JULY..lS, 1937
ANALYTICAL EDITION
tested. Seventy-five compounds not containing the nitro group were tested and were all found to be negative with the exceptions noted above. The test as outlined, when used in correlation with other accepted tests, will be a decided aid in the detection of the nitro group in organic compounds.
Literature Cited (1) Baeyer and Bloem, Ber., 15, 2147 (1882). (2) Bamberger and Demuth, Ibid.. 34. 1330 (1901). (3) Bitto. Ann.. 269. 377 (1892). (4j Bose,’AnaZyst, 56, 504 (1931). (5) Bast and Nicholson, IND.ENG.CHEM., Anal. E d . , 7, 190 (1935). (6) Claison and Thompson, Ber., 12, 1946 (1879). (7) Gabriel, Ibid., 15, 2294 (1882). (8) Jacobs and Heidelberger, J. Am. Chem. Soc., 39, 1435 (1917).
353
(9) Janovsky, Ber., 24, 971 (1891). (10) Kamm, Oliver, “Qualitative Organic Analysis,” p. 161, S e w York, John Wiley & Sons, 1932. (11) Konowalow, Ber., 28, 1850 (1895). (12) Mulliken, S. P . , “Method for Identification of Pure Organic Compounds,” Val. 2, p. 32, New York, John Wiley & Sons, 1916. (13) Mulliken and Barker, Am. Chem. S., 21, 271 (1899). Olivier, Rec. trav. chim., 37, 241-4 (1918). Reitaenstein and Stamm, S. prakt. Chem., 81, 167 (1910). Rosenthaler, L., “Der Nachweis organischer Verbindungen,” p. 68, Stuttgart, Verlag von Ferdinand Enke, 1923. (17) Rudolph, Z . anal. Chem., 60, 239 (1921). (18) Vortmann, “Anleitung zur chemisches Analyse organisehea Stoff e,” (19) Walter, Z. Farbenind., 10, 49 (1911). RECEIVED April 19, 1937
An Improved Reaction Microapparatus D. S. BINNINGTON Grain Research Laboratory, Board of Grain Commissioners for Canada, Winnipeg, Canada
N
tion. The main a b s o r b e r is charged with 3 cc. of 10 per cent p o t a s s i u m iodide solution containing 3 to 4 drops of 0.6 per cent s t a r c h s o l u t i o n prepared according to the method of Nichols ( 1 ) and the secondary absorbing trap with 1 cc. of the above potassium iodide solution. Air is then aspirated through the system at a rate of approximately o n e b u b b l e per second, for 5 hours. At the end of this period the absorption unit is d i s con n e c t e d , t h e upper stopper is loosened, and the contents of the trap are blown into the main absorber which is then washed with two successive 1-cc. portions of the 10 per cent potassium iodide solution. Titration is carried out in the main absorber with 0.001 N sodium thiosulfate.
UMEROUS micromethods
involve t h e e v o l u t i o n and quantitative a b s o r p t i o n of v a r i o u s gases and vapors. The usual setup for this type of analysis is frequently cumbersome and inefficient because of the use of rubber stoppers and connections. The all-glass apparatus described here obviates these difficulties, is very comp a c t , a n d titrations may be carried out directly in the apparatus. It was originally designed for the microdetermination of bromine by evolution and absorption in potassium iodide solution, b u t m a y b e employed without modification for a wide range of analyses. D e t a i 1s of construction are shown in Figure 1, Pyrex glass a n d s t a n d a r d t a p e r ground joints being used throughout. The use of the apparatus is illustrated by the technic employed in carrying out bromine determinations by a modification of the Yates (2) method developed in this laboratory, The sample, equivalent to not more than 500 gamma of bromine, is transferred to the reaction flask with 7 cc. of water, and 2.5 cc. of concentrated sulfuric acid are added through the tap funnel over a period of 10 minutes, cooling the flask in ice water during this addition. This is followed by 4 cc. of chromic acid solution (20 grams of CrOs, 40 cc. of concentrated sulfuric acid, and 120 CC. of water). The inlet to the tap funnel is then connected to a wash bottle containing 20 per cent potassium hydroxide solu-
Prior to the development of this reaction vessel, the perc e n t a g e recovery of bromine was in the order of 95 to 96 per cent, while with its use the recovery ranges between 98 and 100 per cent with greatly reduced variability between replicates.
Literature Cited (1) Nichols, M. S.,I N D .E N G . C H E M . Anal. , Ed., 1, 215 (1929). (2) Ya’tes, E. D . , Biochem. J., 27, 1762 (1933).
SCALE
- Cm.
FIGURE 1. DIAGRAM OF APPARATUS
RECEIVEDApril 14, 1937. Contribution from the Grain Research Laboratory, Board of Grain Commissioners, Winnipeg, Manitoba, with financial assistance from the National Research Council of Canada. Published as paper No. 119 of the Associate Committee on Grain Research, National Research Council of Canada and Dominion D e partment of Agriculture.
