ANALYTICAL CHEMISTRY
1198 butter oils suspected of being adulterated. Many butter samples investigated in this laboratory have been found to contain butylated hydroxyanisole, presumably added as lard, tallow, or a shortening-type product. Thus the presence of animal fats which do not affect the tocopherol content of butter may be detected in some instances b y means of the added antioxidants which they may contain. Qualitative tests for propyl gallate and butylated hydroxyanisole have been published by hlahon et al. (8).
must be avoided, because of the photosensitive nature of the ferric chloride plus 2,2'-bipyridine reagents. Butter oils with tocopherol values of less than 50 y per gram oil should not be considered adulterated on the basis of the tocopherol values, although such butters might be adulterated with lard, tallow, or coconut oil. Butter oils with tocopherol values of 50 to 60 y per gram of oil should be considered suspicious, and tocopherol values in excess of 60 should definitely indicate adulteration. ACKh-OWLEDGMEYT
DISCUS SIOS
In the routine determination of the tocopherol content of a given fat, it is necessary t o employ a fixed-fat concentration, since the slope of the tocopherol calibration curve is dependent upon the concentration of fat present. Employing a 5% solution of butter oil, the calibration curve obeys Beer's law up t o a level of 80 y of tocopherol per 0 5 gram of butter oil (160 y of tocopherol per gram). It has been found satisfactory to conduct these analyses with groups of six separatory funnels-a blank and two unknown samples in duplicates-the reagents are added to each separatory funnel a t 1-minute intervals. This blank value may be used for six unknowns in a second group providing a n Evelyn colorimeter is employed. A new blank must be carried each time fresh ferric chloride and/or 2,2'-bipyridine reagents are prepared, because the blank color increases slightly with the age of these reagents. During the filtration of the alcoholic solution, prior t o measuring the absorbancy at 515 mp, exposure of this solution to strong light
Effect of Ashing Temperature In low-Rank Coal Samples CLAUDE L. WARING U. 5. Geological
T
and
The authors wish to acknowledge the assistance of J. C. Woodward, Chief, Chemistry Division, Science Service, Department of Agriculture, Ottawa, for procuring the genuine butter samples used in these investigations. LITERATURE CITED
(1) Bird, E. W., Petal, D. J., and Handwerk, R. L., J . Dairy Sci., 34,
484 (1951).
( 2 ) Bird, E. W., private communication, 1953. J . .4m. Pharm. Assoc., 40, (3) . . Chapman, D. G., and Carnubell, J. -1,
2i2 (1951). (4) Emmerie, A , , and Engel, C., Rec. trav. chin^., 57, 1351-6 (1938). (5) Fox, S. H., and hlueller, A , , J . Am. Pharm. Assoc., 39, 621 (1950). (6) Handwerk, R. L., and Bird, E. W., J . Dairy Sci., 34, 484 (1951). (7) Lange. W., J . Am. Oil Chemists' Soc., 27, 414-22 (1950). (8) Nahon, J. H., and Chapman, R. A., Axar.. CHEM.,23, 1116-20 (1951). (9) Quaife, XI. L., Scrimshaw, N. S., and Lowry, 0. H., J . Biol. Chem., 180, 1229-35 (1949). RECEIVED for review July 27, 1953. .4ccepted M a r c h 10, 1954.
01 the
Volatility of Germanium
WENDELL P. TUCKER
Survey, Washington 25,
D. C.
HE U.S. Geological Survey is currently investigating radio-
active lignites and low-rank coal on behalf of the *4tomic Energy Commission. As part of this study, many hundreds of samples of ashed low-rank coals are analyzed spectrographically by semiquantitative methods for a total of 69 elements. Germanium is one of the elements of prime importance as a possible by-product in any processes that may be developed to extract uranium from low-rank coal. S a t u r a l low-rank coal samples, ground to -80 mesh, are ashed at temperatures exceeding 500" C. in preparation for spectrographic analysis. The question arises whether germanium is lost by volatilization during ashing and therefore would be undetected in the spectrographic analysis even if present in the sample before ashing. References in the literature ( 1 , 4)caution the analyst about loss of germanium by volatilization if the ashing of the samples of high organic content is conducted a t temperatures exceeding 500" C. S o data, however, have been presented by these authors to show a detectable loss of germanium when the sample were ashed a t higher temperatures or a t various rates of heating. A loss of germanium was observed by Morgan and Davies(5) and by RotynskiI (6). Work a t the Fuel Research Station, Greenwich, England, found no loss of germanium in coals ashed a t 400" C. ( 3 ) . Tests at 900" C. are not yet reported by this station, but thus far results indicate t h a t the losses a t 900" C. are probably well below 30%. These results could fall within the experimental error of the work reported in this paper, Crossley ( 2 ) reported an
average of 0.34% germanium dioxide in the ash of coal prepared at 475" to 500" C., and 0.35% in the ash prepared a t 800" C. H e also investigated the depth of coal layer, rapidity of heating, and restricted ventilation methods for preparing cqal ash at temperatures up to 800" C. These results indicated no detectable loss of germanium. Tests were conducted in the Geological Survey on low-rank coal samples to determine the loss of germanium when the samples are ashed a t various temperatures as high as 1000" C. and when the rate of heating and the surface area of the samples are varied. The identity of germanium compounds in low-rank coal samples is uncertain. Under special conditions germanium halides, oxides, and sulfides volatilize or form volatile compounds. These compounds are very unstable, and it is unlikely t h a t germanium would remain in these unstable states in the presence of air and moisture long enough to volatilize in any appreciable amount. I t is presumed that the unstable germanium compounds oxidize quickly t o the stable dioxide under the conditions of the tests described in this report. EXPERIWEYTAL DAT4
Loss of Germanium by Gradual Heating. This test consisted of gradual heating of the samples, containing three percentage ranges of germanium, to 1000" C. with interruptions a t various temperatures to determine the per cent of germanium.
V O L U M E 2 6 , NO. 7, J U L Y 1 9 5 4 Table I. Sample
1199
Spectrographic Determination of Germanium on Low-Rank Coal Samples Ashing Temp., C.
Ashing Time, Hr.
Ash,
%
Ge in Ash, % a (Spectrographic)
Gradual Heating of Samples 200 4 68.80 3.90 4 500 4 3.87 800 3.80 2 1000 99.94 4 200 4 1.26 500 1.17 4 800 1.28 2 1000 4 85.44 200 4 6.71 400 4 6.78 500 6.70 4 800 1000 2 6.62
E
E
1.12
o:oio
0.013 0.012 , . . b
0.60 0.60 0.60
0.56
Rapid Heating of Samples 4 3.83 800 4 1.09 800 4 6.66 800
R 0
R 0
1,
1'10 1 12
1.10 0.010
0.59
Rapid Heating of Samples in Wide Platinum Dishes 1.13 1000 1 3.70 0.018 1000 1 1.28 0.62 1000 1 6.62
Rapid Heating of Samples in J. L. Smith Crucibles (Small Surface .4rea) 2 3.70 1.10 R 1000 2 1.28 0.012 0 1000 2 6.62 0.61 E 1000 Calculated on baais of ash prepared a t 500° C. b No spectrographic germanium results obtained, owing t o high organic content remaining in sample.
Low-rank coal samples weighing 1 gram were placed in a muffle furnace a t 25' C., and the temperature was gradually increased to 200° C. and held for 4 hours. The samples were cooled and weighed, and a portion removed for spectrographic determinations of germanium. ,4similar procedure was repeated a t 400", 500°, 800", and 1000" C. for sample E; and a t 500°, SOO", and 1000" C. for samples R and 0. Because heating these coal samples to 500' C. and 1000" C. yielded approximately the same weight of ash, the spectrographic comparisons for germanium were made on 10-mg. samples of ash. Gradual heating indicated no detectable loss of germanium even a t the final high temperature. Loss of Germanium by Rapid Heating. The procedure consisted in rapidly heating the -80-mesh coal samples iu porcelain
crucibles over Bunsen burners for 45 minutes, final temperature a t 700 to 800' C., then transferring to a muffle furnace already a t 800' C., and holding the samples a t this temperature for 3.25 hours. The samples were cooled and weighed, and the germanium content was determined spectrographically. The data obtained by this test indicated no detectable loss of germanium. Large versus Small Surface Areas. This experiment was to determine the loss of germanium when ashing was accomplished by the rapid heating of samples in widemouthed containers, where large surface areas were exposed to the air, and also samples with small surface areas. If a large surface area of sample is exposed to air, it is to be expected that, even with rapid heating, any compounds of germanium would be oxidized rapidly t o germanium dioxide which ia not volatile, and therefore, no loss of germanium would occur. Accordingly, 1-gram samples of similar particle size were spread in thin layers in 260-ml. platinum dishes and placed in the muffle furnace at 1000" C. for 1 hour. The results indicate no loss of germanium under these conditions. To test for loss of germanium from samples heated under smallsurface-area conditions, 3 to 5 grams of the coal samples were dried a t 100" C., packed in J. L. Smith crucibles, and placed in a muffle furnace a t 1000" C. for 1 hour. rl violent evolution of gases was observed which persisted for several minutes. Then the samples were transferred to platinum dishes and heated for another hour a t 1000' C. There was no detectable loss of germanium under these experimental conditions. The results of all experiments are given in Table I. LITERATURE CITED
(1) Ahrens, L. H., "Spectrochemical Analysis," p 216, Cambridge, Mass., Addison-Wesley Press, 1950. ( 2 ) Crossley, H. E., "Occurrence and Significance of Certain Minor Constituents of Coal," See. 3, thesis. University of London, 1949. (3) Dept. Sci. Ind. Research. London. Fitel Research 1049-50, (1951). (4) Goldschmidt, V. M., and Peters. C., Abhartdl. Ges. Wiss. Gatingen, Math.-physik. KI., 3, 141 (1933). ( 5 ) Morgan, G., and Davies. G. R., J . SOC.Chem. I d . ,56, ili-21 (1937). (6) Rotynskii, U. M., Compf. r e n d . mad. sc1'. C.R.S.S., 40, 198-201 (1943). RECEIVED for review October 14, 1953. Accepted hlarch 23, 1954. Publication authorined by the Director, C . S.Geological Survey.
Gasometric Method for Determination of Hydrogen in Carbon W. G. GULDNER and A. L. BEACH
&I1
M
Telephone Laboratories, Murray Hill,
N. J.
ICROCHEJIICAL determinations of hydrogen in organic compounds are usually performed by some modification of the gravimetric Pregl method. It was found here, however, that this method does not provide data of adequate precision for hydrogen in carbon samples with low hydrogen content. Because of the need for correlating the chemical and physical properties of carbon prepared by a variety of methods, it became necessary to develop a new technique which would provide precise determinations of hydrogen in carbon. In most cases, the amounts of hydrogen in carbon were too small to be measured by conventional procedures. This low pressure gasometric method described has provided data for the range of 0.0004 to 3.5% hydrogen in carbon. This method involves the combustion of the carbon in a low pressure of oxygen while the hydrogen is converted to water, the
separation of the water vapor from the carbon dioxide and excess oxygen by selective freezing, and the measurement of the water vapor in the gas phase by means of a calibrated closed-end manometer. Recently, ?;aughton and Frodyma (2) used a similar technique in measuring carbon dioxide and water vapor in their modified Pregl apparatus for determining carbon and hydrogen in organic materials. This technique has also been used by Holowchak and Wear ( I ) for the determination of oxygen aa carbon dioxide in organic materials. APPARATUS
This apparatus, developed solely for determining hydrogen in carbon, is shown in Figure 1. I n general, the apparatus consists of a purification train for the oxygen used in combustion of the sample, a combustion furnace employing induction heat-
