Editing Sodium carbonate (section)

===Barilla and kelp===
Several "[[halophyte]]" (salt-tolerant) plant species and seaweed species can be processed to yield an impure form of sodium carbonate, and these sources predominated in Europe and elsewhere until the early 19th century. The land plants (typically [[glasswort]]s or [[saltwort]]s) or the seaweed (typically ''[[Fucus]]'' species) were harvested, dried, and burned. The ashes were then "[[Leaching (chemistry)|lixivated]]" (washed with water) to form an alkali solution. This solution was boiled dry to create the final product, which was termed "soda ash"; this very old name derives from the Arabic word ''soda'', in turn applied to ''[[Salsola soda]]'', one of the many species of seashore plants harvested for production. "Barilla" is a commercial term applied to an impure form of [[Pearlash|potash]] obtained from coastal plants or [[kelp]].<ref>{{cite book |last1=Hooper |first1=Robert |author-link1=Robert Hooper (physician) |title=Lexicon Medicum |date=1802 |publisher=Longman |location=London |pages=1198–9 |edition=1848|oclc= 27671024}}</ref>

The sodium carbonate concentration in soda ash varied very widely, from 2–3 percent for the seaweed-derived form ("[[kelp]]"), to 30 percent for the best [[barilla]] produced from [[saltwort]] plants in Spain. Plant and seaweed sources for soda ash, and also for the related [[alkali]] "[[potash]]", became increasingly inadequate by the end of the 18th century, and the search for commercially viable routes to synthesizing soda ash from salt and other chemicals intensified.<ref name="Clow52">
Clow, Archibald and Clow, Nan L. (June 1952). ''Chemical Revolution''. Ayer. pp. 65–90. {{ISBN|0-8369-1909-2}}.</ref>