Vinegar

Heb. hometz, Gr. oxos, Fr. vin aigre; i.e., "sour wine." The
Hebrew word is rendered vinegar in Ps. 69:21, a prophecy
fulfilled in the history of the crucifixion (Matt. 27:34). This
was the common sour wine (posea) daily made use of by the Roman
soldiers. They gave it to Christ, not in derision, but from
compassion, to assuage his thirst. Prov. 10:26 shows that there
was also a stronger vinegar, which was not fit for drinking. The
comparison, "vinegar upon nitre," probably means "vinegar upon
soda" (as in the marg. of the R.V.), which then effervesces.