On I he 'J'/ieoiy of Mixed Gches. 297 



task, by the author himself. My doubts re- 

 lative to the subject arise partly from mathe- 

 matical considerations, and in part from the 

 evidence of experiment. Certain objections of 

 the first class dispose me to conclude, that an 

 atmosphere constructed on Mr. Dalton's plan, 

 will ap[)ear upon examination to be repugnant 

 to the j)rinciplcs of the mechanical philoso^ 

 ])hy ; and a direct appeal to experiment has 

 moreover convinced me, that well established 

 facts contradict the essential points of the 

 theory. 



To begin with the objections of the former 

 class : I am ready to admit the existence of a 

 fluid mixture, such as we find described at 

 page 543, in the fifth volume of the Man- 

 chester Memoirs, with this reservation, that 

 the concession is made, merely for the purpose 

 of shewing such a combination to be incom- 

 patible with the usual course of things, for a 

 moment ; which being demonstrated, the in- 

 utility of the fundamental hypothesis will fol- 

 low, as a necessary consequence. — To give a 

 concise view of Mr. Dalton*s general notion of 

 the subject, we are to suppose a number of 

 distinct gases to be confined in a space com- 

 mon to them all ; which space may be circum^ 

 scribed by the concave surface of a vessel, or 

 the compressing power of an external fluid : 

 pp 



