July 15, 1933
INDUSTRIAL AND ENGINEERING CHEMISTRY
Figure 4 is representative of the analytical possibilities of the method. It gives a photomicrograph of a f r a g m e n t of wood, identified by its cellular structure, embedded in a tire tread. Following this lead it was found possible to prepare sections of wood by this method, as in the second photomicrograph. Another highly complex subject is illustrated in Figure-5. Brake linings are complex fabrications of semi-hard rubber, asphaltic material, cotton, asbestos, and c o p p e r wire. The second photomicrograph shows the boundary between rubber and solid brass in a product depending on the adhesion of rubber to metal for its usefulness. These photomicrographs suggest the possibilities to which this method for the microscopic examination of technical prodficts may be put.
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IN TIRETREAD ( X 600). POLISHED SECTION FIGURE 4. WOODFRAGXENT OF SYCAMORE WOOD( X 64)
LITERATURE CITED (1) Allen. R . P.. IND. ENG.CHEM..Anal. Ed.. 2 311 (1930). Alling, H. L., and Valentine, W. G., Am. J . S a . , 14, 50 (1927). Breuil, P., Caoutchouc & gutta-percha, 2, 82, 118, 158, 197 (1906). Chamot. E. M.. and Mason. C. W.. "Handbook of Chekiical Microscopy," Vol. I, Wiley, 1930. Epstein, S., and Buckley, J. P., Bur. Standards J. Research, 3, 783 (1929). Grenquist, E. A , , Rev. gBn. caoutchouc, 7, No. 63, 17 (1930). FIGURE 5. CROSSSECTION OF FABRIC IN BRAKELINING ( x 64). CROSS Pohle, H . , " H a n d b u c h der K a u t s c h u k SECTION OF ADHESION ZONE,RUBBERTO SOLIDBRASS( X 600) Wissenschaft," ed. by K. M e m m l e r , S. Hineel, Leipeig, 1930. Pulsifer, H. B., Metals & Alloys, 2, 84 (1931). (11) Short, M. N., U. S. Geol. Survey, Bull. 825 (1931). Rousch, G. A , , J. IND.ENG.CHEM.,3, 368 (1911). (12) Steele, T. F., IKD.ENG.CHEM.,Anal. Ed., 2, 421 (1930). Seyler, C . A., and Edwards, W.J.,"Microscopical Examination of Coal," Dept. Sci. Ind. Research (Brit.), Fuel Research Board, RECEIVED March 30, 1933. Presented before the Division of Rubber ChemPhysical and Chemical Survey of Yational Coal Resources, 16 istry at the 85th Meeting of the American Chemical Society, Washington, (1929.) D. C., March 26 to 31, 1933.
Volumetric Potassium Bromate-Bromide Titration of Furfural Effect of Temperature 0. C. MAGISTAD Experimental Station, Association of Hawaiian Pineapple Growers, University of Hawaii, Honolulu, T. H.
I
(4) published a method for the electrometric titration of furfural by potassium bromate. Youngburg and Purcher ( 5 ) , Kline and Acree (S), and Iddles and Robbins (2) report difficulty in obtaining a good end point, or failure to check the method against other methods. Using fresh solutions of furfural in ethyl alcohol, the author was unable to obtain theoretical titrations, the titer being several per cent too great. Investigation disclosed that a t temperatures of about 18" C. theoretical values could be obtained, while a t 27" C., the laboratory temperature, more bromine was used than expected. Gortner (1) stated that the investigations of Pervier and Gortner were conducted during the winter a t 15" to 18 " C. and that the temperature coefficient was not investigated. Determinations of furfural made by the author by the electrometric method suggested by Gortner and Pervier gave an end point of 20.37 cc. a t 10" C., 20.75 cc. a t 20" C., 1; 1923, Pervier and Gortner
21.05 cc. a t 24" C., and 21.80 cc. a t 36" C., with the theoretical titer (0.09904 gram of furfural) of 20.62 cc., indicating that an increasingly greater titer is obtained as the temperature a t which the reaction takes place is increased. Kline and Acree (3) state that the end point is indefinite because of a second reaction involving the combination of another molecule of bromine with furfural. The extent of the secondary reaction is influenced by temperature, becoming especially marked a t temperatures around 50" C.
LITERATURE CITED (1) Gortner, R. A. Personal communication, April 20, 1932. (2) Iddles and Robbins, IND.ENG.CHEM.,Anal. Ed., 5 , 55 (1933). (3) Kline and Acree, Bur. Standards J . Research, 8 , 25 (1932). (4) Pervier and Gortner, IND.EXG.CHEW.,15, 1255 (1923). ( 5 ) Youngburg and Purcher, J . Bzol. Chem., 61, 741 (1924). RECEIVED March 11, 1933. Technical Paper 58 of the Experiment Station, Association of Hawaiian Pineapple Canners, University of Hawaii. Published with the approval of the director.
