This text examines the physical distinction between heat conduction and heat radiation, noting that radiation is independent of the medium through which it passes. It establishes that heat rays are physically identical to light rays and applies the principles of experimental optics to the study of thermal radiation.
According to [eqn:(176)] (176) is of the dimensions . The same follows from the present equation, when we consider that the dimension of the chemical constant is not, as might at first be thought, that of , but, according to [eqn:(202)] (202), that of .