Definition: Unmercurialness is a concept in physics and chemistry that describes an object or substance as being "insensitive" to changes in temperature. In other words, it remains at its original state even if the temperature of the surroundings changes. This property can be useful for predicting the behavior of objects under different conditions. For example, consider a material that is insulating when cooled below a certain temperature (unmercurialness). If you heat this material to a high enough level (say,