ox CHEMICAL ENERGY. 233 



What now are the factors of chemical energy? If we had a measure 

 for its factor of intensity, as the thermometer is a measure of the 

 intensity of heat, we wouUl be able to determine for each substance 

 Avith reference to another whether it could react with the latter or not? 

 just as the thermometer shows us whether or not heat can be trans- 

 mitted from one body to another. Our answer is that this question 

 has not been completely solved, but that from many phenomena we 

 ah^eady possess a chemometer, as we might call the instrument — in 

 analogy to the thermometer. 



In order however to be able to explain the theory of the chemome- 

 ter, the factors of chemical energy must first be more precisely deter- 

 mined. The factor of capacity is in this case most easily discovered. 

 The chemical energy which is present under given circumstances is 

 proportional to the weight or mass of the .substances involved. Hence 

 we sell and buy chemical energy according to weight. This becomes 

 more clear from the following consideration: When we buy coal, we do 

 not consider the carbcm present, but rather the cheuiical energy, since 

 in the use of the fuel we allow the carbon to escape quietl}' through 

 the chimney as carbon dioxide, without making any effort to retain it; 

 that however which we husband with the greatest care, is the chemi- 

 cal energy of the coal, obtained as heat. I have stated with due con- 

 sideration that the factor of capacity of chemical energy is proportional 

 u) the mass; yet it is not mass, since this conception belongs solely to 

 mechanics. It is therefore by no means more correct to say "atomic 

 mass" instead of "atomic weight," since in this case the degree of 

 chemical capacity is concerned which is proportional to both weight 

 and mass, without being one or the other. 



The term " degree of intensity" of chemical energy has something in 

 common with the conception which has become familiar in the field of 

 chemistry under the term of "chemical affinity," nn)re to denote that 

 field in which a more accurate knowledge was especially desirable thaij 

 to combine by such a word sufticiently definite ideas. The word was 

 there, just as the name of a future street stands on a signboard in the 

 outskirts of a city, in a waste field; tents and barracks of the most 

 curious kind have been erected from time to time only to be deserted 

 again. Only in most recent times solid buildings and i>ermanent set- 

 tlements have found a j)lace on this site, and soon a new section of the 

 city will be created there, whose importance threatens to throw the 

 older portion of the city in the shade. 



J. VVillard Gibbs called the degree of intensity of chemical energy 

 the chemical potential; analogous to the degree of intensity of elec- 

 trical energy, which is called the electrical potential. So, to avoid the 

 vagueness of the term affinity, we will make use of the term chemical 

 potential, or in brief, potential. 



IS^ow, it follows from the definition of the degree of intensity, that 

 two substances with like potential can not act on each other: and, con- 



