Propagation of the Electric Force. 149 



so as to allow the current of electricity to pass along either of the uninsulated 

 wires alone, or to be distributed between both, it was found (as well as could be 

 determined by transposing the galvanometers,) to have divided itself into two 

 equal currents flowing along both wires. 



From the first experiment we may infer that a current of electricity passes 

 with greater facility along the surface of a metal than through the interior of its 

 mass, although we cannot hereby infer that it could not pass through the inte- 

 rior of the metal, when this is the only road open for its transit.* 



To the experiments with phosphorus it might be objected that its capability 

 for conducting an electric current is due to the presence of water, of which some 

 have supposed that it could not be entirely deprived, although the experiments 

 of Sir H. Davy, wherein he obtained hydrogen and oxygen from sulphur and 

 phosphorus by heating them in contact with potassium and sodium, and by sub- 

 mitting them to the electrolytic action of a powerful galvanic battery, did not 

 prove that they were united with the basis of these substances in such proportions 

 as to form water, nor indeed does he appear to have entertained such an opinion 

 himself. His opinion of the nature of sulphur was, that it was "a compound of 

 small quantities of oxygen and hydrogen, with a large quantity of a basis, that 

 produces the acids of sulphur In combustion, and which, on account of its strong 

 attraction for other bodies, will probably be difficult to obtain In Its pure form."f 

 To put the question beyond any further doubt, I will mention some experiments 

 which I tried In the Laboratory of the Royal Dublin Society in the year 1837, 

 having had, through the kindness of Professor Davy, a galvanic battery of sixty 

 pair of plates, five Inches square, put at my disposal. 



When fused phosphorus, sulphur, selenium and Iodine, were submitted sepa- 

 rately to the action of this battery charged with a strong acid solution, they 

 conveyed the electrical current freely during the whole time, giving a spark 

 whenever contact was broken ; yet at the end of two hours they showed not the 



* The high conducting power of mercury for electricity renders it almost impossible to deter- 

 mine, by this method, whether metals in i\ie fluid state obey the same laws of conduction as when 

 in the solid state. If they do not, it is highly probable there is a general law, that all solids condixct 

 along their surface, and all fluids through their substance. The investigation of such general law 

 I propose to continue in another paper. 



I Bakerian Lecture, 1809. 



