|The 2013 book The Physics of Wall Street, by American physicist, philosopher, and mathematician James Weatherall, touches on thermodynamics, and may well represent some aspects of financial thermodynamics, specifically Paul Samuelson's usage in economics. |
In 1926, English radiochemist Frederick Soddy, in his 1926 Virtual Wealth and Debt, attempted to explain the difference between wealth and debt, thermodynamically. 
In 1972, American science writer Daedalus described money as a heat-like entity whose concentration determines a financial temperature, and the interactions of people as a type of molecular sociology. 
“Some while back Daedalus developed a ‘molecular sociology’ an analogy between people and molecules. In particular he identified wealth in people with energy in molecules; he is now developing a financial thermodynamics or thermodynamics of money.”
A 1970s example would be American science writer Daedalus
The 2003 “Thermodynamic Analogies in Economics and Finance: Instability of Markets” by American physicist Joseph McCauley might be a more recent example of an attempt at theorizing on financial thermodynamics. 
● Economic thermodynamics
1. Soddy, F. (1926). Virtual Wealth and Debt - the Solution of the Economic Paradox. London: George Allen & Unwin LTD.
2. (a) Staff. (1972). “Ariadne”, New Scientist (pg. 165), Apr 20.
(b) Staff. (1972). “Ariadne”, New Scientist (pg. 232), Apr 27.
3. McCauley, Joseph l. (2003). “Thermodynamic Analogies in Economics and Finance: Instability of Markets”, Physica A 329 (2003): pp.199-212.
4. Weatherall, James O. (2013). The Physics of Wall Street: A Brief History of Predicting the Unpredictable (thermodynamics, pgs. 18, 65). Houghton Mifflin Harcourt.