He supposes that the law of evolution is deducible from the law of persistent force, and includes in force what is now called energy.
This equation, which is mathematically deducible from the kinetic theory of gases, expresses the behaviour of gases, the phenomena of the critical state, and the behaviour of liquids; solids are not accounted for.
While it is evident that some such conclusion must follow from the attempt to regard the cognitive consciousness as made up of disconnected feelings, it is equally clear, not only that the result is selfcontradictory, but that it involves certain assumptions not in any way deducible from the fundamental view with which Hume starts.
Conversely, if the specific heats of a compound and its constituent elements, except one, be known, then the unknown atomic heat is readily deducible.
The conclusions deducible from their anthropological features - apart from the general difficulty of arriving at safe conclusions on this ground alone, on account of the variability of the ethnological type under various conditions of life - are also rather indefinite.