The Collaborative International Dictionary of English v.0.48:

Thermochrosy \Ther*moch"ro*sy\, n. [Thermo- + Gr. ? coloring.]
   (Physics)
   The property possessed by heat of being composed, like light,
   of rays of different degrees of refrangibility, which are
   unequal in rate or degree of transmission through diathermic
   substances.
   [1913 Webster]