FLUIDITY. The state of bodies when their parts are very readily moveable in all directions with respect to each other. Many useful and curious properties arise out of this modification of matter, which fbrm the basis of the mechanical science called hydrostatics, and are of considera ble importance in chemistry. But the attention of the chemist is chiefly direct ed to the state of fluidity, as it may affect the component parts of bodies.
A solid body may be converted into a fluid by heat. The less the temperature at which this is effected, the more fusible the body is said to be.
All fluids, not excepting the fixed me tals, appear, from various facts, to be dis posed to assume the elastic form, and this the more readily the higher the tempera ture. When a fluid is heated to such a degree as that its elasticity is equal to the pressure of the air, its interior parts arise up with ebullition.
The capacity of a dense fluid for caloric is greater than that of the same body when solid, but less than when in the elas tic state. If this were not the case, the assumption of the fluid and elastic state would be scarcely at all progressive, but effected in most cases instantly as to sense. See CALORIC.
The state of dense fluidity appears to be more favourable to chemical combi nation than either the solid or elastic state. In the solid state, the cohesive attraction prevents the parts from obey ing their chemical tendencies; and in the elastic state, the repulsion between the parts has, in a great measure, the same effects. Hence it has been considered, though too hastily, as a chemical axiom, that corpora non agent nisi fuida.