NATURAL PHILOSOPHY. 185 



conservation. Even when rendered radiant, and for the time giving no trace 

 or signs of ordinary heat action, the assumptions regarding its nature have 

 provided for the belief in the conservation of force, by admitting either that 

 it throws the ether into an equivalent state, in sustaining which for the time 

 the power is engaged ; or else, that the motion of the particles of heat is 

 cmploved altogether in their own transit from place to place. 



It is true that heat often becomes evident or insensible in a manner un- 

 known to us ; and we have a right to ask what is happening when the heat 

 disappears in one part, as of the thcrmo-voltaic current, and appears in 

 another; or when it enlarges or changes the state of bodies ; or what would 

 happen, if the heat being presented, such changes were purposely opposed. 

 We have a right to ask these questions, but not to ignore or deny the con- 

 servation of force ; and one of the highest uses of the principle is to suggest 

 such inquiries. Explications of similar points are continually produced, 

 and will be most abundant from the hands of those who, not desiring to 

 ease their labor by forgetting the principle, are ready to admit it, either 

 tacitly, or, better still, effectively, being then continually guided by it. Such 

 philosophers believe that heat must do its equivalent of work ; that if in 

 doing work it seem to disappear, it is still producing its equivalent effect, 

 though often in a manner partially or totally unknown ; and that if it give 

 rise to another form of force (as we imperfectly express it), that force is 

 equivalent in power to the heat which has disappeared. 



What is called chemical attraction affords equally instructive and sugges- 

 tive considerations in relation to the principle of the conservation of force. 

 The indestructibility of individual matter is one case, and a most important 

 one, of the conservation of chemical force. A molecule has been endowed 

 with powers which give rise in it to various qualities, and these never change, 

 either in their nature or amount. A particle of oxygen is ever a particle of 

 oxygen nothing can in the least wear it. If it enters into combination 

 and disappears as oxygen, if it pass through a thousand combinations, 

 animal, vegetable, mineral, if it lie hid for a thousand years and then be 

 evolved, it is oxygen with its first qualities, neither more nor less. It has 

 all its original force, and only that ; the amount of force which it disengaged 

 when hiding itself has again to be employed in a reverse direction when it is 

 set at liberty ; and if, hereafter, we should decompose oxygen, and find it 

 compounded of other particles, we should only increase the strength of the 

 proof of the conservation of force, for we should have a right to say of these 

 particles, long as they have been hidden, all that we could say of the oxygen 

 iteelf. 



Again, the body of facts included in the theory of definite proportions, 

 witnesses to the truth of the conservation of force ; and though we know little 

 of the cause of the change of properties of the acting and produced bodies, 

 or how the forces of the former are hid amongst those of the latter, we do 

 not for an instant doubt the conservation, but are moved to look for the 

 manner in which the forces are, for the time, disposed, or if they have taken 

 up another form offeree, to search what that form may be. 



Even chemical action at a distance, which is in such antithetical contrast 



16* 



