On the dynamic theory of heat

Abstract

U7. mechanical acttm may he derivei] from heat, and heat may be generated by mechanical action, by means of forces either acting between contiguous parts of bodies, or due to electric excitation : but in no other way known, or even conceivable, in the present state' of science. hence thcrmo-dvnamies falls naturallv *■ *. into two divisions, of which the subjects art1 respectively, the relation of heat to the forces actina hrtireen cnnt'njuoas /ends of t>odies, and the relation if heat to *■ * electrical <i(jenc/i. the investigations of tin* conditions under which thermodynamic (‘fleets arc1 produced, in operations of any fluid or fluids, whether gaseous or liquid, or passing from one state to the other, or to or from the solid statt1, and tin1 establishment of universal relations between the physical properties of all substances in these different states, which have been given in parts i.-v. of the1 present series of papers, belong to that first great division of thermodynamics—to be completed as is intended fob future communications to the royal society) by the extension of similar researches to the thermoelastic properties of solids. the second division, or thermo electricity, which may include many kinds of action as yet undiscovered, has hitherto been investigated only as far as regards the agency of heat in producing electrical effects in non-crystalline metals. in a mechanical theory of electric currents, communicated to the royal society, dec. lõ, us51.* the application of the general laws of the dynamical theory of heat to this kind of agency was made, and certain universal relations precisely analogous to the thermo-elastic properties of fluids established in the previous treatment of the first division of the subject, were established between the thermo-electric properties of non-crystalline metals. the object of the present communication is to extend the theory to the phenomena of thermo-electricity in crystalline metals ; but as recent experimental researches on air have pointed out an absolute therniometric scale,f the use of which in express-