This week, Philadelphia became the first major American city to tax soda and other sugar-added beverages. Supporters tout the levy as a remedy for health problems and school funding. Opponents see it as an illegal overreach of the nanny state and a real headache for the beverage industry. This split will surely play out in court – just as it might, quite literally, in the very etymology of the word soda.
Soda‘s fountain
The Oxford English Dictionary (OED) first cites soda in a 1558 translation of a French medical guide. The manual lists soda as an ingredient in an ointment for hair removal, noting that this soda was obtained from the ashes of grass and used by glassmakers. It also mentions a Venetian soda in a later passage on soap preparation.
Venetian soap and medicinal grass? (It’s no wonder Coke so closely guards its secret formula). Originally, soda was indeed obtained from the ashes of plants, specifically salt-rich marine flora like saltwort, featured above. The alkaline derivative, now largely produced artificially, has long been used in soap and glass.
Problem and solution?
Now, most etymologists agree that soda comes from the Medieval Latin or Italian soda, but they dispute its deeper roots. The OED is conservative on the matter, leaving its origin unknown. Others philologists enjoy a bit more of a sugar high. Skeat and Weekly look to the Latin solidus, “solid,” characterizing the hard products yielded by saltwort plants. Italian eventually contracted this solidus into soda, they write. Skeat goes on to trace the Spanish form of soda, sosa, back to the Latin sal, “salt,” relate to salsa and sausage.
The Barnhart Etymology Dictionary maintains soda ultimately derives from the Arabic, suwwad, the name for a kind of saltwort, which was exported from North Africa to Sicily in the Middle Ages. Suwwad, the dictionary notes, is related to sawad, “black,” referring to the color of a variety of the plant. The dictionary concludes Italian directly borrowed the word, as evidenced as early as the 1300s.
Other scholars, apparently chugging Mountain Dew, have proposed the Arabic suda, “headache.” Some even gloss the word as a “splitting headache,” derived from a verb meaning “to split.” The saltwort plant, as the theory goes, was used to cure such headaches. Latin borrowed the medicine and word as sodanum, a “headache remedy,” thence shortened and spread as soda. It’s a fizzy etymology, but one that most scholars agree has gone flat.
Soda products
In the 18th and 19th centuries, chemists were, well, effervescent about soda. They injected the soda-derived sodium bicarbonate into water, calling it soda water by 1802. This was shortened to soda by 1834. Pop – named for the sound of the cork when the beverage was originally served and preferred in many dialects, including my own – is attested even earlier, in 1812. The OED dates soda-pop to 1863. Today’s soda features carbonic acid, among other additives; baking soda, however, preserves its chemical and linguistic connection to sodium bicarbonate.
In 1807, Humphry Davy isolated an element from caustic soda and so named it sodium. He used the symbol Na as a nod to natrium, a name proposed by his contemporary, Jacob Berzelius. Berzelius was inspired by natron, a naturally occurring soda-solution whose name is related to the Greek nitro and may itself have deeper Middle Eastern roots.
In 1933, Eugene O’Neill debuted his comedy, Ah, Wilderness! In the play, a character asks, “Ever drink anything besides sodas?” The OED cites this usage as the earliest record we have specifically for the modern “drink” or “glass of” soda. It’s a question that still has a sharp bite today. But the answer may not be what Philadelphia has in mind: “Beer and sloe-gin. Fizz and Manhattans.”
Mashed Radish 
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