Litelligence and Miscellaneous Articles. 465 



When it is the positive electrode that is submitted to the imme- 

 diate action of the magnet, there is scarcely any appreciable modifi- 

 cation in the appearance and intensity of the discharge. The effect, 

 however, is exactly the same, whatever the direction of the magne- 

 tization. 



When the circuit contains several consecutive Greissler tubes all 

 placed in the same way upon the upper extremity of the soft iron, 

 each having its negative electrode below, the effect upon the inten- 

 sity of the current which traverses them all is still greater. But if, 

 in addition to the tube or tubes placed under the action of the mag- 

 net, there is one in the circuit out of this action, no effect upon the 

 intensity of its current is produced by the magnet, although the 

 modification which the appearance of the discharge undergoes in the 

 other tubes, placed over the magnetic pole, remains the same. It 

 seems, then, that it is a special and peculiarly intense resistance, 

 having its seat at the issue from the negative electrode, wmich is 

 thus overcome by the intervention of the magnet. 



A final series of experiments support this view, and have shown 

 us that the dimensions of the negative electrode, which notably in- 

 fluence the dimensions of the aureola and the resistance to the 

 passage of the electricity, influence also the augmentation of inten- 

 sity produced by the magnet in the case of an axial discharge. 

 Working with the large bell, we had a very great, less, or almost 

 no augmentation of intensity, according to whether we employed 

 as negative electrode a platinum point or wire, a small ball, or a 

 ball of 4 centims. diameter. 



We confine ourselves here to briefly recording these few obser- 

 vations, without pretending to deduce from them, at least for the 

 present, any theoretical consequence. — Bibliotheque Universelle, 

 Archives des Sciences Phys. et Nat. May 15, 1874, vol. 1. pp. 41-48. 



EXPERIMENTS ON APPARENT ADHESION. BY M. STEFAN. 



By the name of apparent adhesion the author designates the 

 phenomenon that, w T hen two flat plates are laid one upon the other, 

 they cannot be again separated without the expenditure of a force. 

 This phenomenon has been hitherto conceived as conditioned by 

 adhesion — that is, by the molecular forces between the particles of 

 the two plates ; and experiments have been made for the purpose 

 of determining statically its amount. 



In this phenomenon, however, we Irave not to do with a static, 

 but with a dynamic problem. The experiments made by the author 

 showed that the separation of the two plates can be effected by any 

 force whatever ; only the time in which the distance of the plates 

 is changed a measurable quantity by the action of such a force is 

 the greater the smaller the force. 



Simultaneously with the commencement of the action of a sepa- 

 rating force the distance of the plates commences also to increase ; 

 yet the motion is very slow, and grows ever quicker with increasing 

 distance. The apparent adhesion is much greater when the plates 

 are under water or another liquid instead of in air. The distance 



Phil Mag. S. 4. Vol. 47. No. 314. June 1874. 2 H 



