IMPLY PRESENCE OF FORCE. 215 



properties, solidity and fluidity are easily seen to de- 

 pend on a balance of the attractive force of cohesion 

 and the repulsive force of heat, and therefore it is 

 plain that the difference of inherent properties of 

 bodies in these respects is simply how much of the 

 force of heat the particles of each body require to 

 take on before their cohesive force is so far overcome 

 as to make their state of aggregation fluid. It is more 

 difficult to analyze the so-called property of weight, 

 and perceive that it is made up of the capacity of the 

 ultimate particles to be driven towards each other by 

 the force of gravitation, and of the presence of that 

 force. But it is in the development of new properties by 

 means of the force of chemical attraction that the most 

 complete examples of the properties acquired by the 

 union of force and matter are displayed. Every com- 

 bination of different elements gives rise to different 

 relations of the compound to the active and passive 

 forces, and to their affinities to other bodies, and this 

 leads up to the vast variety and complexity of the 

 compound bodies we already know ; while no know- 

 ledge of the chemical powers and properties of matter 

 we already possess enables us to place a limit, beyond 

 which new powers may not be developed by new com- 

 binations and conditions. Here, however, it is always 

 the inherent property or capacity of the substance to 

 "be affected by the force of chemical attraction, viz., 

 affinity, which, as above said, is the determining cause, 

 and, no matter how complex the compound, that must 

 always depend on the property of the ultimate atoms 

 of which it is composed. The potentiality, therefore, 

 of all possible powers of compounds to be developed 



