VOL. XXVI.] PHILOSOPHICAL TRANSACTIONS. 423 



other, and then again striking against other corpuscles, they will be reflected a 

 second time: whence there will arise innumerable conflicts with, and continual 

 resilitions from other corpuscles ; and by their attractive force, their velocity 

 will be continually increased, and there will be a sensible intestine motion of 

 the parts : but according as the mutual attraction of the corpuscles is stronger, 

 or weaker, and according to their different elasticity, these motions will be 

 various, and become sensible in different degrees, and at different times. 



Theorem 25. — If corpuscles, attracting each other, mutually touch, no mo- 

 tion will ensue : for they cannot approach nearer ; if placed at a very small 

 distance from each other, there will be a motion ; but if at a greater, they will 

 attract each other with no greater force, than they attract the intermediate par- 

 ticles of the fluid ; and therefore no motion will be produced. — On these prin- 

 ciples all the phaenomena of fermentation and effervescence depend : and hence 

 appears the reason, why oil of vitriol, into which a little water is put, has an 

 ebullition and effervescence ; for, on pouring in of the water, the saline parti- 

 cles are forced from their mutual contact ; whence necessarily a motion arises, 

 since they attract each other more than they attract the particles of the water, 

 and are not equally attracted on all sides. Hence also appears the reason, why 

 so great an ebullition is produced, on throwing into the said mixture the filings 

 of steel ; for the particles of the steel have a great elasticity ; whence a strong 

 reflection or resilition arises : hence also the reason may be assigned, why some 

 menstrua, if diluted with water, act with greater violence upon, and sooner 

 dissolve any body. 



Theorem 26. — If corpuscles, attracting each other, have no elasticity, they 

 will not be reflected from each other, but form a congeries or moleculas of par- 

 ticles, whence a coagalum will arise : and if the gravity of the said congeries 

 of particles exceed that of the fluid, a precipitation will also ensue: which may 

 likewise arise from the increase or diminution of the gravity of the menstruum, 

 in which the corpuscles swim. 



Theorem 27. — If the figure of corpuscles attracting each other, and floating 

 in a fluid, be such as to have a greater attraction, as also a larger contact in 

 some given parts, than in others ; these corpuscles will unite into bodies of 

 given figures : and hence crystallizations will arise, and the figures of the com- 

 ponent corpuscles may be determined by geometry, from the given figure of the 

 crystal. 



Theorem 28. — If corpuscles be attracted more by the particles of a fluid, 

 than by each other ; they will fly as it were, and recede from each other, and be 

 soon diff'used through the whole fluid. 



Theorem 29. — If any corpuscle interpose between two particles oi a fluid, 



