﻿128 MEIGS ON THE RELATION OF 



supported by experimental proof,) that caloric was the prime mover and cause of all 

 natural phenomena. A forcible writer of our own time and place, maintains this doc- 

 trine with an imposing and comprehensive array of argument.* 



The following brief resume of facts, connects itself with the question under con- 

 sideration : — 



Cohesion varies inversely with the temperature, generally increasing as the latter 

 diminishes, and vice versa. Heat expands bodies, rendering those that were hard, 

 soft and even liquid and gaseous. This change in bulk and condition, corresponds to 

 an increased separation of atoms. A sufficient reduction of temperature solidifies all 

 bodies. Liquids and gases may be regarded as solid matter, plus a certain amount 

 of caloric, the amount varying with the species of matter. Otherwise, the particular 

 temperatures at which bodies undergo these changes would not be so very different, 

 nor would they alwaj's be constant for the same body. Heat is certainly the cause 

 of fluidity, gasefaction and evaporation. The most permanent gases — those which 

 manifest the greatest resistance to being deprived of the gaseous form, by external 

 pressure and cooling — are those in which the most intimate union exists between the 

 ponderable matter and heat. Gases contain more heat than liquids, are more elastic, 

 therefore, and manifest a tendency to expand without limit, if not opposed by ex- 

 ternal obstacles ; liquids contain more heat and are more mobile than solids, which 

 contain least of all the forms of aggregation. Gases by their refinement, superior 

 activity and expansive power, pass through openings impervious to liquids ; so liquids 

 escape through openings impassable to solids. Ponderable matter is made to occupy 

 a larger or smaller space, according as it is combined with more or less of the repellant 

 material — caloric. 



Dr. Black, whose researches may be considered as constituting the foundation of 

 the science of thermotics, showed, quite clearly, that the structure and properties of 

 solids varied according as their combined heat was increased or diminished. Accord- 

 ing to this observer, the malleability and ductility of metals depend upon the quantity 

 of latent heat they contain. When hammered, they become red hot in consequence 

 of the disengagement of heat ; at the same time, while their density, and consequent- 

 ly specific gravity increase, their malleability diminishes and they become brittle. 

 Malleability is restored by heating. In the first volume of his valuable Hand Book 

 of Chemistry, Gmelin has given numerous and very striking instances, showing that 

 heat imparts to many ponderable bodies particular colors, which vary according to 

 the quantity of heat contained in the bodies. Those metals which increase most in 

 specific heat, when exposed to an elevated temperature, are found to have their rate 

 of expansion also most rapidly increased. According to Dulong and Petit, when the 



*Dr. S. L. Metcalfe, Caloric, its Agencies in the Phenomena of Nature. 



