84 Intelligence and Miscellaneous Articles. 



For closed circuits the differences compensate one another, but 

 the parts which the individual elements of the circuit have iu the 

 total action are different. Thus, according to the electromagnetic 

 theory the elements of the vertical circuit of a tangent-compass 

 all act with equal deflecting force upon the very short needle ; 

 according to Ampere the elements situated in the vertical diameter 

 exert no action, while those in the horizontal diameter act twice as 

 powerfully as according to the other theory. 



In the memoir the electromagnetic is compared with the general 

 electrodynamic theory, which also assumes transversally-actiug 

 forces, and was developed by the author in his memoir "On the 

 Fundamental Formulae of Electrodynamics," published in vol. lix. 

 of the Sitzunysberichte of the Academy (1869). 



The comparison has reference, first, to the forces, and, secondly, 

 to the pairs of forces, which a current-element exerts upon an ele- 

 mentary current. In the former respect Ampere's theory, and all 

 those which also assume transversal forces, though of such a nature 

 that they cannot move the common centre of gravity of two cur- 

 rent-elements, agree with the electromagnetic theory. In the 

 second respect the electromagnetic theory corresponds only with 

 Grass mann's. But as these two theories differ in the expressions 

 for the forces, there is not any electrodynamic theory containing 

 in itself the electromagnetic. With the exception of G-rassmann's, 

 all the theories contain, though not in like manner, continuous ro- 

 tations of the magnets by the action of the component of the 

 current-element in the connecting-line. — Kaiserliche Akademie cler 

 Wissenscliaften in Wien, maih.-naturw. Olasse, April 17, 1879, pp. 

 110, 111. 



ON THE PRODUCTION OF BARIUM FROM BARIUM-AMALGAM. 

 BY JULIUS DONATH, OF GRAZ. 



Iii this note we are informed that the amalgamated barium easily 

 obtained by Crookes's metkod, by digesting solution of barium 

 chloride with sodium-amalgam, does not after distillation contain any 

 pure barium at all, but leaves only an amalgam rich in barium, which 

 may contain 62-77 per cent, of mercury. 



It was already mentioned by Bunsen that the barium- or calcium- 

 amalgam that appears at the amalgamated platinum electrode in the 

 electrolysis of aqueous solution of chloride of barium or calcium 

 respectively, also obstinately retains mercury. 



In all probability S. Kern's method, viz. heating oxide and iodide 

 of barium with sodium, extracting with quicksilver, and distilling, 

 will yield no better result. All the statements about the silvery- 

 white metallic lustre of barium must evidently be referred to the 

 amalgam. Pure barium, as obtained by Bunsen and Matthiessen 

 by electrolysis of the fused chloride, is bronze-coloured. This colour, 

 it is true, is sometimes exhibited by the most superficial layers of 

 the barium-rich amalgam, which under the action of a very elevated 

 temperature have been deprived of mercury ; but even such por- 

 tions of the amalgam are grey on the inside, and in water they 

 leave considerable traces of mercury. — Kaiserl. Alcad. d. Wissensch. 

 in Wien. math.-natumv. Classe. 1879, INo. X. p. 109. 



