I 



On Electric Phenomena. 23 



mended, particularly in the somewhat altered form, which 

 Siemens and Halske have given them. 



From the two effects of the electrical current, which we 

 have already observed, the one, the electrolysis, takes place 

 in the interior of the body which conducts the current; the 

 other, the deviating effect of the magnetic needle, is carried 

 out by the current through the air in the distance. Besides 

 these differant actions the current possesses many more, which 

 we cannot singly discuss. Thus it heats, for example, all 

 conductors through which it flows, and this heating can in- 

 crease to glowTQg, so that we can, with the assistance of a 

 fitting conductor, make a wire, at a great distance from the 

 chain, red hot. 



This is used to spring mines, and in surgery to disperse 

 swellings without the loss of blood. If we conduct the cur- 

 rent of a strong chain through two ends of coal, which touch 

 each other, and then separate them a little from one another, 

 small particles of glowing coal will be drawn from one end 

 over to the other, and w^e obtain a brilliant electrical light^ 

 which is now very much used for illuminations. The most 

 important effect of the current is, in every case, the magne- 

 tizing^ of which we will speak more at large, as the whole of 

 telegraphy is founded upon it. 



If we wind a quantity of wire round a rod of soft iron 

 and conduct through it an electric current, the iron becomes 

 magnetic and retains this capacity as long as the current lasts; 

 it is, however, immediately non-magnetic, as soon as the cur- 

 rent is interrupted. In this manner it is possible for us to 

 procure a magnet or load-stone, and then again to transform 

 it into an ineffective piece of iron according to our own plea- 



(145) 



