Abstract
Conventional methods for determining fluorine in cryolite, including those by Offerman, Willard-Winter, Ion-exchange resine and ALCOA, were examined, and a simple and rapid method was proposed. The outline of this method was as follows.
By using the apparatus of Willard-Winter, 0.2g of cryolite was taken into a Claisen flask, and 12g of anhydrous silica, 50ml of 68% sulfuric acid and 10ml of 85% phosphoric acid were added. It was steamdistilled for 3.5 hours at 135140°C. Then, fluorine in the distillate was determined by the thorium nitrate titration.
