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Mr. A. Kellas. On the Percentage of [Nov. 28. 



II. " On the Percentage of Argon in atmospheric and in 

 respired Air." By Alexander Kellas, B.Sc, Assistant in 

 the Chemical Department of University College, London. 

 Communicated by Professor Ramsay, F.R.S. Received 

 November 14, 1895. 



Although blood invariably contains a small amount of dissolved 

 nitrogen, it appears that with animals no absorption of that gas 

 takes place save what is due to its solubility in the serum of the 

 blood. Nor is nitrogen eliminated from the system in the ele- 

 mentary state. 



At Professor Ramsay's suggestion, experiments have been made on 

 the comparative amount of argon in ordinary air, and in air which 

 had been frequently breathed, with the view of ascertaining whether, 

 if the proportion of oxygen and carbon dioxide in air be very much 

 altered, argon would either enter into, or be expelled from, the 

 respiratory system. The result of the experiments to be described 

 is to show that the proportion of argon to nitrogen remains nearly 

 normal, even when the air has been greatly altered in composition by 

 respiration. 



1. Percentage of Argon in Atmospheric Air. — A mercury reservoir, 

 the capacity of which was accurately determined by weighing with 

 water, held 555'2 c.c. The upper end was fitted with a three-way 

 tap, sealed on to the glass. Through this tap was admitted air, 

 purified by passage over soda- lime and phosphoric anhydride, to 

 remove water-vapour and carbonic anhydride. This reservoir was 

 jacketed with water of known temperature, so that the volume of 

 the air could be measured with great exactness. The other branch 

 of the three-way tap led to a tube filled with copper, in order to 

 absorb oxygen ; one containing copper oxide to destroy any organic 

 matter which might have been present, and one filled with magne- 

 sium turnings to absorb nitrogen ; these tubes were kept red-hot. 

 Other tubes were filled with soda-lime and phosphoric anhydride, so 

 as to remove water and carbon dioxide, which might have been pro- 

 duced. The air was circulated over these absorbents until little but 

 argon was left. The gas-holder was filled three times at 18'8° C, 

 and 752'1 mm. pressure. After absorption had nearly ceased, the 

 remaining gas was*pumped out of the tubes, mixed with oxygen, and 

 sparked for many hours in presence of caustic soda, to remove the 

 last traces of nitrogen. The residue, after absorption of oxygen 

 with potassium pyrogallate, measured 1591 c.c. at 21*4° 0., and 

 754"5 mm. pressure. 



Reducing both volumes to standard temperature and pressure, it 

 appears that 



