Large-Capacity Soxhlet Extractor and Reflux Condenser ANGUSE. CAMERON,' University of Minnesota, Minneapolis, Minn.
T
HE need for a device of large capacity which would serve for the extraction of considerable quantities of solid material led the author to design a modification of the Soxhlet extractor. The extractor described here, shown in detail in Figure 1, is rugged in design and construction and is not particularly difficult to make. The most convenient s t a r t i n g point seemed to be a 5-liter Pyrex balloon flask. Larger flasks would involve such quantities of solvent that it seemed more desirable to build a battery of 5-liter extractors rather than to make larger ones. The stem, A , which carries t h e vapor to the condenser, is made of tubing havi n g a n o u t s i d e dia m e t e r of 30 to 35 mm. and contains the siphon tube, R, which i s m a d e of 8-mm. t u b i n g . To insure certain s i p h o n i n g , the bend a t the top of t h e s i p h o n tube is allowed to flatten s o m e w h a t and the o p e n i n g where the lower end is sealed through the stem is allowed to constrict until i t i s a b o u t 3 mm. in diameter. Thorough annealing of the e x t r a c t o r is necessary, T h e s t e m can be lined up in the middle FIGURE 1 of the flask and the reflux condenser, D, offset somewhat, as shown, to return the condensate to the extractor. It is preferable that these extractors be supported by a large ring rather than by a clamp around the neck. They may be fitted with groundglass joints if desired. The joints need not be larger than those used with the customary small Soxhlets. I n order to prevent clogging of the siphon, if the solid being extracted has a tendency to crumble, a layer of glass beads covered with cotton may be used as a support in the bottom of the flask. The problem of securing sufficient condensate from a reflux condenser to make extractors of this size useful led the author to develop what he believes to be a novel condenser. The 1 Present address, Institute of Applied Optics, University of Rochester, Rochester, N. Y.
proper design of a large-capacity reflux should take several factors into account. It is preferable that the condensate not be returned down the tube, which is carrying vapor to the cooling surface, for with high vapor velocities, choking will occur. It would be desirable to avoid passing vapor over portions of the condensing surface which are already working a t capacity, and the vapor should have only a short way to go before reaching the condensing surface. To secure these desired features, the use of a straight or bulbed tube of large diameter is not of itself desirable. The condenser must be efficient in oDeration. simple in design, and rugged in construction if it s; to be practical for laboratory use. The condenser is shown in Figure 2. A large tube, A , 25 to 30 mm. inside diameter thin-wall Pyrex, is used for the inner tube. Up the center of this passes another tube, B, 10 mm. smaller, which is sealed off at the upper end and is perforated with two vertical, diametrically opposite, rows of holes 8 to 10 mm. in diameter and spaced 18 to 20 mm. apart, measured from center to center. The vapor is directed against the condensing surface from these ports, and their arrangement in vertical rows a l l o w s uninterrupted flow of c o n d e n s a t e down part of the c o n d e n s e r w a l l . The condensate is returned to the flask from sump D through ct 6-mm. tube, E, sealed in as shown in the sketch. Three glass guide-pins, F , sealed to the manifold, B, are fitted by filing the ends before the manifold is sealed in at 0. They provide the support necessary to prevent breakage due to rough h a n d l i n g , and yet allow the manifold to expand when hot vapor passes through it. The inner tube of the condenser is constricted 2 to 3 cm. above the end of the m a n i f o l d , giving room for a safety bulb, H, about 6 to 8 cm. long, which will take care of surges when the condenser is working a t capacity. It is advantageous to bend the water inlet and outlet downward as shown and to have an enlargement, I, in the FIGURE2 nose of the condenser t o rest upon the stomer. The approximate dimensions of the condensers which the author has constructed are as follows: length of jacket and condensing surface, 60 to 70 cm.; over-all length, 90 cm.; length of nose of condenser, 20 cm. Condensers of these dimensions have a capacity of 8 to 10 liters of acetone per hour with cooling water temperature of 7" C. They will not reach capacity with alcohol or acetone in a 5-liter
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October 15, 1932
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INDUSTRIAL AND ENGINEERING CHEMISTRY
flask heated on a steam bath. The capacity for ether is surprising, and only a faint odor can be detected at the top. Since condensation is favored by a film of cold liquid running down the inner tube, the condenser has not reached capacity when the vapor is condensing clear to the top of the manifold.
ACKNOWLEDGMENT The author wishes to acknowledge the valuable assistance of Milton E. Ryberg, also of the University of Minnesota, in the construction of the extractors, RECEIVED April 29, 1932.
Specific Test for Orange Honey R. E. LOTHROP, Bureau of Chemis$try and Soils, Washington, D. C. WING to its pleasant flavor, orange honey is generally considered to be one of the most desirable floral types for table use. In California orange is one of the important sources of honey. The trees bloom in April, and the flow of nectar is extremely abundant, a t times being secreted in such quantities that men working in the orchards are saturated with it. The flow lasts about three weeks, and during this time strong colonies of bees usually average 60 or more pounds of orange honey per colony. One case is recorded in which more than 170 pounds of orange honey were stored by a single colony of bees in 10 days. The honey from orange is white in color, heavy in body, of the finest quality, and is much in demand in the markets. This has created an incentive for some unscrupulous honey dealers to attempt the marketing of honey labeled "orange" in which some less expensive light colored honey is substituted for part of the orange. I n some cases honey is sold as orange honey which contains very little orange or none a t all. The writer recently secured a sample of honey being sold in California as orange that proved from examination of the pollen1 to consist chiefly of Hawaiian algaroba honey. Although microscopic examination of the pollen was effective for determining the floral source of the honey in this particular case, this method cannot be relied on for determining the floral source with reasonable certainty in all cases. As pointed out by Nelson ( I ) , the distinctive pleasant aroma of orange honey is due to the presence of methyl anthranilate. Methyl anthranilate, or the methyl ester of o-amidobenzoic acid, CaH4(NH2) (COOCH,), is rather widely distributed in nature. It occurs as a constituent of oil of orange flowers, to which it imparts the characteristic aroma. It also occurs in a number of other fragrant oils in small amounts. A test for detecting methyl anthranilate in fruit juices in quantities as small as 0.1 mg. has been devised by Power (2). In order to determine whether or not detectable quantities of methyl anthranilate are present in other floral types of honey besides orange, tests for methyl anthranilate were conducted on a considerable number of representative floral honeys,.special attention being given to those which constitute the main source of honey produced in California. The test for methyl anthranilate, essentially that described by Power, was carried out as follows: One kilogram of the honey to be tested is dissolved in 600 to 800 cc. of distilled water, and the resulting solution distilled in a current of steam until about 700 cc. of distillate are collected. The distillate is extracted with three successive portions of chloroform of 35 cc. each, the united chloroform liquids are passed through a dry filter and carefully evaporated in a small beaker on a water bath, a current of air being passed over the surface until the solvent is just completely removed. The residue is then immediately treated with 2 cc. of 10 per 1 The examination of the pollen of this sample wa8 carried out by G. L. Keenan, microanalyst of the Food and Drug Admimstration, U.8. Department of Agriculture.
cent sulfuric acid, and the solution is transferred to a test tube, when it is ready for the specific test. (If a residue obtained by the evaporation of the chloroform is kept for any length of time exposed to the air before treatment with the dilute acid, volatilization of the ester will occur.) The acid liquid is cooled, one drop of a 5 per cent solution of sodium nitrite is added, and subsequently a few crystals of urea are added in order to destroy any possible excess of nitrous acid. The diazotized liquid is now added to a mixture consisting of one cc. of 0.5 per cent pure b-naphthol (prepared by dissolving 0.5 gram of pure &naphthol in 2 cc. of 10 per cent sodium hydroxide, and diluting to 100 cc.), one cc. of 10 per cent sodium hydroxide, and one cc. of 10 per cent monohydrated sodium carbonate. If not less than 0.0001 gram of methyl anthranilate is present, a yellowish red precipitate will be produced. TABLE I. RESULTSOF TESTSFOR METHYLANTHRANILATE IN HONEYS O F VARIOUS FLORAL TYPES PREDOMINANT FLORAL SOURCE"
ORIQIN
QUANTITY DISTILLED RESULT^ OF TEST Grams
Algaroba Sage Alfalfa Holly Manzanita
Hawaiian Islands California California California California
1000 1000 1000 1000 1000
Negative Negative Negative Negative Negative
Tar weed Eucalyptus Sumac Cotton White clover
California California Connecticut Texas Ohio
1000 1000 1000 1000 1000
Negative Negative Negative Negative Negative
500 1000
Strong positive test Strong positive test (heavy orange-red PPt.1
Parmetto Calif. orange 1 Calif. orange 2
Florjds
1 .
California California
Mixture: 60% orange and 50% tullp poplar 1000 Strong positive test Mixture: 26% orange and 76% tu11 poplar IO00 Strong positive teat Mixture: lo'$ orange, and 90% tuh poplar 1000 Positive Mixture: 5 g orange and 95% tul& Doular 1000 Negative .- _ - 0 Considerable care was taken t o procure Sam les that truly represented floral types given. Each sample was obtained K o m a reliable dealer in a region which is known t? produce that particular kind of honey and a t a time of sear when honey 18 ordinarily extracted. Floral types we;e ohecked by careful nqtation of physical properties, such as flavor and aroma, color, and granulation propertlea, and a comprehensive ohemlcal apalysis of ea(th was made. I n addltion, pollen of each sample was exammed t o obtam confirmatory data relative to floral source.
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The results obtained by application of the test described above to honeys of various floral sources are given in Table I. From the results it is seen that, of the honeys tested, only orange responded positively to the test. Apparently methyl anthranilate is a flavoring compound peculiar to orange honey, not occurring in other floral types, a t least in amounts that can be detected by this test. Its detection in honey, therefore, serves as a specific test for orange honey. By using
