Fkbruaky 24, 1899.J 



SCIENCE. 



279 



In the meantime Mr. Baly has made 

 exact measurements of the lines of tlie neon 

 spectrum, at the same time eliminating all 

 the lines which belong to argon and to 

 helium by superposed plates. The values 

 were compared with iron lines photographed 

 upon the same plate, and the measurements 

 were carried out by means of different pairs 

 of these known lines. The most important 

 lines are the following : 



MOST IMPORTANT LINES OF THE NEW SPECTRUM. 



Red. Red. Red. Yellow (Dj). Blue 



6402 6267 6096 5853 4716*- 



6383 6218 6074 Green 5401 4722 



6335 6164 6030 5341 4710 



6143 5331 4709 

 4704 



Up to the present we have had little time 

 to study thoroughly the other companion of 

 argon in the atmosphere. Dr. Travers and 

 I have, however, worked upon it. The 

 heavier fraction of the air contains three 

 gases, one of which appears very perplex- 

 ing. We have named it ' metargon.' This 

 gas remains, mixed with excess of argon, 

 after the evaporation of liquid air or argon. 

 Up to this time we have not succeeded in 

 obtaining it in a condition free from argon. 

 Its peculiarity is that when it is mixed with 

 oxygen and subjected to the influence of the 

 electric spark in presence of caustic potash 

 it shows constantly the ' Swan-spectrum ' 

 as of carbon monoxid. We have treated 

 a mixture of carbon monoxid and argon 

 in a similar way, and, after fifteen minutes' 

 sparking, all the carbon had disappeared ; 

 in a Pliicker tube no trace of the carbon 

 spectrum could be recognized. I will, how- 

 ever, not yet venture to express an opinion 

 as to the natui-e of this gas. It needs 

 further investigation, and for this at present 

 we have no time. 



As regards krypton, which is distin- 

 guished by three brilliant lines, one in red, 



* The third figure in this number is probably a mis- 

 print (Tr.). 



one in yellow and one in green, we are in 

 much the same position. We have col- 

 lected a considerable quantity of the im- 

 pui-e gas, which shows the spectrum finely, 

 although that of argon is also present. We 

 hope that we shall soon be able to pursue 

 this portion of our work further. We can 

 merely note here that the specific gravity 

 of the gas which shows this spectrum in 

 such a marked way is not far different from 

 that of argon. 



The heaviest of these gases we have 

 weighed, although in impure condition. Its 

 density is 32.5. I need not call you^r at- 

 tention to the fact that there is space for an 

 element of the helium group between bro- 

 min and rubidium. Such an element should 

 have an atomic weight of 81-83, which cor- 

 responds to a density of 40.5-41.5, under 

 the very probable supposition that, like the 

 other gases of this group, it is monatomic. 

 The spectrum of this gas, which we have 

 named 'xenon' — the stranger — has many 

 lines ; none of these are of marked inten- 

 sity, and in this respect the spectrum re- 

 sembles somewhat that of argon. It is also 

 analogous to argon in another particular, 

 that the spectrum undergoes a remarkable 

 change when a Leyden jar is put into the 

 circuit. As with argon, many new, blue 

 and green lines appear, while other lines, 

 mostly in the red, either disappear or lose 

 much of their intensity. Further than this 

 we have not proceeded in studying xenon ; 

 for our attention has been given chiefly to 

 neon, as well as to a problem regarding 

 argon. 



' We have repeatedly met the question : 

 "Are the properties of argon not appreciably 

 changed by the presence of this new gas ?" 

 In order to settle this question we have 

 fractioned 25 cubic centimeters of liquid 

 argon several times and have collected 

 separately about 200 cubic centimeters of 

 the lightest and as much of the heaviest 

 fraction. This operation was repeated three 



