Recovery of Iodine from Metallic Iodides by Oxidation with Technical Nitric Acid RUSH Fox MCCLEARYAND ED. F. DEGERING,Chemical Laboratory, Purdue University, Lafayette, Ind.
IN
THE preparation of zinc ethyl in this laboratory, it seemed advisable to devise a simple procedure for the recovery of iodine from the zinc iodide residues. The various methods for iodine recovery suggested by Torossian (6),
E
a zinc iodide cake. The procedure proposed by Lachman (3) involves the hazard of breaking the flask while crushing the hard cake of zinc iodide and unreacted zinc, and the procedure is a little involved. The apparatus shown in the figure eliminates this hazard, and also has the advantage of a simple procedure which gives a good initial yield of crude iodine. Flask A contains the hard residue from the zinc ethyl distillation. B is an ordinary bell jar fitted with a ground-glass lid, and is surrounded by an ice bath. The system may be kept slightly evacuated through the water trap E by partially closing stopcock d. Crude concentrated nitric acid in slight excess of the calculated amount is introduced into flask A , in small portions, through funnel D. Stopcock d is left partly open and air is slowly and continuously drawn through the water trap E . This entrains the iodine vapors efficiently into the bell jar. lodine which collects on the walls of flask A is easily removed by heating gently with a direct flame. Flask C is kept cool by means of circulating tap water.
F
I n a recovery of zinc iodide residues which were calculated to contain 315.8 grams of iodine, 308.7 grams of crude iodine were recovered in the initial sublimation. This initial sublimate showed a purity of 90.83 per cent when titrated with standardized thiosulfate solution. By resublimation in the same apparatus, additional purification may be effected. LITERATURE CITED (1)
Arndt, F., Ber., 52B,
1131-4
(1919);
Chem.-Ztg., 47, 16-17
(1923).
(2) Kleinstuck, M., and Koch, A., Zellstof u. Papier, 3, 261 (1923). (3) Lachman, A., Am. Chem. J., 24, 31-9 (1900). (4) Puig, I., Q u h . e ind., 2, 1-4 (1926). (5) Stephenson, Ha F.1 A n a l ~ t t431 165-6 (1918). Torossianl '*I J* IN=' 68 83 (1914''
Stephenson (5), Arndt ( I ) , Kleinstuck and Koch (Z), and Puig (4) are applicable to solutions or finely divided solids, and are not readily adapted to the recovery of iodine from
RECEIVED July 21, 1933
Modified Design for Mercury Bulb of Thermostat G. B. HEISIGAND A. E. CAMERON, School of Chemistry, University of Minnesota, Minneapolis, Minn.
T
HE conventional thermostat regulator bulb is filled with
toluene, and exPan'ion of the toluene Cu'SS' change in height of a mercury column which makes or breaks the relay circuit. I n spite of the smaller thermal expansion of mercury it is preferable as liquid for a control bulb because creeping of the setting due to seepage of toluene past the mercury column is avoided. Since only the layer of mercury which is in contact with the glass of the bulb can be effective for small and comparatively rapid fluctuations in bath temperature, it is desirable that the surface of the bulb be large. Filling a large bulb with mercury entails a considerable expense and supporting the heavy and rather fragile bulb becomes inconvenient. The authors have designed and used a bulb which is mercury-filled, has a large surface, and yet uses a small amount of mercury.
tube, B, of 0.8-mm. bore was sealed to one end of the cylinder. A small bulb, C, was provided to catch any overflow of mercury from the capillary. For the adjustable contact an iron or platinum wire was inserted into this capillary. Diametrically opposite the capillary was sealed a stopcock, D. A tungsten wire Was Seded though the
~ ~ ~ ~ ~ . c :$:k T ~ ~ i ~C ~ b ' ,
Two pieces of Pyrex tubing, as thin-walled as was consistent with mechanical strength, of diameters 3.5 and 2.5 cm., respectiveiy, were placed one inside the other and sealed together at the ends to form a double-walled cylinder, a longitudinal section of which is shown at A in the accompanying sketch. A ca,pillary 420
filled with mercury and a wire dipped into it to make contact t o the mercury in the control bulb The bulb was filled by it and running clean, dry mercury in through t h e c a p i l l a r y or through the stoPcoCk, a5 was
&:
~~~it~o$v~~$$.in bulb could be varied by opening the stopcock and allowing mercury t o run into the bulb from the tube above the stopcock or by sucking mercury out o f , t he bulb into this
reservoir.
November 15,1933
I N D USTR IAL AND E N G I N E ER I N G C H E M I ST R Y
The control was immersed in the thermostat up to the stopcock key in such a location that water from the stirrer was circulated through the inside and around the outside of the cylinder. Using this control bulb and a radio tube relay device, the temperature of a 25-liter thermostat was maintained a t 25' * 0.002' C. A modification of the original design was suggested to one of the authors by Doctor Kingslake of the Institute of Applied Optics a t the University of
421.
Rochester (New York). The inner tube of the cylinder was extended and drawn down as indicated a t F to permit a hose to be attached to it. Water could then be drawn through the center of the bulb for use in maintaining a constant temperature in an apparatus which could not be immersed in a thermostat. RI+C~IVED **gust 25,1933,
Improved Lamp for Determination of Sulfur in Light Petroleum Products E. R. GILLIS,Casper Laboratory, Standard Oil Co., Casper, Wyo.
I
T IS GENERALLY realized that the flame of the standard A. 8. T. M. lamp is not readily controlled. This causes con-
siderable loss of time, annoyance, and some inaccuracy in determining sulfurs by method D90-30T. Substitute lamps such as the Vapor Cresolene lamp (made by the Vapo-Cresolene Co., 62 Cortlandt St., New York, N. Y.) allow of ready flame control but have serious faults; the metal burner becomes very hot and causes undue evaporation of volatile oils such as light gasoline. This causes falsely low sulfur determinations and also makes it almost impossible to check results on such light petroleum products.
b
FIGURE1. IMPROVED LAMP A lamp completely assembled E : adjusted sleeve with wire control. Approximate tubing size 0.125 X 2 inches (0.3 X 5 cm.) C, outer tubing, approximately 1.5 inches (3.75 om.) long and sufficiently large to slip over adjusting sleeve
The Edgar and Calingaert (1) lamp is very satisfactory but is not readily available in all laboratories and is not, properly speaking, an A. S. T. M. lamp. A slight modification of the regular A. S. T. M. lamp has been devised in this laboratory which is easily made by anyone and allows ready regulation of flame size without the necessity of taking the lamp from under the chimney. The single piece of glass tubing of the regular A. S. T. M. lamp has been replaced by two pieces of different size, one within the other. The smaller piece is the same inside diameter as the old single piece and is recessed slightly near the bottom to allow a
piece of line wire about 7.5 om. (3 inches) long and 0.5 mm. (0.020 inch) in diameter to be twisted around it. The larger piece is of sufficient size just to allow the smaller to slip freely within the larger. The larger, or outside piece of glass tubing, is held tightly in the cork. The smaller piece extends through and rojects out of the larger at the bottom about 1.25 cm. (0.5 incg) To regulate the flame, the smaller piece which holds the wick is raised or lowered inside the larger by the wire which extends u p through a groove in the cork. This groove is small enough to hold the wire by friction, which in turn holds the glass sleeve a t any set position. Any vapors from light gasoline that pass up between the inner and outer tubing are burned in the flame along with gasoline fed through the wick. In other words, the vent for this lamp is the small annular space between the two ieces of glass tubing. The flame of course remains at the top of t i e larger piece at all times. The author has run several samples of winter-grade gasoline and others even more volatile, using this new lamp, and finds that it gives very good results and requires much less attention than does the regular A. S. T. M. lamp. Some comparative results on the improved type of lamp and on the standard A. S. T. M. lamp are given below. Four runs were made with each type of lamp, using a cracked winter-grade gasoline of high sulfur content. IMPROVED LAMP Sulfur % 0.249 0.255 0.252 0.247
A. 8.T.M. L A M P Sulfur % 0.240 0,209 0 237
Too badly smoked t o titrate
None of the lamps of the improved type heeded any adjusting or attention after the first 10 minutes of burning, while the A. S. T. M. lamps required full attention from the start until the finish of the burn. I n the author's opinion, this new lamp is in many ways superior to the A. S. T. M. lamp for running gasolines of high volatility, and works equally well on heavy gasolines and illuminating oils.
LITERATURE CITED (1) Edgar and Calingeert, IND. ENO.CHEM.,Anal. Ed., 2, 104 (1930).
RECEIVED August 5, 1933.
Stirring Rod with Fritted Glass Disk JOHNE. S. HAN, 155/3 Route Stanislas Chevalier, Shanghai, China
F
OR general use, the author has designed a stirring rod with a disk of fritted glass fused onto an end. The rod was made by the Jena Glass Works of Schott und Gen. and
-
found to be highly serviceable in boiling off the excessive bromine during Eschka's sulfur determination and in similar operations. The rod is, however, not recommended for quantitative work where precipitation is involved, as precipitate is liable t o lodge in the fritted glass. RECEIVED September 26, 1933
