1901.] on Gases at the Beginning and End of the Century. 737 



over, and the latter condensed in a solid form in D, while any gas 

 incondensable at the boiling point of hydrogen filled the vessel at 

 a low pressure, the latter being recorded by the manometer /. When 

 a small fraction of the liquid in B had thus distilled, the stopcock d 

 was turned so as to close the communication between D and b and open 

 that between D and e. Gas from D passed into the sparking tube g, 

 but in so doing it had to pass through the portion of e which was 

 immersed in liquid hydrogen, so that condensable matter, like 

 nitrogen or oxygen vapour, carried forward by the stream of gas, 

 was frozen out. 



On passing electric discharges through the tubes containing the 

 most volatile of the atmospheric gases collected as above, they glow 

 with a bright orange light, not only in the capillary part, but also 

 at the poles, and at the negative pole in particular. The spectro- 

 scope shows that this light consists in the visible part of the 

 spectrum chiefly of a succession of strong rays in the red, orange, 

 and yellow, attributed to hydrogen, helium, and neon. Besides 

 these, a vast number of rays, generally less brilliant, are distributed 

 through the whole length of the visible spectrum. They are 

 obscured in the spectrum of the capillary part of the tube by the 

 greater strength of the second spectrum of hydrogen, but are easily 

 seen in the spectrum of the negative pole, which does not include 

 the second spectrum of hydrogen, or only faint traces of it. Putting 

 a Leyden jar in the circuit, while it more or less completely oblite- 

 rates the second spectrum of hydrogen, it also has a similar effect on 

 the greater part of these other rays of, as yet, unknown origin. The 

 violet and ultra-violet part of the spectrum seems to rival in strength 

 that of the red and yellow rays, if we may judge of it by the inten- 

 sity of its impressions on photographic plates. 



As these gases probably include some of the gases that per- 

 vade interplanetary space, search was made for the prominent 

 nebular, coronal and auroral lines. No definite lines agreeing with 

 the nebular spectrum could be found, but many lines occurred closely 

 coincident with the coronal and auroral spectrum. Before any 

 final conclusion can be reached, larger quantities of the gases must 

 be collected, but this will not be difficult now that the method of 

 separation has proved a success. It may safely be predicted that 

 liquid hydrogen will be the means by which many obscure problems 

 of physics and chemistry will ultimately be solved, so that the 

 liquefaction of the last of the old permanent gases is as pregnant 

 now with future consequences of great scientific moment as was 

 the discovery of the liquefaction of chlorine in the early years of 

 the century. 



Vol. XVI. (No. 95.) 3 c 



