Vesuvius in Eruption

A painting by Turner was copied by onto a room-divider screen hiding her TARDIS. It depicted a volcano. Upon the approach of an unauthorised person, the painted volcano would erupt with mustard gas.

Upon encountering the painted screen, the Sixth Doctor commented that the painting was an odd choice for the Rani, because it was "too passionate for the Rani's sterile tastes". Affixing a string to the top of the volcano, he and Peri stood back from the painting while he gave it a gentle tug. This tripped the Rani's trap, and the volcano erupted, momentarily incapacitating the time travellers with its deadly gas. (TV: The Mark of the Rani)

According to another account, the painting on the Rani's screen was Eruption of Souffrier. (PROSE: The Mark of the Rani)

Behind the scenes
While the painting, unnamed in the serial, was clearly based on J. M. W. Turner's 1817 Vesuvius in Eruption, the novelisation described it differently and named it as Eruption of Souffrier, a different Turner painting.