402 Dynamic Theory. 



pound of ice is equal to the energy represented by raising a pound of 

 water 143, or 143 fibs. 1, and the work of tearing apart the mole- 

 cules of water represents the energy required to raise 967 pounds of water 

 one degree. No two solid bodies at the same temperature contain the 

 same amount of heat. Or, rather, if two bodies of the same temper- 

 ature be cooled to a lower but still equal temperature, one will be found 

 to have given out more heat than the other, and converse^ if they both 

 be raised to a higher but still equal temperature, one will be found to 

 have absorbed more heat than the other, or, in other words, more heat 

 is required in one case than the other, to give them the same temper- 

 ature. It is obvious that the heat thus entering into a body and disap- 

 pearing, becomes some other form of energ}^ When a body has any 

 heat in it whatever, we are simply to understand that its molecules are 

 being thrust asunder against their attraction of cohesion, and that as a 

 resultant of the struggle between two opposing forces the molecules re- 

 ceive an oscillatory motion. We can suppose that the difference in the 

 constitution of bodies is such, that a greater amount of energy will be 

 expended in the production of a certain degree of oscillation in one than 

 in another. And this is proved to be the case in all the solid elements. 

 At every different degree of temperature their molecules occupy a differ- 

 ent relationship to each other, and before a new degree of temperature 

 can be manifested, the preliminary rearrangement of the molecules must 

 be made, a process requiring the expenditure of a part of the applied 

 heat in work, or cold motion. A part of the heat thus disappears in 

 this work, and after the work is done the molecules upon which it has 

 been expended occupy a position of potential energy toward each other, 

 as is proved when the body is cooled by its giving out an amount of 

 heat greater than the degree of fall in its temperature. We are to con- 

 ceive here two forces at work, one of which is the attraction the parti- 

 cles have for each other cohesion, and the other this foreign energy 

 which counteracts cohesion and rolls the particles over into a con- 

 strained position against their polarity, without increasing the size of the 

 body, or pushes them bodily asunder, thereby expanding the body as a 

 mass. The quantity of heat going into a body is thus divided, only a 

 part of it remaining as heat, and the quantity of heat which is required 

 to raise the temperature of a body differs in different bodies. The sub- 

 joined table from Wurtz, gives the relative amount of heat required to 

 raise the temperature of the different solid elements a given number of 

 degrees, an equal weight of each element being used, and the heat re- 

 quired to raise the temperature of water being called 1.00. The quan- 

 tities got in this way are called specific heats. In the first column of 

 the table are given the specific heats, water being 1. In the second col- 

 umn are given the relative weights of the atoms of the bodies, com- 



