1895.] Argon, a new Constituent of the Atmosphere. 267 



chemical nitrogen does not depend upon the use of a red heat in the 

 process of purification. 



The five results obtained in more or less distinct ways for chemical 

 nitrogen stand thus : 



From nitric oxide \ 2*3001 



From nitrous oxide 2*2990 



From ammonium nitrite purified at a red heat 2*2987 



From urea 2*2985 



From ammonium nitrite purified in the cold . . 2*2987 



Mean 2*2990 



These numbers, as well as those above quoted for " atmospheric 

 nitrogen/' are subject to a deduction of 0*0006 for the shrinkage of 

 the globe when exhausted.* If they are then multiplied in the ratio 

 of 2*3108 : 1*2572, they will express the weights of the gas in grams 

 per litre. Thus, as regards the mean numbers, we find as the weight 

 per litre under standard conditions of chemical nitrogen 1*2505, that 

 of atmospheric nitrogen being 1* 25 72. 



It is of interest to compare the density of nitrogen obtained from 

 chemical compounds with that of oxygen. We have N" 2 : 2 = 

 2*2984 : 2*6276 = 0*87471 ; so that if O 2 = 16, N 2 = 13-9954- Thus, 

 when the comparison is with chemical nitrogen, the ratio is very 

 nearly that of 16 : 14 ; but if " atmospheric nitrogen " be substituted, 

 the ratio of small integers is widely departed from. 



To the above list may be added nitrogen prepared in yet another 

 manner, whose weight has been determined subsequently to the isola- 

 tion of the new dense constituent of the atmosphere. In this case 

 nitrogen was actually extracted from air by means of magnesium. 

 The nitrogen thus separated was then converted into ammonia by 

 action of water upon the magnesium nitride and afterwards liberated 

 in the free state by means of calcium hypochlorite. The purification 

 was conducted in the usual way, and included passage over red-hot 

 copper and copper oxide. The following was the result : 



Globe empty, Oct. 30, Nov. 5 2*82313 



Globe full, Oct. 31 0*52395 



Weight of gas ............ 2-29918 



It differs inappreciably from the mean of other results, viz., 

 2*2990, and is of special interest as relating to gas which at one stage 

 of its history formed part of the atmosphere. 



Another determination, with a different apparatus, of the density 



, 'U3n the Densities of the Principal Gases," 'Roy.Soc. Proc.,' vol. 53, 

 p, 1.34, 1893. 



U 2 



