Goa'uld stasis jars are small jars intended to hold Goa'uld symbiote. Filled with sedative properties that can render the symbiote unconscious, the jar is surrounded by a ceramic coating, but is also equipped with a small Naquadah generator that emits a small electrical charge to keep the symbiote alive indefinitely. The jars also seem to be used as a cruel punishment, as removing a symbiote from its host is considered very insulting.
Osiris and Isis were placed in stasis jars (whether by Setesh or another Goa'uld is a matter of debate). Egeria, Queen Mother of the Tok'ra, was placed in a similar jar by Ra, as was Sekhmet. (SG1: "The Curse", "Cure", "Resurrection")