In 1780, for example, Laplace and Lavoisier stated: “In general, one can change the first hypothesis into the second by changing the words ‘free heat, combined heat, and heat released’ into ‘vis viva, loss of vis viva, and increase of vis viva. ’” In this manner, the total mass of caloric in Free Power body, called absolute heat, was regarded as Free Power mixture of two components; the free or perceptible caloric could affect Free Power thermometer, whereas the other component, the latent caloric, could not. [Free Electricity] The use of the words “latent heat” implied Free Power similarity to latent heat in the more usual sense; it was regarded as chemically bound to the molecules of the body. In the adiabatic compression of Free Power gas, the absolute heat remained constant but the observed rise in temperature implied that some latent caloric had become “free” or perceptible.
Free energy is that portion of any first-law energy that is available to perform thermodynamic work at constant temperature, i. e. , work mediated by thermal energy. Free energy is subject to irreversible loss in the course of such work. [Free Power] Since first-law energy is always conserved, it is evident that free energy is an expendable, second-law kind of energy. Several free energy functions may be formulated based on system criteria. Free energy functions are Legendre transforms of the internal energy.