Kali Turgida - Alkali and Soda Ash

Alkali and Soda Ash

The plant is a halophyte, i.e. is grows where the water is salty, and the plant is a succulent, i.e. it holds lots of water (and the water is salty). When the plant is burned, the sodium in the salt ends up in the chemical sodium carbonate. There are a number of practical applications for sodium carbonate including as an ingredient in making glass, and making soap. In the medieval and early modern centuries the Kali plant and others like it were collected at tidal marshes and seashores. The collected plants were burned, and the resulting ashes were mixed with water. Sodium carbonate is soluble in water. Non-soluble components of the ashes sunk to the bottom of the water container. The water with the sodium carbonate dissovled in it was transferred to another container, and then the water was evaporated off, leaving behind the sodium carbonate. Another major component of the ashes that is soluble in water is potassium carbonate. The resulting product consisted mainly of a mixture of sodium carbonate and potassium carbonate. This product was called "soda ash" (was also called "alkali"). Soda ash extracted from the ashes of Kali turgida/Kali tragus contains as much as 30% sodium carbonate. The soda ash was used primarily to make glass (secondly used as a cleaning agent). Another notable halophilic plant that was collected for the purpose was Salsola soda. Another was Halogeton sativus. Historically in the late medieval and early post-medieval centuries the word "Kali" could refer to any such plants. (The words "alkali" and "kali" come from the Arabic word for soda ash, al-qali). Today such plants are also called saltworts, referring to their relatively high salt content. Because of their use historically in making glass, they are also called glassworts. In Spain the saltwort plants were called barilla and were the basis of a large industry in Spain in the 18th century; see barilla. In the early 19th century, plant sources were supplanted by synthetic sodium carbonate produced using the Leblanc process.