. Carnegie Institution of Washington publication. A REVISION OF THE ATOMIC WEIGHTS OF IODINE AND SILVER. 125. possible traces of chlorides, and was preserved in a platinum flask. Even when made from the chloride, the doubly distilled product was absolutely free from chlorides. The approximate concentration of the solution was determined shortly before use by titration against a standard solution of iodic acid or potassiimi permanganate. PreUminary experiments showed that there is no danger of the reduction of the silver salts by a slight excess of hydrazine in nitric acid solution. Special pai
. Carnegie Institution of Washington publication. A REVISION OF THE ATOMIC WEIGHTS OF IODINE AND SILVER. 125. possible traces of chlorides, and was preserved in a platinum flask. Even when made from the chloride, the doubly distilled product was absolutely free from chlorides. The approximate concentration of the solution was determined shortly before use by titration against a standard solution of iodic acid or potassiimi permanganate. PreUminary experiments showed that there is no danger of the reduction of the silver salts by a slight excess of hydrazine in nitric acid solution. Special pains were taken in the reduction of the iodic acid with hydrazine to avoid any possibiUty of loss of iodine by volatiUzation. The solution of the iodic acid was trans- ferred to an 8-liter bottle with a carefully ground stopper, and, after the iodic acid had been neutralized with ammonia, very slightly less than the theoretical quantity of hydrazine hydroxide was added. Since in alkaline solution hydrazine is without effect upon iodic acid, the solution was next made acid by slow addition of nitric acid. As soon as the neutral point has been passed, iodine is freed by interaction of the hydriodic acid with the iodic acid. Lest any of this iodine be volatilized from the solu- tion before it could be reduced by the hydrazine the nitric acid was introduced at the bottom of the solution through a long funnel. Thus iodine was sure to be completely re- duced before reaching the surface of the solution. A specially devised stopper, shown in the accompanying diagram, pro- vided for the escape of the nitrogen through a long col- imin of bulbs, which served to catch spatterings or soluble vapors, if any reached this point. As a further precaution against the escape of iodine a small quantity of sulphurous acid was poured into the bottle through the train of bulbs. This sulphurous acid served also to complete the reduction of the iodic acid. The amount of sulphuric acid formed in this way w
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