ANALYTICAL EDITION
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Vol. 6, No. 5
The absorber was tested by the method of Friedemann Typical results with the absorber described, given in and Kendall (2), in which it was substituted for the usual Table I, show that the determination of carbon can be glass bead column. After complete combustion of the sample carried out successfully with complete absorption of carbon (30 minutes’ digestion period) the absorber was raised to dioxide when less than 5 per cent of the alkali remains a convenient height above the bottom of the flask and the unneutralized. This was further evidenced by the fact alkali washed out with hot water free from carbon dioxide. that no precipitate appeared in a trap tube to which barium Usually three washings of 40 cc. each were sufficient. I n hydroxide solution (0.3 N ) had been added and through order to hasten the washing, a hand aspirator connected with which the air was passed after leaving the absorber. a soda-lime tube was used to force the water out of the SUMMARY absorber. The carbonate was then precipitated by adding barium chloride solution, and the stoppered flask was proThe sintered glass absorber described has several adtected with a soda-lime tube while cooling. It has been found vantages over the glass bead absorber previously used for this convenient to use a mechanical stirrer while titrating the determination. It is unnecessary to maintain a large excess excess alkali. To obtain consistent results, carbon dioxide- of alkali and consequently the method has a wider range of free air should be passed over the solution while titrating, application. Washing the alkali from the absorber is easier. particularly when using mechanical agitation, because Difficulties due to the disintegration of the glass beads by the otherwise air is drawn into the flask. Blanks should be run alkali are eliminated. in exactly the same manner as the determination, to correct LITERATURE CITED for carbon dioxide in the apparatus and reagents. (1) Bruce, W. F., and Bent, H . E., J. Am. Chem. SOC.,53, 990 TABLEI. DETERMINATION OF CARBON BY WET COMBUSTION (1931). USINGSINTERED GLASSABSORBER (2) Friedemann, T. E., and Kendall, A. I., J. Biol. Chem., 82, 47 (Butyl alcohol added, 0.5 per cent) CARBON TAKEN SODIUM HYDROXIDE PERCBNTOP ORI~INAL (A0 8ODIUM USaD IN SODIUM HYDROXIDE CARBON OXALATB) ABSORBERo UNNEUTRALIZED FOVND &om
4
Qram
0.1436 0.1436 0.1435 0.0722 0.0717 0.0719 0.0278 0.0277 0.0279 60 ml. used.
0.5 N 0.5 N 0.5 N 0.5 N 0.5 N 0.5 N 0.1N 0.1 N 0.1 N
4.2 4.2 4.2 51.8 52.2 62.0 7.4 7.6 7.0
0.1430 0.1430 0.1430 0.0724 0.0718 0.0719 0.0277 0.0275 0.0277
(1929). (3) Friedrichs, F.,Chem. Fubrilc, 4,203 (1931). (4) Halberstadt, S.,IND.ENO.CHEM..Anal. Ed., 4, 425 (1932). (6) Jenaer Glaswerk Schott und Gen., U. 8.Patent 1,620,815(1927). (6) Kirk, P. L., Craig, Roderick, and Rosentels, R. S., IND. ENO. CHEM.,Anal. Ed., 6, 164 (1934). (7) Rhodes, F. H., and Rakestraw, D. R., Ibid., 3, 143 (1931). (8) Sieverts, A., and Halberstadt, S., Chem. Fabrilc, 3,201 (1930). ., Ed., 5, 193 (1933). (9) Thomas, M.D.,IND.ENQ.C H ~ MAnal. Rmcairvmn May 18, 1934. The 240th contribution from the Color and Farm Waste Diviaion, Bureau of Chemistry and Soils, U. 6 . Department of Agriculture.
A New Ultraviolet Microscope Illuminator Preliminary Studies of Its Use with Rayons THOMAS HILLDAUGHERTY AND ELMER V. HJORT, University of Pittsburgh, Pittsburgh, Pa.
T
HE analytical uses of fluorescence effects due to ultraviolet irradiations have been summarized by Danckwortt (4) and by Radley and Grant (17). Apparatus for both macro and micro observation has been built or suggested by Lehmann (7), Wasicky (24), Reichert ( I @ , Naumann (11), Auer (2)’ Silverman (21),and Singer (23). One or more of the following factors limit the equipment cited above: the expense of quartz lenses, slides, and other acceswries; unsuitability for both macro and micro investigations; lack of flexibility in making the microscope available for other work; lack of suitable ultraviolet intensity; and inability to use the higher powers of the microscope. To eliminate these undesirable features as far as possible, it was decided to make use of an oblique cone of ultraviolet light impinging on the object, securing thereby an even and full illumination with the elimination of shadows, an increased depth of focus causing uneven structures to appear in relief, and the production of as true color values as can be obtained with artificial light. For visible light these results have been obtained with the Silverman illuminator (20, 28), Preston’s top light illuminator (16), and the Leitz ultropaque (8). For fluorescence, the last named has secured these effects using glass equipment. The apparatus described below was designed to secure still further advantages. The apparatus consists of an enclosed annular quartz
mercury arc (Figures 1 and 2). The experimental quartz model of the arc was built to the writers’ specifications by the Hanovia Chemical and Manufacturing Co. This arc operates on line voltages from 110 to 220 direct current, with best results a t about 155 volts, and a lamp bank resistance is used in series, such that the voltage drop across the arc is about 85 volts. From 1 to 2 amperes are required for starting, depending on the voltage. The arc is mounted just above the stage, so that the objective can occupy the position shown in Figures 1 and 2. The mounting is light-proof except for the filters which transmit the ultraviolet rays to the object under examination. It is cooled by fins attached to the arc and by a circulating water system. It is necessary to use a filter to remove as much as possible of the visible light emitted by the mercury arc (4), because its relative intensity obscures the fluorescence. The transmissivity of different filters may cause confusing phenomena. Thus Kogel (6) reported that certain filters transmit red rays which may be mistaken for red fluoresence. The published reports of fluorescence work often fail to specify what filters were used, and in most reports the use of only one filter is mentioned. To avoid the resulting confusion in reportirfg results, data obtained with a number of commercially available filters were recorded. The best results with rayons were obtained by using Heat-
September 15,1934
INDUSTRIAL AND ENGINEERING CHEMISTRY
Resisting Red P urple Ultra, No. 587 (S),and a combination of t h e U v e t Glas filters, Nos. 1 a n d 2 (19), possibly 12.7cm. because of a 8.5cm. suitable range in the ultravioaa’ let, together w i t h low int e n s i t y in the d 1ooc visible. In the case of Violet Ultra, No. 586 (S), the visible i s n e a r l y excluded, but no lines are shown FIGURE 1. ANNULAR MERCURY ARC with the merA. Plan B. Elevation cury azc below a d . Luminous ath of arc 3300A. The b. Position of ofjective c. Mercury results with this d . Tungsten electrodes e. Evacuation tip (must be on cool part of arc) filter were poor, in accordance with the work of Lewis (IO), who showed that the best region for the fluorescence of cellulose products lies in a region of shorter wave length. The silvered quartz filter completely excludes the visible, but is weak in the ultraviolet. Consequently, poor results were obtained with it.
FLUORESCENCE OF RAYONS The chemical and microscopic methods (1) for the identification of rayons are still tentative. The chemical method is laborious. The use of fluorescence for identifying natural fibers (5,9,IS) is fairly successful, but the results for rayon are conflicting (12, 14, 16). The results obtained from the examination of thirty-seven undyed, unmordanted fibers, using the filters which gave the best results, are summarized in Table I. These fibers are authentic samples secured from the leading manufacturers of this country. The word “shadows” as used in the table refers to transmitted visible colors which simulate fluorescence, in accordance with the descriptions used by Nopitsch (12). TABLE I. FLUORESCENCE CHARACTERIBTICS
OF
RAYONS
FILTERS FIBPR Raw silk Cuprammonium rayon Nitrate rayon Acetate rayon
Viscose rayon
HEAT-RIOSIBTINQ RIOD P U R P L I ULTRA, 687
U V E T QLAB-1 COMBINBD WITH UVET QLAS-2
Yellow to buff: brighter Yellow to buff, much brighter than nitrate rayons, than nitrate and viscose paler than viscose rayons White with purple shad- White. bright whereas acetate ows: bright, whereas ray& are dull and tend to be tinted acetate rayons are dull Pale yellow without the Dull, pale yellow without ,the brown t i i t s present in brown tints In silk; distincsilk or visooae tion from viscose a matter of observer‘s experience Dull white with or Dull white usually with wibhout tinted shadtidted shahowa: much jess ows: much less bright bright than cuprammonium than cuprammonium rayon, which is not tinted rayon Deep yellow to brown: Faint yellow to buff: easily deeper than the tints distin uishable from raw of nitrate rayon or silk. &tinction from nitrate raw silk. less bright ray& a matter of observer’a than raw’silk experience
Easily bleached dyed fibers gave substantially the same results as the undyed, and could be recognized even if a slight additional hue was present. Mixed fabrics revealed the fluorescence of the constituent fibers microscopically, but showed macroscopically a single
371
color which was a combination of the constituent hues. Although the same t y p e of p r o d u c t made by different manufacturers shows slight differences in the tints obtained, these differences cannot be utilized for identifying t h e source of the fiber, because they may r e s u l t from the fluorescence of imARCWITH purities incidental FIGURE2. USE OF ANNULAR MICROSCOPE to the manufactura. Microscope b. Slide ing and finishing e . Arc support processes. d. Circular arc e. Shield to enclose arc The method f. Filter, 7.94 om. (3.125inch) square withhols in center 1.7 om. (0.67 inch) ’diameter. r e q u i r e study of The filters slip into a slot for easy interauthentic samples changing by anyone contern- u. Water cooling system h. Metallic cone to shield objective from heat plating using it bei, Cooling of arc fins cause Of the diffij. Auxiliary shield culty of exact description of the colors observed. Further work is desirable, not only for the study of specimens which are difficult to bleach, but also with other ways of treating fibers before testing.
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ACKNOWLEDGMENT The authors are grateful for the assistance rendered by W. N. St. Peter of the University of Pittsburgh and by the various manufacturers of silks and rayons. LITERATURE CITED Amer. Assoc. Textile Chem. Colorists, “Rayon Identification
(Tentative Method) ,” by Rayon Subcommittee, reprinted from 1931 Year Book. Auer, A,, Mikrokosmos, 24, 69 (1931). Corning Glass Works, Catalog, “Glass Color Filters,” pp. 12,
15, 16. Danckwortt, P. W., “Lumineszenz-Analyse im Filtrierten Ultravioletten Licht,” Akademische Verlagsgesellschaft m. b. H., Leipzig, 1929. Ellinger, H. W., Jentgen’s Rauon Rev., 2, 96 (1930). Kogel, G., Chem. Fabrik, 1, 55 (1928). Lehmann, H., 2. wiss. Mikroskap., 30, 417 (1914). Leitz, E., Inc., N. Y., Pamphlet 1199, “Leitz Ultropaque Microscope Equipment.” Le Trayas, H., Russa, 4, 171 (1929). Lewis, S. Judd, J. SOC.Dyers Colourists, 40, 29, 111 (1924). Naumann, H., Mikrokosmos, 22, 199 (1929). Nopitsoh, M., Kunstseide, 10, 321 (1928). Nopitsch, M., Melliand Textilber., 9, 136, 241, 330 (1928). Picavet, P., Russa, 4, 539 (1929). Preston, J. M., J . RoyalMicroscop. Soc.,(3)51,115 (1931). Radley, J., Rayon Record, 6, January, 1933. Radley, J. A., and Grant, J., “Fluorescence Analysis in Ultraviolet Light,” D. Van Nostrand Co., N. Y., 1934. Reichert, C., Optical Works, Vienna, Catalog 6065e. Schott & Genossen, Jenaer Glaswerk, Catalog 4777, pp. 3 , 7 . Silverman, A., J. IND. ENQ.CHEM.,9, 971 (1917); 10, 1013
(1918). I b k r 1 7 , 573 (1925). Silverman, A., U. S. Patents 1,267,287 (May 21, 1918); 1,311,185 (July 29, 1919); 1,311,186 (July 29, 1919); and 1,444,400 (February 6, 1923). Singer, E., Science, 75, 289 (1932). Wasicky, R., Pharm. Post, 46, 877 (1914). R~CBIVED March 17, 1934. Contribution 2S1 from the Department of Chemistry, University of Pittsburgh. From the Ph.D. dissertation of Thomas Hill Daugherty. February, 1934.
