IMS 



J. Trowbridge — Gaseous Constitution, etc. 



hood of the H.H. lines. It is seen that strong lines of 

 calcium are conspicuously absent in fig. 1. 



Fig. 3 shows the gaseous lines obtained in a quartz tube 



Fig. 1 



Fig. 2 



Fig. 3 



Fig. 4 



filled apparently with hydrogen. A strong group of magne- 

 sium lines are added for comparison., 



These magnesium lines are the strongest lines of that metal 

 between wave lengths 3000 and 2000. 



Fig. 4 gives also the same comparison spectrum of magne- 

 sium and reversed lines of the gas contained in the quartz tube. 



Jefferson Physical Laboratory, Harvard University. 



