soda: [16] Soda comes from medieval Latin soda, which may have been derived from Latin sodānum ‘samphire, glasswort’ (the plant samphire was burned to obtain soda for making glass). Another of the uses of samphire was as a headache cure, and it has been speculated that sodānum may have come ultimately from Arabic sudā ‘headache’, a derivative of sada’a ‘split’. Sodium was coined from soda in 1807 by the English chemist Humphry Davy. => sodium[soda etymology, soda origin, 英语词源]