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To Obtain Iodine

Saturate the residual liquor of the manufacture of soap from kelp (or other iodine lye) of a specific gravity of 1.374, heated to 230° Fahr., with some deoxydizing agent, as sulphurous acid or morphia; and as it exists in the iodides, not until the base is saturated with an acid (as the sulphuric or nitric), when iodine being set free, immediately reacts upon the starch.

An excess of either acid or alkali destroys the action of the test. By mixing the liquid containing the iodine with the starch and sulsulphuric acid diluted with half its weight phuric acid, and lightly pouring thereon a of water; cool, decant the clear, strain, and small quantity of aqueous chlorine, a very to every 12 fluid ounces add 1000 grains of visible blue zone will be developed at the line black oxide of manganese, in powder; put of contact. (Balard.) Solutions containing the mixture into a glass globe, or matrass iodates yield, with nitrate of silver, a white with a wide neck, over which invert another precipitate, soluble in ammonia; the iodides, glass globe, and apply heat with a charcoal under the same circumstances, give a pale fire; iodine will sublime very copiously, and yellowish precipitate with nitrate of silver, condense in the upper vessel, which, as soon scarcely soluble in ammonia; a bright yellow as warm, should be replaced by another; and one with acetate of lead; and a scarlet one the two globes thus applied in succession as with bichloride of mercury. The iodates long as violet vapor arises. It may be deflagrate when thrown on burning coals, washed out of the globes with a little cold water. A thin disc of wood, having a hole in its centre, should be placed over the shoulder of the matrass, to prevent the heat from acting on the globular receiver. On the large scale, a leaden still may be employed, and receivers of stoneware economically substituted for glass ones. The top of the leaden still is usually furnished with a moveable stopper, by which the process may be watched, and additions of manganese or sulphuric acid made, if required. The addition of the sulphuric acid should be made in a wooden or stoneware basin or trough. To render the iodine pure, it should be dried as much as possible, and then resublimed in a glass or stoneware vessel. (Ure.) but the iodides do not. The iodates may also be tested as iodides, by first heating them to redness, by which they lose their oxygen, and are converted into iodides.