A PLAN OF A EESEAECH UPON THE ATMOSPHERE. 397 



the proportion of oxygen and carbonic acid in the atmosphere, and the influence, 

 upon the quantity of these constituents, of day and night, winter rfind summer, 

 rain and drought, of storms, and of elevation. These results have been obtained 

 for Europe, with the exception of Lewy's experiments in South America, upon an 

 atmosphere subject to disturbances from the carbonic acid emitted from volcanoes. 



The natural tendency of a dense population and a sparse vegetation would 

 be to increase the carbonic acid and to diminish the oxygen of the atmosphere ; 

 hence, the United States being in this respect diflferent from Europe, it is of im- 

 portance to know how our atmosphere difiers, as to these gases, from the air of the 

 old country. The research has never been made in America for obvious reasonc. 



Beside, the increased knowledge in respect to the nature of the atmosphere 

 which such a research would yieltl, important practical results would flow from 

 it with regard to ventilation, to the hygiene of cities and of military hospitals, 

 to agriculture and the clearing away of forests, &c. 



The examination of the ventilation of the Capitol extension, which has occu- 

 pied my attention during the past six or seven months, has deeply impressed 

 me with the great importance of experiments upon the atmospheric constituents, 

 and practice in the kind of analyses required has led me to propose to co-operate 

 with the Smithsonian Institution in the accomplishment of such a research. 



In this co-operation I will undertake the analysis of specimens of air collected 

 by myself where located, and of such as may be procured by the Institution 

 from different points in the United States, the localities to be settled by the 

 meteorological experience of the Smithsonian Institution. I will bear the ex- 

 pense of analysis myself, in respect to the determination of carbonic acid, and 

 to a less extent of the oxygen. If, however, a large number of oxygen deter- 

 minations are made, I would be glad if the Institution would furnish me with 

 the apparatus of Regnault, or with some other improved one, in order to multi- 

 ply the observations. 



[The investigation proposed by Dr. Wetherill is one of much interest, and as 

 full confidence is placed in his skill as an analytic chemist, and his consciencious 

 accuracy in the statement of the results of his experiments, the assistance required 

 will be furnished by the Institution as soon as the Dr. is prepared to undertake 

 the research. It is probable, however, that he cannot commence the work im- 

 mediately, since some time will be required to enable him to become familiar with 

 the duties of his new position as professor of chemistry in the Lehigh University. 



J. H.l 



