484 Intelligence and Miscellaneous Articles. 



If the two currents of the bobbin are used, the globule does not 

 stir ; it is merely agitated by a very energetic vibratory mo- 

 tion. The mercury is then brilliant at its two ends, and the tar- 

 nished part of it exists in the middle. This arises from the fact 

 that each end is alternately positive and negative. When oxide is 

 formed by the direct current at the anterior part of the globule, 

 the hydrogen, which the inverse current brings there, immediately 

 reduces this oxide. 



It may happen that the globule is displaced even if traversed by 

 alternate currents ; but this phenomenon is not frequent, and is not 

 easily produced at will. The motion in this case is due to the 

 difference in the action of the two currents : the break working at 

 its maximum speed, the direct current passes entirely ; but the 

 inverse current, whose duration is longer, is only partially dis- 

 charged. 



With a powerful coil it is easy to put a mass of mercury even 

 into rapid motion along the entire length of a tube 1 -50 metre in 

 length. If the spark which breaks in the air is too short, the mer- 

 cury vibrates without undergoing any motion of translation ; the 

 inverse current has then sufficient tension to overcome the resist- 

 ance of the layer of air. 



It is important to observe that the transport of mercury is easier by 

 induction-currents of high tension than by the voltaic current. If we 

 take a battery incapable of producing a motion of translation, but 

 sufficient to polarize the mercury (which is easily recognized by the 

 aspect of the mercury), the current of this battery sent into an in- 

 duction-coil transforms it into an induction-coil powerful enough 

 to impart considerable velocity to the mercury. A powerful mag- 

 neto-electrical machine arranged for effects of quantity may serve 

 to illustrate the same phenomenon ; but the experiment only suc- 

 ceeds with a short tube, say of 30 to 40 centims. 



Conductivity of the matter carried is one of the conditions ne- 

 cessary for motion ; a globule of sulphuret of carbon introduced 

 into the liquid column is insensible to the passage of the current. 



In this experiment it is a mechanical action exerted by the cur- 

 rent which produces the motion of translation (whether it emanates 

 from the positive electrode, or is formed at the surface of separa- 

 tion of the water and the mercury, owing to their difference of con- 

 ductivity) ; the pressure of the hydrogen which may be disen- 

 gaged at the negative end of the globule is of no account in 

 effecting the phenomenon : when the experiment is well made, an 

 inappreciable amount of gas is disengaged ; and if there is much, the 

 globule either does not move at all or moves very slowly. More- 

 over, into the mercury at its negative extremity a knob of amalga- 

 mated copper may be introduced : the mercury sticks to it ; hydro- 

 gen is disengaged upon this knob, which remains at rest, but the 

 lower part of the globule becomes detached and begins to move 

 if the current is strong enough. — Comptes Rendus, March 18, 

 1867. 





