History of Air-Analysis 



49 



and sections of the same race, of small variations in the amount of oxygen 

 in the atmosphere. 



Finally, Smith distinguishes between pure and impure air (such as 

 that collected in outhouses) and maintains that pure air deviates from 

 21 by 0.065 per cent. 



Hinman, 1 using an explosion apparatus, made analyses of air freed 

 from carbon dioxide, obtaining on April 25, 1874, 20.94 and 20.93 per cent 

 of oxygen, and on April 26, 1874, 20.94 and 20.92 per cent of oxygen, 

 respectively. 



Using Bunsen's method, A. R. Leeds 2 analyzed many samples of air 

 collected in July, August, and September of 1876, near Hoboken, New 

 Jersey, at the Centennial Exposition in Philadelphia, and at several 

 places in the Adirondack Mountains. His results are given in table 32. 



Table 32. Determinations of oxygen made by Leeds in samples of outdoor air. 



Date. 



Location. 



1876. 

 July 

 Aug. 



Aug. 



Aug. 

 Aug. 

 Aug. 



Sept. 



4 

 2 



11 



29 

 30 

 31 



1 



Stevens Institute . 

 .Do 



Do 



Do 



Do 



.Do 



.Do 



Oxygen. 



p. ct. 

 20.957 

 20.957 

 20.821 

 20.843 

 20.954 

 20.934 

 20.942 

 20.952 

 20.957 



Date. 



1876. 



Sept. 7 



Aug. 15 

 Aug. 18 

 Sept. 26 

 July 17 



July 21 



Location. 



Oxygen. 



Stevens Institute j 



Centennial grounds 

 ....Do 



Stevens Institute . . 



Keene Flats, Adi- 

 rondack^ 



Mount M a r c y 

 (summit). 



p. ct. 



20.932 

 20.944 

 20.962 

 20.918 

 20.915 



21.029 

 20.928 

 20.926 



In testing a gas-analysis apparatus, using copper immersed in an 

 ammoniacal solution of ammonium chloride to absorb oxygen, Schlosing 3 

 found 20.80 and 20.96 per cent oxygen in two samples. 



In the decade between 1879 and 1889 an unusually large number of 

 researches on the composition of the air appeared, each of far-reaching 

 importance. Prominent among these are the papers of von Jolly, Morley, 

 Kreusler, Vogler, and Hempel. 



No paper since that of Regnault stimulated so much subsequent re- 

 search on the composition of the air as did the publication of von Jolly's 4 

 investigation. Working with extreme care in an attempt to weigh the 

 gases in atmospheric air, he found in 1876 changes in oxygen content 

 amounting to 0.5 per cent. Placing in the bulb of an air thermometer a 

 copper spiral which could be heated by an electric current to incandes- 

 cence, von Jolly was able to absorb the oxygen by the heated copper 

 and thus determine the percentage of ox3'gen. His apparatus was ex- 

 tremely ingenious and also very complicated. His results are given in 

 table 33. 



1 Hinman, American Journal of Science, 1874 (3), 8, p. 188. 



2 Leeds, Annals Lyceum of Natural History, New York, 1878, p. 193. 



3 Schlosing, Chemisches Centralblatt, 1869, p. 678. 



4 von Jolly, Wiedemanns Annalen, N.F., 1879, 6, p. 520. 



