Definitions for sal ammoniac
Random House Webster's College Dictionary
Ref: ammonium chloride.
Origin of sal ammoniac:
ammonium chloride, sal ammoniac(noun)
a white salt used in dry cells
a rare mineral composed of ammonium chloride found around volcanic fumaroles and guano deposits.
Sal ammoniac is a rare mineral composed of ammonium chloride, NH4Cl. It forms colorless to white to yellow-brown crystals in the isometric-hexoctahedral class. It has very poor cleavage and a brittle to conchoidal fracture. It is quite soft, with a Mohs hardness of 1.5 to 2, and has a low specific gravity of 1.5. It is water-soluble. Sal ammoniac is also the archaic name for the chemical compound ammonium chloride. The Romans called the ammonium chloride deposits they collected from near the Temple of Jupiter Amun in ancient Libya 'sal ammoniacus' because of proximity to the nearby temple. Salts of ammonia have been known from very early times; thus the term Hammoniacus sal appears in the writings of Pliny, although it is not known whether the term is identical with the more modern sal-ammoniac. In any case, this salt ultimately gave ammonia and ammonium compounds their name. It typically forms as encrustations formed by sublimation around volcanic vents. It is found around volcanic fumaroles, guano deposits and burning coal seams. Associated minerals include sodium alum, native sulfur and other fumarole minerals. Notable occurrences include Tajikistan; Mt. Vesuvius, Italy; and Parícutin, Michoacan, Mexico.
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