ANALYTICAL CHEMISTRY
246 (158) Sun, Tak-Ho, Willems, F., and Geller, W., Arch. Eisenhcttenw., 17,207-10 (1944). (159) Tananaev, I. V., Zavodakaya Lab., 12, 248-9 (1946). (160) Tananaev, I. V., and Silnitschenko, V. G., Ibid., 12, 140-1 (1946). (161) Thrun, W. E., and Bartelt, C. H., Iron Age, 160, 40-2 (1947). (162) Thrun, W.E., and Heidbrink, C. R., Ibid., 158, 68 (1946). (163) Touhey, W. O., and Redmond, J. C., ANAL. CHEM.,20, 202 (1948). (164) Traub, K. IV., IND. EKG.CHEM.,ANAL.ED., 18, 122-4 (1946). (165) Tuttle, H. A., and Nahstoll, H. A , , Iron Age, 160, 68-72 (1947). (166) Uri, Xorbert, Analyst, 72, 478-81 (1947). (167) Usatenko, Yu, I., and Datsenko, 0. V., Zavodskaya Lab., 13, 116-17 (1947). (168) Vance, E. R., Steel, 121, 92 (1947). (169) Vaughan, E. J., and Whalley, C., J . Iron Steellnst., 155, 535-62 ( 1947). (170) Vincent, H. B., and Sawyer, R. A., J . Optical SOC. Am., 32, 686 (1942). (171) Waldbauer, Louis, and Ward, Kellie, IND.ESG. CHEM.,AKAL. ED., 14, 727-8 (1942). (172) Watters, J. I., and Kolthoff, I. &I., Ibid., ED., 16, 187-9 (1944). (173) Weinberg, Sidney, Proctoi, K. L., and Slilner, Oscar, Ibid., 17, 419-22 (1945). (174) Weissler, Alfred, Ibid., 16, 311 (1944). (175) Ibid., 17, 695-8, 775-7 (1945). (176) Weissler, Alfred, and White, C. E., Ibid., 18, 5 3 0 4 (1946). (177) Welcher, F. J., “Organic Analytical Reagents,” New York, D.
(178) (179) (180) (181) (182) (183) (184) (185) (186) (187) (188) (189) (190) (191) (192) (193) (194)
Van Nostrand Co., Vols. I, 11, and 111, 1947; Vol. IV, 1948. Wells, J. E., and Barraclough, K. C., J.Iron Steel Inst., 155, 27 (1947). Wells, J., and Pemberton R., Analyst, 72, 185 (1947). West, J. L., Ibid., 70,82-6 (1945). T\“eSt, P. I$‘., IND. ENG.C H E M . , -4N.4L. ED.,17, 740 (1945). West, P. W., and Dean, J. F., Ibid., 17, 686-8 (1945). Westwood, W.,and Mayer, A , , Analyst, 73, 275-82 (1948). White, C. E., Weissler, Alfred, and Busker, David, ANAL CHEM.. 19. 803-5 (1947). Willard, H. H., and Center: E. J., IND.EKG.CHEM.,ANAL.ED., 14,287-8 (1942). Wilson, H. N., A n a l . Chem. Acta, 1, 330 (1947). Wilson, J. T., and Bennett, Josephine, Foundry, 73, 81, 218 (1945) Wolfe, R. A., and Fowler, R. G., J . Optical SOC.Am., 35, 86-91 (1945). Wooten, L. A., and Guldner, W.G., IND.EKQ.CHEM.,ANAL. ED.,14,835-8 (1942). Yoe, J. H., and Armstrong, A. R., ANAL. CHEEri., 19, 100-2 (1947). Yoe, J. H., and Jones, A. L., ISD.ENG.CHEM.,AXAL.ED., 16. 45-8 (1944). Young, R. S., and Hall, A. J., Ibid., 18, 2 6 2 4 , 264-6 (1946). Young, R. S.,Pinkney, E. T., and Dick, R., Ibid., 18, 474 (1946). Zan’ko A. M., Geller, B. A . , and Nikitin, A . D., Zavodskaya Lab., 13, 299-300 (1947).
RECEIVED December 14. 1948
NONFERROUS METALLURGY H. V. CHURCHILL, Aluminum Comporny of America, New Kensington, P a .
B
ECAUSE the analytical chemists serving nonferrous metallurgy use many, if not most, of the analytical procedures and techniques covered in the general and specific literature of analysis, detailed descriptions of techniques and procedures are avoided in this review. The scope of use of techniques and procedures and their application to the analysis of nonferrous metals are stressed. Fundamentally, the most important analytical procedures in the nonferrous field are gravimetric and volumetric in nature. This is well illustrated by the fact that, for the most part, methods for the analysis of nonferrous metals presented by the American Society for Testing hIaterials (9)are almost wholly gravimetric or volumetric in nature. This fact should not be construed as minimizing the importance of other procedural methods, but rather as indicative of the fact that from the standpoint of demonstrable accuracy, gravimetric and volumetric methods have advantages not attainable by methods which, while not necessarily so accurate, exhibit the advantages of speed and adequate precision. Most of the accessory methods used for purposes of speed and convenience are comparative in nature and depend for their reliability on standards evaluated by the more reliable, even if more laborious, methods of gravimetric and volumetric analysis. During the past five years, there has been little advance in the gravimetric and volumetric methods used in the field of nonferrous metallurgy. In general, these methods closely parallel the procedures outlined in what is generally accepted as the analytical bible of nonferrous analytical chemistry, Hillebrand and Lundell’s “Applied Inorganic Analysis” (16). I n general the gravimetric and volumetric methods used in the nonferrous field are covered in essence by the text of Lundell and Hoffman (31). In this area of analysis, wide use is made of standard texts on quantitative analysis such as that by Kolthoff and Sandell ($0). Texts such as the latter are of great value as regards fundamental theory and practice, but must be supplemented by literature which covers specific fields, as the application of certain basic or fundamental methods t o the determination of elements in a specific matrix or in the presence of certain interfering ele-
ments often makes necessary the provision of specific procedures for the separation of such interfering elements prior t o the measurement of the element sought by weighing or titration. In such cases, texts such as Scott’s “Standard Methods of Chemical Analysis” (28) are of great value. In the same category as Scott’s compendium of methods are such publications pertaining t o particular or specific fields as “Analytical Methods for Aluminum Alloys ” ( 2 ) or “Chemical Analysis of Aluminum” (1). Electroanalysis has continued to be an important procedure in nonferrous analytical laboratories. However, no particularly new or novel advance has characterized the use of such procedures in the nonferrous field during the past five years. S o particularly noteworthy application of potentiometric methods has been made during the past few years, although there is a gradually increasing use of potentiometric procedures t o supplant less precise and convenient procedures. -4lthough there has been no recent important development in the field of organic reagents as precipitants, the use of dimethylglyoxime, nitroso-P-naphthol, and many other such reagents in the nonferrous field is widespread. The increasing use of 8hydroxyquinoline is particularly noteworthy. Nonferrous chemists are keenly aware of the possibilities involved in organic precipitants, particularly those with selectivity or specificity as to elements, and are alert to new developments in the field. TRACE ANALYSIS
In the nonferrous field, few metallic elements are determined when they are the matrix or base metal of the alloy. General practice is to determine the concentration of certain impurities, summate the total of these, and report the difference between these and 100% as the concentration of the major or matrix metallic element. Many trace elements or those without known metallurgical effects are often not determined. However, the number of elements not determined continually grow less as metallurgical investigations reveal the specific effects of many elements, even when present in minute amounts. The determination of elements present in minute amounts has been greatly
V O L U M E 21, NO. 2, F E B R U A R Y 1 9 4 9 facilitated by the development of colorimetric, spectrochemical, and polarographic procedures. Attention is called to the recent publication of Sandell’s “Colorimetric Determination of Traces of Metals” (M), which is generally accepted as authoritative, helpful literature in the field of trace analysis. The analytical chemistry of nonferrous metallurgy, as it developed, was historical in character; comp,tratively little actual control analysis was accomplished. During the process of production of either the metal itself or the alloy, the metal in process was not analyzed in time for modification, correction, or adjustment of composition to be made. I t is true that certain step or end products were analyzed, but these were made t o establish historically the result of other control procedures and to establish the quality of product. The condition arose from necessity and not from desire. The simple fact was that the traditional methods available could not be speeded up sufficiently to enable their use as practicable control procedures. The development of physicochemical methods during the past 25 or 30 years, however, offered a possible solution to the problem and, today, methods of adequate precision and speed either are available or are in process of development to enable the introduction and use of spot control procedures which must inevitably result in better quality of product and in greater economy of production costs. Another advantage of the physicochemical methods is their much greater objectivity in contrast to the large element of subjectivity in the traditional gravimetric and volumetric procedures. Although instrumentaton and mechanization have been incorporated into the traditional or classic methods, nevertheless, over-all progress along that line has not served t o stem the increasing use of the newer physical procedures. I n 1938-39, there appeared Bottger’s excellent treatise entitled “Physikalische Methoden der analytischen Chemie” (6)although no English translation of this work has been published, i t has had a stimulating influence on the development of methods of analysis in the nonferrous field. R. H . Muller’s article on “Instrumental EDITION RIethods of Analysis” (23) published in the ANALYTICAL O f INDUSTRI.4L AND ENGINEERING CHEMISTRY in 1941, which has been supplemented by several additional papers in the same journal by the same author, gave great impetus to the objectivization and speeding up of analytical work in the service of nonferrous metallurgy. Also worthy of note is Gibb’s excellent volume pub1i;hed in 1942 ( I S ) . COLORIMETRlC METHODS
Much specific use of colorimetric methods has been made by nonferrous chemists. However, such methods, as yet, have not attained the status of general use. Indicative of progress in the more general use of colorimetric procedures in the nonferrous field is the intensive attention being paid to this type of procedure by the nonferrous division of Committee E-3, American Society for Testing Materials. Certain methods and procedures along these lines appear in recent editions of the A.S.T.M. volume on “Methods of Chemical Analysis of Metals” ( 3 ) . The availability of photoelectric instrumentation has given great impetus toward the more general adoption of colorimetric or photometric methods as they are referred to increasingly. Volume I of Snell’s “Colorimetric Methods of Analysis” (SO) is a nridely used source book: as is Yoe’s “Photometric Chemical Analysis” ( 3 2 ) . Sandell’s book on trace elements (26) also is attaining wide acceptance. While photometric methods present many interesting possibilities, it is probable that such methods are used in nonferrous analytical laboratories to only a limited extent and for very specific purposes. Closely allied to colorimetric or photometric methods are those called spectrophotometric procedures. I n the nonferrous field, spectrophotometry is used mainly in the investigation and setting up of coIorimetric or photometric procedures, wherein the spectrophotometer is supplanted or replaced by the photoelectric colorimeter, usually of the filter type.
247 The most popular physicochemical methods are those commonly referred to as spectrographic but more definitely as spectrochemical. I n general, such procedures have found wide acceptance throughout the whole field of nonferrous metal analysis, but, perhaps, are more widely used for the analysis of magnesiumand aluminum-base metals than for the analysis of other nonferrous materials. Although there has been n o such generally accepted compilation of spectrochemical methods as the A.S.T.M. methods, which are largely in the traditional or classic vein of gravimetric or volumetric analysis, the fundamental principles and techniques are well covered in two texts-Brode’s “Chemical Spectroscopy” ( 7 ) and Sawyer’s “Experimental Spectroscopy” (27’). The adaptation of spectrographic procedures t’o the analysis of particular base metals is covered in many separate and the Journal of publications, such as ~ A L Y T I C A LCHEMISTRY the Optical Society of ,4merica. In the case of some metals such as aluminum, methods specific for that metal are available from a producer. Sources of information along spectrochemical lines, particularly of a nonferrous nature, are given in the bibliography appended to this review. Considerable information of great value is also available from manufacturers of apparatus and equipment. In general, the methods employed are adaptations or modifications of the so-called internal standard type. The use of visual comparison methods still persists but is gradually being abandoned. This has been caused mainly by the better adaptation of internal standard spectrochemical methods to the mass or speed production of analytical data. Spectrochemical methods are comparative in nature and depend for reliability and validity of results obtained by their use upon the availability of reliable standards upon which to base working curves, adjustment of instruments, and control of analytical operations. The status and availability of spectrographic standards for use in the nonferrous field are well covered in a report by Brode and Scribner. Many standards for use in the analysis of specific nonferrous alloys or metals are available from metal or alloy producers. Most standards used in the nonferrous field are secondary standards, for few primary standards have been prepared. The advantages of spectrochemical methods for the mass and speed production of analytical data were attained only by a drastic and stringent establishment and maintenance of appropriate conditions and practices. However, experience revealed that the photographic variables were the most difficult to control. Mainly in an effort to overcome such difficulties, cooperation between spectrochemists and instrument manufacturers led t o what is probably the most significant development in t,he field of nonferrous analytical chemistry-the so-called direct reading spectrographs. Two such types of instrumentation are currently serving in the field of nonferrous metallurgy, though further developments are apparently in the offing. I n essence, these instruments replace the photographic plate or film with photoelectric receivers positioned to receive radiation on any desired wave length. These receivers are built around multiplier phototubes, the output of which is used to charge condensers. Available instruments vary in the method of measuring the charge on the condensers, but regardless of the method of measurement, the charge on the condenser is a direct and calculable function of the radiation which has impinged on the multiplier tube. The measurement may be registered as a count of impulses and the tape or other counting device may be directly calibrated so that the measurement may be read in percentage of element spectrally excited. I n one nonferrous industry, laboratories engaged in routine metal analysis produce analytical determinations using traditional methods a t the rate of about five per man-hour. This rate per man-hour is arrived a t by dividing the total determinations reported per day, first by the number of hours in the work day, and then by the number of productive chemical workers. Lab-
248
ratories doing work on similar samples by conventional spectrographic methods show a production of about twenty-five determinations per man-hour. When the work is done on direct reading spectrographs, the output reaches as high as eighty per man-hour. This speed of production is not obtained with any sacrifice of precision or accuracy. As a matter of fact, careful statistical studies show that the standard errors of direct spectrographic results are no greater, and often are less, than the standard errors of results obtained routinely by the use of conventiorisl chemical methods. I n general, ordinary spectrographic methods are acceptable for concentrations of less than about 4%; however, cases can be cited when this limit of concentration is exceeded. I n the case of direct reading spectrographs, concentrations up t,o 13% are being determined satisfactorily and adequately . One very important use uf the spectrograph in the nonferrous field is for qualitative purposes. RIariy nonferrous analytical 1at)oi.atories routinely check samples of current production for the preserice of unexpected elements. Another pxvalent use of the spectrograph is the identification of the alloy type of aiiinples of nictals anti ::llo;:s, This identification of alloy types or qualitative compositions is more satisfactory and definitive than the use of clieniical spot tests. Experienced spectrographic xorkers become expert in their qualitative work and their results are rightly referred t o as seniiquantitative. One widespread practice is to report qualitative results on a decimal scale, thus listing elements as 10 to loo%, 1 to 10% 0.1 to 1.0%, 0.01 to O.lO%, 0.001 to 0.017,, and leas than 0.001% Tlie spectrograph is also widely used for the sampliiig and identification of scrap. Such procedures have been of great value in the postwar period when vast quantities of scrapped nonferrous material wpre in process of recovery. Much of the nonferrous rneia1 used commercially is of secondary origin, and its composit ion is often controlled by spectrographic procedures. h n interesting variant of spectrochemical analysis of the usual type is the combination of direct reading spectrographic techniques with the flame excitation of spectra which was proposed by Lundeghrdh in Korway. The apparatus is known as the fianie photometer. Two such instruments are a t present, available coniniercially and are receiving increasing acceptance by nonferrous analytical laboratories. I n flame photometer procedures, the sample, after solution, is atomized into a gas flame. Tlie radiation from this flame is fed into the apparatus, wherein, by the use of either filters or a refracting prism, radiation on particular n a v e lengths is allowed to impinge on a photosensitive surface. By measurement of the element current produced and comparison Kith similar radiation from known standards, the concentration of the emitting element can be calculated. Although the method has proved to be of value mainly in the case of alkali and alkaline earth metals, many other elements are also sufficiently spectrally sensitive to be determined. I n the nonferrous field, only threshold experience has been had with this instrument, but it apparently offers great promise. Analyses by x-ray spectrography, x-ray diffraction, mass spectrography, and radiometry have not, as yet, become particularly important in the nonferrous field, and for the purposes of this review are recognized only by name. It is to be expected that some or all of them will become increasingly useful, particularly in specific applications, but it is doubtful if for some time to come they will challenge in popular use the more widely used methods already described. Chromatographic methods do not, as yet, seem to offer much promise t o the nonferrous analytical chemist as a major procedure. hlicroanalysis and chemical microscopy are, of course, used t o some extent in the field of nonferrous metals, b u t have proved to be useful only in isolated specific cases. There is little in the literature to indicate that nonferrous analytical chemists have contributed much to the development of these techniques which
ANALYTICAL CHEMISTRY have proved t o be of great value in other fields. The spot testing techniques of Feigl ( l a ) are rather widely used in nonferrous qualitative work. POLAROGRAPHIC PROCEDURES
There remains one other type of analytical procedure that offers considerable promise in the field of nonferrous analysis namely, polarographic procedures. While the techniques of polarographic analysis stemming from the work of Heyrovskf. have been the subject of many publications, the American nonferrous analytical chemist has based most of his work on the book by Kolthoff and Lingane (28). Attention is called to Kolthoff’s paper (16), which outlines workable procedures for applying polarographic techniques to the analysis of aluminum alloys. This particular paper is cited because i t shows that polarographic procedures are applicable to a nonferrous sample. It is doubtful that polarographic procedures can compete on a routine basis with other methods now in wide use in nonferrous analytical laboratories, particularly from the standpoint of economy of laboratory manpower. However, the time seems to be rapidly approaching when polarographic equipment will be considered essential and standard in a modern nonferrous laboratory, The following publications are specifically useful for the identification of published material on nonferrous analysis: Chemical Abstracts, AMERICAN CHEMICALSOCIETY, Washington 6, D. C., published since 1907; and Metallurgical Abstracts, The Institute of Metals, London, England, published since 1934. CONCLUSIONS
During the past few years nonferrous analytical laboratories have been going through a process of evolution from a state wherein the analytical data were largely historical in character to a state where most data are provided in sufficient time actually to serve as a control on the composition of metal in process. This change has been particularly marked during and since World War 11. I t has been characterized by a change from the more subjective methods of traditional analytical chemical methods of a few years ago to the increasingly objective methods of today. However, all this has been accomplished by the intelligent use of the traditional or classic procedures to produce adequate standarde upon which to base the comparative methods which are tieing u s ~ dto an increasing extent. BIBLIOGRAPHY (1) Aluminum Co. of America, “Chemical Analyses of Aluminum,”
1949. (2) Aluminum Research Institute, Chicago, “Analytical Methods for Aluminum Alloys,” 1948. (3) American Society for Testing Materials, Philadelphia, “A.S.T.M. Methods of Chemical Analysis of Metals,” 1946. (4) Berry, J. W., Chappell, D. G., and Barnes, R. B., IND.ENQ CHEJI.,ANAL.ED.,18, 19 (1946). (5) Bottger, W., “Physikalische Methoden der analytischen Chemie,” Ann Arbor, iMich., Edwards Brothers, 1943. (6) British Aluminum Co., London, England, “Analysis of Aluminum and Its Alloys,” No. 405, 1947. (7) Brode, W. R., “Chemical Spectroscopy,” New York. John Wiley & Sons, 1943. (8) Churchill, H. V., and Bridges, R. W., New Kensington, Pa., “Chemical Analysis of Aluminum,” 1941. (9) Churchill, J. R., IND. ENG.CHEM.,ANAL.ED.,16, 653 (1944). (10) Ibid., 17, 66 (1945). (11) Corliss, C,. H,.,“Report on Standard Samples for Spectrochemical Analysis, Philadelphia, American Society for Testing Materials,. 1947. (12) Feigl, F., “Qualitative Analysis by Spot Tests,” New York, Nordemann Publishing Co., 1939. (13) Gibb, T. R. P., “Optical Methods of Chemical Analysis,” New York, McGraw-Hill Book Co., 1942. (14) Hasler, M. F., Lindhurst, R. W., and Kemp, J. W., J. Optical SOC.Am., 38, 789 (1948). (15) Hillebrand, W. F.. and Lundell, G. E. F., “Applied Inorganic Analysis,” New York, John Wiley & Sons, 1929.
V O L U M E 2 1 , NO. 2, F E B R U A R Y 1949 (16) Kolthoff, I. M . , IND. ENG.CHEM.,ANAL.ED., 17, 615 (1945). (17) Kolthoff, I. >I., and Furman, N. H., “Potentiometric Titrations,” New York, John Wiley Br Sons, 1931. (18) Kolthoff, I. M., and Lingane, J. J., “Polarography,” New York, Interscience Publishers, 1941. (19) Kolthoff, I. M . , and Matsuyama, G., ISD. ENG.CHEM.,Ais.4~ E D . ,17, 615 (1945) (20) Kolthoff, I. M . , and Sandell, E. B., “Textbook of Quantitative Inorganic Analysis,” Ken. Yoi,k, Macmillan Co., 1943. (21) Lundell, G. E. F., and Hoffman, J. I.. ”Outlines of Methods of Chemical Analysis.” Kern York, John Wiley 6: Sons, 1929. 122) SIeggers, W. F., and Scribner, B. F., “Index to the Literature on Spectrochemical Analysis, 1920-1939,” Philadelphia, Ainericaii Society for Testing Materials, 1041. (23) hfLIUller, 11. H.. ISD. ESG. C H E Y . . A S I L . ED., 13, 667-754 (1941). (24) Prodinger, IT., “Orgmic Reagents Used in Quantitative Inorganic Analysis,” New York, Elsevier Publishing Co., 1940. (25) Sandell. E. B., “Coloriinetric Determination of Traces of Metals,” New Y o I , ~Interscience . Publishers, 1947.
249 (26) Saunderson. J. L., Crtldecourt, V . J . , and Peterson, E. W., J . OpticaZSoc. A m . , 35, 6S1 (1945). ( 2 7 ) Sawyer, R. 4., “Experimental Spectroscopy,” New York. Prentice-Hall, Inc., 1944. (28) Scott, V. IT., “Standard XIetliods of Chemical Analysis,” New York, D. Van Nostrand Co., 1939. (‘291 Scrihner, B. F., and hleggers. W.E’., “Index to the Literature on Spectrochemical Analysis, Part 11, 1940-1945,” Philadelphia. American Society for Testing Materials, 1947. (30) Snell, F. D., and Snell, C . T., “Colorimetric Methods of Analysis,’’ Vol. I (Inorganic), Vol. I1 (Organic), New York. D. Van Kostrand Co., 1936. (31) Standel:, G . IT.. ISD.ESG. CHEM., ANAL.ED.,16, 67.5 (1944). (32) 1-oe, J. II., “Photometric Chemical Analysi3,” New York, John Wiley Br Sons, 1925. (33) Yoe, J. H., arid Sarver, L. A., “Organic Analytical Reagents,” New York, John Wile>-& Sons. 1941. R E C E I V E DS o l e m b e r I ? , 1948.
PETROLEUM HARRY LEVIN. The Texas Company, Beacon,
T
111: trend of developmerit and progress in analysis is a good index of dcvelopmerit and progress in the petroleum industry geiierally, as these have paralleled each other closely. This revic.w iiicludes the period from just before our entry into Korld War I1 until September 1918. So much progress in this field arid iti clieniistry generally has been stimulated by requirements ‘imposed by wartime products and processes, that’ reaching t h a t far into tlic past seemed necessary to give a good picture of the advniicv that have been made. As i t 1 other industrial fields, the increased acceptance of relatively nctwcr tools of analysis i j quickly manifested. I n this c:ategor,y ai’e microchemistry, refractometry, polarography, chioiriiit,ogi,ai)li?’, radiation chemistry including ultraviolet, irifrai,ed, and Itaman, emission spectrometry, x-ray, mass q)cctronietry, arid refinements in high and low temperature ltriitlytical distillation. CRUDE OIL
lloi~iic (103) determined salt in crude oil by dissolving the
sariiplc iri xylene, adding a destabilizer to prevent emulsification, extract iny the salts with water, and titrating x i t h silver nitrate. Neilsoii (27f) used a somewhat similar procedure, employing pheiiol tJo break emulsions, and removing interfering sulfur compouirds by preliminary treatment with cadmium salts. hf ukherjee (169),using alumina, applied a chromatographic method in wliicli fluorescence of solutions of the adsorbate was used to diffc:reritiate crude oils. GAS
1,udernan (142) described a method for determining the dissolution temperature of aniline and butanes and Francis (71) applied dissolution temperature in o-nitrotoluene t o determine the composition of binary mixtures of iso- and n-butane. Ferber (67) used alumina and active carbon at low temperatures in a study of adsorption and desorption for analysis of gaseous hydrocarboii mixtures, in which olefins were preliminarily hydrogenated, as the method is for paraffin hydrocarbons. Turner (225) employed a column of charcoal for adsorption and by heating separated the constituents in the zones up to, and including, hexane. Miller (164) analyzed mixtures of propane, isobutane, and n-butane for plant control by a simple weathering test conducted in a centrifuge tube. Liljenstein (138) used a combination absorption-weathering test in which the volume of residue was the
;V.
Y.
basis for determining isobutane and heavier and pentanes arid heavier; it is used for plant control purpoLea. I-Iamblen (90) used a weathering test for plant control, in determining propane contamination in butane. Tooke ( 2 2 3 , in plant control, used a time-temperature distillation curve t o analyze n-butaiie for isobutanc, propane, and pentane. Solomon (21.3) described a hydrometer for determining the density of small samples of liquefied butane-isobutane niiutures. Echols (62) analyzed three-component light hydrocarbon niivturea by isothermal distillat ion. Eberl (61) employed silver sulfate in dilute sulfuric acid to determine ethylene in butane, claiming no butane absorption. Cuneo (50), in determining butadiene in mixtures with saturated and other unsaturated hydrocarbons, used a mercuric nitrate reagent to obtain a volumetric determination of mono-olefins plus diolefins. Francis (72) employed mercuric sulfate in dilute sulfuric acid to determine ethylene and claimed the reagent was applicable t o determination of total olefins. Mapstone (166) studied numerous reagents for determining ethylene and total olefin in gas and concluded t h a t mercuric sulfate reagent was best. Stanerson (214) collected gaseous sample in cold chloroform, titrated this solution with bromine in glacial acetic acid, and concluded t h a t the method is comparable in results with hydrogenation but simpler t o conduct. Houtman (104) employed aqueous hydrochloric acid at room temperature to determine isobutene in mixtures with other unsaturated and saturated hydrocarbon gases; only isobutane reacted to form tertbutyl chloride. Cyclopentadiene was determined colorimetrically by Chrig (228) after prior condensation with benzaldehyde to form its highly colored fulvene I n determining ethylacetylene and vinylacetylene in C, hydrocarbon gases, Thomas (261) employed silver nitrate titration, hydrogenation, bromine titration, and maleic anhydride absorption. Robey (194) improved the hydrogenation procedure of Mclfillan by correcting for nonideal behavior of gaseous hydrocarbons. Corner (46) employed selective hydrogenation involving a nickel-kieselguhr catalyst partially deactivated with mercury t o determine cyclopropane in the presence of propylene. Ransley (183) described a micromethod for analyzing gaseous mixtures, applicable to 0.1 ml. of sample, in Rhich the volume is kept constant and the individual constituents are determined from changes in pressure on reaction with specified reagents. Pyke (181), employing the apparatus of Blacet and Leighton in microdeterminations of gaseous olefins, used a paste containing
