Southall---I just did a very quick internet search for "Spirits of salts" and came up with the following
Hydrochloric acid was first discovered around 800 AD by the alchemist Jabir ibn Hayyan (Geber) and his contemporaries, by mixing common salt with sulfuric acid ("vitriol").[1][2] Jabir and contemporaries discovered many important chemicals, and recorded his findings in over twenty books, which carried his chemical knowledge of hydrochloric acid and other basic chemicals for hundreds of years. The 14th century description by Pseudo-Geber of the gold-dissolving aqua regia, consisting of hydrochloric acid and nitric acid, was of great interest to alchemists searching for the philosopher's stone.[1][2][3]
In the Middle Ages, hydrochloric acid was known to European alchemists as spirits of salt or acidum salis (salt acid). Both names are still deployed, notably in non-English languages, such as German: Salzsäure and Dutch: Zoutzuur. Gaseous HCl was called marine acid air. The old (pre-systematic) name muriatic acid has the same origin (muriatic means "pertaining to brine or salt"), and this name is still sometimes used. Notable production was recorded by Basilius Valentinus, the alchemist-canon of the Benedictine priory Sankt Peter in Erfurt, Germany, in the fifteenth century. In the seventeenth century, Johann Rudolf Glauber from Karlstadt am Main, Germany, used sodium chloride salt and sulfuric acid for the preparation of sodium sulfate in the Mannheim process, releasing hydrogen chloride gas. Joseph Priestley of Leeds, England prepared pure hydrogen chloride in 1772, and in 1818 Humphry Davy of Penzance, England, proved that the chemical composition included hydrogen and chlorine.[1][2][3]
Jabir ibn Hayyan, medieval manuscript drawing.During the Industrial Revolution in Europe, demand for alkaline substances increased. A new industrial process by Nicolas Leblanc (Issoundun, France) enabled cheap large-scale production of sodium carbonate (soda ash). In this Leblanc process, common salt is converted to soda ash, using sulfuric acid, limestone, and coal, releasing hydrogen chloride as a by-product. Until the British Alkali Act 1863 and similar legislation in other countries, the excess HCl was vented to air. After the passage of the act, soda ash producers were obliged to absorb the waste gas in water, producing hydrochloric acid on an industrial scale.[1][3][4]
In the twentieth century, the Leblanc process was effectively replaced by the Solvay process without a hydrochloric acid by-product. Since hydrochloric acid was already fully settled as an important chemical in numerous applications, the commercial interest initiated other production methods, some of which are still used today. After the year 2000, hydrochloric acid is mostly made by absorbing by-product hydrogen chloride from industrial organic compounds production.[3][4][5]
Since 1988, hydrochloric acid has been listed as a Table II precursor under the 1988 United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances because of its use in the production of heroin, cocaine, and methamphetamine.[6]
This fits right in with Maryaks advise to use dilute hydrochloric acid as a preperation for soldering in post #247.---Brian
