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Variations of the 1st Law of Thermodynamics
[1] Hess, H. (1940). Paper: 'Law of Constant Summation'. Source: Encyclopedia Britannica (2002 Deluxe Edition CD-ROM).

[2] Mayer, Robert (1841). Paper: 'Remarks on the Forces of Nature"; as quoted in: Lehninger, A. (1971). Bioenergetics - the Molecular Basis of Biological Energy Transformations, 2nd. Ed. London: The Benjamin/Cummings Publishing Company.

[3] Joule, J. (1843). Paper on the Mechanical Equivalent of Heat. Source: [URL]

[4] Helmholtz, H. v. (1947). "The Concervation of Force: A Physical Memoir." In Selectied Writings of Hermann von Helmholtz (1971), ed. R. Kahl, pgs. 3-55. Middletown, CT: Wesleyan University Press.

[5] Clausius, R. (1850). Monograph: Uber die bewegende Kraft der Warme.

[6] Rankine, W. (1853). Source: [URL].

[7] Helmholtz, H. v. (1863). Introductory Lecture to a series Delivered at Carlsruhe: Winter (1862-1863). Modern History Sourcebook: Hermann Ludwig Ferdinand von Helmholtz: "On the Concervation of Force, 1863" [URL].

[8] Clausius, R. (1965). Source: Bent, H. (1965). The Second Law – an Introduction to Classical and Statistical Thermodynamics.  (textbook). New York: Oxford University Press

[9-10] Planck. M. (1897). Treatise on Thermodynamics (texbook). New York: Dover Publications, Inc.

[11] Einstein, A. (1905). Letter to Conrad Habicht, written during the summer of 1905.  See: Rigden, J. (2005). Einstein 1905 - the Standard of Greatness. Cambridge: Harvard University Press.

[12] Fermi, E. (1936). Thermodynamics. New York: Dover Publications, Inc.

[13] Keenan, J. (1941). Thermodynamics (textbook). New York: John Wiley & Sons.

[14-15] Klotz. I. (1950). Chemical Thermodynamics (textbook). New York: Prentice Hall. Inc.

[16] Bazarov, I. (1964). Thermodynamics (textbook). New York: The Macmillan Company.

[17-18] Bent, H. (1965). The Second Law – an Introduction to Classical and Statistical Thermodynamics.  (textbook). New York: Oxford University Press.

[19] Lehninger, A. (1971). Bioenergetics - the Molecular Basis of Biological Energy Transformations, 2nd. Ed. London: The Benjamin/Cummings Publishing Company.

[20-21] Adkins, C. (1983). Equilibrium Thermodynamics, 3rd Ed. (textbook). Cambridge: Cambridge University Press.

[22] Sandler, S. (1989). Chemical and Engineering Thermodynamics, 2nd Ed. (textbook). New York: John Wiley & Sons.

[23] Black, W. & Hartley, J. (1996). Thermodynamics, 3rd Ed. (textbook). New York: Harper Collins.

[24-25] Kondepudi, Dilip. & Prigogine, Ilya. (1998). Modern Thermodynamics – From Heat Engines to Dissipative Structures (textbook). New York: John Wiley & Sons.

[26] Wark, R. & Richards, D. (1999). Thermodynamics, 6th Ed. (textbook). New York: McGraw-Hill.

[27] Schroeder, D. (2000). An Introduction to Thermal Physics. (textbook). New York: Addison Wesley Longman.

[28] Cengel, Y. & Boles, M. (2002). Thermodynamics – an Engineering Approach, 4th Ed. (textbook). New York: McGraw Hill.

[29] Clark J. (General Editor) (2004). The Essential Dictionary of Science. New York: Barnes & Noble Books.

[30] Smith, J., Van Ness, H., & Abbott, M. (2005). Introduction to Chemical Engineering Thermodynamics, 6th Ed. (textbook). New York: McGraw Hill.

[31]. Penrose, R. (2005). The Road to Reality - A Complete Guide to the Laws of the Universe. New York: Knopf [Random House, Inc.]

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James Joule [1818-1889]
Robert Mayer [1814-1878]

Most jointly cite Robert Mayer (1841), James Prescott Joule (1842), and Hermann von Helmholtz (1847) as being the primary originators of the first law of thermodynamics [See: example]

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1. The heat absorbed or evolved in any chemical reaction is a fixed quantity and is independent of the path of the reaction or the number of steps taken to obtain the reaction [Hess’s Law]. Hess

2. Energy can be neither created nor destroyed. Mayer

3. The mechanical power exerted in turning a magneto-electric machine is converted into the heat evolved by the passage of the currents of induction through its coils; and, on the other hand, that the motive power of the electro-magnetic engine is obtained at the expense of the heat due to the chemical reactions of the battery by which it is worked. Joule

4. Vital heat is the product of mechanical forces within the organism; all heat is related to ordinary forces; force itself can never be destroyed. Helmholtz

5. There is a state function E, called ‘energy’, whose differential equals the work exchanged with the surroundings during an adiabatic process. Clausius

6. All different kinds of physical energy in the universe are mutually convertible. Rankine

7. The quantity of force which can be brought into action in the whole of Nature is unchangeable, and can neither be increased nor diminished. Helmholtz

8. The energy of the world is constant. Clausius

9. The principle of the conservation of energy applied to phenomena involving the production or absorption of heat. Planck

10. It is in no way possible, either by mechanical, thermal, chemical, or other devices, to obtain perpetual motion, i.e. it is impossible to construct an engine which will work in a cycle and produce continuous work, or kinetic energy, from nothing. Planck

11. The relativity principle, in association with Maxwell’s fundamental equations, requires that the mass be a direct measure of the energy contained in a body; light carries mass with it.
[E/m = constant = c2]

12. The variation in energy of a system during any transformation is equal to the amount of energy that the system receives from its environment. Fermi

13. If any system is carried through a cycle, the end state being precisely the same as the initial state, then the summation of the work delivered to the surroundings is proportional to the summation of the heat taken from the surroundings. Keenan

14. The change in the internal energy dE, an exact differential, within a bounded region of space is found as a matter of experiment to be equal to the quantity of heat absorbed DQ, an inexact differential, and the amount of work done DW, an inexact differential, by the system. Koltz

15. dE = DQ - DW Koltz

16. The internal energy of a system is a single-valued function of its state and varies only under the influence of external actions. Bazarov

17. Etotal = constant Bent

18. [Etotal]Final State = [Etotal]Initial State Bent

19. The total energy of the system plus the surroundings must remain constant. Lehninger

20. If the state of an otherwise isolated system is changed by the performance of work, the amount of work needed depends solely on the change effected and not on the means by which the work is performed nor on the intermediate stages though which the system passes between its initial and final states. Adkins

21. An extension of the principle of conservation of energy to include systems in which there is a flow of heat. Adkins

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20. Energy is a conserved property. It can be neither created or destroyed; only its form can be altered from one form of energy to another. Black & Hartley

21. When a system undergoes a transformation of state, the algebraic sum of the different energy changes, heat exchanged, work done, etc., is independent of the manner of the transformation. It depends only on the initial and final states of the transformation. Prigogine & Kondepudi

Prigogine & Kondepudi

26. When any closed system (control mass) is altered adiabatically, the net work associated with the change of the state is the same for all processes between two given equilibrium states. Wark & Richards

27. ΔU = Q + W Schroeder

28. Energy can neither be created nor destroyed; it can only change forms. Cengel & Boles

29. Energy can be neither created nor destroyed; heat and mechanical work being mutually convertible. Clark

30. Although energy assumes many forms, the total quantity of energy is constant, and when energy disappears in one form it appears simultaneously in other forms. Smith, Van Ness & Abbott

31. The total energy after the process is equal to the total energy before the process. Penrose

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