4 Sir 11. Davy on the Magnetic Phfennmena [Jan. 



charged : a similar wire was placed in sulphuric ether, and the 

 charge transmitted through it. It became surrounded by glo- 

 bules of gas ; but no other change took place ; and in this 

 situation it bore the discharge from twelve batteries of the same 

 kind, exhibiting the same phaiuomena. When only about an 

 inch of it was heated by this high power in ether, it made the 

 ether boil, and became white liot under the globules of vapour, 

 and then rapidly decomposed the ether, but it did not fuse. 

 When oil or water was substituted for the ether, the length of 

 the wire remaining the same, it was partially covered with small 

 globules of gas, but did not become red hot. 



On trying the magnetic powers of this wire in water, they were 

 found to be very great, and the quantity of iron tihngs that it 

 attracted was such as to form a cylinder round it, of nearly the 

 tenth of an inch in diameter. 



To ascertain whether short lengths of fine wire, prevented 

 from fusing by being kept cool, transmitted the whole electricity 

 of powerful voltaic batteries, I made a second independent 

 circuit from the ends of the battery with silver wires in water, so 

 that the chemical decomposition of the water indicated a resi- 

 duum of electricity in the battery. Operating in this way, I 

 found that an inch of wire of platinum of -rj-iVo^* kept cool by water, 

 left a great residual charge of electricity in a combination of 

 twelve batteries of the same kind as those abovementioned ; and 

 after making several trials, I found that it was barely adequate 

 to discharge six batteries. 



V. Havmg determined that there was a limit to the quantity 

 of electricity which wires were capable of transmitting, it became 

 easy to institute experiments on the different conducting powers 

 of different metallic substances, and on the relation of this power 

 to the temperature, mass, surface, or length, of the conducting 

 body, and to the conditions of electro-magnetic action. 



Th6se experiments were made as nearly as possible under the 

 same circumstances, the same connecting copper wires being 

 used in all cases, their diameter being more than one-tenth of 

 an inch, and the contact being always preserved perfect ; and 

 parts of the same solutions of acid and water were employed in 

 the different batteries, and the same silver wires and broken 

 circuit with water were employed in the different trials ; and 

 when no globules of gas were observed upon the negative silver 

 wire of the second circuit, it was concluded that the metallic 

 conducting chain, or the piimary circuit, was adequate to the 

 discharge of the combination. To describe more minutely all 

 the precautions observed, would be tedious to those persons 

 who are accustomed to experiments with the voltaic apparatus, 

 and unintelligible to others ; and after all, in researches of this 

 nature, it is impossible to gain more than approximations to true 

 results ; for the gas disengaged upon the plates, the different 

 distances of the connecting plates, and the slight difference of 



