PART II. POLAR MAGNETIC PHENOMENA AND TERRELI.A EXPERIMENTS. CHAP. V. 



635 



The agreement, as will be seen, is so striking that it seems to leave little room for doubt that we here 

 have phenomena that must be intimately connected with one another. 



For the purpose of seeing and studying how a substance containing carbon is discharged as a 

 cathode in a vacuum-tube, I have made, as already mentioned, numerous experiments with cathodes of 

 ordinary coal, coke, graphite, and pice'in over a metallic cathode. I have further employed an extremely 



1820 



1830 



1850 1860 1870 

 Fig. 230. 



1880 



1890 



1900 



fine jet of CO.,, which was introduced through a very narrow capillary tube, and flowed out from the 

 end of a narrow silver tube which served as cathode. 



I succeeded several times in making this jet luminous, so that it had the appearance of a fine 

 needle of light shooting out from the cathode, sometimes as much as 5 cm. in length. 



A cathode of coal also sent out similar long needles of light from various points on its surface, 

 round which the coal even became glowing. 



Pice'in emitted long, thin pencils of light, often more than 10 cm. in length, one after another, as 

 if by violent eruptions. These light-phenomena gave the impression that the electric discharge from 



Fig. 231. 



both the coal cathode and the cathode with pice'i'n, was accompanied by eruptive outbreaks of gaseous 

 rays, that were made luminous in the same way as the above-mentioned carbonic acid jet. Fig. 231, i 

 and 2 show discharges of this kind. 



From a cathode of graphite there came long, steady pencils of light, which greatly resembled the 

 so-called eruptions or jets in comets. 



Fig. 231, 3 shows an experiment with graphite. 



In these experiments with cathodes containing carbon, the rapid disintegration of the cathode was 

 especially remarkable. In the course of two or three minutes, large dark patches appeared on the glass 

 walls just where the long pencils of light had come in contact with them. Fig. i shows an instance of 



