i82 ikfr. D ALTON on the constitution of the atmosphere. 



permanent ? Would a mixed atmosphere, which in fact as a 

 whole, consisted of equal weights of carbonic acid and hydro- 

 gen, continue to exhibit at the surface of the earth equal 

 volumes only in mixture ? Or, on the other hand, would not 

 the whole be wrought up in due time into one uniform com- 

 position in all its extent, of 20 volumes of hydrogen with one 

 of carbonic acid, as many suppose to be the nature of the 

 earth's atmosphere with regard to its component parts ? 



Before these questions are discussed we shall put the case 

 in a different form : suppose a mixture of 20 volumes of 

 hydrogen and one volume of carbonic acid (that is equal 

 weights of each ) , were put into a large reservoir under the 

 constant pressure of 30 inches of mercury, and from this 

 reservoir were passed by means of a stop-cock into the inde- 

 finite perpendicular tube. A, perfectly void, till such time as 

 the equilibrium between the reservoir and the tube was 

 established : query, what would be the final arrangement of 

 the two gases in the tube ? I believe it will be allowed by 

 all, that the final arrangement of the mixture of gases will 

 be precisely, the same in this case as in the one previously 

 stated, whatever that arrangement may be. 



Now I apprehend it is demonstrable, from what we know 

 of the nature of mixed gases, that each of the two gases 

 would be disposed just the same as if the other was not 

 present. They would be mixed in equal volumes at the 

 earth's surface ; the carbonic acid would rapidly diminish in 

 density in ascending, and terminate perhaps at 28 or 30 miles 

 of elevation ; the hydrogen would slowly diminish in den- 

 sity, and terminate perhaps at 11 or 12 hundred miles of 

 elevation. 



