ANALYTICAL CHEMISTRY Haseltine, T . R., W a t e i & Sewage Works, 94, S o . 5, 187-91 (1947).
(74) Pieters, H. A. J., A n a l . Chim. d c t a , 2, 272-80 (1948). (75) Ibid.. DD. 409-10. (76) Pieters, H. A . J., Bull. ceiztie belge &de et document. eauz (Lidge), 1948, KO.1, 9-16. (77) Pilc, V., Tech. Hlidka KoieZuh.t, 23, 1-9 (1948). (78) Riehm, H., 2 . anal. Chem., 128, 249-64 (1948). (79) Robinson, R. J., and Thompson, T . G., J . Marine Research (Sears Foundation). 7. 33-41 11948). (80) Ibid., pp. 42-8. (81) Ibid., pp. 49-55. (82) Rochford, D., Australia, Council Sci. Ind. Research, B d l . 22 (1947). (83) Rossum, J. R., A N A L . C H E N . , 21, 631 (1949). (84) Rudy, H., and Mnller, K. E., Angew. Chem., A60, 280-2 (1948) (85) Scheminzky, F., Spectrochim. Acta, 3, 191-205 (1948). (86) Schmassmann, H., Schweiz. Arch. angew. Wiss.- u. Tech., 13, No. 9, 275 (1947). (87) Schwaraenbach, G., and -kcliemian, H., H e h . Chim. Acta, 30, 1798 (1947). (88) Sebald, J. F., Am. SOC. Testing Materials. Proc., 47, 1121-37 (1947). (89) Shock, D. A,, World Oil, 128, KO.3, 141-2 (1948). (90) Shvedov, 5’. P., Z h u r . Ami. K h i m . , 3, 147-52 (1948). (91) Skopintsev, B. A , , Doklady A k a d . Nauk S.S.S.R., 62, 243-6 (1948). (92) Snyder, L. J., Barnes, W. I{., and Tokos, J. \‘., ANAL. C H E x , 20, 772-6 (1948). (93) Sokolov, I. Yu., and Koniarova, .4.I., Zavodskaya Lab., 13, 753-4 (1947). (94) Spoor, W.A , , Science, 108, 421-2 (1948). (95) Stetter, H., Chem. Ber., 81, 532-40 (1948). (96) Stevens, J. .4.,J . S. d f r i c a n Chem. Inst., 1, No. 1, 1-4 (1948). (97) Taras, >I., ANAL. CHEM., 20, 1156-8 (1948). (98) Taras, >I., J . Am. Water W o r k s Assoc., 41, 527-31 (1949). (99) Todt, F., Arch. Metallkunde, 1 , 469-71 (1947). (100) Trakhtman, N. N., Gigiena i Sanit.,13, No. 7, 9-11 (1948). (101) Tuve, R. L., U. S. Patent 3,440,315 (April 27, 1948). (102) Van Beneden, G., B d l . centre belge &de et document. ta7j.z (Lidge), 1949, KO. 3. 177-82. (103) Verbestel, J., Springuel, J., and Royer, V., Ibid., 1948, KO.1, 45-50. (104) Vibert. A,, Gdnie civil, 124, 410-12 (1947). (105) Weil, B. H., et al., Georgia Inst. Technol., State Eng. Expt. Sta., Spec. Rept. 28 (1948). (106) Wenger, P. E., Monnier, D., and Hoffmann, I., Helv. Chim. Acta, 31, 290-2 (1948). (107) West, P. W., Proc. 10th -4iin. Short Course Water Sewerage Plant Supts. and Operators, 1947, Louisiana State Univ., Eng. E s p t . Sta Bull., Ser. 11, 41-3 (1948). (108) West, P. IT., and Compere, XI.; ANAL.CHEM.,21, 628-30 (1949) (109) Wilson, H. S . , Anal. Chim. d c t a , 1, 330-6 (1947). *
Headington, C. E., and Sassaman, W. A , , Petroleum Re.fiiaer, 26, No. 5, 492-4 (1947). Hirano, S.,J . SOC.Chem. I n d . J a p a n , 45, 1204-5 (1942)). Hoek, H., Chimia (Switz.), 2, 227-9 (1948). Ingols, R. S.,and Ridenour, G. M . , J . Am. Water W o r k s Assoc., 40, 1207-27 (1948).
Janssen. C.. A n a l . C h i m Acta. 2. 622-7 (1948). Janssen; C.; and Spruit, D., Ibid:, 2, 94 (1948j. Ibid., pp, 330-58. Kaufmann, W., Water ( S e t h . ) , 32, 217 (1948). Kauko, Y . , and Komulainen, L., Monatsh., 79, 272-8 (1948). Killner, W., J . Soc. Chem. I n d . (London), 68, 97-8 (1949). Kirschman, H. D., and Pomeroy, R., ANAL.CHEM., 21, 793-7 (1949).
Klement, R., Z . anal. Chem., 128, 431-5 (1948). Konen, H., Ibid., 128, 127-8 (1948). Kroener, R., Arch. Wtirmewirt, 25, 137 (1944); Dept. Sci. Ind. Research (Brit.), Fuel Abstracts, 2, No. 5 , 137 (1947). Kuper, A. I., Gigiena i Sanit.,12, No. 9, 11-14 (1947). Lamar, W. L., ANAL.CHEM.,21, 726-7 (1949). Lecoq, H., Bull. soc. roy. sci. LiBge, 12, 323-31 (1943). Leithe, W., Mikrochemie ver. Mikrochim. Acta, 33, 310-15 (1948).
Lopez, R. C., et al., Anales bromatol. (Madrid),1, S o . 1, 87-99 (1949).
Lopez, R. C., and Fungairiifo, L. 5’., Anales f i s . u p i t i m . ( M a d r i d ) , 40, 692-708 (1944). Love, S.K., ANAL. CHEM., 21, 278-84 (1949). Lur’e. Yu. Yu.. and Stefanorich. S. N.. Zavodskaua Lab.. 13. 660-3 (1947).
Mahan, W. A , , Water & Sewage W o r k s , 96, 1 7 1 4 (1949). Mehrotra, R. C., Tewari, R.-D., and Dube, H. L., J . I n d i a n Chem. Soc., 24, 165-6 (1947). Mika, J., 2 . anal. Chem., 128, 159-64 (1948). Milton, R. F., Analyst, 74, 54 (1949). Moore, E. W., Morris, J. C., and Okun, D. A, Sewage W o r k s J., 20, 1041-53 (1948).
Moore, W. A , , Kroner, R. C., and Ruchhoft, C. C., -1s.4~. CHEM.,21, 953-7 (1949). Kesmeyanov, S. A , , Gigiena i Sanit., 13, No. 3, 1-6 (1948). Orchin, M., Wender, I., and Friedel, R. A., ANAL.CHEW., 21, 1072-3 (1949).
Oahiganov, I. N., Zatodskaya Lab.. 13, 489-90 (1947). Palin, A. T., J . I n s t . Water Engrs., 3, 100-22 (1949). Parks, T. D., Johnson, H. O., and Lykken, L., ASAL. CHEW, 20, 822-5 (1948).
Patrick, W. A., and Wagner, H. B., Ibid., 21, 752-3 (1949). Pekkarinen, A., Svensk K e m . T i d . 60, 157-65 (1948). Ibid., pp. 165-8. Ibid., 61, 1-7 (1949). Pfeiffer, H., 2 . Lebensm.-Cntersuch. u.-Porsch., 88, 287-90 (1948).
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RECEIVED December 19, 1040.
ORGANIC MICROCHEMISTRY C. 0. W I L L I T S A N D C. L. OGG Eastern Regional Research Laboratory, Philadelphia 18, Pa.
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S KEEPISG with the policy of ANALYTICAL CHEMISTRY to continue the review of analytical chemistry on a yearly basis (lob),the review for 1949 was prepared. As expected, the number of papers increased. Emphasis was given to methods of analysis that extend microchemical procedures for determining single compounds in mixtures. That the procedures for elemental organic analyses can be improved is shown by the large number of new and modified methods reported. The AMERICAN CHEMICAL SOCIETYCommittee on Standardization of Microchemical Apparatus critically examined different apparatus which i t thinks should be standardized for the benefit of both the analyst and the manufacturer. Further collaborative n ork was done leading to the establishment of standard microprocedures for the .4ssociation of Official Agricultural Chemist q.
METHODS OF 4NALYSIS
Carbon and Hydrogen. The “unpacked” tube is probably the most interesting feature of the carbon and hydrogen methods of analyses reported. Conventional copper oxide, platinum, and other catalyst fillings and asbestos separators have been eliminated, and instead quartz wool is used. Whether the quartz acts as a catalyst or merely as a heater for the passing gases is not certain. The “unpacked” tube requires a much higher rate of oxygen flow and higher combustion-tube temperatures. Colson (15) used 40 ml. of oxygen per minute and 800” C.; granular sib-er maintained a t 600” C. was used to remove the halogens and sulfur, and lead dioxide held a t 180” C. was used to remove oxides of nitrogen from the combustion products. Korshun and Kliniova
V O L U M E 22, NO. 2, F E B R U A R Y 1 9 5 0 (69) used a similar rapid rate of oxygen flow but a temperature of
900"C. Solid samples were placed in a special microthimble; volatile liquids were p u t in a coiled capillary tube. "Unpacked" combustion tubes promise greater rapidity of analysis. To make the procedure generally applicable, however, further studies are required to ascertain the correct combination of size of tube, rate of oxygen flow., rate of volatilization of sample, and temperature of combustion. Of all the microprocedures reported for carbon and hydrogen it ivas claimed that the packed-tube method of Fischer (26) offered the greatest improvement in accuracy. With his semiautomatic apparatus, sensitized catalysts, and 10- to 20-mg. samples, an accui'acy of *0.02% was reported. Lescher (68) described a semimiwo modification, especially adapted to the analysis of liquid samples, in which the liquid was slowly vaporized and burned in a flanie at the tip of an ampoule container. As in the unpackedtube methods, the rate of oxygen flow was much higher than normal. Changes in combustion-tube filling were suggested by Bennett ( 6 ) , who placed a 180-mm. section of "reduced" copper in front of a 1Xknim. section of copper oxide, making it unnecessary to use lead dioxide with nitrogenous organic compounds. Combustion was carried out in a stream of nitrogen containing a small amount of oxygen. The reported results were high, but all were within the acceptable range. Heron (46) recommended an increase in the quantity of lead dioxide or a liquid absorber to remove more effectively the oxides of nitrogen. La Force, Ketchum, and Ballard (65)successfully analyzed carbonates, cyanides, and alkali or alkaline-earth organic salts for carbon by covering the sample with sodium bisulfate, then performing the combustion in the usual manner. Two new methods employing the Van Slyke-Folch n-et coinbustion reagents for carbon were reported in which carbon is collected as barium carbonate. Farrington, Xemann, and Svift (84) described a method that eliminates the need for the Van Slyke manometric apparatus; Lindenbaum, Schubert., and Armstrong (69) changed the usual procedure to make it applicable to analyses involving isotopic carbon. Goulden (58) used a macrobalance with the method of Sucharda and Bobranski. The time required for a n analysis is shortened by increasing the rate of oxygen flow and the amount of copper oxide filling. The probable sources of error in the semimicromet,hod of ter Meulen and Heslinga were discussed by Guzman (41). Renard (88)reviewed the literature describing open and closed absorption tubes. For determination of hydrogen alone, PepkoLYitz and Proud (86) proposed a gasonietric micromethod which depends on diffusion of the hydrogen from organic and inorganic compounds from a sealed iron capsule into a simple vacuum system. Accuracies comparable with those of standard combustion procedwes were reported; none of the other elements interfered. Nitrogen. KJELDAHL.Report of a collaborat,ive study by \Tillits and Ogg (106) emphasized the wide discrepancy betn-een nitrogen values for a refract,ory compound (nicotinic acid) obtained by different analysts. Good nitrogen values, hon-ever, were obtained by some of the procedures. White, Secor, arid Long (104) accurately analyzed amino acids containing refractory nitrogen by digesting with a mercury catalyst. Although there is a tendency to omit selenium, Rauen and Buchka (81)claimed that 1-hour digestion after the mixture clears is sufficient for ])-sine and proteins containing lysine if sulfuric acid containing 0,7'$c selenium oxide is used. One point which most workers have not stressed but which appears to be critical is the teniperature of the digestion mixture. A modification of the Parnas apparatus reported by Johanson (61) includes a steam jacket for distillation, removal of spent liquor, and simple construction and assembly. Machenier and hIcKabb (71) found an average error of approximately O.lyc in distillation of ammonia into 4% boric acid and titration with methyl red indicator. Day, Rernstorf, and Hill (19) suggested a modifiration of
269 Sobel's microaeration t'echnique in which aeration is carried out a t 70" C. Kotlyarov (60) proposed a new formula for calculation of nitrogen by which the colorimetric micromethod can be used to determine 10 to 100 micrograms with an accuracy of 2 to
3%. D r ~ a s . Most of the changes in the Dumas procedure proposed have been in the apparatus rather than in the technique. ilfter a critical study, Bussniann (12) recommended the Zinimerman method because it reduces the possibility of errors due t o leakage of air into the system under reduced pressure. Hei,on (46) proposed a banded tube filling of alternate layers of coarse and fine copper oxide for volatile compounds low in nitrogen. Brancone and Fulmor (11) raised the temperature of the burning furnace from 700" t o 900" r, to aid in the decomposition of refractory ring compounds. Carbon dioxide generat,ors were described by Schoniger (89) and Furter and Bussmann (SO). The AMERICANCHEYICAL SOCIETY Committee for the Standardization of Microchemical apparatus (16) described a sturdy all-metal needle valve that allows the same precise control of the rate of gas flow as does the more fragile Hershberg-Southrvorth valve. .4 weight nitronieter that eliminated disassembly was described by Koch, Simonson, and Tashinian (56). Halogens. Schumb and Radimer (91) reported a method for determining fluorine in volatile compounds in Lvhich the sample is decomposed with moist oxygen in a platinum tube a t 1100" C. The absorption unit is saran tubing and the final measurement is made colorimetrically. Here, as in the carbon and hydrogen determinations, a high yatio of oxygen t o oxidizable material is important. Lingane and Small (70) suggest,ed an interesting coulometric method for determining halide ions by which either a single halide or niistures of iodide and bromide or iodide and chloride are determined. This method measures the electricity required for the quantitative reaction of the halide ion \\-ith a silver anode having controlled potential. Kirsten (54) improved his titrimetric procedure for chloride and bromide ions by substituting mercuric nitrate for the mercuric acetatti previously used. Two papers described determination of bromine. One, by illicino, Crickenberger, and Reynolds ( I ) , is based on an iodometric procedure that reduces the time required for anal>-sis. The other, by Daudel, Flon, and Herczeg ( I @ , uses the Parr bomb technique t o destroy organic matter so that radioactive bromine can be measured more accurately. Spectrophotometric methods for iodine were more involved than the volumetric procedures but were applicable to the analyses of smaller amounts of iodine. Custer and Katelson ( I ? ) pointed out that ultraviolet spectrophotometric measurements of solutions of elemental iodine in benzene, toluene, and potassium iodide permitted determination of as little as 0.2 microg~,am. Shakrokh and Chesbro (92) measured iodine spectrophotometrically after chromic acid oxidation of organic matter, reduction by phosphorus, oxidation to the iodate by chlorine, and reduction to free iodine by potassium iodide in acid solution. Gross, \Yood, and McHargue (40) used a similar series of reactioni hut added starch and measured the starch-iodine blue complex by its light absorption in the visible region. The volumetric methods of Grangaud (39), Schulek ( g o ) , and Lacourt and Timmermans (64) used the reactions silver iodate and filtration, chlorine water, and T'iebock and Brecher's bromine method to obtain the iodine as iodate. The iodate was determined iodonietrically with thiosulfate. The method of Lacourt and Timmermans can be used for simultaneous determination of carbon, hydrogen, and iodine, b u t a long time is required for iodine analysis. Intonti and Gargiulo (60) determined two of t,he three halogens (chlorine, bromine, or iodine) simultaneously from the weight of the two silver salts and from thr amount of the silver used, n-hich \vas det~rrninedby either gi avimetric or volumetric analyses.
270 Metallurgia published some critical reviews of micromethods for particular elements. One, by Beaucourt ( 5 ) , is a review of procedures for determination of halogens. Sulfur. A gravimetric method by Stragand and Safford (99) is simple, direct, and generally applicable to organic sulfur analysis. The sulfur trioxide from catalytic combustion of organic material is caught on silver gauze, and its weight determined; or if halogens are present, the silver sulfate is dissolved in water, and the amount of sulfur is calculated from t,he loss in weight. Two methods were reported for determining sulfur in compounds in which sulfur is readily converted to the sulfide. Klimenko (55)used alkali to convert the sulfur in proteins and tissues to sulfide or hydrosulfide. These are converted to sulfate, which in turn reacts with barium chromate; the liberated chromic acid is measured iodometrically with thiosulfate. Acid was used by Pepkowitz (84) to liberate hydrogen sulfide, which was distilled into standard calcium hypochlorite; the excess hypochlorite was determined iodometrically, Two critical reviews, one, by Lam0 (66), of semimicromethods and the other, by Thomson (100), of micromethods, discuss gravimetric as well as direct and indirect, volumetric methods of sulfate analysis. Unsaturation. In the past, unsaturation has been determined largely by macroprocedures using halogenation methods; there have been relatively few analyses by direct hydrogenation. Hydrogenation has tvio advantages; it is not empirical, and it is satisfactory for conjugated unsaturation, for vinyl and allyl compounds, and for double bonds that are inaccessible t o halogens because of steric hindrance. Microhydrogenation is less timeconsuming and less subject to interference by catalyst poisons. Ogg and Cooper (81) presented a simplified apparatus and procedure for quantitative catalytic microhydrogenation. For microhalogenation, Phillips and T a k e (86) used a special reaction flask and technique. A met,hod for determination of the iodine number of lipides in blood serum ITas described by GirautErler and Grimberg ( 3 2 ) . Acetyl. Elek and Hart’s method for acetyl determination was modified by Bradbury (10) to eliminate the sulfur dioxide correction and avoid errors due to carbon dioxide. Water. Determination of xater in small amounts of material, by the calcium carbide method was described by Gorbach and Jurinka (35). Fischer (27) suggested three methods for detection of water: Potassium lead iodide in gasoline when heated with a trace of moisture or water of crystallization forms yellow lead iodide and bubbles; calcium carbide emulsion in peanut oil when heated with water leads to bubbles that remain visible after cooling; and phosphoric acid formed by adding traces of water to a gasoline solution of phosphorus pentoxide and bromocresol purple causes a change in the color of the indicator. Alcohols. X quantitative colorimetric microdetermination of methanol was reported by Boos ( 9 ) to be rapid and specific. Opfer-Schaum (82) detected glycerol in mixtures by forming acrolein hydrazone and determining its eutectic temperature with p-nit,rophenylhydrazine microscopically. De Jleio (20) described a microextraction procedure for separating phenol before determining the phenol spectrophotometrically. Acids. Although organic acids are now detected and determined largely by chromatographic techniques, some purely chemical methods have been reported. Komet’iani and Sturua (57) described a micromethod for citric acid, and Volpi (103) described a method for detection of succinic acid in the presence of aconitic and tricarboxylic acids. Other micromethods reported include a polarographic method for amino acids (74) and a new procedure for tryptophan (96). peri-Naphthindantrione hydrate was substituted for ninhydrin in amino acid analysis by Rloubasher and Awad (79). Steele, Sfortunato, and Ottolenghi (94) applied Schneider’s method to the microanalyses of nucleic acids. Tracey (101) developed a manometric method for measurement of uronic acids.
ANALYTICAL CHEMISTRY Carbohydrates. Methods for determining glucose and mannitol in blood mere described by Nosto and Cavanna (78) and Hamburger et al. ( 4 4 , respectively. Mosto and Cavanna’s paper also includes a method for urea analysis in which the urea is measured by nesslerization after treatment with urease. Use of partially hydrolyzed dextran as a substitute for blood in the treatment of shock led Hint and Thorsen (47) to develop a micromethod for dextran in blood. Miscellaneous. 1-Nicotine was recovered from animal tissue and determined by Trim (102), who observed a linear relation between color and concentration over the range 1.5 to 20 micrograms of nicotine per milliliter of solution. Shkitin (93) developed a method for identifying azo dyes on paper or thread. Hamburger and Rasch (43) compared different micromethods for determining 17-ketosteroids in urine. Methods were reported for riboflavin (as),phosphatase (%), diastase (77), albumin (28), and globulin (13). In addition, Kunzmann (62) discussed the use of micromethods in the cosmetic industry, and Kretchmer (61) reviewed the application of micromethods in lipide chemistry. Molecular Weight. b n isothermal diffusion method was proposed by Wright (108), in which solutions of a known and an unknown \yere placed on separate pieces of filter paper and left with their vapor phases in common. The molecular weight of the unknown was calculated from the weight of solvent on the two papers. Wilson (107) published a comprehensive review of molecularweight methods. With Magee (73), he recommended that a cloth sleeve be used on Beckman microthermometers to minimize temperature fluctuations encountered in ebullioscopic methods. APPARATUS
Balances. h submicrobalance of the torsion type and some techniques and applications were described by Ingram (48, 49). St’ock and Fill (98) controlled the swings in semimicro weighings by an air jet. Feuer (86)discussed a new type microbalance utilizing radiation from radioactive material, with a load capacity of 25 to 50 grams per pan and with high sensitivity and stability. Miscellaneous. Modifications of the horizontal burets of Conway and Benedetti-Pichler have been proposed (45, 58, 63), t,ogether with three new displacement-type microburets (31, 97). Two new stirring devices for microtitrations have been described (14,96). Several distillation apparatus have been reported for volumes from 0.1 to 4.0 ml. with improved means of fraction recoveries (4, 7 , 37, 42, 67). Three metal block-type melting point apparatus, one gas and two electrically heated, have been described (78, 75, 8 3 ) ; all use an optical magnification system for detecting the melting point, and that of Matthews (75) is equipped with a cooling device. An apparatus for microsublimation using an electric light as source of heat was proposed by Meyer (76). A pipet (33) for spray rinsing of pipets with a measured volume of liquid has been described, and the drainage of micropipets has been studied ( 3 ) . Other apparatus include a micromuffle (34), high-temperature coil and ring gas burners for microcombustions (ia ? liquid-liquid ), extractor (53),microadapters for the Evelyn colorimeter (28) and the Beckman p H meter @ I ) , and a thermostatically controlled micropolarimeter tube (62). Apparatus for making vapor pressure measurements (8, 80) have been proposed, and a versatile microapparatus for filtration, extraction, and distillation has been designed (22). ACKNOWLEDGMENT
The authors are indebted to Frances J. Cooper for searching the literature.
V O L U M E 22, NO. 2, F E B R U A R Y 1 9 5 0 LITERATURE CITED
Alicino, J. F., Crickenberger, Anne, and Reynolds, Beatrice, ANAL.CHEY.,21, 755 (1949). Aluise, V. A,, Ihid., 21, 746 (1949). hnderson, H . H., Ibid., 20, 1241 (1948). Babcock, M. J . , Ihid., 21, 632 (1949). Beaucourt. J. H., Metallurgia, 38, 353 (1948). Bennett, A , , Analyst, 74, 188 (1949). Bering, P., Suensk. Kem. Tid., 61, 10 (1949). Bonhorst, C. W., .4lthouse, P. M., and Triehold, H . 0..J . A m . Oil Chcmists' Soc., 26, 3 i 5 (1949). Boos, R. N . , A4X.kL. CHEJ1.. 20, 964 (1948). Bradbury, R. B., Ihid., 21, 1139 (1949). Brancone. L. M., and Fulmor, Wm., Ibid., 21, 1147 (1949). Bussmann. G., Helv. Chim. Acta. 32, 995 (1949). Chow. B. F., Hall, L., Duff?. B. J., and .4lper, C . . J . Lab. Clin. M e d . , 33, 1440 (1948). Claff, C . L . . Science, 108, 67 (1948). Colson, -4. F., A n a l y s t . 73, 541 (1948). Committee for the Standardization of Microchemical Apparatus, AAX-\I.. CHEJI., 21, 1283 (1949). Custer, J. J., and Natelson Ibid.. 21, 1005 (1949). Daudel, P., Flon, 11..and Herczeg, C., Compt. rend., 228, 1059 (1949). . Day. H . G . , Bernstorf, Eileen, and Hill, R . T.. A X ~ LCHEx, 21, 1290 (1940). De RIeio, R . H.. Science. 108, 391 (1948). Dietz, V. H., Ihid.. 108, 338 (1948). . 21, 1273 (1949). Dubbs, C . A,, A N ~ LCHEM.. Ecker. l?. E . , and Likover, B.. .J. Lah. Clin. Jfed.. 32, 1500 (1947). Fnrrington, P. S.,Kieniann, C., and Swift. E. H . , AX.
