1895.] Argon in atmospheric and in respired Air. 



67 



1542*0 c.c. of air yielded 14'45 c.c. of argon, or 

 100*0 c.c. of air contain 0*937 c.c. of argon. 



Calculating the percentage in atmospheric nitrogen, we have : — 



100 c.c. of mixed atmospheric nitrogen and argon contain 1*186 c.c. 



Owing to the avoidance of the presence of water during these 

 experiments, they are probably more accurate than the original 

 experiments of Lord Rayleigh and Professor Ramsay. They found* 

 1*04 and 1*03 in two experiments in which the nitrogen was re- 

 moved by sparking with oxygen in presence of dilute caustic soda ; 

 and I'll when the nitrogen was removed by means of magnesium. 



Owing to the vacation, it has not been possible to put this result 

 on record before now. And M. Th. Schloesing, fils, has recently 

 publishedf the results of a series of estimations in which the per- 

 centage of argon in atmospheric nitrogen was found to be 1*180 to 

 1*185, or as a mean 1*183 per cent., a number almost identical with 

 that just recorded. M. Schloesing has re-calculated the ratio which 

 ought to subsist between the densities of atmospheric and " chemi- 

 cal " nitrogen on the basis of his determinations ; but in doing so, 

 he has made use of the value 1*2505 gram as the weight of 1 litre of 

 the latter, instead of 1*2511. J Moreover, he has assumed Regnault's 

 value, now superseded, for the weight of 1 litre of hydrogen, viz., 

 0*0896 gram, instead of that given by the more recent determinations, 

 0*0899. § These are not serious errors, but it is more satisfactory to 

 calculate the correct number. The question is : — If the weight of a 

 litre of pure nitrogen is 1*2511 gram, and of argon 1*7818 gram, and 

 if atmospheric nitrogen contain 1*185 per cent, of argon, what 

 should be the weight of a litre of the latter ? The answer is 1*2574. 

 Lord Rayleigh found the number 1*2572, one almost exactly 

 identical. 



For material for the second part of this research, I have to express 

 my thanks to Dr. Marcet, F.R.S., and his assistant, Mr. Floris. Tho 

 air was analysed before having been breathed, and had the normal 

 composition : — 



Nitrogen and argon 79*02 per cent. 



Oxygen 20*93 „ 



Carbon dioxide 0*05 „ 



100-00 



* "Argon," 'Phil. Trans.,' 1895, A, p. 221 and 214. 

 t ' Coinptes Kendus,' vol. 121. p. 605. 

 t 1 Phil. Trans.,' 1895, A, p. 189. 

 § Ibid., p. 202. 



