in the above-described experiments the brick can be replaced by a vase of thin glass, filled with salt water, and previously exposed to the sun's rays; the effect is very marked. It is certainly due to the salt water, for the empty vase is without effect. This is a unique example of a phosphorescence phenomenon in a liquid body. It is true that the wave-lengths of "N" rays are very different from those of luminous rays, as results from measurements which it is my intention to describe very soon.
The eye of an ox, killed the day before, rid of its muscles and the tissues adhering to the sclerotic, proved to be transparent to "N" rays in all directions, and became itself active by sun-exposure; it is the storing-up of the "N" rays by the media of the eye which causes the retardation observed in the appearance and cessation of the phenomena which are the subject of the present note.
Sea-water and the stones exposed to solar radiation store up "N" rays which they afterwards restore. Possibly these phenomena play some hitherto unperceived part in certain terrestrial phenomena. Perhaps, also, "N" rays
