Page:"N" Rays (Garcin).djvu/83

Rh The radiations of very small wave-length, discovered by M. Schumann, are to a very great extent absorbed by air; "N" rays are not. This implies the existence of absorption bands between the ultra-violet spectrum and "N" rays. The wave-length of "N" rays increases with their refractive index, contrary to what occurs with luminous radiations.

If the increase in brilliancy of a small luminous source by the action of "N" rays is to be attributed to a transformation of these radiations into luminous radiations, this transformation is in conformity with Stokes' law.

Though "N" rays have no intrinsic action on the photographic plate, it is nevertheless possible to utilize photography to reveal their presence and study their action. This object is attained, as I showed as long ago as May 11, 1903, by making a small, luminous source