24< 0/1 the Hi/pothesis of Gaseous Bepulsion. 



a change in such motion being able to affect the repulsion of 

 distant unconnected bodies. We may as well affirm that the 

 I'otation ot" two tops at a distance from one another would make 

 them recede ; a circumstance so })alpably absurd, that we might 

 almost say every child who can spin a top knows it to be wrong. 



As to any other motions ; for instance, revolutionary motions 

 of the particles about each othei", they cannot exist with repul- 

 sive forces ; because, to maintain periodical revolutions, any- 

 thing like die planetary, evidently requires centripetal not 

 centrifugal forces. 



Whatever view therefore we take of the subject, whether we 

 assume hetit to be a substance as caloric, or to be motion, re- 

 pulsion does not explain even a small part of the properties of 

 aeriform bodies. We may consequently conclude, that re- 

 pelling forces have not been by nature selected for the produc- 

 tion ot" aeriform phaenomena. 



The following piece was sent to the Editor of the Annals, to 

 be annexed to my " Remarks," &c. published in the Annals of 

 Philosophy for May; but it seems it arrived too late to be added 

 to tliat paper ; namel}', after the sheets were made up. Cha- 

 racteristical explanations, besides what are contained in the 

 piece, are to be found in the original paper. Annals for May. 



Let G be the specific gravity of the gas and vapours over 

 water, V the volimie, and P the pressure or elasticity of the 

 mixture. Then 



V. < G — t'. „• .,, , ,. , [ = the weip-ht of ijas in the mix- 



p t' 



tare ; and V. — p — = the volinne the gas v»'ould liave under 

 tlie pressure P. Therefore the specific gravity of tlie dry gas 



= pZ^>- \ ^^—^- ^s.f^+L) \ = S- Whence 



putting G' for tlie specific gravity of the atmosphere at tlie 

 temperatiu'e F'. 



From this theorem we gather, that, when g is less, equal to, 



or gi-eater than — G', the specific gravity of the mixture is 



greater, equal to, or less than that of the dry gas; and that 

 wiien g is about f of G', the error that would arise from neg- 

 lecting the influence of the vapour, is very small in estimating 

 the specific gravities ; and on the contrary, much greater in 



Sases considerably lighter or considerably heavier. So that 

 encc such an error in ammonia would fall much short of that 

 in phosgene gas, and still more short of that in hydrogen. 



Again, 



