In science, vital heat refers to heat associated with life produced with in a living body. It is generally viewed as an historical term, a cousin of sorts to the concept of vitalism. The term is used significantly in the human thermodynamics works of French physicist Gustave Hirn. 
● Animal heat
● Vital energy
1. (a) Donkin, Byran. (1893). “The Scientific Work of Gustav Adolph Hirn in 7 Chapters (1845-1888)” (pgs. 145-201); Ch. V: Human thermodynamics, pg. 176-83)”, Transactions of the Manchester Association of Engineers (table of contents: human thermo-dynamics, pg. 176). Herald & Walker Printers.
(b) Hirn, Gustave. (1868). Philosophical Implications of Thermodynamics (Métaphysique et conséquences philosophiques de la thermodynamique: l'analyse fondamentale de l'univers) (Metaphysics and Philosophical Implications of Thermodynamics: Basic Analysis of the Universe). Paris: Gauthier-Villars.
● Vital heat – Wikipedia.