November 15,1933
I N D U S T R I A L A N D E N GI N E E R I N G C H E M I S T R Y
was a linear relation between the amounts of dextrose present and the amount of copper reduced. I n order to derive an expression of this relation which would be more applicable under the authors' conditions than the published ratios, a straight line was fitted by the method of least squares to the results of 46 determinations (omitted). This linear estimating equation was found to be: Mg. of glucose = 0.458 (mg. of copper reduced) - 1.546, with a standard error of 0.74 mg. of glucose, over the range between 35 and 125 mg. of glucose.
Continuous Liquid Extractor ABRAHAMMAZUR,ROBERTROSENTHAL, AND BENJAMIN HARROW College of the City of New York, Convent Ave. and 140th St., New York, N. Y.
A
CONTINUOUS liquid extractor for solvents having a lower specific gravity than the liquid to be extracted is shown in the figure. The receiving flask A , containing the solvent, can be made from a 250-cc. Erlenmeyer flask. The container D consists of a large test tube constricted a t both ends, the size of the tube varying with the quantity of liquid to be extracted. The side tubes G and F for filling the receiver and container. a s well a s H , a r e made by constricting the mouth of a 15 X 1.5 cm. t e s t t u b e . The glass stopcocks I a n d J a r e u s e d to drain the apparatus. If a glass-blower i s available, H may be made with a mercury s e a l connecting t h e c o n d e n s e r and the container, thus doing away with a stopper. The tube E is joined to D a t the upper end by an inner seal and G extends down almost to the bottom of the tube; or, to do away with this inner seal, E can be joined to D by a stopper at the upper end. The circuit is completed by the tube L which joins the receiver A and the container D. The solvent (ether) is placed in A by means of the side tube G. The ether is boiled on the steam bath K , vaporizes up B, condenses in C, and flows down E, bubbling up to extract the liquid (some aqueous solution). The ether extract forms a layer on top of the liquid and when it reaches tube L flows back into the receiver. Pure ether boils again to extract continuously. After complete extraction, the ether extract may be drained by means of I and the liquid removed from D by means of J . The apparatus is absolutely stationary and never has to be moved or adjusted. It may be taken apart but can be filled and drained without disassembling very easily. A series of three or four of these extractors may be set u p on a steam
d!kF
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These data indicate that the combined carbonate-citrate method gives results closely paralleling those published by the authors, but because of the number of factors which affect the reduction each analyst should carefully standardize his technic and for the more accurate work should derive an expression of the relation between the amount of dextrose present and the amount of copper reduced (or set of copper: glucose ratios) which is applicable under the conditions prevailing in his laboratory. RECEIVED June 7, 1933. Published with the approval of the Director of the North Carolina Agricultural Experiment Station as Paper 72 of the Journal Series.
bath in a small hood. Both receiver and container may be varied in size, depending upon the quantities to be used. The container D, however, should be kept narrow, so as to have as much surface of the liquid as possible exposed to the ether bubbles. Complete extraction of a compound difficultly soluble in ether is accomplished in 5 to 10 hours. RECEIVED July 31, 1933.
Apparatus for Filling Large ClosedEnd Manometers ANGUS E. CAMERON School of Chemistry, University of Minnesota, Minneapolis, Minn.
T
HE ordinary method of filling a closed-end manometer and boiling out gases from the mercury during evacuation is attended with considerable danger of breakage when the manometer is of large bore and sufficient length to enable one to read pressures over a range of one atmosphere. Distillation of mercury into the manometer through a side tube seemed to permit trapping of gas or vapor below the wall of mercury vapor in the tube and result in unsatisfactory manometers. The apparatus shown in the figure overcomes both difficulties. The purified mercury was placed in the bulb and the upper end of the short water-jacketed condenser sealed t o a high-vacuum line. The s y s t e m w a s evacuated and the manometer flamed. The mercury in the bulb was boiled with an electric heater or with a Bunsen burner. The mercury vapor condensing above the jet was delivered into the manometer tube and water vapor and gas passed up through the condenser. Once set in operation the system required no attention until sufficient mercury had accumulated in the manometer and then the closed end was sealed off a t the s t r i c t u r e d portion. Evacuation w i t h a good oil pump should be sufficient to give a well evacuated manome duce the mercury is essentially a diffusion pump. RECEIVED August 26, 1933.
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