Glass Unit for Liquid and Vapor Phase Extraction Emfloying a Single Processing Chamber. Harold A. Sauer, B111 Telephone Laboratories, Inc., Murray Hill, 5 . J. extiactor and vapor degreaser has wen deA scribed . Soxhlet [Sauer, H. -I., 1x1).ESG. Er., 73 GLASS
CHEU., ~ A L .
18,
(1946)] in which the condenser is integral with the extra( ting and degreasing compartments. The treating chambers are irovided Kith open tops, so that there is access to them a t all time: without disturhing the operation of the equipment.
feature might be more easily realized in a modification of the all-glass unit in which metal condenser shells are adapted to the treating chamber. All-glaqs units have a distinct advantage over part metal, part glass in that rach aspect of the operation is clearly in view and cleaning of the apparatus is greatly simplified. Although an asbestos wapping on the treating chamher perceptibly reduces heat los~es,it has been eliminated because it obstructs the view of the intei ior and therefore considerably increases the danger of hreakagr The operation of this equipment is similar to that of the previousmodel. Because of the size of the treating section, it is necessary to provide a firm support, which includes a mechanism for raising and lowering it. This provides a convenient means for emptying the reservoir quickly and ea5iIy. The diagram indicates where support is made, and shon s the cushioning seal (metal bellows), interposed between the treating Fection and the reservoir in order to prevent undue pressure upon the glass flask, which may cause breakage when the treating section is brought into contact with the reservoir. Smaller units of this design need not be elaboratelxsupported, but are conveniently set up for operation employing conventional laboratory support q for glassware. Versatile Electronic Manostat. \Villiam E. Erner and Kenneth S . Campbell, University of S o t r e Dame, S o t r e Dame, Ind. SENSITIVE
manostat that would function equally w l l at,
A atmospheric and reduced pressures was needed to control
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E SPHERICAL
JOINT.
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DRAIN
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CUSH ON S E I .
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SPIIEC C I L J O N 1
5000 ML FLASK
While this unit finds much use in this laboratory, the I ize of the equipment and the space requirement for installation tc nd to increase somewhat out of proportion to the size of the ob ect to be treated. This situation was encountered when the need for a larger capacity was indicated. Accordingly, a unit was designed and constructed, as s h o m in the diagram, consisting of a solvent reservoir and a single-chamher processing section, which serves as a compartment for liquid or vapor phase treating. Conversion from one type to the other can be quickly effected by manipulating the stopcock in the direct line connecting the chamber with the solvent reservoir. Although the condenser is integral with the treating section, unlike the earlier design, the upper end is open. From a glassblowing standpoint, it is possible to equip a glass unit of this size with a double glass-seal condenser, but the
the vaporization rat,e in a 100-theoretical-plate Hyper-cal column and a 120-theoretical-plate Strdnian-type column. Salt water manostats work well at atmospheric pressures, but the vapor pressure of the solution is too high for vacuum operation. llercury offers the advantages of high electrical conductivity and low vapor pressure, but because of its high density, it cannot ordinarily be used in manostats sufficient1)srnsitive t,o control the vaporization rate in columns with a ver>small back-pressure. Hall and Palkin ( 1 ) devised a mineral oil manostat utilizing the surface meniscus to actuate a photocell, hut this type of manost,at is difficult to construct and adjust. Hershberg and Hunt,ress ( 2 ) used sulfuric acid as a manostat fluid. Sulfuric acid is objectionable because it has a considerable vapor pressure a t low operating pressures, it tends to absorh t h r vapors of many organic compounds, and there is the inherent. danger of apparatus breakage near delicate equipment. Triethylene glycol (Q), with a few drops of sulfuric acid added to increase the electrical conductivity, seemed to offer the most advantages. The electrical conductivity was sufficient,ly high to actuate an electronic relay, Euch as vias devised by Serfass ( 5 ) . Triethylene glycol has a lox vapor pressure, a lo^ densit,y, and very little tendency to absorb paraffin vapors.
-4simple U-tube was used for the manostat. One electrode \vas sealed into the wall of the tube below the normal liquid level. The other electrode consisted of a piece of fine gold-plated hrass chain from an item of dime-store jewelry. The chain was weighted a t the bottom with 1 gram of solder and contact with the liquid was effected with a 1-cm. length of platinum wire sharpened to a needle point. The upper end of the chain was secured t o a piece of platinum wire sealed into a simple windlass made from the inner member of a 12-mm. standard taper joint (Figure 1). h length of hairlike copper ri-ire was t,hreaded through several links of the chain and secured a t both ends t o assure good electrical contact. The U-tube was provided a t the top TTith a stopcock cross bridge that was normally closed and mas opened before distillations f o r air flushing of the system; it also served as a safety valve for possible emergencies. The left arm of the U-tube was provided with an outlet leading to the still pot of the column and to a 1232
