of the Galvanic Battery. 461 



place in tke conducting liquid ; but there is no doubt of the fact 

 that each atom of chlorine has to take the hydrogen from another 

 atom of chlorine after each decomposition, and then to get over 

 so as to touch the positive plate, while the hydrogen gets next 

 to the negative plate. These atomic motions have been long 

 since shown to take place in the conducting liquid. Now when 

 a current of electricity is passing through a liquid, it produces 

 upon any contiguous magnet the same effects as the same cur- 

 rent running through a metallic conductor. You will see, when 

 I send the current of my battery through this tube full of liquid, 

 that the needle will be deflected exactly in the same manner as 

 if I sent a current of equal strength through a rod of metal. 

 Metallic conductors transmit with facility from the positive plate 

 those vibrations which carry over the force needed for the libera- 

 tion of the metals at the negative plate ; while liquids sluggishly 

 and reluctantly allow a similar vibration to take place along their 

 constituent atoms, so as to enable the atoms to get into the places 

 where they are wanted for the chemical action; but the liquid is 

 always behindhand with its work, and opposes the chief resist- 

 ance to the completion of the galvanic circuit. 



We have now got to the point to which I wanted to bring you, 

 and I will not attempt any further particulars. Our fairy wand 

 differs from an ordinary copper wire by having pulsations going 

 through its length from atom to atom, which transmit mechanical 

 force from a process of combination which disengages it, to a 

 process of decomposition which absorbs force. Any heating- 

 effects, or lighting effects, or magnetic or electrical, or chemical 

 work which the wire is made to do are so much resistance to the 

 chemical action of the battery, and afford outlets for some of that 

 redundant force evolved by its combustions which, if the battery 

 were closed by a short thick wire, would go to heating the liquids 

 in the cells. You see how the resistance opposed by this plati- 

 num wire is overcome by the energy of my battery, which forces 

 the heavy atoms of this metal to an unaccustomed energy of 

 action, more, in fact, when I shorten somewhat the wire, than it 

 can bear without fusion ; or if I discharge it through the steel 

 substance of this short file, you see how little able is even this 

 material to withstand its action in contact with the air. Again, 

 if I discharge it between these carbon points when in contact 

 with each other, and then screw them a little asunder, I get a 

 luminous discharge from the intensely heated state of the parti- 

 cles of carbon. 



I must now leave for your consideration this outline of the 

 chemical theory of the battery. What we know of the working 

 of this wonderful instrument is no doubt very little compared to 

 what yet remains to be discovered ; and of that little I have de- 



