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INDUSTRIAL AND ENGINEERING CHEMISTRY
tion mas tried as base solution, but increased the rate of flow of the mercury drops to such a n extent that no readings could be made. Since each compound results in a characteristic rise a t a specific voltage with the use of the proper base solution, the interference of such substances as cystine and glutathione would be eliminated. The acid base solution used for this ascorbic acid determination inhibits the production of current rises by these compounds. They are determined polarographically in ammoniacal solutions of cobaltous chloride in ammonium chloride (1). Since this work was only preliminary, no quantitative determinations of ascorbic acid were run. However, results obtained indicated that this method could be adapted for accurate quantitative analysis by comparing the curves obtained when an unknown solution mas used with calibration curves.
Vol. 13, No. 9
Acknowledgment The author is indebted to C. G. King of the University of Pittsburgh for assistance and guidance during the investigation and to the Buhl Foundation for a research grant which made the investigation possible. The investigation mas carried out on an Elecdropode kindly supplied by the Fisher Scientific Company.
Literature Cited (1) Brdicka, R., CoZZ. Czech. Chem. Commun., 5, 112-28, 148-63 (1933). (2) Fisher Scientific Co., Laboratory, 10 (9,97 (1939). (3) Kodicek, E., and Wenig, K., Nature, 142, 35 (1938). (4) Kolthoff, I. M., and Lingane, J. J., Chem. Rev., 24 ( l ) ,1 (1939). ( 5 ) Muller, 0. H., Ibid., 24 ( l ) , 95 (1939). APPROVED by the Director of the Kew York State Agricultural Experiment Station for publication a8 Journal Paper 391.
A Simplified, Water-Jacketed, Fraction Receiver R. S. TOWNE, E. E. YOUNG, AND L. T. EBY University of Notre Dame, Notre Dame, Ind.
W
ITH the development of precision fractionating columns for use under reduced pressure has come a need for a receiver which will permit a n indefinite number of fractions to be obtained without disturbing the pressure within the still. The older types of vacuum receivers, such as the Bruhl receiver, and the many varieties of multiple rotating receivers (2) are inadequate since the number of fractions which may be obtained with them is strictly limited. Several variations of the Thorne (4) distillation triangle are described in Morton ( g ) , some of them very satisfactory. Cloke ( 1 ) has recently proposed a water-jacketed modification, and Noonan (3) has designed a vacuum receiver in which the usual four two-way stopcocks have been replaced by a single multiple-way stopcock. The greatest disadvan-
tage of these receivers is that they are expensive, owing to the large number or special nature of the stopcocks required, or that they require considerable glass-blowing skill to make. The accompanying figure shows a fraction receiver which the authors developed in the organic preparations laboratory a t the University of Notre Dame. I t combines the advantages of the earlier types with greater simplicity of manufacture and operation, and reduced cost. It can be easily made by an amateur glass-blower. Only two standard 2-mm. bore stopcocks are required: a three-way T stopcock (Corning KO. 7420) and a three-way parallel stopcock (Corning KO. 7380). The cost is considerably less than that of four twoway stopcocks. The dimensions given are those which have been found most satisfactory with the ordinary laboratory stills, but a larger or smaller reservoir may be made for special work. The operation of the apparatus is simple. The sample is transferred from the reservoir of the fraction receiver to the receiver through stopcock B. B is closed and A is given a half turn, so that the receiver is disconnected from the pump but the still remains under vacuum. Air is admitted t o the receiver through B. After the receiver containing the fraction has been removed and a fresh receiver attached, B is closed and A is turned clockwise a quarter turn, so that the still is temporarily disconnected from the pump while the new receiver is being evacuated. When the correct pressure has been established in the receiver, A is turned clockwise again a quarter turn, so that the still and the receiver are both connected to the vacuum line as shown. Ground-glass joints may be used to connect the fraction receiver to the column and to the receiver, but this raises t h e cost without materially adding to the usefulness of the apparatus. A double tube may be used to connect the fraction receiver to the receiver to avoid any difficulty with viscous liquids rising in the equalizing arm, but for the most part this refinement has not been found necessary.
Acknowledgment The authors wish to thank Kenneth N. Campbell for his suggestions during the course of this work.
Literature Cited (1) Cloke, J. B., IXD. EXQ.CHEM.,ANAL.ED.,12,329 (1940). (2) Morton, A. A., “Laboratory Technique in Organic Chemistry”, p. 110, Kew York, McGraw-Hill Book Co., 1938. (3) Noonan, E., IND.ENG.CHEM.,ANAL.ED.,10, 34 (1938). (4) Thorne, L. T., Ber., 16, 1327 (1883).
