Effervescent in mineral spirits?
A fish-tank bubbler with needle valve or regulator would not only provide bubbles but be controllable and would not need to be replenished, as would chemicals.

N.B. However you make bubbles in mineral spirits, it would help the highly-flammable liquid to evaporate, creating a potential explosion and fire hazard. You might get better images with less-miscible mineral or silicone oil, with less danger.