Oh, and about the
oxos (‘vinegar’, ‘sour-wine’):
it was probably the Roman beverage known as
posca, made by mixing sour wine/wine vinegar (i.e. wine that was spoiled by faulty storage) with water, in some cases, flavoring herbs or eggs were also mixed. It originated in Greece as a medicinal mixture of vinegar mixed with water (
oxykraton) with no general name, sometimes drunk or sometimes used externally. Eventually it became a favorite everyday drink for the Roman army and the lower classes from around the 2nd century BC, continuing to be used throughout Roman history and into the Byzantine period.
The word is derived from either the Latin
potor, ‘to drink’ or from the Greek
epoxos ‘very sharp’. It was initially an unfamiliar beverage in the largely Greek-speaking eastern Mediterranean region, where more sweet-tasting wines were preferred. As the Greeks originally lacked a word for
posca, sources written in Greek, such as Plutarch and the Gospels, use the word
oxos in its place (translated as
acetum in the Vulgate). The word eventually migrated into Greek from about the 6th century AD onwards as the Byzantine army continued the Roman tradition of drinking what they now termed
phouska.
Wine vinegar didn’t have any alcohol left, but was wine that had turned, well, sour. It is made by the action of acetic acid bacteria on alcohol to produce acetic acid. Since the bacteria that cause this reaction are aerobic, they require that the wine be exposed to oxygen in order to form vinegar. (Hey, we must note that our English word vinegar actually comes from the Old French
vin aigre, ‘sour wine’!

)
Posca was increasingly heavily used by the Roman army during the Republican period when it became a standard beverage for soldiers. The drinking of quality wine was considered a sign of indiscipline, to the point that some generals banned imported vintage wine altogether. Appian records both
posca and wine as being among the provisions of the army of Lucullus in his Spanish campaign of 153 BC. The
Historia Augusta records that by Hadrian’s time it was a standard part of the normal “camp fare” (
cibus castrensis). A decree from the year 360 instructed the lower ranks of the army to drink
posca and wine on alternate days.
Although it was primarily associated with soldiers and the lower classes, some higher-ranked Romans also drank
posca to express solidarity with their troops. According to Plutarch, Cato the Elder was particularly noted for liking it.
In Ancient Rome - or in most of the ancient world in general, it was dangerous to drink pure water since it contained so much bacteria it could lead to diseases. This was one of the reasons why
posca was so popular: it was affordable enough and is one of the better alternatives to tap water. The wine’s acidity took longer to spoil, it killed all the harmful bacteria and the flavoring helped to overcome the bad smell and taste of local water supplies. As well as being a source of liquid, it provided calories and was an antiscorbutic, helping to prevent scurvy by providing vitamin C. It was apparently also refreshing and made a decent thirst-quencher.