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to form the superoxide, KOJJwhich is the stable oxide at room temperature, in the presence of normal partial pressures of oxygen. Gilbert [Chem.Eng. News, 26, 2605 (194811 states that the rather frequent explosions which occur in handling potassium can be attributed to the formation of superoxide on the surface of the metal a t room temperature. The cause of this explosion is not completely understood. Such an explosion has been observed in this laboratory with a sample of sodium-potassium heavily coated with oxide. The use of a dry boy is apparently mandatory when denling with such samples. BASEDon work performed for t h e Atomic Energy Commission by Carbide and Carbon Chemicals Corp., a Division of Union Carbide a n d Carbon Corp.
Apparatus for Hot Filtration, Extraction, and Recrystallization with Volatile and Flammable Solvents. Haruo Shiba, Chemical I,aboratory, Facult,y of Engineering, Pniversity of Hiroshima, Hiroshima, Japan. organic solution may be filtered through Rer4. gam1 and Stange’s hot filter (3),or for higher temperature FLAMMABLE
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long enough to pour the solution onto the filter paper. Even if crystals deDosit on the filter paper during filtration, subsequent refluxing is sufficient to extract the substance out of the filter paper; therefore no loss of crystals is caused. The upper rim of the funnel must be wide enough to prevent the escape of the solvent vapor through the ground-glass joints, Q and R, of the funnel and the condenser. The upper part of the funnel may also be constructed as shown in Fighre 2, if the Figure 2. special H~~ funnel is relatively small. But, it is diffiFilter cult to remove the condenser from the funnel, if the ground-glass joints of the funnel and the condenser become tight, owing to the heat of reflusing liquid. This apparatus may also be uaed for the cont’inuous and automatic extraction of solid substances-e.g., as a substitute for a Soshlet ( 2 , 7 ) . I t is not nereswry to use n Ppecial thimble made of filter paper.
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1’:iul’s hot filter ( 5 )may he used. Hut in either case, the evaporation of volatile and flammable solvents cannot be prevented. Especially in recrystallization, the deposition of crystals on the filtrr paper owing to evaporation of the mother liquor will cause troublesome manipulation and serious loss in yield. Hot filtration through a preheated Riichner funnel into a preheated suction flask msy not be advimble, as loss of volatile solvent can occur. Houlmi’s device (3)-set,ting a round-bottomed flask upon a stemless funnel and circulating cooling water through the flask:tlthough the same as the following in principle, is provisional and not gas-tight for the rising vapor of the solvent. Extractors of Kulilman and Gerschson ( i ) ,of Rudernian (6), and of Dreschel ( l i , are also similar in principle to the following, but are more r\priiiive or complicated. The author has devised a simple :tiid convenient hot filter. as shown in Figure 1, with which recrystallization with volatile organic solvents can be accomplished with ease and without loss of either solvent or the crystals deposited on the filter paper by ev:iporation of solvent. The glass apparatus includes a conical flask, A , connecting through ground joint, D, to a specially coiistructed funnel, E , having a some what constricted neck and two groundglass joints, E and R. The upper joint, R, has a broad rim which is ground flat to fit the similar joint, Q, ou the umbrellalike “skirt,” S, of the condenser, C. I n order to facilitate the rise of the solvent vapor through the apparatus, holes H and Z< are bored through the stems of the funnel and the condenser. T o manipulate the apparatus, fit a fluted filter paper, P, into the funnel, pour some of the aolvent to be used for recrystallization into the conical flask, and boil gently to preheat the funnel and the filter paper. IVhile the vapor of the solvent is rising among the flutes of the filter paper, take care t h a t the vapor does not reflux over the upper rim, R, of the funnel, because of the flammability of the solvent. As an added precaution, place the condenser on the funnel before refluxing. Then after removing the Bunsen burner flame to prevent possible ignition of the solvent, take off the condenser
Figure 1. Apparatus for Hot Filtration a nd Recrystallization
REFERENCES
(1) Drewhel, J . p r a k t . Chem.. 123, 350 (187;). (2) Fieder, L. F., “Experinletits iii Organic Chemistry,” pp. 37, 41, New York, D. C. Heath Co., 1941. (3) Houben, J.. “Die Methoden der Organisclien Chetiiie,” 3rd ed., T-01. I. pp. 435-8, Leipsig, Georg Thieine. 1925. (4) Kuhlrnari and Gersrhson, 2 . anal. chem., 106, 145 (1936). ( 5 ) Paul, Th.. Ber., 25, 2209 (1892). (6) Kuderrnan, IND. EXG.CHEM..AX.AL.ED., 16, 332 (1944). ( i )Keigand, C.,
“Organisch-Cheniische Experinientierkiinst.” pp.
61-4, Leipsig, Johann Ambrosius Barth, 1938. (8) Weissberger, A,, “Technique of Organic Chemistry,” T’ol. 3. g p . 236-40, New York, Interscience Publishers, 1949.
All-Glass Atomizer for Chromatographic Analysis Procedures. Victor H. Ortegren \Vesteix Regional Research Laboratory, .%lbany. Calif. ail atomhe1 t o a developer solution on paper Tusedu ~ine chromatography is a common procedure requiring ot
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equipment that will produce a fine spray with a minimum of larger drops. The atomizer should be resistant t o chemical attack so that it does not contaminate the developer solution, convenient to use and easily cleaned, sturdy to avoid breakage, and inevpensive and relatively simple t o construct. Over 50 atomizere of the design described here have been made h! the author during the past yea1 in the glass-blowing shop in this laboratory. They have pi oved highly satisfactory and popular with the chemists using them. Rate of atomization can ea& be controlled, larger droplets of liquid that may be formed in the atomizing zone (especially on starting) are not discharged a i t h the spray nor allowed to run down on the outside of the apparatus but are automatically returned to the supply vessel, and the atomizer can be used R ith any vessel, even an open beaker 01 test tube, as the reservoir is not under poiitive pressure. Figure 1 represents an elevation in cross section. Figure 2 represents a plan view in cross section taken on AA’of Figure 1. The liquid to be atomized is contained in bottle 1 provided Mith a standard-taper ground joint (19/22), outer 2. The level of liquid in the 250-ml. reagent bottle, 1, is represented by line 3. The atomizer, 4, has a spherical jacket, 6 (about 45 mm. in diameter) provided with a large opening, 7 (about 18 mm. in diameter), for discharge of the atomized liquid. The bottom of a standard-taper ground joint (19/22), inner 5, is attached to tube 8 (11 mm. in outside diameter), provided with a vent, 9. For supplying liquid to the atomizing jet, a capillary tube, 10 (1 mm. in inside diameter), is used, which is rigidly supported in place by rods 11, 12, and 13. Air for atomizing the liquid is introduced via a conduit, 14, which tapers to a small nozzle, 15, as shown. Diversion conduit 16 connects with air conduit 14, and leads to a finger-controlled port, 17, on the outside of jacket 6. The air-supply conduit, 14, is connected to a source of com-
