24 Composition of the Atmosphere 



being attained. Kruger reported to Vogel the result of four analyses, made 

 with a Volta eudiometer, of sea-air taken on a half mile from shore, in 

 which he never found over 20.59 per cent of oxygen. The author's explana- 

 tion of this low figure is that the oxygen had been absorbed by the water. 

 Another investigation of air from the Baltic Sea was made by Hermb- 

 stadt 1 in 1821. Although his method of sampling is questionable, he 

 asserts that he employed a "very exact" Volta eudiometer. Air taken 

 5 feet above the surface of the sea gave 21.5 per cent of oxygen; air 16 feet 

 above the sea, 20.5 per cent; and air 24 feet inland from the shore, ex- 

 actly 20 per cent. The author concludes that the larger oxygen content 

 of air from the sea is due to the continuous evolution of oxygen from either 

 the sea-water or marine life. 



Thomson, 2 in Edinburgh, was occupied in air-analysis many years and, 

 indeed, states that in 1801 he made experiments which showed that the 

 composition of the air in Edinburgh was the same as that found by Davy 

 and Berthollet elsewhere. In 1824 he made a new series of tests, employ- 

 ing the Volta eudiometer. After much experimenting as to the proper 

 volume of hydrogen to use, he found, as the average of 10 experiments, 

 79.9335 per cent of nitrogen and 20.0665 per cent of oxygen. Thomson's 

 analyses and conclusions are so obviously dominated by the precon- 

 ceived notion that air is a chemical compound consisting of four parts of 

 nitrogen and one of oxygen, that his contribution has very little quanti- 

 tative interest. 



Another Englishman, John Dalton, whose theoretical discussions were 

 of great importance to chemists, also analyzed air upon a number of 

 occasions. On January 8, 1825, 3 he found as a result of many experiments, 

 21.15 per cent of oxygen in air sampled in the country, the barometer 

 being 30.9 inches, and the wind blowing very moderately from the north- 

 east after 3 days of calm and a light frost. He states that ordinarily the 

 atmosphere has only 20.7 to 20.8 per cent of oxygen. Dalton's concep- 

 tion of the independent nature of each gas and the computed differences 

 in composition of the air at different heights greatly stimulated research in 

 this direction. In contradiction of his expressed views upon the solu- 

 bility of gases in water, he collected samples by letting the water run out 

 of a bottle and then corking the bottle. Frequently it was opened under 

 water and allowed to stand several months. In the Philosophical Maga- 

 zine, 1838, 12, p. 397, Dalton gives further experimental evidence to sup- 

 port his view, but is evidently convinced that the theoretical compu- 

 tations are not verified by experiment. Thus he states : 



From the experiments about to be related, I have reason to believe that the higher 

 regions of the atmosphere are somewhat less abundant in the proportion of oxygen than 



1 Hermbstadt, Journal fur Chemie und Physik, 1821, 32, p. 283. 



2 Records of general science, by Robert D. Thomson, M.D., 1836, 15, p. 179. See 

 also Journal f iir praktische Chemie, 1836, 8, p. 359. 



3 Dalton, Annals of Philosophy, 1825. 10, p. 304. 



