Device for Subliming Iodine
This apparatus has found a variety of uses in this laboratory, such as drying and subliming iodine recovered from aocumulated iodine “residues” by wet methods, recovering
JACOB CORNOG AND LEONARD OLSON University of Iowa, Iowa City, Iowa
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ANY books on analytical chemistry give directions for subliming iodine in quantities of a few grams, but the authors have not found in the literature a description of a device that may be assembled from materials found in most laboratories and used for subliming iodine in lots ranging up to 500 grams (1 pound) in weight. Such a device is described in this article. As indicated in the figure, the device consists of IL desiccator of Pyrex glass, having a diameter of approximately 2.50 mm., and bearing a 40-to 60-watt light bulb in the lid. Lead wires from an ordinary municipal lighting circuit are soldered to the metallic base, E, of the bulb, which is sealed in the hole in the desiccator lid with plaster of Paris, D,in such a way that no metallic surface is exposed to the interior of the desiccator and also so that the plaster does not touch the wire soldered t o the central terminal of the bulb, which is covered with de Khotinsky or a similar cement. The tile, C, supports the beaker or evaporating dish, A , containing the iodine to be sublimed and the beaker, B, containing a drying agent such as phosphorus pentoxide. If a resistance is placed in series in the external circuit, closer regulation of heating temperatures is assured. When a current is passed through the bulb, the top of the desiccator becomes warmer than the bottom and iodine vaporizes and condenses on the lower sides and the bottom. The rate of sublimation may be increased by using devices which increase the difference in temperature existing between the upper and lower parts of the desiccator, such as insulating the top or cooling the bottom of the desiccator.
iodine mixed with broken glass and dirt resulting from the breaking of bottles in transit or by dropping them on the floor, and in the drying and purification of substances, such as iodine monochloride, that are volatile, corrosive, and easily decomposed a t relatively low temperatures.
Rapid Operating Device for Orsat Apparatus FRED COOK, Bituminous Casualty Corporation, Rock Island, 111.
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P/PetS
Water /#/et
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A study of the operation of a standard analysis procedure will indicate that a large portion of the total time is used in returning pipet solutions to their original marks, balancing the pressure, and reading the buret. These operations are complicated by the fact that the confining liquid in the buret is not perfectly controlled, but is free to surge between the buret and the leveling bulb, and cannot be brought to rest quickly. The device described below permits a positive control on the confining liquid (mercury must be used) by the presence of an incompressible fluid (water) over the mercury in the leveling bulb. This means of control so facilitates the operation of any type of gas analysis equipment that considerable saving of time should result. I n the analysis of coal-mine air (carbon dioxide, oxygen, carbon monoxide, methane) with a standard laboratory-type apparatus, using contact and slowcombustion pipets, the total time of analysis may be cut in half with this device.
HE operation of ordi-
nary gas analysis equipment is somewhat tedious and requires the constant attention of the analyst. Automatic absorption pipets (I, 2, 3) and a hydraulically o p e r a t e d device for transporting the mercury bulb ( 4 ) have been suggested t o decrease the time consumed and to relieve the opera t o r during a portion of the analysis. Each has
Description The essential difference between this device and the conventional Orsat apparatus is that the motivating force here is water pressure which is applied over the mercury in the leveling bulb. This change necessitates the use of a leveling tube (a tube parallel to the buret, open at the top and connected a t the bottom to the buret and to the leveling bulb) so that an estimate of the pressure in the buret may be obtained if desired. The usual long rubber 551
