Improved soxhlet extraction apparatus - Analytical Chemistry (ACS

Improved soxhlet extraction apparatus - Analytical Chemistry (ACS...

1 downloads 92 Views 260KB Size

I N D U S T R I A I, A N D E N G I N E E R I N G C H E M I S T R Y

January 15, 1932



2 3 4 5 6








A12OP %










0.35 0.39 0.02



0.00510 0.00324 0.00272 0.00265 0.00315 0.00675

0.00150 0.00084 0.00024

0.00309 0.00289 0.02310 0.00620 0.00650 0.00677


0.03 0.03 0.04 0.06 Determined b y the

0.04 0.27


0.072 0.004

0.019 0.010 0,012

0.034 0.024

0.041 0.040 0.041




0.00072 0,00156 0.00087




0.272 0.227


0.407 0.295 0.173 0.405

TOTAL 01 I N STEEL % 0.065 0.054 0.103

0.070 0.044 0.088

direct hydrochloric acid method.

furnace, and with ferromanganese and ferrosilicon in the ladle, have been analyzed for manganous silicates by the electrolytic, Dickenson, and chlorine gas extractions. These samples were cut from adjacent positions and so should be nearly identical in regards to oxide content. The extractions were carried out in the same manner as has been outlined, and the results are shown in Table V. The total oxygen in the steel is calculated from the oxygen of the silicon dioxide and the manganous oxide on the assumption that the steel is completely deoxidized, and all the oxygen is combined in these oxides. Table V shows the Dickenson method to be very destructive to the manganous silicates found in the killed steel. However, it is true that an analysis of the residue recovered by this method may give an indication of the relative amounts of manganous oxide and silicon dioxide in the silicates. The time required for the determination is prohibitive t o routine analysis. The chlorine gas extraction a t the low temperature used gives apparently good results, but the fact that only 10 grams may be used in the extraction causes the oxide residue to be so small that very accurate results are difficult to obtain. Also, the small sample makes the analysis representative of a local condition. Another difficulty is that a t this low temperature of volatilization the manganese is not volatilized but remains in the residue and must be washed out with the cold water.

Carbon has a power of absorption that makes this step difficult, and error may occur here as the actual manganous oxide is present in such small quantities. The electrolytic extraction gives the best results, most nearly representative of the steel. A large sample is used and the oxides extracted are enough for an accurate analysis. All the methods use clean and polished solid pieces of steel, eliminating any surface oxidation which may occur in any method using drillings or millings. I n Table VI are shown types of results obtained through electrolytic extraction on rimmed carbon steels. LITERATURE CITED Bardenhauer, P., and Oberhoffer, P., Mitt. Kaiser- Wilhelna Inst. Eisenforsch. DUsseldorf, 9, 195-200 (1927). Diekenson, J. H. S., J . Iron Steel Inst. (London),113, 177 (1926). Fresenius, R., 2.anal. Chem., 4, 72 (1865). Herty, C. H., Jr., Fitterer, G. R., and Eokel, J. F., Bur. Mines, Carnegie Inst. Tech., and Mining Met. Advisory Boards, Mining Met. Inves., Co6p. Bull. 37 (1928). Herty, %. H., Jr., Fitterer, G. R., and Marshall, W. E., Jr.. Ibid., 44 (1929). Wasmuht, R., and Oberhoffer, P., Arch. EisenhQttenw., 2, 829-42 (1929). Westoott, B. B., Eckert, E”. E., and Einert, H. E., IND. ENQ. CHEM.,19, 1285 (1927). RECEIVED April 1, 1931.

Improved Soxhlet Extraction Apparatus I). S. BINNINGTON, Department of Agricultural Chemistry, University of .Wanito3z, Winnipeg, Canada


LTHOUGH a large number of different devices are available for the continuous extraction of solids with volatile solvents, the familiar Soxhlet apparatus is still widely used because of its general adaptability. The various types of Soxhlet apparatus now in use have, however, certain manifest disadvantages. The use of cork stoppers is undesirable because of leakage and the presence of extractable matter (3). Ground-glass connections, although obviating the latter difficulty, do not entirely eliminate leakage and are distinctly fragile. In extraction apparatus such as the Wiley-Soxhlet of 1912 ( 2 ) ,the Underwriters Laboratory model of 1912 ( I ) , the Bailey-Walker of 1914 (5),or the Pickel of 1919 ( d ) ,these disadvantages have been overcome, but in these types the solvent functions a t or near its boiling point which is undesirable, as pointed out by Ford in 1912 ( 2 ) , when working with nonhomogeneous solvents. A further objection is the limited amount of sample that the extraction tube will contain. Probably the most successful type of Soxhlet extractor now available is that employing a ground-glass joint between the condenser and extractor, and a mercury seal between the extractor and flask. I n the apparatus described here the mercury seal is retained, but all other joints exposed to the

vapor of the boiling solvent are eliminated-a characteristic of the improved types of apparatus referred to above. The modified apparatus is illustrated in Figure 1, which is practically self-explanatory. The body of the extractor is extended considerably above the vapor inlet, and condensation is effected by means of a separate condenser inserted into this upper portion, and is held in place by a wide flange on the top. The entire apparatus is constructed of Pyrex glass, which, together with the absence of fragile ground joints, makes a very rugged and serviceable outfit, well adapted to routine work. It will be noted that the water inlet and outlet tubes of the condenser are practically vertical, instead of the usual bent-at-right-angles type. This arrangement was adopted for convenience in setting up a battery of extractors, such as illustrated in Figure 2, which shows a battery of six modified extractors heated by a water bath operated by a 330-watt immersion heater. A set-up of this kind is perfectly safe for use with the most volatile or inflammable solvents, and has been operated in these laboratories for some time with excellent results. Ether and carbon bisulfide extractions extending over a period of 3 to 4 days have been made without any


Vol. 4, No. 1


extractors have proved of great value in large-scale extractions, enabling the entire operation t o be performed within all-glass equipment, thus replacing metal apparatus and eliminating cork stoppers and rubber or ground-glass connections. LITERATURE CITED (1) Cary-Curry, H.J , J. IND. ENQ.C H ~ M4, . , 535 (1912). (2) Ford, T. B., J. Am. Chem. SOC.,34, 552 (1912). (3) Lamar-Cohn, “Organic Laboratory Methods,” translated by Oesper, 1st ed., p. 195, Williams & Wilkins, 1928. ’ (4) Pickel, J. M., J. IND. ENO.CHEM.,11, 1053 (1919). (6)Walker, P. H., and Bailey, L. H., Ibid., 6,497 (1914). RECEIVED October 6, 1931.

Mechanical Shaking Device 0. W. CHAPMAN AND FREDCINOTTO, Kansas State ‘

Teacher’s College, Pittsburg, Kans.


HE accompanying diagram shows the construction of an


attention whatsoever and without any addition of solvent after the initial charge has been introduced. The modified apparatus is no more difficult to operate than the conventional Soxhlet with attached condenser, A short loop of stiff wire is made across the water inlet and outlet tubes, and is used to suspend the condenser from a hook of brass rod, placed a t such a height that the condenser freely ‘clears the top of the extraction tube during the introduction or removal of sample or solvent. If the thimble containing the sample is plugged with extracted absorbent cotton, it may be removed by simply inverting the apparatus, for otherwise it is necessary to employ a pair of long dissecting forceps.


The dimensions given in Figure 1 correspond with those of the standard Soxhlet designed to take a 33 by 80 mm. thimble, but extractors of identical construction and of very large capacity have been made in this laboratory by the use of the largest Pyrex tubing available (60 mm. in diameter). These

inexpensive shaking device which may easily be made in the laboratory. It was designed for use in the study of the corrosive action of milk on metals, and so made that the liquid flowed constantly over the immersed strips of metal. The device consists of a metal water bath, 12 inches (30.5 cm.) in diameter by 20 inches (51 cm.) high. The remaining parts are of wood, painted to prevent warping. The drive shaft is connected to a metal eccentric, which is attached to the chuck of a friction drive stirrer. This permits convenient regulation of the rate of shaking, while the length of the stroke is controlled by the point of attachment of the drive shaft. )To chuck of Cenco Friction Drive Stirrer



The apparatus desoribed furnished a satisfactory shaking device at a low cost. RIWEIVH~D July 28, 1931.