248 Rev. J. B. Emrnett on the [April, 



Let A B C D be a capillary pore in any solid ; 

 take E any point within it ; immerse the solid 

 in the liquid ; it attracts those parts of the liquid 

 which are within a certain minute distance from 

 the surface ; these parts tend to enter at E ; and 

 since the force of attraction is inversely as the 

 square of the distance, and all liquids are incom- 

 pressible, or indefinitely nearly so, the tendency 

 will be inversely as the distance of E, and the 

 whole force upon one side of that pore will be as 

 that side directly and its distance from E 

 inversely. Take abed similar to A B C D, and 

 e similarly situated to E ; the tendency of the liquid to enter at 

 E : that at e : : a b : A B ; but the area of one side A B : area of 

 one a b :: A B 2 : a b-; therefore the whole force upon the side 

 A B : that upon ai::AB: a b : now if equal solids be taken, 

 the number of such pores contained under equal sections will be 

 inversely as the square of the homologous lines of those pores ; 

 hence the whole expansive force acting upon equal surfaces will 

 be inversely as the diameters of the pores. Q. E. D. 



Cor. 1. — In different substances, the force will be as the 

 actual attraction existing between them and the liquid directly, 

 and the magnitude of the pores inversely. 



Cor. 2. — When an insoluble solid is immersed in a fluid, if the 

 tendency of the liquid to enter its pores be greater than its cohe- 

 sive force, its parts will be separated. 



Scholium. 



By Lemma 2, we may see the reason why corpuscular forces 

 are so great as they are found to be, and why the forces are cor- 

 puscular. The demonstration of this and several other parts is 

 omitted for the sake of brevity, and they will subsequently 

 appear as a separate work in an enlarged form. From this the 

 reason is evident why an elastic fluid of so amazingly great 

 rarity as caloric can produce the observed powerful effects ; for 

 distances from the surface of a particle being taken in harmonial 

 progression, the repulsive force of the calorific atmosphere 

 decreases in geometrical progression, and therefore distances 

 may be found, such, that this may equal any finite force. Upon 

 the same principle depends the immense force of water when 

 admitted into the capillary apertures of porous solids. 



Other curious phenomena admit of easy solution. From the 

 great tenacity of melted glass, it appears that the utmost limit of 

 expansion is produced before the glass is melted ; that is, when 

 the angles A, B, C, D (Prop. V.) have become right angles, the 

 particles are yet preserved in contact by a powerful cohesive 

 force. On account of this tenacity and the great rapidity with 

 which it increases as the temperature is reduced, the particles 

 cannot readily yield to any force which may be impressed upon 



