Prof. E. Wartmann's third Memoir on Indtiction. '211 



sensible as it takes place at a less distance from the others, 

 and resemble more or less decided hyperbolic arcs. The 

 figure is of a truly geometric symmetry. 



107. With three centres placed on the summits of an equi- 

 lateral triangle (fig. 12), the dividing right lines proceed from 

 an internal point situated at an equal distance from the sum- 

 mits, and are prolonged perpendicularly to the three sides of 

 the triangle which are here the lines of the least interval. The 

 divergent rays in two directions curve in a very marked man- 

 ner. For the rest, the figure which they produce is perfectly 

 symmetrical. 



108. The radiations which appear to render visible the lines 

 according to which the affinities are developed, are not sen- 

 sibly altered by magnetism ; this is at least the result of an 

 experiment unfortunately unique. But availing ourselves of 

 the attraction which causes the cylinders to adhere to the 

 arms of a magnet to give them a moderate motion of transla- 

 tion, we see the whole figure, and especially the dividing line 

 which constitutes the most marked part of it, transterretl also 

 without any alteration of form, A vibration, a sudden trans- 

 fer, detaches, on the contrary, the solid particles which were 

 geometrically grouped : they are precipitated to the bottom, 

 and all is spoiled. 



109. I suppose these particles to consist of a sub-sulphate 

 of copper*; but I have not been able to collect a sufficient 

 quantity of it to subject it to analysis. I propose however to 

 publish soon a new series of researches on this interesting- 

 subject, 



§ XIII. Is there any reaction bet-ween currents of induction and 

 continuotis electric currents\'i 



110. The apparatus which has served for the examina- 

 tion of this question is an electric machine constructed by 

 M. Bonijol. On its reel are coiled two copper wires; one 

 which makes SiOO turns is traversed by the inductor current; 

 the other, which is finer, tlirming 3400 revolution?, is the 

 seat of the currents induced by the rapid alternatives of 

 opening and breaking of the circuit of its neighbour. This 



• Mr. H. Rose has tolil me iliat he is of the same opinion. (October 1.) 

 + Tills paragraph was coinniiinicated to tlie Societo cle Physique -et 

 d'ilist. Naiiirelle of Geneva, April !), 1842. See also the Jitillotiii.s dcs 

 S'ances of the Societe Vaudoise des Sciences Natiirelles, tome i. p. (iH. M. 

 dc la Rive has arrived at similar conclusions in his Mimoirc sur taciion 

 coml/ln'c dcs cmiranls d'iiidin/ion ct dcs cnuranls /ii/drv-c/eclrkjucs, — 

 Arcliives des •Sc'wnceii Fliiji. ct Nal., tome i. p. 39.3 (1846). 



