1823.] M. Schweigger's Electromagnetic Multiplier. 439 



to call the attention of philosophers to this class of experiments 

 which are equally interesting as regards the theory of solution 

 and that of the excitation of the electric current. M. Avogadro 

 mentions also that arsenic acts with respect to antimony as a 

 positive metal in concentrated nitric acid and as a negative in 

 dilute acid. This phenomenon appears interesting in relation 

 to the chemical effect of this acid upon the two metals in its 

 different degrees of concentration. 



Among the experiments to which the electromagnetic multi- 

 plier gives rise, it may be stated that by its use, we may 

 show, that when two pieces of the same metal are immersed in 

 an acid capable of acting upon them, that which is first immersed 

 acts towards the other as the most positive metal ; this experi- 

 ment is extremely well performed with two bars of zinc and 

 diluted sulphuric or muriatic acid. It would be extremely inte- 

 resting to examine the electromagnetic changes which take 

 place during every period of the action of acids and alkalies 

 upon the metals, and nothing affords greater facility for this 

 purpose than the electromagnetic multiplier. 



Notice read at the Academy of Sciences of some new Thermoelectric 

 Experiments made by M. Le Baron Fourier and M. Oersted. 



1 have had the honour of exhibiting to this illustrious Aca- 

 demy the remarkable experiments by which M. Seebeck has 

 shown that an electrical current may be produced in a circuit 

 formed of solid conductors only by disturbing the equilibrium of 

 the caloric. We are therefore in possession of a new kind of elec- 

 tric circuits, which may be called thermoelectric circuits, thus 

 distinguishing them from galvanic circuits, which may in future 

 be denominated hydroelectric. On this subject an interesting 

 question arises respecting electromagnetism, and which relates 

 also to the theory of the motion of heat in solid bodies ; the 

 question is to examine whether the thermoelectric effects may 

 be increased by the alternate repetition of bars of different mat- 

 ters, and how it will be necessary to proceed to obtain the 

 sum of these effects. It does not appear that the author of the 

 discovery of the thermoelectric circuit has as yet directed his 

 researches to this point. But M. Le Baron Fourier and I agreed 

 to examine this question together experimentally. 



The apparatus with which we performed our first experiments 

 is formed of three bars of bismuth, and three other of antimony, 

 alternately soldered together; so that they form an hexagon, 

 and thus constitute a complex thermoelectric circuit, consisting 

 of three elements. The bars are about 4-7 inches long, 0-6 of 

 an inch wide, and nearly 0-16 of an inch thick. We placed this 

 circuit upon two supports, in an horizontal position, taking 

 care to give to one of the sides of the hexagon the direction of 

 the magnetic needle, and we placed a compass as nearly as 



