Nature . following is the new method, of which a very brief de-scription will be suHicient. In the ordinary method, the twistedend of the thermo-junction A (Kig 1) is in the heatedmass of metal 11 under examination, and its free ends are con-nected with the galvanometer o. In the new method (Kig 2)two thermo-junctions, A and A„ are employed. One of tnese April 13, 1899] NATURE 567 is placed in the piece of metal n, and the other in a compen-sating piece of copper platinum of fire-clay c. A sensitivegalvanometer Go, connected to both thermo-couples, measureson a large scale the differen
Nature . following is the new method, of which a very brief de-scription will be suHicient. In the ordinary method, the twistedend of the thermo-junction A (Kig 1) is in the heatedmass of metal 11 under examination, and its free ends are con-nected with the galvanometer o. In the new method (Kig 2)two thermo-junctions, A and A„ are employed. One of tnese April 13, 1899] NATURE 567 is placed in the piece of metal n, and the other in a compen-sating piece of copper platinum of fire-clay c. A sensitivegalvanometer Go, connected to both thermo-couples, measureson a large scale the difference between the temperatures of Hand c, and magnified records of the evolutions of heat in B canthus be obtained, which are not affected by the general fall oftemperature of the system The actual temperature of the pieceof metal B is simultaneously registered by the less sensitive gal-vanometer G, in the usual way. In the new method, therefore,the heat lost by the cooling mass of metal B (Fig. 2) is com-. pensated or balanced by the heat lost by a mass of platinum result is, that the effect on the galvanometer Gj of anyevolution of heat in the cooling mass B is greatly heat suddenly evolved by the mass of iron or steel B, whichis liable to molecular change, is, as has already been indicated,not masked by the fact that the mass is itself rapidly losing heat,as the temperature of the entire system does not affect thesensitive galvanometer, and the heat which is evolved by themass E is free to make itself felt. Hence the curves recordedby its mirror possess extraordinary sensitiveness. In the Figs. I was deposited from a solution of ferrous chloride which hadbeen purified with scrupulous care, the anode being a plate ofelectro-iron. The iron so deposited weighed five grammes, andits appearance, magnified four diameters, is shown in the accom-panying Fig. 3. It was then arranged as shown in Fig. 2, and placed in aporcelain tube glazed inside and out and rendere
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