue-numbing" and "almost-stinging". Salty liquorice is an acquired taste and people not familiar with ammonium chloride might find the taste physically overwhelming and unlikeable. Salty liquorice candies are almost always black or very dark brown and can range from very soft to very hard and may be brittle. The other colours used are white and variants of grey. Carbon black is used as a food colouring agent in these candies. Salty liquorice is also used as a flavouring in other products, such as ice creams and alcoholic beverages.
The words salmiak and salmiakki are derived from an archaic Latin name for ammonium chloride, sal ammoniacus, meaning "salt of Ammon". "Ammon" in turn refers to the temple of Ammon at Siwa Oasis, where ancient Greeks found ammonium chloride. The word ammonia has the same origin. Ammonium chloride has a history of being used as a cough medicine as it works as an expectorant. Finnish author Jukka Annala speculates that salty liquorice has its origins at drug stores which manufactured their own cough medicine. Where and when ammonium chloride and liquorice were first combined to produce salty liquorice is unclear, but by the 1930s it was produced in Finland, Norway and the Netherlands as a candy.
Different languages often refer to salty liquorice as either "salmiac liquorice" (such as salmiaklakrits in Swedish, or salmiaklakrids in Danish), or simply "salty liquorice". In addition to ammonium chloride, salty liquorice candies are sometimes flavoured with other strong flavours like table salt and pepper, as in the case of Tyrkisk Peber candies. In Germany there is a variety available that is silvered by a metal powder that, as a side effect, makes it electrically conductive. A common shape for salty liquorice candies is a black diamond-shaped lozenge. This diamond shape is so typical that in Finnish, the word "salmiakki" can sometimes refer to this shape instead of the candy.