422 PHILOSOPHICAL TRANSACTIONS. [aNNO I7O8. 



body A tends towards b will be to the velocity with which the particle c, sepa- 

 rated from the body, would tend towards the same body b, as the particle c is 

 to the body a ; therefore the velocity of the body a is far less than would be 

 that of the particle c, separated from it: hence it is that the motion of great 

 bodies is naturally so languid and slow, as to be commonly retarded by the cir- 

 cumambient fluid, and other circumjacent bodies, while the smallest corpuscles 

 are vigorous, and several effects are produced by them: so much greater is the 

 energy in smaller, than in greater bodies. From hence appears the reason of 

 that chemical axiom, viz. that salts do not act till dissolved. 



Theorem 20. — Two corpuscles that do not touch, may be placed so near each 

 other, that the force with which they tend towards each other, shall far exceed 

 that of gravity; 



Theorem '21. — If a corpuscle, placed in a fluid, be on every side equally at- 

 tracted by the circumambient particles ; there will be no motion of that cor- 

 puscle ; but if it be attracted more by some particles, and less by others, it will 

 tend to that part where the attraction is greater; and the motion produced will 

 correspond to the inequality of the attraction, viz. the motion will be greater in 

 ii greater, and less in a less inequality. 



Theorem 22. — Corpuscles floating in a fluid, and attracting each other more 

 than they attract the intermediate particles of the fluid, will drive away the par- 

 ticles of the fluid, and approach each other, with that force by which their 

 mutual attraction exceeds the attraction of the particles of the fluid. 



Theorem 23. — If any body be placed in a fluid, whose particles attract those 

 of the fluid more than the said particles are attracted by each other ; and there 

 be a great many pores in the body, pervious to the particles of the fluid ; that 

 fluid will soon diflbse itself through these pores: and if the cohesion of the 

 parts of the body be not so compact, but that it may be overcome by the im- 

 petus of the rushing particles of the fluid, there will hence arise a solution of 

 the immersed body. — Hence there are three things requisite to make a men- 

 struum fit to dissolve a given body: viz. 1. That the parts of the body attract 

 the particles of the menstruum, more than the said particles are attracted by 

 each other. 2. That the body have pores, open and pervious to the particles 

 of the menstruum. 3. That the cohesion of the particles, which constitute 

 the body, be not so great, as that it may not be overcome by the impetus of the 

 rushing particles of the menstruum. Hence it also appears, that the particles 

 erf" which spirits of wine consist, are attracted more by each other, than by the 

 particles of the saline body immersed in them. 



Theorem 24. — If corpuscles floating in a fluid, and tending towards each 

 other, be elastic; after their concourse, they will mutually recede from each 



