THE METHOD OF POSITIVE RAYS 



5 2 3 



Fig. 2. 



of the convenience of the 

 method, for a single photo- 

 graph of the positive rays 

 reveals at a glance the gases 

 in the tube. I now turn to 

 the photograph of the lighter 

 constituents shown in Fig. 3 ; 

 here we find the lines of he- 

 lium, of neon (very strong), 

 of argon, and in addition 

 there is a line corresponding 

 to an atomic weight 22, which 

 can not be identified with the 

 line due to any known gas. 

 I thought at first that this 

 line, since its atomic weight is 

 one half that of C0 2 , must be 

 due to a carbonic acid molecule 

 with a double charge of elec- 

 tricity, and on some of the 



plates a faint line at 44 could be detected. On passing the gas slowly 

 through tubes immersed in liquid air the line at 44 completely disap- 

 peared, while the brightness of the one at 22 was not affected. 



The origin of this line presents many points of interest; there are 



no known gaseous compounds 

 of any of the recognized ele- 

 ments which have this mo- 

 lecular weight. Again, if we 

 accept Mendeleef's periodic 

 law, there is no room for a 

 new element with this atomic 

 weight. The fact that this 

 line is bright in the sample 

 when the neon line ' is ex- 

 traordinarily bright, and in- 

 visible in the other when the 

 neon is comparatively feeble, 

 suggests that it may possibly 

 be a compound of neon and 

 hydrogen, N"eH„, though no 

 direct evidence of the com- 

 bination of these inert gases 

 has hitherto been found. I 

 fig. 3. have two photographs of the 



