60 Composition of the Atmosphere 



In connection with his research on the influence of the ingestion of 

 food on metabolism, Magnus-Levy 1 , in Zuntz's laboratory, described a 

 new form of gas-analysis apparatus in which phosphorus is used to absorb 

 oxygen. To demonstrate the accuracy of his apparatus he reports the 

 determinations of the oxygen percentages in a series of 16 air-analyses, 

 as follows: 



Leduc 2 in 1890, recognizing the discrepancy between the results of 

 Regnault on the one hand and of Dumas and Boussingault on the other, 

 sought to explain the difference on the grounds of slight errors in Reg- 

 nault's determinations of the densities of the gases. One year later 

 Leduc, 3 having questioned the accuracy of absorbing oxygen by copper, 

 inasmuch as nitrogen combined with the hydrogen of the reduced copper, 

 used Brunner's method, in which the oxygen is absorbed by phosphorus, 

 and weighed both the air and the nitrogen remaining. Two experiments 

 carried out with the greatest care gave 23.244 and 23.203 per cent of oxy- 

 gen by weight, or 21.024 and 20.987 per cent by volume, respectively. 

 The author obtained the same results by determining the densities of 

 nitrogen and oxygen. 



Wanklyn and Cooper, 4 using the pyrogallic-acid method, obtained on 

 three samples 20, 20.8, and 20.5 per cent of oxygen, respectively. By 

 explosion with hydrogen they obtained 21.34, 20.94, and 21.34 per cent 

 of oxygen. 



Using an alkaline ferroso-tartrate solution for an absorbent, de Ko- 

 ninck 5 found as the mean of four determinations 21.00 per cent of oxygen. 



Laulanie 6 in 1894 published the description of a eudiometer in which 

 the oxygen was determined by absorption with phosphorus. He claimed 

 very accurate results, with a constant oxygen percentage of 20.9. 



Using a modified Bunsen apparatus, Schaternikow and Setschenow 7 

 made analyses of laboratory air in Moscow, and report 12 analyses of out- 

 door air. The oxygen percentage ranged from 20.874 to 21.036, with an 

 average of 20.962 per cent. 



By passing a measured amount of air and nitric oxide through hydri- 

 odic acid, Kreider, 8 in New Haven, Connecticut, determined the free 

 iodine thus liberated by means of 1/10 normal arsenious acid by titration. 

 He gives a series of results with outdoor air on two samples collected over 



1 Magnus-Levy, Archiv fur die gesammte Physiologic, 1894, 55, p. 1. 



2 Leduc, Comptes rendus, 1890, 1 11, p. 262. 



3 Leduc, Comptes rendus, 1891, 1 13, p. 129. 



4 Wanklyn and Cooper, Air analysis, London, 1890, p. 35. 



5 de Koninck, Chemical News, 1891, 64, p. 45. 



6 Laulanie, Archives de Physiologie, 1894, 26, p. 739. 



7 Schaternikow and Setschenow, Zeitschrift fur physikalische Chemie, 1895, 18, p. 56.3 



8 Kreider, Zeitschrift fur anorganische Chemie, 1896, 13, p. 423. 



