1858.] On the Conservation of Force. 461 



may become very variable, so as to be utterly inconsistent with 

 the idea of the conservation of two separate forces (the elec- 

 trical and the chemical), but perfectly consistent with the con- 

 servation of a force being the common cause of the two or 

 more sets of action. 



It is perfectly true that we cannot always trace a force by its 

 actions, though we admit its conservation. Oxygen and hy- 

 drogen may remain mixed for years without showing any signs 

 of chemical activity ; they may be made at any given instant to 

 exhibit active results, and then assume a new state, in which again 

 they appear as passive bodies. Now, though we cannot clearly 

 explain what the chemical force is doing, that is to say, what 

 are its effects during the three periods before, at, and after 

 the active combination, and only by very vague assumption can 

 approach to a feeble conception of its respective states, yet we 

 do not suppose the creation of a new portion of force for the 

 active moment of time, or the less believe that the forces 

 belonging to the oxygen and hydrogen exist unchanged in 

 their amount at all these periods, though varying in their 

 results. A part may at the active moment be thrown off as 

 mechanical force, a part as radiant force, a part disposed of we 

 know not how ; but believing, by the principle of conservation, 

 that it is not increased or destroyed, our thoughts are directed 

 to search out what at all and every period it is doing, and how 

 it is to be recognized and measured. A problem, founded on 

 the physical truth of nature, is stated, and, being stated, is 

 on the way to its solution. 



Those who admit the possibility of the common origin of all 

 physical force, and also acknowledge the principle of conserva- 

 tion, apply that principle to the sum total of the force. Though 

 the amount of mechanical force (using habitual language for 

 convenience sake) may remain unchanged and definite in its cha- 

 racter for a long time, yet when, as in the collision of two equal 

 inelastic bodies, it appears to be lost, they find it in the form 

 of heat and whether they admit that heat to be a continued 

 mechanical action (as is most probable), or assume some other 

 idea, as that of electricity, or action of a heat-fluid, still they 

 hold to the principle of conservation by admitting that the sum 

 of force, i. e. of the "cause of action," is the same, whatever 

 character the effects assume. With them the convertibility of 



