ANALYTICAL EDITION
July 15, 1943
the final results, but merely a balancing. The moisture content is read directly, no further calculations being required. After the analyst has acquired experience, a moisture determination can be made within 10 minutes. T o speed up the results further, the author has employed two metal containers, so that while one sample is being deaerated, the sample in the other container is being cleaned and made ready for the new determination. Thus by rotating, the time for the determination can be further reduced. Certain precautions must be taken in the use of this method: 1. SufEcient dispersing agent must be added to liquefy the
sample. 2 . The entrapped air must be completely removed; otherwise the results will be high. A good test for the completeness of air removal is to tap on the bottom of the beaker or flask containing the liquefied sulfur paste with the finger. If the sound has a ring, the air has not been completely removed. A little experience soon accustoms the analyst to the difference in sound. 3. The distillation method should be used as a periodic check until the analyst has assured himself that the resulte are correct and that the samples are uniform. An occasional sample has been received from which it was impossible to remove the entrapped air. The samples are generallj from sulfur recently made from the sulfur by-product recovery system.
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No difficulty has been encountered in the use of the rapid density moisture method, even though used by various members (at least eight) of the laboratory staff. This method is in constant use at this laboratory, especially during t h e spring when the sulfur paste is being prepared for market. Acknowledgment The author wishes to acknowledge the cooperation of members of the laboratory staff, and in particular Theodore R. McCann in carrying out this work.
Literature Cited (1) Bowman, L. B., Am. Gas Assoc., 14th Prod. & Chem. Conf., 1941. (2) Colbert, F. D., Gas Age-Record, 65, 783 (1930). (3) Cooper, J. F., Ibdd., 65, 506 (1980). (4) Geiger, C. W., Ibid., 60, 41 (1927). (5) Gollmar, H. A., IND. ENQ.CHEM.,26, 130 (1934). ( 6 ) Jacobson, D. L., Gas Age-Record, 63, 895 (1929). (7) Sauchelli, V., IND.ENG.CHEM.,25, 363 (1933). ( 8 ) Shnidman, L., IXD. ENG.CHEY.,A N ~ LED., . . 7 , 2 4 6 (1935). (9) Sperr, F. W., Proe. Am. Gas Assoc., 3, 28%(1921). (10) Sperr, F. W., Proc. Canadian Gas Assoc. (July, 1926). PREBENTED before the Division of Gas and Fuel Chemistry at the 105th Meeting of the AMERICAN CHEMICAL SOCIETY,Detroit, Mich.
Qualitative Test for Methoxv and Other Allroxy Groups J
Compounds Encountered in Pharmacology and Toxicology WALTER C. TOBIE, Division of Chemistry and Physics, Army Medical School, Washington, D. C.
A
LTHOUGH numerous modifications of the Zeisel method (6) for the quantitative determination of methoxy and
other alkoxy groups have been described, and much elaborate apparatus has been designed for the determination, a simple and reliable qualitative test for such groups has hitherto been lacking. Beckmann (2) a n d Feist (3) detected methoxy groups in a few compounds by splitting off the methyl radical in such a way as to methylate known compounds, then determining the melting point of the resulting methylated derivative. Such a procedure is slow and inconvenient. Neave and Heilbron (4) merely described a very crude qualitative Zeisel procedure, heating compounds to 140" C. with hydriodic acid and passing the evolved methyl or ethyl iodide into silver nitrate, without provision for remo\
