Uses
Historical medical use: to alleviate the pain of a sore throat. Powdered ammonium chloride is placed into a long paper open cone. The sharp end is placed deep inside the throat of the patient, while the care taker gently blows the dust through the wide end. The dust sticks to the irritated tissue and causes instant relief. Currently discontiniued due to the availability of more efficient methods.
It is commonly used as a flux in the soldering of stained-glass windows. In both jewellery-making and the refining of precious metals, potassium carbonate is added to gold and silver in a borax-coated crucible to purify iron or steel filings that may have contaminated the scrap. It is then air-cooled and remelted with a one-to-one mixture of powdered charcoal and sal ammoniac to yield a sturdy ingot of the respective metal or alloy in the case of sterling silver (7.5% copper) or karated gold. Anything other than 24-karat gold has silver and copper added. Usually the addition of silica, zinc, and deoxidants in very small amounts relative to the pennyweight (dwt.) of gold are processed into gold from as low as 8-karat to as high as 23.5-karat gold. This is added to prevent porosity or cracking while milling the ingot further into wire, sheet, or tubing. Without those additives an otherwise poor-quality ingot will result in open crucible melting with a hand torch or blowpipe and flame, as was done before electric melting furnaces were invented for use in the precious metals industry.
Sal ammoniac has also been used in the past in bakery products to give cookies a very crisp texture, although that application is rapidly dying due to the general disuse of it as an ingredient. However, in some areas of Europe, particularly Scandinavia, it is still widely used in the production of salty licorice candy known as Salmiak or Salmiakki.
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