1821.] Causes of Calorific Capacity, Latent Heat, fyc. 257 



arrangement or manner of intestine motion of the particles, or 

 produce any degree of relative fixity in the parts : such a body 

 would be a perfect fluid. But if the atoms or particles have a 

 certain fitness or adaptation of figure, the cohesive tendency, as 

 I have shown in the above paper, will be greater than if the 

 atoms or particles were spheres ; and in proportion to this adap- 

 tation will be the cohesive tendency or adherence of the atoms 

 or particles. If the particles of a solid, by whose vibrations the 

 temperature of the solid is measured, be composed of atoms or 

 other particles of different degrees of adaptation, then, because 

 the cohesive tendency of the parts of the particle will always 

 remain nearly the same, the intensity of the collision of the par- 

 ticles on one another, arising from the temperature, may be so 

 increased as to overcome this adhesion of the parts of less adap- 

 tation, and, consequently, disunite them from the other portions 

 of their respective particles. The parts of, perhaps, several 

 contiguous particles disunited in this way, having but a small 

 individual motion, may, with a slight adaptation, easily unite, and 

 form a new particle or particles ; so that, perhaps, out of four, 

 five, or six particles, there may be formed five, six, seven, or 

 more. Should it happen, as it is most probably the case, that 

 the cornered irregular parts are disunited, the particles afterwards 

 having a more spherical form, as well as a greater latitude of 

 motion from their diminution of size, will have a greater freedom 

 of motion among each other ; and, consequently, compose even 

 at the same temperature a body of a more soft and fluid nature. 

 If the disunited parts happen to be sufficiently great, the remain- 

 ing parts may be sufficiently spherical, and from their diminution 

 have so increased a latitude of motion as to compose a body 

 nearly perfectly fluid, such as water, mercury, &c. In other 

 cases, this disunion of parts may not absolutely take place. The 

 fluidity may result entirely from the latitude of motion being 

 gradually augmented, until it be great enough to enable the par- 

 ticles in their vibrations to exceed the influence of the irregula- 

 rity of figure in restraining a perfect freedom of motion. Such 

 bodies will have their rigidity gradually diminished until they 

 become quite fluid. Tallow, wax, glass, pitch, tar, &c. seem to 

 be bodies of this kind. Other bodies again may have their rigi- 

 dity gradually diminished, and at certain temperatures disunions 

 beside take place ; by which view of things there seems to be the 

 greatest scope for expounding every possible variety of phaeno- 

 mena. Amidst all these different bodies, however, it is manifest 

 that any one body will always have the same degree of liquidity, 

 or softness, at the same temperature; and, therefore, whether 

 the given temperature be produced from a higher or a lower 

 temperature, the liquidity at that temperature will be the same, 

 ;i'_Teeable to experience. 



V\ hen certain parts of the particles are incapable of remaining 

 in union beyond a certain temperature, if the solid at a much 



New Series, vol. n. s 



