1820.] Mathematical Principles of Chemical Philosophy. 139 



cles be supposed to have any part of their surface plane, the 

 observed phenomena cannot be produced. It appears, Newtoni 

 Princip. hb. 1, prop. 11, that the planetary spheres tend towards 

 each other, the force varying reciprocally as the square of the 

 distance between their centres; and from prop. 71 and 74, 

 cor. 3, every particle of which these bodies are composed 

 attracts every other particle, according to the same law. This 

 force has generally been considered incapable of producing the 

 phenomena of cohesion from reasons similar to the following : 

 Suppose a corpuscle or minute mass of matter to be placed upon 

 a sphere of considerable magnitude ; experiment proves that 

 their mutual attraction is insensible ; let the diameter of the 

 sphere be continually diminished, and the attraction will dimi- 

 nish as the diameter of the sphere (Princip. lib. 1, prop. 72); 

 much more then will the attraction be insensible when the 

 sphere is reduced to the magnitude of one of the ultimate atoms 

 of matter ; besides, if the attraction of such a sphere be sufficient 

 to produce cohesion in contact, it must be sensible at even a 

 considerable distance from contact (Princip. lib. 1, prop. 74). 

 This difficulty has induced some philosophers to assume the 

 existence of another species of centripetal force, which decreases 

 as the cube, or some higher power of the distance. The exist- 

 ence of such a force cannot be admitted without sufficient proof; 

 it has been introduced to free the subject from one difficulty, 

 and at once involves it in many of much greater magnitude. 

 Suppose chemical attraction to result from the operation of such 

 a force ; since it is inherent in, and exerted by, all the particles 

 of matter, masses composed of such must possess an attractive 

 force, which is made up of this, and of that which is known to 

 exist, and which varies reciprocally in the duplicate ratio of the 

 distance. Now by the united researches of the most eminent 

 mathematicians, all the phenomena of the motions of the bodies 

 belonging to the solar system have been demonstrated to result 

 from the operation of the latter force only ; but if the former 

 force, which has been assumed by chemists for the sake of con- 

 venience, existed, there must arise a new set of disturbing forces 

 which are inconsistent with, and inexplicable upon, the Newto- 

 nian system, particularly in the moon's motion ; and had such 

 existed, from the present perfect state of astronomical science, 

 they could not have escaped observation : also the perihelia of 

 the planetary orbits must be affected with a very considerable 

 motion, inexplicable by the known operation of that force which 

 has been proved to exist; for instance, the perihelion of the 

 earth's orbit would have an annual motion of 1' 5", if we increase 

 ^y TTTWyth part the power of the distance to which the solar 

 gravity is proportional ; whereas the real observed motion is 

 only 11-G" (Laplace's System of the World, vol. ii. p. 12), and 

 this results from the operation of the Newtonian law of gravita- 

 tion only. It would be useless to investigate the nature of these 



