216 LORD RAYLEIGH AND PROFESSOR W. RAMSAY ON ARGON, 
the eighth and ninth days oxygen alone was added, of which about 500 cub. centims, 
was consumed, while there remained about 700 cub. centims in the flask. Hence the 
proportion in which the air and oxygen combined was as 70:96. On the eighth day 
there was about three hours’ work, and the absorption slackened off to about one 
quarter of the previous rate. On the ninth day (September 8) the rate fell off still 
Fig. 6. 





more, and after three hours’ work became very slow. The progress towards removal 
of nitrogen was examined from time to time with the spectroscope, the points being 
approximated and connected with a small Leyden jar. At this stage the yellow 
-nitrogen line was faint, but plainly visible. After about four hours’ more work, the 
yellow line had disappeared, and for two hours there had been no visible contraction. 
It will be seen that the removal of the last part of the nitrogen was very slow, mainly 
on account of the large excess of oxygen present. 
