THE 



LONDON AND EDINBURGH 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[THIRD SERIES.] 



OCTOBER 1838. 



XXXIII. Remarlcson the Constitution of the Atmosphere; ad- 

 dressed to Dr. Dalton, F.R.S., by John William Draper, 

 M.D., Professor of Chemistry in Hampden Sydney College, 

 Virginia, Member of Acad. Nat. So. Philad., S^c. ^^c* 



Hampden Sydney College, Virginia, U. States, 

 Respected Sir, June 25, 1838. 



I HAVE this morning read, with much pleasure, the re- 

 marks inserted by you in the Numbers of the London and 

 Edinburgh Philosophical Magazine for February and May 

 last, in relation to the constitution of the atmosphere, and other 

 important points connected with investigations of its composi- 

 tion. 



It fully appears, if we admit the hypothesis brought for- 

 ward many years ago by you, and generally received by che- 

 mists, that a gas acts as a vacuum to the particles of one of 

 another kind, that the constitution of the atmosphere is not 

 such as it ought to be. The hypothetical result, contrary to 

 what is popularly imagined, would indicate a continuous vari- 

 ation in the composition of air at different altitudes, and give 

 us two limits, the one marking out an elevation beyond which 

 oxygen could not be found, and the other the same for the 

 azote. From a long experience in these matters, and a per- 

 fect acquaintance with these theories, you have given it as 

 your opinion, that in the higher regions of the air, the pro- 

 portion of oxygen to azote is less than at the surface of the 

 earth, but not nearly so much as the theory of mixed gases 

 would require, and that the reasons for this must be found 

 in the incessant agitation of the atmosphere from winds and 

 other causes. 



In America, partly for the foregoing reason, and partly for 



* Communicated by the Author. 

 Phil. Mag. S. 3. Vol. 13. No. 82. Oct. 1838, R 



