The Preparation and some of the Properties of Pure Argon. 189' 



turned out to be rich in neon, and to contain helium.* The remainder 

 of the argon boiled back into the gasometer until the last few drops 

 were left ; the residue solidified, and finally gave a gas to which we 

 gave the name metargon; it was collected in mercury gasholders.! As 

 will be subsequently shown, the krypton and xenon in this quantity of 

 argon are too minute for detection. A similar operation for the pur- 

 pose of separating the lighter as well as the heavier constituents was 

 afterwards repeated three times, the middle portion of argon being 

 always returned to the gasholder D (fig. 1). A fourth liquefaction 

 was carried out in which six mercury gasholders were filled with six 

 separate fractions of argon, each taken after each successive fifth of the 

 total argon had evaporated. These fractions were next purified from 

 any nitrogen accidentally present by sparking with oxygen over caustic 

 potash. After the removal of the oxygen the density was determined.. 



%of Arc/on. 

 J u 



For a preliminary determination of the density of the various 

 samples a bulb of about 33 c.c. capacity was employed. It is much 

 easier to ensure the purity of a small sample of gas than of a large 

 one; and it will be seen that very concordant determinations are 

 obtainable with a small quantity. The limit of error is probably not. 

 greater than one part in a thousand. The results are expressed in 

 terms of = 16. 



Capacity of bulb. Temp. Pressure. Weight. Density, 



c.c. mm. gram. 



(1) 32-762 19-05 535-1 0-03786 19-65 



(2) 15-70 712-0 0.-05265 19-95 



(3) 17-00 662-2 0-05012 19*95 



(4) 14-55 749-8 0-05460 19-91 



(5) 15-60 740-4 0-05389 19-97 



(6) 16-15 760-2 0-05501 19-95 



The spectrum of No. 4, examined later, showed a trace of nitrogen ;, 

 the density of No. 6 was confirmed by other two determinations, each 

 made after further sparking. 



No. 1 was the first portion boiled off, and therefore its density is 

 lower than that of the other fractions, probably owing to its still 

 containing some neon and helium. The rest of the samples have a 

 constant density, approximately 19 '95. 



A larger quantity of No. 5 was then purified by long-continued 

 sparking, and its density was determined in a bulb of greater capacity.. 

 To show the influence of such purification results are given, obtained 



* ' Eoy. Soc. Proc,,' vol. 63, p. 437. 

 f Loc. cit., p. 439. 



