FUNCTION OF CRITICISM IN ADVANCEMENT OF SCIENCE. 361 
This analysis of phenomena shows that variations of energy 
in their transformations are known only as the product of 
two terms. Of energy itself, the primal quantity, we know 
nothing as yet. Whether it ever can be known to man re¬ 
mains to be seen. Of the two factors which measure the 
change in energy, the first is called the intensity and the 
second the capacity. Examples of intensity are the absolute 
temperature, velocity of motion, the potential function, the 
double kinetic energy, force, surface tension, pressure, height, 
the Newtonian potential function, chemical intensity, electric 
and magnetic tension, electric and magnetic currents. These 
quantities are the gauges of the condition of the substance 
through which the work of the transformation of the energy 
is performed. Thus the temperature or pressure of a body 
prescribes the amount of the work required to produce a 
given rise in its heat or volume respectively. Now, the pre¬ 
requisite that there shall be any transfer of energy whatso¬ 
ever is that there must be differences of intensity in contact 
with each other. For any transfer of heat there must be 
two bodies in contact having different temperatures, as hot 
and cold pieces of metal; or two bags of air with different 
pressures, which are spherical before contact, but become 
deformed on touching each other, the bag of low^er pressure 
yielding more than the one at higher pressure. Next, the 
transfer of energy is always from the substance of higher in¬ 
tensity to the one of lower intensity, as from the hot to the 
cold body, from the high pressure to the low pressure body. 
The second law of thermodynamics therefore becomes gen¬ 
eral by saying that every energy form endeavors to go over 
from a higher to a lower intensity. This is the intensity 
law and is universally applicable, so far as now known. 
The second factor in energy changes is called the capacity, 
and examples of it are entropy, force, molar mass, the cyclic 
moment, distance, surface, volume, weight, resistance, chem¬ 
ical mass, electricity, magnetism, electric and magnetic 
density. The capacity measures the amount of the energy 
transferred from one body to another. If intensity measures 
52—Bull, Phil, Soc., Wash., Vol. 13. 
