Stockton uses the semi-extended metaphor of heat and fire to describe the princess in "The Lady, or the Tiger?":
Think of it, fair reader, not as if the decision of the question depended upon yourself, but upon that hot-blooded, semi-barbaric princess, her soul at a white heat beneath the combined fires of despair and jealousy.
The princess burns metaphorically as she watches her lover in the arena and imagines the outcome behind either door. She fears the claws and teeth of the tiger gnashing at the beautiful youth beneath her. She also fears the look upon his face should a fair and lovely lady emerge instead—joyous. Her despair and jealousy raise her naturally hot-blooded temperament to a white heat, which is a term used to describe something that has attained a tremendously high temperature, or a tremendously intense state of passion.
The cruel will of “fairness” compels the condemned to a game of chance. She, however, has lifted the veil of “fairness” and learned which door guards which terror. Her lover knows she has, because he knows her nature, and it assures him. She knows that he knows and that he will follow her subtle instruction. He does so without hesitation. The reader is left to decide whether she's chosen despair or jealousy.