Is Shine In Dark

Snmp addttional experiments have been made in France, it appears, to determino the specitic action of a considerable lo wering of temperature upon :he britliancy of certain bodlea which shine in the dark after having been exposed to sunlisht. Tubes of glass filled with the powdered sulphides of calcium, barium, Btrontlum, etc, all substances possesslng the property of phosphorescence in a htgli .-xposed to the solar rays and afterward proved to be luminous in the dark, this being done in such a way as to lix upon the memory the mean valué of the pr gressive diminution of the emitted light, and the time also was noted during whleh the Hght was strong, less strong and weak, respectlVely. The tubes w re next placed In bright sunlight for one minute and thon BUddenly introduced into a double-walled glass cylinder, the interspace of which was iilled with nitrous oxide at WO degrees O. In about five or six minutos the temperature of the tubes was Bome 100 degrees. They were then withdrawn, apd, when observed in a perfectly dark chamber, nc luminosity whatever w ptible. As the tubos recovered thelr normal temperatura, however, the phosphorescence returneV without the exciting apency of the sun's rays or of diffused Ilght. These resulta were proved to bt ral for all phosphoreseent substances employpd. The experiments Bhowed, too, tiiat the production of thi phospl i dulrea a certai moveroeht of the constituent moléculas of bodi's.