The Romans mined salt from deposits in the ground, then dissolved it in water, making a brine solution that would be boiled in large uncovered pans over fire. To help the salt come together and form crystals, they would add some kind of coagulating agent such as blood, and to help any organic matter float to the surface where it could be skimmed off, a bit of urine.
Roman salt pans were found at Algarve, Portugal. Indeed, they all are throughout Europe, many still in use. Romans called salt pans “salina.”
The Roman Salt as Salary Myth
Roman soldiers got paid in money. The salary varied depending on what rank they held, and what period in the Empire you are thinking of (remember, the Western Roman Empire existed for around 800 years.) Out of their money, soldiers were expected to to pay for their clothing, food, and even their weapons and armour. The items weren’t actually sold to the soldiers per se: rather they were given to them, and the cost deducted. Classicists have estimated that after deductions, they were left with about a fifth of their pay cheque. No portion of their salary was dedicated to salt, just as it was not dedicated to bread, shoes, helmets or bedding either.
They were not paid in salt, nor did they get special money for salt. That part is a myth. They got paid in coins; and a quick browse of any Roman coin collectors’ books or web sites will spell out not only that, but how their salary changed over various periods of the empire.
Romans themselves speculated where the word “salarium” came from. Pliny, in Natural History xxi.41, speculated that the “ancients” derived the word salarium from sal (salt.)
The Romans didn’t actually plough the ground of Carthage with salt. They did raze the city in the spring of 146 BC, under Scipio.
Berthold Georg Niebuhr (1776-1831) started the idea in his book “History of Rome” that Scipio had Carthage not just razed, but ploughed. B.L. Hallward (1901 – ), in The Siege of Carthage (Cambridge Ancient History Vol. VIII, published between 1924 and 1939), sprinkled in the salt for good measure. Hallward was probably drawing on biblical imagery from the Book of Judges (9:45). At the time, salt was worth more than its weight in gold. Romans may have been pissed at Carthage, but they weren’t stupid. The Carthaginian (or “Punic”) Wars had already cost them a fortune as it was.
Literature & Lore
“It was a medicinal herb, salt. Good for wounds, wasn’t it? And back in the really old days, hadn’t soldiers been paid in salt? Wasn’t that where the word salary came from? Must’ve been good, then. You went on a forced march all week, building your road as you went, then you fought the maddened blue-painted tribesmen of the Vexatii, and you force-marched all the way back home, and on Friday the centurion would turn up with a big sack and say, “Well done, lads! Here’s some salt!” — Terry Pratchett, The Last Continent