THERMOCHEMISTRY, a branch of Energetics, treating of the thermal phenomena which are associated with chemical change.
Ostwald (who styled its author the "founder of chemical energetics") in 1891 and into French by H.
Other branches of this subject are treated in the articles Chemical Action; Energetics; Solution; Alloys; Thermochemistry.
Another branch, related to energetics, is concerned with the transformation of chemical energy into other forms of energy - heat, light, electricity.
In accordance with the principles of energetics, any change which involves a decrease in the total available energy of the system will tend to occur, and thus the necessary and sufficient condition for the production of electromotive force is that the available energy of the system should decrease when the current flows.
The name thermodynamics is given to that branch of the general science of Energetics which deals with the relations between thermal and mechanical energy, and the transformations of heat into work, and vice versa.
The more general case is discussed in the article Energetics, and in the original memoirs of Willard Gibbs and others.
Returning now to the aether, on our present point of view no such complications there arise; it must be regarded as a continuous uniform medium free from any complexities of atomic aggregation, whose function is confined to the transmission of the various types of physical effect between the portions of matter.
Iv., Applied Energetics, or Theory of Prime Movers, because its subject matter is now treated in various special articles, e.g.