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and fixity of terms is a necessity when a new thought has to be adapted to an 

 old language, and really this word " energy " is one that was only advanced, 

 as it were, the other day. The word " force " is an old word, and one we are 

 all accustomed to ; but we have here the new word " energy," used in an 

 entirely different sense from what used to be its meaning ; and it seems to 

 have been employed because some confusion was found to arise in the use 

 of the old word " force." My own view of the subject is that force is an 

 inherent property of matter, like the affinities which all things possess. What 

 is called chemical affinity is only one kind of affinity. I think that affinity 

 is perhaps the most universal term by which to express the forces. It may 

 possibly include gravitation, and the reason why two bodies approach each 

 other may be that they have affinities causing them to attract each other ; for 

 when the magnet attracts an atom of iron, the attraction is not all on one 

 side. The magnet has the power of attraction ; but the little piece of iron 

 attracts the magnet as truly as the magnet attracts the particle of metal. In 

 like manner, when it is said that the sun attracts the earth, it is equally true 

 that the earth in a proportionate degree attracts the sun. In fact it may be 

 said generally that all particles of matter have an attraction for all other 

 particles of matter. This of course deals with masses. If you go to chemical 

 affinity, there must be that degree of propinquity which brings molecules 

 within the range of their mutual action. You cannot " deprive any body or 

 any substance of its affinities. Oxygen will attract carbon, and so on, and 

 certain combinations will be formed by all the different chemical elements 

 which have affinities for each other. These are inherent properties which 

 they cannot lose. The conditions may be altered, but the affinities cannot be 

 altered. This is a point on which Dr. M'Cann agrees with me ; but with 

 regard to the conservation of energy it is really very difficult to grasp the 

 subject at all so as to form a clear idea of it, for it may be said to be almost 

 in its infancy. We have been shown that the greatest intellects of the age, • 

 some of whom are alluded to, have actually been guilty of great confusion 

 of thought, or at all events, of language. It does not seem to be always the 

 case that confusion of language is at the same time confusion of thought. 

 In a work entitled " Habit and Intelligence," by Mr. Murphy, of Belfast, 

 the writer accuses Mr. Justice Grove of some want of precision in his 

 language, and quotes a passage in which Mr. Grove asserts that gravity, or 

 motion of some kind, was transmitted or converted into chemical affinity, 

 and he apologizes for saying this by telling us that he does not mean to 

 accuse Mr. Grove of confusion of thought, because the nomenclature of the 

 subject is not understood, and people do not always think of using the 

 right word exactly in the right place. These two words "force" and 

 " energy " are so like each other in the way they are used, that it is very 

 hard to employ them without making mistakes. For instance, the only 

 source of energy is force, and yet energy cannot always be reconverted into 

 force. Gravity, which always exists between masses of matter, is force, 

 this may give rise to energy ; but when an object set in motion by gravity 

 reaches the earth, the force of gravity remains, whilst that form of energy 



