depending on how long the wall is, one jack may not suffice to lift the wall. Set 2 jacks in toward the center of the wall from the ends about 1/3 of the way for each jack. Or try one jack in the middle.
A new, full length ( inside girder to outer band) double joist placed under the wall would be the ideal solution though.
With older homes, I've seen interior walls placed on top of diagonal 1x floor sheathing spaced one inch apart along with 24" joist spacing so the walls would sag to no limits. Back when those homes were being built 1x meant a full 1" thick piece of lumber and some of the boards are/were up to 1 1/4" thick! so that makes for a strong floor to start with but the walls still made the wood sag.