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Their beautiful city is a great centre of attraction for scientific men, and many European electricians make a practice of coming over every Saturday to stay till Monday. Here are the colossal thermo-electric batteries which work throughout the year by there being stored up in immense solid blocks of aluminium the heat of summer and the cold of winter.
Mr. Munro is, with the aid of Mr. Warwick's manipulative skill, extending this portion of his investigation further by experimenting with gauzes and coils of various metals forming other couples in the thermo-electric series, as well as with iron and other gauzes electrotyped with bismuth and other metals, and we hope in due time to lay the results of those experiments before our readers. Mr.
The thermo-battery, the discovery of Seebeck in 1822, was alluded to as a means of converting heat into electric energy in the most direct manner; but this conversion could not be an entire one, because the second law of thermo-dynamics, which prevented the realization as mechanical force of more than one seventh part of the heat energy produced in combustion under the boiler, applied equally to the thermo-electric battery, in which the heat, conducted from the hot points of juncture to the cold, constituted a formidable loss.
This combination, which is called a "thermo-electric couple," is clearly analogous to the voltaic couple, with heat in place of chemical affinity. The direction of the current within and without the couple shows that the bismuth is positive to the antimony.
A very feeble thermo-electric effect can be produced by heating the junction of two different pieces of the same substance, or even by making one part of the same conductor hotter than another. Thus a sensitive galvanometer will show a weak current if a copper wire connected in circuit with it be warmed at one point.
It must be borne in mind that although the bismuth and antimony of this thermo-electric battery, like the zinc and copper of the voltaic or chemico-electric battery, are respectively positive and negative to each other, the poles or wires attached to these metals are, on the contrary, negative and positive.
Munro, and to which the name thermo-microphone might be given, as it is a microphone in which thermo-electric currents are employed in the place of voltaic currents, its special feature of interest lying in the fact that the heated junction of the thermo-electric couple is identical with the microphone contacts of the two electrodes.
A recent experimenter in electric and super-physical force, M. Tessier d'Helbaicy, states this theory: "Taking as his premise the fundamental law of physical science, that all chemical reaction is accompanied by a generation of heat and electricity, he said to himself that the human body, with the innumerable and incessant chemical reactions presented by all its cells, should create a thermo-electric pile of great power.
The electromotive force of each thermo-electric element did not exceed 0.036 of a volt, and 1,800 elements were therefore necessary to work an incandescence lamp. A most useful application of the thermo-electric battery for measuring radiant heat, the thermo pile, was exhibited.
It is in the same way possible, as Professor Lorentz has shown, to give a very satisfactory explanation of the thermo-electric phenomena by supposing that the number of liberated electrons which exist in a given metal at a given temperature has a determined value varying with each metal, and is, in the case of each body, a function of the temperature.
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