•120 On ihc Theory of Mi xdii Gases, 



in the following words, hiid not the hurry of 

 writing induced him to express his thoughts in 

 a manner, which appears to be somewhat too 

 general. " The force of gravity upon a par- 

 " tide of the atmosphere is infinitely surpassed 

 *' by the repulsive force, which the same par- 

 " tide exerts on the nearest corpuscles of its 

 *' own kind.'* The preceding maxim cannot 

 be called a self-evident truth ; because it is 

 derived in the following way, partly from ex- 

 periment, and partly from argument. . The 

 air has been found by experimental philoso- 

 phers to have weight and elasticity ; which 

 properties are supposed to reside in* the con- 

 stituent particles of the mass. Hence it happens, 

 that each particle endeavours to descend per- 

 pendicularly ; but is prevented from falling 

 below a certain point, by the repulsive force of 

 the next inferior particle lying in the same ver- 

 tical line : thus the latter particle sustains the 

 former with all the pressure, which urges it 

 downwards at the time ; that is, it supports 

 the whole weight of the incumbent column, 

 consisting of gaseous particles of its own kind. 

 Now as the number of incumbent particles is 

 indefinitely great in thc>'jiether parts of the 

 atmosphere, the weight of any one corpuscle 

 cannot have an assignable ratio to the united 

 pressure of the whole ; ^hich is equal to .the 



