thermodynamically (thermodinamikali)

In accordance with the laws of thermodynamics. Jour. Franklin Inst., CXXVIII. 467. thermodynamicist (thermō-di-nam'i-sist), n. [ thermo-electrically (thèr"mō-e-lek'tri-kal-i), adv. In accordance with the laws of thermo-electricity. Encyc. Brit., VIII. 94. thermo-electricity (ther"mō-e-lek-tris'i-ti), n. [ Thermo-electric Multi plier. The electric current produced in a circuit of two or more di imilar metals, or in a circuit of one metal different parts of which are in di imilar physical states, when one of the points of union is heated or cooled relatively to the remainder of the circuit; also, the branch of electrical science which treats of electric currents so produced. If, for example, a bar of bismuth and one of antimony are soldered together and the point of union is heated while their other extremities are connected by a wire, it is found that an electric current pa es from bismuth to antimony, and through the wire from antimony to bismuth. Such a pair of metal bars is called a thermo-electric couple or pair, and it is found that the thermoelectromotive force, as it is called, is, for a circuit composed of the same pair of metals, proportional to the difference of temperature between the hot and the cold junc ion. It is found, further, that it dif Thermo-electric Couple. fers for different metals; and the list of the metals, arranged in order according to the direction of the current generated, is called the thermo -electric series (analogous to the electromotive series in voltaic electricity): for example, bismuth, lead, zinc, copper, iron, antimony. If more than one couple are employed, the whole electromotive force is the sum of the separate forces for the succe ive junctions. A number of couples of the same two metals joined together form a thermo-electric battery, or thermopile; they are arranged so that one set of junctions can be heated while the other is kept cool. When connected with a delicate galvanometer, the thermopile can be used to detect and measure very small differences in temperature, as especially small differences in radiant heat; for this purpose one end of the thermopile is generally coat thermograph ed with lampblack so as to absorb the heat incident upon it, and a cone of polished bra may be added to collect more heat. Thermo-electric couples give a comparatively low electromotive force, which has, however, great constancy if the two sets of junctions are kept at a uniform temperature. What is called the Peltier phenomenon or effect is the rise or fall of temperature at the junction of two different metals due to the pa age of an electric current from one metal to the other acro the junction. This thermal effect is distinct from the rise of temperature due to the electrical resistance of the metals, and changes sign when the direction of the current acro the junction is changed.