78 ELECTRIC DISCHARGES. PAET i. 



magnet ; and the effect of magnetism on the stratified 

 appearance of the electric light in highly rarefied air 

 shows how powerful its action is. In the year 1858, 

 Mr. Gassiot published a series of observations on stratified 

 light; subsequently various publications appeared on 

 the subject both by Mr. Gassiot and by Professor Pliicker, 

 who made a series of very interesting observations on 

 the nature of the stratifications, but" more especially on 

 the effects produced when they are under the influences 

 of magnetism. Since that time, Mr. Gassiot has published 

 several papers on the subject, and still continues his 

 experiments on the stratifications of electric light, which 

 give a visible proof of the connection between electricity 

 and magnetism. He first showed that the stratified 

 character of the electric discharge tjirough highly at- 

 tenuated media is remarkably developed in the Torri- 

 cellian vacuum ; latterly he has made his experiments 

 by passing electricity through closed glass tubes of 

 various lengths and internal diameters, filled with highly 

 attenuated gases and vapours. 1 Two among the many 

 brilliant experiments of this gentleman may be selected 

 as illustrations of the property of electric light. 



One of these closed glass tubes containing a highly 

 attenuated gas was 38 inches long with an internal 

 diameter of about an inch, and had the extremities of 

 two platinum wires fused into the same side 32 inches 

 apart. When these wires were put in connection with 

 the wires of an induction battery and brought into 

 contact, and the electricity passed through the tube, 

 the luminous appearances at the extremities or poles of 

 the platinum wires were very different, but simultaneous. 



1 They are called vacuum tubes, and are filled while open by putting one 

 end in communication with the vessel in which the gas is generated, and the 

 other end in communication with an air pump. As soon as the atmospheric 

 air is pumped out, the gas rushes in and fills the tube, the communication 

 with the vessel containing the gas is cut off by fusing up that end of the 

 tube, and as soon as the gas is sufficiently rarefied the other end is fused up 

 also. An electrical discharge that will. not pass through one inch of air, 

 will pass through thirty or forty inches in a vacuum tube. 



