424 Sir W. Ramsay. Estimate of the Relative [Mar. 9, 



These ratios were mapped against the absolute temperatures of 

 mercury, and were found, as usual, to give straight lines. The lines 

 were extrapolated to lower temperatures, and the vapour pressures 

 required were calculated from the extrapolated curves. 



The portion of interest is given in the following table :— 



Temp. C. 



Yap. press, of krypton. 



Yap. 



press. 



of xenon. 



- 205° 



• 27 mm. 



o- 



0005 



mm. 



-200 



0-97 „ 



0' 



007 



?j 



-195 



2-8 „ 







02 



>i 



-190 



7-5 • „ 







•04 



55 



-188-8 



9-0 „ 







•11 



>J 



-182-4 



17-4 „ 







•17 



55 



The last two data for krypton are the results of direct measure- 

 ment. It may be mentioned here that the melting point of krypton 

 is about - 169°, and that of xenon - 140° ; and the boiling points at 

 atmospheric pressure are, krypton - 151°*7, and xenon - 109°4. 



The nitrogen was removed from the 50 litres of gas by passing it 

 •over red-hot magnesium-lime mixture. The resulting crude argon 

 measured 12*5 litres at 16° and 770 mm. • its weight is calculated from 

 its known density as 21*3 grammes. 



This argon was liquefied in a bulb immersed in liquid air, boiling 

 under reduced pressure, so as to reduce the vapour pressure of the 

 krypton and xenon ; and the major part was re-transferred through a 

 Topler pump to the gas-holder from which it had passed to the 

 liquefying bulb. About 1500 c.c. of the last portions to distil away 

 were collected in five mercury gas-holders, each of a capacity of 

 •300 c.c. The argon was now methodically fractionated according to 

 the accompanying scheme. 



The 1200 c.c, numbered (1) was, as described, distributed in five 

 gas-holders. The contents of the first — the one first filled is termed A 

 — were liquefied, and half the amount replaced in gas-holder A. The 

 contents of B were liquefied, and A was filled, by allowing the liquid 

 argon to evaporate under reduced pressure. The contents of C were 

 liquefied along with what remained of B ; and B was filled in like 

 manner. D was liquefied, and C filled ; and, finally, E, and D filled. 

 The residue in the liquefying bulb, which evaporated very slowly after 

 the argon had boiled away, was removed through the pump, and 

 collected in a tube over mercury. The contents of A, B, C, D, and E 

 are labelled (2), (3), (4), (5), and (6). The process was repeated and 

 with this explanation the scheme can be understood. 



