52 



HABIT AND INTELLIGENCE. 



[chap. 



Djniamic 

 equiva- 

 lents of 

 the ele- 

 ments. 



I do not propose this notation as adapted for general 

 use, but I believe that it would be a concise and lucid 

 way of stating important facts : and it could not cause 

 any confusion, because the present notation would not 

 be in any degree changed, but only added to.^ 



But what is there in a thermo-positive compound to 

 represent the energy that appears as heat on its decom- 

 position ? I cannot suggest any answer whatever to this 

 question. It is a form of static actual energy, but, unlike 

 electricity and magnetism, it does not appear to be any 

 kind of strained elasticity. 



Nor can we tell what there is, in or between^ two 

 elements previous to their combination, to represent the 

 energy that they give out, as heat or electricity, on their 

 combination. The emission of heat is not due, as Lavoisier 

 supposed, to condensation. Such a cause is probably in- 

 adequate in nearly all cases, and in the case of the com- 

 bination of hydrogen with chlorine it fails altogether ; for 

 after they have combined and formed hydrochloric acid 

 gas, they continue to occupy the same space as before. 

 The tendencies of elements to combine, and to give out 

 energy on combining, are in all jDrobability ultimate pro- 

 perties, no more to be explained or accounted for than 

 gravitation. But this very important question remains for 

 solution : Can we assign dynamic equivalents to the 

 elements? We know the thermal equivalents of many 

 products of spontaneous combination, as water, hydro- 

 chloric acid, and carbonic acid. Can we assign dynamic 

 equivalents to their elements, so that the thermal equi- 

 valent of any compound (that is to say, the quantity of 

 energy which from being potential in the elements becomes 

 actual in the act of combination) shall be the sum, or the 

 prodiict, or some other joint function, of those equivalents 

 of their elements ? — ^just as the potential energy due to 



1 It might also prevent mistakes from being made by classing sub- 

 stances of unlike thermo-chemical properties in the same or homologous 

 series. But I do not know enough of the higher chemistry to be certain 

 whether there is any danger of this. 



2 See p. 43. 



