1903.] Relative Amounts of Krypton and Xenon in Air. 



421 



" An Attempt to Estimate the Relative Amounts of Krypton and 

 of Xenon in Atmospheric Air." By Sir William Ramsay, 

 K.C.B., F.R.S. Received March 9 —Read March 26, 1903. 



When Dr. Tracers and I isolated krypton and xenon from air, we 

 had very little idea of the total amount of liquid air from which, by 

 its evaporation, these gases had been obtained. And we were then 

 more concerned with the isolation of the gases in a pure state than in 

 the determination of the proportion in which they exist in the atmo- 

 sphere. Our knowledge of the composition of the air, however, is not 

 complete until the total yield of krypton, xenon, neon, and helium has 

 been determined. An estimation of the two last is being undertaken 

 by Dr. Travers. 



In our experiments on these gases* we did not measure the total 

 quautity of air evaporated. We used liquid air for various purposes, and 

 for some months we collected the dregs, allowing them to evaporate 

 into a large gas-holder. We guessed (but it was only the roughest 

 estimate) that we had accumulated in this manner the residues from 

 about thirty litres of liquid air • and on this assumption we thought 

 the following estimates not improbable : — Helium, 1 — 2 parts per 

 million of gaseous air ; neon, 1 per 100,000 ; krypton, 1 per million ; 

 xenon, 1 per 20,000,000. But they rested on a very insecure founda- 

 tion of fact. 



The first preliminary experiment was made to ascertain how much 

 of the air which passes through the Hampson liquefier is converted 

 into liquid. The results, however, were inaccurate, and I would rather 

 cite the conclusions given by later experiments on a much larger scale. 

 The compressor was run for several hours every morning and afternoon 

 during six and a half days ; the liquefied air was weighed after each 

 run ; and the escaping air passed through a large gas-meter, where its 

 volume was registered. The air escaping had a somewhat lower 

 density than ordinary air, owing to the partial removal of oxygen 

 and argon ; but the experiments were not sufficiently accurate to make 

 it worth while to take this into account. The volumes given are, 

 however, corrected for alterations of pressure and temperature. In 

 all, 179*7 kilos. ' of gaseous air passed the meter, and 10'8 kilos, of 

 liquid air were collected. During the collection, about 6 per cent, 

 of the liquid air evaporates ; adding this, 11*4 kilos, must have been 

 the total weight of air liquefied. The total weight of air taken in by 

 the compressor, therefore, and delivered to the liquefier was conse- 

 quently 179*7 + 11*4 = 191-1 kilos, and the percentage liquefied a 

 little under 6 per cent. The number may be taken without sensible 

 •error as 6 per cent, liquefaction. 



* " Argon and its Companions," ' Phil. Trans.,' A, -vol. 197, pp. 47—89. 



