1869.] Physics. 567 



" I believe that the true theory of electricity will result from the 

 principle that electricity is not a motion {mouvement), but a change 

 of the quantitative and dynamic equilibrium of the ether which 

 constitutes the atoms of the substances, and that the propagation of 

 such a change is brought about by the moving of the ether from 

 one atom to another ; this motion shakes, disturbs the ether of the 

 atoms, and thus produces heat." 



An electrical phosphoroscope has been described by M. Laborde ; 

 its essential parts are a Euhmkorff induction apparatus, the spark of 

 which throws light on the phosphorescent object, and of a sliding 

 frame, one of the ends of which hides the object during the brief 

 moment it is illuminated by the electric spark. This sliding frame 

 is 40 centimetres in length, by 10 centimetres in breadth ; it is fixed 

 at its centre on an axis, which may be made to move rapidly by 

 means of a pedal. The arrangement of this apparatus is such as 

 to render it serviceable for studying the phosphorescence excited by 

 a blow, as well as by friction. The phenomena of phosphorescence 

 of substances which, like nitrate of uranium, are only of very short 

 duration, can be observed by means of this instrument equally well 

 as the long-continued and strong phosphorescence induced by 

 friction in pieces of porcelain or glass. 



MM. Mure and Clamond have made a thermo-electric battery 

 with galena. It is composed of sixty elements, made up of small 

 bars of galena, 40 mm. in length by 8 mm. thick, and bars of thin 

 sheet iron, 55 mm. in length by 8 mm. in width, and • 6 mm. 

 in thickness. These materials have been arranged so as to form a 

 hollow cylinder, which, when it is intended to be used, is to be 

 heated by a peculiarly constructed gas-burner. The specimen of 

 this battery exhibited at a meeting of the French Academy had an 

 electro-motive force of 1^ Bunsen element. M. Becquerel read a 

 lengthy paper on the subject of this battery, the result of which is 

 that thermo-electric batteries constructed either of metalhc alloys, 

 or, as in this case, of a metalhc sulphide and a metal, are not 

 economical in use, and are too Uable to changes brought on by the 

 effects of the heat. 



M. J. Meunier proposes to make use of the well-known experi- 

 ment of Leichtenberg's electric figures to separate from each other 

 the divers mineralogical constituents of some kinds of rock. We 

 briefly remind our readers that the experiment alluded to consists 

 in charging with electricity a cake of resin or sealing-wax, by means 

 of a previously-charged Leyden jar ; it is thus possible to charge 

 certain portions of the cake with positive, others with negative, 

 electricity. In order to exhibit this to sight it is usual to blow, by 

 means of a small pair of bellows, on to the cake of resin, a mixture 

 of very finely-powdered red-lead and sulphur ; the friction on 



