V O L U M E 19, NO. 1 1
936 as small as possible or by including a nonvolatile oil damping arrangement on the moving inner brass tube. In most cases, however, the occasional loss of a drop will be small enough to render this refinement superfluous. There is one electromagnet for each receiver, connected as shown in Figure 2 in such a way that two diagonally opposite magnets operate simultaneously on each occasion. In the diagram there are six positions of the soft iron, and therefore six receivers. Six fractions can then be collected over a period of hours determined by the gearing of the time witch. The electromagnets are wound with cotton-covered and enameled 21 B S T gage copper vire and have a core built up to 0.25-inch diameter with 18 BSW gage iron wire. The length of winding is approximately 1.25 inches and the over-all diameter approximately 0.5 inch. One lead of each magnet is connected to a common lead, R. The other leads are interconnected as shown in Figure 2, so that one lead from each pair of magnets is taken to the time switch a t A , B , and C. The current can be supplied by a 4-volt storage battery. Time Switch Control. To operate the electromagnets a time switch is required which will complete each circuit in turn for a short interval a t the required times. The time interval for which any one circuit is completed is not of great importance and the circuit can be on for 5 or 10 minutes without overheating the electromagnets. A convenient and reliable time switch driven by a small synchronous electric motor, of the type made by the Venner Time
Switch Co., Xew Malden, England, is shown in Figure 3. This is geared down by the makers to the required speed, such as one revolution every 12 hours, and can be ordered as a n M T clock unit, the required speed being stated. This motor can be made to operate 3 microswitches, which are made by The Burgess Products Co., Ltd., Sapcote, England, and the model known as Type B, GRL is provided with spring strips as shown in Figure 3. These switches make contact with a very small movement of the press button on which the strip presses. They can thus be adjusted to make contact just before the operating pin leaves the end of the spring strip. If the motor is connected to a shaft on which three disks are mounted, each with two pins, the switches will make contact for a few minutes a t intervals of 2 hours. Intervals of 4 hours are obtained by removing one pin from each disk. ACKXOW LEDGMENT
The authors wish to thank the Board of Trinidad Leaseholds Limited for permission to publish this work. LITERATURE CITED
(1) Smith, V. C., Glasebrook, A. L., Begeman, T. R., and Lovell, W. G., IND.ENQ.CHEW,ANAL.ED.,17,47(1945). (2) Steffens, L., and Heath, D. P., Ibid., 16,525(1944).
RECEIVED October 31, 1946.
Removal of Higher Alcohols from Ethanol HAROLD W. COLES' m D WILLIAM E. TOURNAY2 Mellon Institute of Industrial Research, Pittsburgh, Pa.
I'HE
authors needed a very pure ethyl alcohol for a standard in studies on the determination of fusel oil in alcohol (1). For obtaining a pure alcohol efforts were directed toward removing the contaminating alcohols from a very good grade of commercial absolute alcohol and synthesizing an alcohol by a 1 2
method and under conditions permitting a minimum of secondary products. The Kornarowsky color reaction was used in analyzing the results by the Coleman spectrophotometer. EXPERIMENTAL
The apparatus and technique employed were the same a8 described previously (I), except that the color reagent, p-di-
Present address, Bausch and Lomb Optical Co., Rochester, N. Y. Present address. Linde Air Products Co., Tonawanda, N. Y.
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450 500 550 600 650 W A V E LENGTH M I L L I M I C R O N S
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8. Untreated alcohol (90% by volume) C. Untreated alcohol (95% by volume) D . Untreated alcohol (97% by volume) E. Alcohol (97% by volume) recovered from Komarowsky reaction mpeotrophotometer mtandarda. Same volume relationships of alcohol (same proof) and sulfuric acid but no color reagent added
I
I
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W A V E LENGTH
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Figure 2. Spectral Transmittance Curves of Komarowsky Colored Solutions of Synthetic Alcohols Compared with Commercial
Figure 1. Spectral Transmittance of Komarowsky Colored Solutions of Commercial Grain Alcohol A . After filtration of alcohol (90% by volume) through fuller's earth
400
Grain Alcohol A. B
Synthetic alcohol (63%by volume) Synthetic alcohol 76% by volume) C: Grain alcohol (63d by volume) D . Grain alcohol (76% by volume) spectrophotometer standards. Same volume relationships of grain alcohol (same proof) and sulfuric acid
N O V E M B E R 1942
937
methylaminobenzaldehyde, was dissolved (50 mg. per cc.) in the sulfuric acid used in the test, thus eliminating the usual alcohol solvent as a variable. The solution against which the spectrophotometer was standardized was prepared simultaneously with the other solutions, received exactly the same treatment, and contained the same percentage of alcohol. Purification of Commercial Absolute Alcohol. The absolute alcohol (Rossville 200-proof Gold Shield) was allowed to filter by gravity through a 15-em. (6-inch) column of fuller’s earth. Residual aldehydes were removed ( 3 ) and the alcohol was redistilled from a weak hydrochloric acid solution. The spectrophotometer showed (Figure 1) that about 25y0 of the substances responding to the Komarowsky test had been removed in the filtration (curves A and B ) . This treatment reduced the higher alcohol content to approximately 1 part in 100,000 of ethanol. Immobilization of the higher alcohols as colored complexes, removal of these by absorption on fuller’s earth, neutralization of the colorless sulfuric acid filtrate, and recovery of the ethanol by high-vacuum distillation gave a product which gave a strong Komarowsky reaction even in the cold (curve E , Figure l), much more pronounced than untreated alcohol.
three times from dilute hydrochloric acid and washed repeatedly on the funnel with boiled distilled water. The moist solid was gradually added to the refluxing sodium hydroxide solution (130 grams in 500 cc. of boiled distilled water) contained in a 2-liter round-bottomed flask as rapidly as the ester went into solution. The refluxing was continued 0.5 hour after the ester had completely disappeared. The flask was chilled, the contents acidified slightly with hydrochloric acid, and the alcohol slowly distilled (preferably in the presence of nitrogen) through a very clean fractionating column and condenser. The distillation was discontinued a t 90” C. Yield: 85% of the theoretical. The alcohol was stored in amber glass-stoppered bottles in darkness and in contact with a piece of copper wire. Figure 2 shows the comparison of two synthetic alcohols of different proofs with a good grade of commercial alcohol of the same proof. The comparisons demonstrate that the synthetic alcohol has much less of the components present which give the Komarowsky reaction than does commercial alcohol of high purity.
Synthetic Ethyl Alcohol. Methods which did not involve the use of reagents that might contain higher alcohols were considered for the synthesis of the ethyl alcohol. The saponification of p-aminobenzoate ethyl ester w&s found entirely suitable.
(1) Coles, H. W., and Tournay, U’. E., IND.EXG.CHEM.,ANAL. ED., 14, 20 (1942). (2) Stout, A. W., and Schuette, H. A , , IND.ENG.CHEM.,ANAL.ED.,
The ethyl p-aminobenzoate (benzocain) was saponified in an all-glass apparatus. Five hundred grams were recrystallized
R BCEIVED March
LITERATURE CITED
5, 100 (1933).
4. 1947.
Sand Filters in Analytical Chemistry SVERRE STENE Statens Institutt for Folkehelse, Oslo, Norway
HE principles of sand filtration, used in water purification, Tmay be applied in analytical chemistry with advantage in a number of cases, partly by using “sand” layers as an efficient support for other filtering media, and partly by using sand as the filtration medium proper. The products of the abrasives industry are available in finely graded powders of a great variety of grain sizes, made according to strict specifications, so that filters of highly reproducible characteristics can be made. Figure 1, A , shows a sand filter proper during a hot filtration, such as is regularly used a t this institute in the determination of starch in sausages by Grossfeld (3), modification by of Mayrhofer’s (6) method, where the proteins are dissolved by hot treatment with 8 yo alcoholic potassium hydroxide, filtered, and washed with 90% alcohol, and the starch is dissolved in cold hydrochloric acid and estimated by polarization. Grossfeld used filters of asbestos on glass wool. But it proved difficult t o obtain filters of sufficient retentivity coupled with a low reproducible filter resistance for use in routine work. The filter tube is suspended by a copper wire in the form of a hook a t the lower end, with a loop around the neck of the flask, which is placed on a hot water bath during filtration, the filter being kept hot by the vapors. I n the bottom of the filter a n unspherical glass bead is placed. Above it are two layers of specially treated alloxite (aluminum oxide), first a 1- to 2-cm. layer of grain size KO.36 and then a 3- to 4-em. layer of S o . 80. Such filters have proved very satisfactory for a number of years and may be used repeatedly. If the bead fits too closely, the filter may be filled with water, and the bead pushed upward a little with a glass rod. Some grains slip down between the bead and the wall, forming an annular space for the outlet of the filtrate. In place of the glass bead a little glass wool may be used. If a filter is to be used only once, it is advantageous to prevent the trapping of air bubbles by closing the outlet, filling the filter LTith water, and pouring the grains through the water. In permanent filters the top layer may be stirred with a glass rod, after the filter is filled with liquid. If the surface of the filter gets clogged during filtration, stirring the surface with a rod will often be of advantage. If very fine grains are to be used for the filter, an additional supporting layer of medium-sized grains may have to be introduced. Then it is an advantage to have the top layer
as shallow as possible. In order to prevent this layer from being stirred up during filtration, it may be covered by a layer of coarse grains. In some tentative experiments on the determination of cellulose in polluted rivers the replacement of a surface filtration by a filtration in depth seemed promising, using Bmall filters of 8- to 10mm. inside diameter and an 8-cm. filter height of coarse-medium coarse grains. Ordinary surface filters were rapidly clogged, but in these special filters the cellulose fibers were retained by the uppermost coarse layer, while the fine silt was allowed to pass through the filter, so that a large quantity of water could be filtered rapidly, if necessary in the field. The cellulose might be
u Figure 1
