Fluorescence
in optics, a quality which exists in the rays of light by which, in certain circumstances, they undergo a change of refrangibility.
Hence, Hence, certain solutions which, when viewed by transmitted light, are colorless, become bluish under reflected light. Fluorescence was discovered by Stokes in 1852.
FLUORINE. A very pale yellow gas, atomic weight 19, molecular weight 38, density (compared to air = 1) 1.31. It does not occur in the free state, but its compounds (fluorides) are found in abundance; the best known being fluorspar and chrysolite. It is considered to It be the most active of the elements. decomposes water with formation of hydrofluoric acid, oxygen and ozone; all metals are attacked by the gas, some taking fire in it, spontaneously, and many other elements combine with it with incandescence. It is prepared by the electrolysis of a solution of potassium fluoride in anhydrous hydrofluoric acid, hydrogen being evolved at the kathode and fluorine at the anode.