As a lawyer his greatest public efforts were his lectures (1799) at Lincoln's Inn on the law of nature and nations, of which the introductory discourse was published, and his eloquent defence (1803) of Jean Gabriel Peltier, a French refugee, tried at the instance of the French government for a libel against the first consul.
When a current is passed through a solid alloy, a series of Peltier effects, proportional to the current, are set up between the particles of the different metals, and these create an opposing electromotive force which is indistinguishable experimentally from a resistance.
When the Revolution developed the importance of the press, Rivarol at once took up arms on the Royalist side, and wrote in the Journal politique of Antoine Sabatier de Castres (1742-1817) and the Actes des Apdtres of Jean Gabriel Peltier (1770-1825).
Peltier (1785-1845) in 1814 discovered that a current passed across the junction of two metals either generated or absorbed heat.
JEAN CHARLES ATHANASE PELTIER (1785-1845), French physicist, was born at Ham (Somme) on the 22nd of February 1785.
Peltier Ef f ect.-The discovery by J.
Peltier (1834) that heat is absorbed at the junction of two metals by passing a current through it in the same direction as the current produced by heating it, was recognized by Joule as affording a clue to the source of the energy of the current by the application of the principles of thermodynamics.
It had been observed by Peltier and A.
The order of the metals in respect of the Peltier effect was found to be the same as the thermoelectric series.
But on account of the difficulty of the measurements involved, the verification of the accurate relation between the Peltier effect and thermoelectric power was left to more recent times.
The coefficients, P and P', are called coefficients of the Peltier effect, and may be stated in calories or joules per ampere-second.
The Peltier coefficient may also be expressed in volts or microvolts, and may be regarded as the measure of an E.M.F.
Of the couple, and if the flow of the current does not produce any other thermal effects in the circuit besides the Joule and Peltier effects, we should find by applying the principle of the conservation of energy, i.e.
By equating the balance of the heat absorbed by the Peltier effects to the heat generated in the circuit by the Joule effect, (P - P')C=CR=EC, whence E=P - P..
Clausius (1853) that the Peltier effect varied directly as the absolute temperature, and that the E.M.F.
(2) If the Peltier effect was proportional to the thermoelectric power and changed sign with it, as all experiments appeared to indicate, there would A B be no absorption of heat C in the circuit due to the Peltier effect, and therefore no thermal source to account for the energy of the current, in the case in which the hot junction was at or above the neutral temperature.
Like the Peltier coefficient, it may be measured in joules or calories per ampere-second per degree, or more conveniently and simply in microvolts per degree.
Consider an elementary couple of two metals A and B for which s has the values s and s" respectively, with junctions at the temperature T and T+dT (absolute), at which the coefficients of the Peltier effect are P and P+dP. Equating the quantity of heat absorbed to the quantity of electrical energy generated, we have by the first law of thermodynamics the relation dE/dT =dP/dT+(s' - s").
(7), Eliminating (s' - s") we find for the Peltier effect P = TdE/dT = Tp. .
(9)' From these relations we observe that the Peltier effect P, and the difference of the Thomson effects (s' - s"), for any two metals.
The signs of the Peltier and Thomson effects will be the same as the signs of the coefficients given in Table I., if we suppose the metal s to be lead, and assume that the value of s may be taken as zero at all temperatures.
Mag., December 1852), to make experiments to verify quantitatively the relation P/T =dE/dT between the Peltier effect and the thermoelectric power.
The most accurate measurements of the heat absorption due to the Peltier effect at present available are probably those of H.
The Peltier effect was only a small fraction of the total effect, but could be separated from the Joule effect owing to the reversal of the current.
According to this formula, the Peltier effect is a linear function of the temperature.
Taking the lead-iron couple as an example, the value of dE/dt at the hot junction too° C. is 10.305 microvolts per degree, and the value of the Peltier coefficient P = TdE/dT is +3844 microvolts.
At the cold junction the iron is supposed to be connected to a piece of lead at o° C., and there is a sudden drop of potential due to the Peltier effect of 3648 microvolts.
The flow of the current will produce a fall of potential ER'/R in the lead from cold to hot, and ER"/R in the iron from hot to cold, but the potential difference due to the Peltier effect at either junction will not be affected.
4 for cadmium in which both the specific heat and the Peltier effect are positive, and also for platinum and nickel in which both coefficients are negative.
- It is now generally conceded that the relatively large differences of potential observable with an electrometer between metals on open circuit, as discovered by Volta, are due to the chemical affinities of the metals, and have no direct relation to thermoelectric phenomena or to the Peltier effect.
The Peltier effect and the thermo-E.M.F., on the other hand, do not depend on the state of the surfaces, but only on the state of the substance.
It is equally evident that chemical affinity between the metals cannot be the explanation of the Peltier E.M.F.
Although it is possible that differences of potential larger than the Peltier effect might exist between two metals in contact on open circuit, it is certain that the only effective E.M.F.
In p ractice is the 89 S.-9 2000 = Cd 0 +471= o° T 409= E to o° 100' Peltier effect, and that the difference of potential in the substance of the metals when the circuit is complete cannot be greater than the coefficient P. The Peltier effect, it may be objected, measures that part only of the potential difference which depends upon temperature, and can therefore give no information about the absolute potential difference.
But the reason for concluding that there is no other effective source of potential difference at the junction besides the Peltier effect, is simply that no other appreciable action takes place at the junction when a current passes except the Peltier generation or absorption of heat.
DE, namely, dE =dP+(s' - s")dT = (P/T)dT = pdT = (p" - p')dT, in which the coefficient, P, of the Peltier effect, and the thermoelectric power, p, of the couple, may be expressed in terms of the difference of the thermoelectric powers, p and p", of the separate metals with respect to a neutral standard.
In this case, however, in order to account for the phenomenon of the Peltier effect at the junctions, it is necessary to suppose that there is a real convection of heat by an electric current, and that the coefficient P or pT is the difference of the quantities of heat carried by unit quantity of electricity in the two metals.
The Peltier effect, on the other hand, may be ascribed entirely to convection.
If, therefore, we are prepared to admit that an electric current can carry heat, the existence of the Peltier effect is no proof that a corresponding E.M.F.
In order to explain the Peltier effect, Kohlrausch further assumes that an electric current, C, carries a heatflow, Q= ABC, with it, where " A is a constant which can be made equal to unity by a proper choice of units."
If A and Bare constant, the Peltier effects at the hot and cold junctions are equal and opposite, and may therefore be neglected.
P = Coefficient of Peltier Effect.