] 20 Progress of Foreign Science. 



this peculiarity, are lead and bismuth; lead and tin ; iron and 

 bismuth; cobalt and antimony. M. Avogrado says, that the effect 

 which occurs at the instant of immersion of the metals in the con- 

 centrated acid, is the same with that obtained with (he dilute acid, 

 and that it is only in the long run that the contrary effect is 

 exhibited. 



If we plunge, at two different instants, two pieces of the same 

 metal into an acid capable of attacking them, that of the two 

 pieces first plunged will comport itself towards the other, like the 

 most positive metal. Two plates of zinc, with dilute sulphuric or 

 muriatic acid, answer well. Of the metals in the following series, 

 each comports itself as a negative body, in reference to all those 

 which follow it; and as a positive body with regard to all those 

 which precede it, platinum, gold, silver, arsenic, antimony, 

 cobalt, nickel, copper, bismuth, iron, tin, lead, and zinc. These 

 results do not agree with those formerly obtained with Volta's 

 condenser ; but the difference may arise from the degree of con- 

 centration of the acid. As gold and platinum are not attacked by 

 nitric acid, these metals give no electric developement, unless aqua 

 regia be used for them. This is a new proof of the necessity of 

 a chemical action for the production of a voltaic current. — Ann. 

 de Chhn. et de Phys. xxii. 358. 



15. On some new Thermo-electric Experiments made by Baron 

 Fourier and M. Oersted. 



M. Seebeck has proved that an electrical current can be es- 

 tablished in a circuit formed exclusively of solid conductors, by 

 disturbing merely the equilibrium of temperature. We are thus in 

 possession of a new kind of electrical circuits, which may be called 

 thermo-electric, in distinction of the galvanic circuits, which it 

 may be henceforth proper to denominate hydro-electric. A ques- 

 tion interesting to electro-magnetism, as well as to the theory of 

 the movement of caloric in bodies, here presents itself. The object 

 is to examine, if the thermo-electric effects may be increased by 

 the alternate repetition of bars of different materials, and how we 

 must proceed in order to obtain such effects. It does not appear 

 that the author of the discovery of thermo-electricitij has hitherto 

 directed his inquiries towards this point. The apparatus which 

 MM. Fourier and Oersted first employed, was composed of three 

 bars of bismuth and three others of antimony, soldered alter- 

 nately together, so as to form a hexagon, constituting a thermo- 

 electric circuit, which includes three elements. The length of the 

 bars was about 12 centimetres (4.7 inches Eng.), their breadth 

 15 millimeters (0.59 of an inch), and their thickness 4 millimetres 

 (about 0.16 of an inch.) This circuit was put upon two supports, 

 and in a horizontal position, observing to give to one of the sides 



