1824.] Conductors when transmitting the Electric Current. 285 



the hydrogen disengaged in bubbles from a metallic wire 

 plunged into the mercury is this actual radiant hydrogen, con- 

 veyed and collected on its surface from all parts of the mercury. 

 That, 4thly, the friction of the hydrogen so radiated produces 

 the electricity, and not the electricity the hydrogen. And, 

 lastly, that the gyration of the fragments themselves is a conse- 

 quence of the re-action of the hydrogen they dart out during 

 their oxidation by the water. 



59. All these phsenomena, however, are much better accounted 

 for on the principles of this Lecture, from a knowledge of the 

 properties conferred on mercury by alloying it with potassium ; 

 but, first, it is necessary to premise, that the mere contact of a 

 metal capable of amalgamating, even for an instant, communi- 

 cates its peculiar properties, almost in the moment of contact, to 

 the whole mass. The experiments in Art. 33, abundantly prove 

 this ; and it may be readily shown also by the following. Let a 

 quantity of mercury be placed in a vessel of muriatic acid ; no 

 action takes place; but if touched with a zinc wire it presently 

 becomes covered with bubbles, copiously disengaged from every 

 part of the surface. 



60. In the circumstances of M. Serrulas's experiments, it is 

 therefore obvious that his mercury must have been always sen- 

 sibly impregnated with potassium and the supernatant liquid, a 

 solution of potash ; and that it was so, is proved by the effects 

 of the electric current, which agree precisely with those I have 

 stated, as being always produced in such circumstances (Arti- 

 cles 18, 28) ; but the cause assigned to these effects by Mr. S. 

 viz. the electro-positive energy of the pellicle, is proved not to be 

 the real one by the simple fact, that the violence of the motion is 

 always proportional to the cleanliness of the surface, and is 

 greatest when there is no pellicle at all ; besides which the 

 pellicle here consisted of metallic bismuth, a substance incapable 

 of producing any such effect as shown in Art. 38. 



61. The gyration of the fragments is produced as follows: a 

 strong Voltaic excitement takes place at the point of contact of 

 two metals so different as mercury and potassium. The mercury 

 becomes strongly positive, and the floating fragments negative. 

 The circuit is completed by the alkaline liquid ; and the mercury, 

 being alloyed with a portion of potassium, and being itself the 

 positive pole of the combination, we have here the case of 

 Art. 21 ; and the result, as stated by M. Serrulas, is precisely as 

 in that experiment, the currents radiating from the point of 

 immersion. These once produced, drive before them the frag- 

 ment in which they originate, in the direction in which it 

 exposes the greatest surface to their action. 



62. The attraction of the pellicle to a metallic rod plunged 

 into the mercury is also a direct consequence of the alloy of 

 potassium present in the mercury, as is also the disengagement 



