62 Composition of the Atmosphere 



terminations obtained at this time are reported in a second article dis- 

 cussing the abnormal carbon-dioxide percentage of the air in Greenland, 

 and the general relations between atmosphericandoceanic carbon dioxide. 1 

 On 22 days samples of air were taken from a number of different places 

 in Greenland, 47 determinations of oxygen being made. Excepting one 

 observation of 20.84 per cent, which was attributed by the author to a 

 possible analytical error, the results exhibit variations from 20.92 to 

 21.015 per cent. Omitting the very low value of 20.84 per cent, the 

 average of the determinations is 20.960 per cent. Of particular signifi- 

 cance is the fact that analyses made on the same samples showed ex- 

 tremely high values for carbon dioxide, ranging at times from 0.025 to 

 0.07 per cent. 



In a private communication from Dr. Krogh, he reports that a series 

 of experiments made by him in Greenland in 1908 showed oxygen per- 

 centages ranging from 20.895 to 20.980, with an average of 20.945. The 

 unusually high carbon-dioxide percentages of former years were not ob- 

 tained, although two observations gave 0.055 per cent. Dr. Krogh also 

 writes that in 1907 and 1908 Dr. Lindhard of Copenhagen made obser- 

 vations in northeast Greenland (Denmark Haven) using the identical 

 modified Pettersson apparatus described by Dr. Krogh in a former paper. 

 He reports that Lindhard's results would be liable to about 0.001 per cent 

 error, and they agreed perfectly with those found by himself on the west 

 coast. Lindhard generally found about 0.035 per cent of carbon dioxide, 

 but on one or two days it was below 0.03 per cent, and on 5 days out of 23, 

 0.04 per cent or more. The maximum value found was 0.062 per cent. 



Dr. Krogh, commenting upon his own determinations of oxygen, 

 writes that they may have an error of several hundredths of a per cent, as 

 the absolute accuracy may be much affected by dirt accumulating in the 

 burette and by variations and gradual displacement of the contained 

 water. He says: "I do not think that it is at all possible to determine 

 oxygen with great absolute accuracy except by analyzing dry and in a 

 perfectly clean burette." 



It should be borne in mind that Dr. Krogh's original investigation 

 dealt simply with the carbon-dioxide tensions in air and in water, and the 

 oxygen determinations were quite incidental; likewise, the oxygen deter- 

 minations in 1908 were made in connection with experiments with the 

 respiration apparatus for determining the gaseous exchange of Eskimos. 

 As one of the foremost investigators in gas-analysis, Krogh's experiences 

 are doubly valuable. 2 



1 Krogh, Meddelelser om Groenland, 1904, 26, p. 409. 



2 On a recent trip to Copenhagen, I was accorded the privilege of seeing a new gas- 

 analysis apparatus devised by Dr. Krogh in which the conditions outlined by him above 

 are fully realized. Unfortunately, at the time of going to press with this report, Dr. 

 Krogh has not completed satisfactorily his experiments with this apparatus. 



