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LX\'I. Experimental Inquiry info the Proportion of the. 

 several Gases or Elastic Fluids constituting the Atmo- 

 sphere. By John Dalton*. 



J.N a former paper which I submitted to this society, " on 

 the constitution ot" mixed gases," I adopted such propor- 

 tions of the simple elastic fluids to constitute the atmosphere 

 as were then current, not intending to warrant tlie accaracv 

 of them all, as stated in the said paper : my principal ob- 

 ject in that essay was, to point out the manner in which 

 mixed clastic fluids exist together, and to insist upon what 

 I think a very important and fundamental position in the 

 doctrine of such fluids ; — namely, that the elastic or repuL 

 sive power of each particle is confined to those of its own 

 kind; and consequently the foixe of such fluid, retained in 

 a given vessel, or gravitating, is the same in a separate as 

 in a mixed state, depending upon its proper density and 

 temperature. This principle accords with all experience, 

 and I have no doui)t will soon be perceived and acknow- 

 ledged by chemists and philosophers in general ; and its 

 application v/ill elucidate a variety of facts which arc 

 otherwise involved in obscurity. 



The objects of the present essay are, 



1. To determine the weight of each simple atmosphere, 

 abstractedly ; or, in other words, what part of tlie weight 

 of the whole compound atmosphere is due to azote, what 

 to oxygen, 8cc. &rc. 



2. To determine the relative weights of the different 

 gases in a given volume of atmospheric air, such- as it is 

 at the earth's surface. 



3. To investigate the proportions of the gases to each 

 other, such as they ought to be found at diflerent elevations 

 above the earth's surface. 



To those who consider the atmosphere as a chemicai 

 compound, these three objects are but one; others, who 

 adopt my hypothesis, will see they are essentially distinct. 

 With respect to the flrst : it is obvious, that, on my hypo- 

 thesis, the density and clahtic force of each gas at the earth's 

 surface are the cifccts of the weight of the atmosphere of 

 that gas solely, the diflferent atmospheres not gravitating 

 one upon another; whence the flrst object will be obtained 

 i)y ascertaining what share of clastic force is due to each gas 

 in a given volume of the compound atmosphere ; or, which 



• From MancheUcT TransaiUviLii, ivcon^scviitii vol. i. 



amounts 



