FLUORINE

(symbol, F; atomic weight, 19), an element which occurs widely distributed in small quantity, always in combination with metals, e.g. fluor-spar (CaF,), cryolite (AIFs'3NaF), . Owing to the great activity of the element it is extremely difficult to isolate. Moi an in 1886 obtained fluorine by electrolysis of a solution of pota ium fluoride in hydrofluoric acid contained in a platinum tube. It is a greenish-yellow gas, and is éxtremely active, combining readily with most elements with the exception of oxygen. It decomposes water, gla , ., and explodes on mixing with hydrogen. In the combined state fluorine has been detected in bone, teeth, blood, milk, and urine; in plants and in numerous rocks and minerals. Combined with hydrogen it forms hydroflyoric acid.