A text-book on chemistry : for the use of schools and colleges . ts.— Thermo-electricity.—Production of Heat and Cold by ElectricCurrents.— Thermo-electric Pairs.—Peculiarity of theseCurrents. — Electro-motive Power of Heat. — MellonisPile and Thermometer.—Improvements in Thermo-elec-tric Pairs.—Animal Electricity.—Steam Electricity. Soon after the relation between electricity and magnet-ism was established, M. Ampere discovered that thereare reactions between electric currents themselves. Two electric currents flowing in the same direction at-tract each other, but two electric currents flowin
A text-book on chemistry : for the use of schools and colleges . ts.— Thermo-electricity.—Production of Heat and Cold by ElectricCurrents.— Thermo-electric Pairs.—Peculiarity of theseCurrents. — Electro-motive Power of Heat. — MellonisPile and Thermometer.—Improvements in Thermo-elec-tric Pairs.—Animal Electricity.—Steam Electricity. Soon after the relation between electricity and magnet-ism was established, M. Ampere discovered that thereare reactions between electric currents themselves. Two electric currents flowing in the same direction at-tract each other, but two electric currents flowing in op-posite directions repel; or, more briefly, Like currentsattract, and unlike ones repel. If a conducting wire be bent in the form of a helix,its terminations returning toward its middle, as shown inFig. 127, it exhibits all the properties of an ordinary mag-netized bar; for as soon as the current passes, it points Describe the horseshoe electric currents ? M2 What is the law of reaction 138 PROPERTIES OF A Fig 187. north and south, and is attracted and re- pelled by the poles of a magnet, just asthough it were a magnet itself. A veryneat arrangement for illustrating theseresults is seen in Fig. 128. A small sim-ple circle, consisting of a zinc and copperplate, connect- ^ig. 128. ed together bymeans of a wirebent so as totry?? form a flat coil,is floated bymeans of a cork in acidulatedwater. The current runs roundthe coil in the direction of thearrows, and the arrangement,obeying the magnetic influenceof the earth, turns, with its planepointing north and south, just asa magnet would do if introduced into the interior of thecoil, in the position shown in the figure by the dark infers, from the analogy of these instruments,that the magnet owes its qualities to electric currents cir-culating in it in a transverse direction. The directiveaction of the magnetic needle or the electric helix dependson the reaction of e
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