1915] on Problems of Hydrogen and the Rare Gases 549 



Gautiee's Observations of 1901. 



Hydrogen 



City air 200 



Mountain air ......... . 170 



Sea air 190 



Charcoal has less condensing power for the rare gases than for 

 nitrogen ; so that if the proportion of nitrogen in the charcoal gases 

 after a long air current at 85° Abs. be lower than in ordinary air, we 

 should expect the proportion of the rare gases to be still more greatly 

 diminished. The values observed prove that this is so : only 1*64 

 parts per million of the rare gases helium and neon being present, 

 instead of the '22 'b parts in ordinary air, and the total of the helium, 

 neon and hydrogen is only 7*7, instead of 25*1. Although the 

 proportion of hydrogen is exceedingly small in air, yet it is quite 

 appreciably condensed by charcoal at liquid air temperature, having 

 been increased from 1*G to 6*1 by such treatment. Its proportion 

 has, in fact, been increased ten-fold, while that of the helium and neon 

 has been reduced to one-fourteenth, due to the charcoal having 

 practically little power of absorption for these gases at liquid air 

 temperatures. 



In a second experiment the air with which the charcoal was 

 treated was taken from a steel bottle in which it had been first com- 

 pressed ; the amount of hydrogen in the evaporated product was. 

 then higher by one-half — 9 * 8 instead of 6 * 1 — although the neon and 

 helium value was not sensibly different. The higher proportion of 

 hydrogen is explicable by the chemical action of water on the iron 

 storage receptacle. Gautier, in 19Ul, employed metallic tubing in 

 his apparatus for measuring the amount of hydrogen present in air, 

 with the result that he obtained a value as high as 200 parts per 

 million with city air, the lowest amount being 170 in mountain air. 

 This must have arisen from the chemical action on the metallic 

 tubing producing hydrogen. On the subject of the relative dis- 

 tribution of the atmospheric rare gases in thermal springs and air, 

 Moureu, in 1913, found that the ratio of any two of the gases 

 present in air to the same pair in the gas from thermal springs is 

 roughly constant except where helium is concerned. The table on 

 the following page epitomises his results. Krypton and xenon, as 

 well as the more common argon, are less volatile than the ordinary 

 atmospheric gases oxygen and nitrogen, whereas helium is the most 

 volatile known gas. 



