ANALYTICAL EDITION
356
Vol. 5, No. 5
between the pairs of analyses was 0.004 per cent for carbon dioxide and 0.004 per cent for oxygen, with a maximum difference of 0.014 and 0.010 per cent for carbon dioxide and oxygen, respectively.
ing day every carbon dioxide percentage was lower (average 0.027 per cent), whereas the oxygen percentage remained nearly the same in half the pumps and increased by a small amount in the rest. On repeating this 24-hour storage test on 12 pumps with the TABLEI. RESULTSOBTAINED FROM ANALYSESOF SAMPLES gas thoroughly dried, the carbon dioxide percentage on the IN 24-HOUR STORAGE TESTIN PUMPS second day averaged 0.004 lower thab the first day, whereas DAY GAB-ANALY 81s the average oxygen percentage increased 0.002. The results OF APPARATUS CARBON PUMP RESP. ANALYEIS NO. DIOXIDE OXYQEN QUOTIENT of this test are tabulated in Table I. Pump 10A was not No. % % considered satisfactory. When a sample was stored overFirst 19.534 2 112 1.036 0.665 38 1,032 First 19.537 0.664 night in pump 10A in a later test, an analysis on the second Second 19.535 112 1.030 0.661 day gave percentages for both carbon dioxide and oxygen Fjrst 38 1.025 19.546 3 0.663 First 19.548 0.667 20 1.028 that agreed within 0.001 with the results obtained on the 19.545 Second 0.660 38 1.022 previous day. Thus these pumps, if clean, dry, and airFirst 19.494 38 1.061 0.663 6 19.513 First 112 1.061 0.673 tight, will store dry gas for approximately 24 hours without Second 19.498 3% 1.058 0.662 detectable change in composition of the gas. First 19.546 38 1.031 0.666 9A 10A 11 14A 16 17 18 22 23
Second First Second First Second Firat First Second First Second First Second First Second First Second First Second
38 112 112 38 38 20 38 38 112 112 38 38 20 38 112 112 112 112
1.034 0.936 0.914 0.861 0.858 0.933 0.933 0.924 0.921 0.922 0.887 0.886 0.928 0.923 0.891 0.890 0.947 0.947
19,539 19,674 19.703 19.791 19.789 19.669 19.675 19.680 19.699 19.699 19.744 19.749 19.690 19.689 19.743 19.743 19.667 19.662
0.667 0.666 0.662 0.674 0.669 0,660 0.664 0.659 0.668 0.670 0.666 0.669 0.669 0.663 0.670 0.669 0.670 0.667
Each pump that was proved tight and had been previously dried was then tested to determine if it would store a sample of gas overnight (approximately 24 hours) without appreciable change in the composition of the gas. The pumps were filled with a gaseous mixture obtained as described above. I n one trial the samples were not completely dried. Duplicate analyses on the same day agreed well, but on the follow-
SUMMARY A metal pump, which is less fragile than glass, does not use mercury, can propel gas itself, has a capacity of 370 cc., and can be easily handled, has been adapted as a gas sampler. When clean, dry, and air-tight it will store dry air approximately 24 hours without measurable change in carbon dioxide or oxygen percentage. With this sampler it is possible to duplicate analysis of air on the same or different apparatus and a series of such analyses shows good agreement.
LITERATURECITED (1) (2) (3)
Benedict, F. G., Boston Med. Surg. J.,197, 1161 (1927). Benedict, F. G., and Benedict, C. G., Ibid., 188, 567 (1923). Benedict, F. G . , and Ritzman,E. G . , Wiss. Arch. Landw., Abt. B ,
Tierernahrung u. Tierzucht, 5, 28 (1931). (4) Carpenter, T. M., Lee, R. C., and Finnerty, A. E., Ibid., 4, 1 (1930) ; Carpenter, T. M., “Abderhalden’s Handbuch der biologischen Arbeitsmethoden,” Abt. IV, Teil 13, p. 593, Urban and Schwarzenberg, 1933. (5) Haldane, J. S., “Methods of Air Analysis,” p. 5,
Griffin, 1912.
RECEIVED May 24, 1933.
Determination of Ethyl Alcohol in Gasoline-Alcohol Mixtures Using a Zeiss Immersion Refractometer F. S. MORTIMER AND ELMERH. GIESE, Illinois Wesleyan University, Bloomington, Ill.
T
HE increasing demand that alcohol, made from farm products, be added to gasoline makes desirable the development of a method for the determination of the amount of alcohol present in such mixtures. The following procedure permits determinations with an average deviation of 0.2 per cent of the amount of alcohol present. Known mixtures containing 2,5, 5, 7.5, 10, and 15 per cent, by volume, of anhydrous ethyl alcohol in gasoline were prepared. All measurements were made with burets, using 50-cc. samples for the analysis. Each sample was placed in a glass-stoppered graduated cylinder and 25 cc. of distilled water were added. The contents were then shaken thoroughly in order to have the two layers come to a state of equilibrium. The water layer was drawn off from each sample and the refractive index was determined a t 20” C. by the use of a Zeiss immersion refractometer. Solutions were made from the regular gasolines of Texaco, Phillips “66”, D-X, and Deep Rock, respectively. Also some completely denatured alcohol (Formula 188) was dehydrated and mixed with Deep Rock gasoline, to find effect of denaturants upon the readings. The results obtained are shown in Table I. It will be observed that the refractive indices obtained from each of the types of basic gasolines, even when denatured alcohol
is used, agree very closely. From these data the mean values of the refractive indices were determined and can be plotted against the per cent of ethyl alcohol by: volume. Using these data a graph may be drawn, from which the per cent of ethyl alcohol present can be read directly. TABLEI. REFRACTOMETER READINGS TYPESOFGAEOLINE Texaro Phillips “66” D-X gas Deep Rock Deep Rock and complete!y denatured alcohol
0% 2.5% 5% 7.5% 10% 15% ALCO-ALCO-ALCO- ALCO-ALCO-ALCOHOL
HOL
150 15 15 15
20.5 20.5 20.9 20.5
26.2 32.4 37.8 26.2 32.4 38.0 2 7 . 0 33.0 38.3 27.0 32.8 38.3
15
20.5 27.5 32.6 38.2 49.0
HOL
HOL
HOL
HOL
48.3 48.3 48.5 49.0
SP.& 0.728 0.712 0.724 0.731
...
Average readings 15 20.6 26.6 32.6 38.1 48.5 0.724 0 The refractometer was set t o read 14.5 in distilled water.
METHODOF ANALYSIS Measure exactly 50 cc. of gasoline-alcohol solution into a glass-stoppered separatory funnel. Add 25 cc. of distilled water, shake the contents thoroughly to bring the two la ers t o a state of equilibrium, and draw off the water layer. !betermine its refractive index at 20” C. by means of the Zeiss immersion refractometer. RECEIVED April 27, 1933.
