A N A L Y T I C A L CHEMISTRY
1434
I n the article, the authors did not state that their intervals were adjoining; they merely stated that the intervals were “not overlapping.” If the intervals were not adjoining, it would be necessary to have a very precise method of sampling in order that they might have a true representation of conditions. By use of our apparatus we did not have to meet the problem of sampling, because our intervals wele all adjoining. H. -4.BOWMAS Time Section National Bureau of Standards Jvashington, D. C. SIR: Bowman’s observations concerning frequency errors in timing with electric clocks in the Washington area are significant in that they indicate the magnitude of such errors for another area and another power network. It is obvious that our conclusions were too broad when we stated that the frequency control in other metropolitan areas was probably comparable with that in the Pittsburgh area.
Although there seems to be no doubt that frequency errors in this locality are less than in the areas supplied by thePhiladelphia power network, in my opinion the cause of the difference is not definitely established. Bowman is of the opinion that the difference in the total generating capacity of the two systems is responsible for difference in quality of frequency control. Undoubtedly this is a factor. Perhaps it is the major factor. However, the character of the industrial load borne by the Pittsburgh system is of such a nature &s a t least partially to nullify the capacity factor. I have recently learned that the Pittsburgh system has an electronically operated automatic system for frequency control, whereas the system servicing Washington is, to the best of my knowledge, controlled manually. This may also contribute to the more precise control of frequency here. The time intervals chosen in our study were all adjoining. W.E. WALLACE University of Pittsburgh Pittsburgh, Pa.
Electron Microscope Society of America F. -4.IIAMM, General Aniline & Film Corporation, Easton, P a .
HE seventh annual meet,ing of the Electron Microscope SoTciety of America was held a t the National Bureau of Standards, Washington, D. C., on October 6, 7 , and 8, 1949. The attendance was the largest to date, with some 250 people attending. E. U. Condon, director, Sntionnl Bureau of Standards, and F. 0. Schmitt, president, Electron Microscope Society of America, opened the meet,ing with a few introductory remarks. L. A . Chambers, Camp Detrick, Frederick, &Id., who served as chairman of the committee on local arrangements, and R. G. Picard, Radio Corporation of America, Camden, K.J., who served as program chairman, deserve much credit, for planning this successful meeting. The customary Friday evening banquet was held a t the Wardman Park Hotel. For the first time in the history of the society, no after-dinner speeches were given. Incumbent president F. 0. Schmitt introduced president-elect R. W. G. Wyckoff, National Institutes of Health, Bethesda, Md., who will begin his term as president of the society in January 1950. The program of this meeting is abstracted below; only those CHEMISpapers of general interest to the readers of ASALYTICAL TRY are included. Consequently the papers dealing with biological problems are omitted. The first session consisted of contributed papers dealing primarily with instrumentation. Temperature of Electron Microscope Specimens. G. D. SCOTT FRANCES D a w ~ sUniversit,?. , of Toronto, Toronto, Ontario, Canada.
AKD
Although tremendous thermal energies may be generated (localories per second) in a strongly electron absorbing specimen, :t good portion of the heat is dissipated by radiation to the walls of the instrument. Stable materials such as alumina or sodium chloride can be made to melt. The Formvar substrate absorbs little infrared radiation, so that it absorbs heat only where contact with the specimen is made. Thus, the very high temperatures experienced by electron microscope specimens under strong illumination by elect’ron beam must be taken into consideration. Vibration Studies Related to Electron Microscopy. F. A. 1-I.kmr . ~ X D F. C. SXOWDEN, General Aniline & Film Corp., Easton, Pa. Ari oscillographic trace due to (L voltage generated piezoelectrically by a phonograph (crystal) pickup can be used to detect arid measure vibration, and as a guide for properly locating an electron microscope where building vibration is a problem. Furthermore, this scheme makes it possible to correlate qualitatively image shift’swith vibration amplitude. Because building vibrations are usually only periodically prohibitive, the scheme described can be used a8 a guide for high resolution electron microscopy. The circuit and calibration procedure were briefly described.
Performance Tests on the RCA Model EMC Electron hlicroscope. S. G. ELLIS,RCA Laboratories, Princeton, N. J. I t is not possiblz to increase the resolution of this instrument beyond about 50 A., primarily because the angular aperture of illumination cannot be further lowered. This value is not ordinarily realized, but by mechanically modifying the specimen stage (to prevent thermal drift) and by improving the objective lens asymmetry, a resolution of 50 A. is possible. The normal wide angle cone of rays from the projector causes reflection of extraneous electrons onto the photographic plate. Insertion of a projector aperture is therefore desirable because image contrast is improved. Testing of Electron hlicroscope Objectives. JAMES HILLIER HENRY FROVI,.~, RCA I,aboratories, Princeton, N. J.
ASD
Virtually all electron microscope objective pole pieces exhibit some astigmatism. By photographing a test object (carbon black) defocused by known amounts in the range 1OOp to - 1001 a series of Fresnel fringes is recorded. A chart illustrating the width (and number) of these fringes versus known object displacement, but having used a well corrected objective pole piece, is then prepared. The image at the same magnification, recorded with the uncorrected lens being tested, is compared with the chart. One direction through the image must be in sharp focus, the nature of the fringe along the perpendicular direction is then used to assign a value (in microns) to the lens asymmetry. An asymmetry of less than a few microns is n prerequisite to high resolution.
+
Technique for Comparison of Identical Surface areas in Light AND RUTHH. and Electron Microscopes. ERNESTF. FULLAM PETCHER, Knolls Laboratory, General Electric Co., Schenectady, N. Y. This technique facilitates the correlation of light and electron micrography of the same metal surface. An acute angle is made near the area of interest by means of a sharp needle. The initial nitrocellulose replica is then replicated by a thin double film of beryllium and quartz. This double film is necessary because the final replica is supported by a specimen screen having a large hole in the center to eliminate masking due to specimen screen wires. The first organic film is removed with solvent vapor. The acute angle near the important structure aids in its location and in the interpretation of shadows.
A Centerable Condenser Aperture for the RCA Model B ElecAmerican Viscose Corp., tron Microscope. F. F. MOREHEAD, Marcus Hook, Pa. The alignment of this instrument is simplified by employing a mechanical arrangement for centering the condenser aperture while the instrument is in operation. -4 pair of spring tension ad-
V O L U M E 21, N O . 11, N O V E M B E R 1 9 4 9 justment screws represents the essential feature of the nicchanism. The time required for alignment is greatly reduced. Permanent Magnet Lenses. JOHN H. REISSER,RCA \Yetor Division, RCA, Camden, N. J. Permanent magnets made with .Ilnico Y iron have been made to exert the same magnetic flus as the present electromagnetic lenses used in commercial instruments. Stray magnetic fields which often adversely affect the resolution in high magnification images are eliminated in this new system. Focusing is done by varying the accelerating potential of the electron beam. Several configurations utilizing more than one magnet afford a variety of possibilities in lens design. Beam Deflection Focusing Device. HAROLI) T. Naval Medical Research Institute, Rethcsda, M d ,
\fERYJf.4S,
Two coils with polarities reversed are placed inside thc specimen chamber above the specimen holder. The angular aperture of illumination to the specimen is increased during focusing, so that the smaller depth of focus enables t’he operator to focus more critically. This technique appears to be superior to the electrostatic method because in the latter met,hod the focusing deflection plates are very close to the electron beam, so t h t traces of dirt may sometimes charge up and affect the beam. Motion Pictures of Electron Microscope Images. .JOHS H. L. \VATSONAXD LUTHERE. PREUSS, Edscl B. Ford Institute for Medical Research, Detroit 2, Mich. RIotion pictures (8-mm. film) of phenomena occurriug in the electron microscope were illustrated for the first time at a meeting of this kind. The opportunities afforded are numerous, especi?lly in determining the effect of the electron beam on the specimen. The three-dimensional aspect and the speed with yhich t,he. frames are recorded make the interpretation of the image easier. The melting and subsequent growth of tungsten oxide and sodium chloride cryst’als were illust,rated. Radiation-chemical effects rather than purely thermal effects may also be studied. The movie camera is mounted on a tripod in front of t’he front viewing window. The image in the electron microscope is reflected to t,he camera by tilting the final viewing screen. The second session was devoted exclusively t o papers on sectioning. Improved Sect’ioning Technique for the Electron Microscope. RICHARD F. B.4KER b X D DANIELC. PE.4SE, University of Southern California, Los Angeles, Calif. These authors have slightly modified their earlicr 1echnique, which was really the first one reported [Proc. Soc. Ezptl. B i d . Med., 67,470 (1948)] in which an ordinary hand microtome was used to cut sections for the electron microscope. The superiority of osmic acid as a fixative for general use was discussed. h new procedure for sharpening knives on a rotating glass plate with fine alumina abrasives was also described.
1435 used to cut 0.02-micron sections \\.it11 no dctectable variation5 in thickness. Uniform compression of the specimen during rutting is apparently the secret to eliminating distortion. Serial Sections for Electron Micrography. MARKGETTSER, HILLIER, Sloan-Kettering Institute, New York, N. Y . ,AXD JAMES RCA Laboratories, Princeton, 9.J. Tissue sections sufficiently thin to lie examined in the electron microscope are difficult t,o see and manipulate. Friction between the knife and section usually causes the section to roll up or fold over. T o eliminate this and thus to permit serial sectioning with subsequent ease of manipulation, a reservoir was attach to t,he cutting knife. This is filled with an alcohol-\vat, ture whose meniscus approaches the knife edge. This causes each section to float (flat) on the liquid surface, and the sections are joined in a head to tail fashion tiecause each svrtion is pushed onto the liquid surface by the leading edge of t,he succeeding section. The flat sect,ions are t,hen handled in tho usual way. .2 truly serial sectioning technique is somctimcs necessary for tissue st,ructure determination. A Technique for Preparation of Grease or Solid Samples. 11 Greaselike Rledia for Examination xith the Electron Microscopc. .\. Y. MOTTLAY, Standard Oil Dcvclopmcnt Co., Linden. K. ,J. This technique precludes the removal of water-soluble soa11s fundamental to some greases. The older techniques caused removal of this component,. The procedure is essentially that, of imbibition of a thin film of grease onto a Formvar coated sprcimen screen, followed by estraction of the oil (carrier) in naphtha. The resultant specimen illustrates tlie nature of the d i d particles as they occurred in the original grease. Samples of catalysts or powdered pigments can be convenimtly dispersed and prepared for electron microscopy by using,a similar technique. A white petrolatum is deliberately added in ])reparing the smear for imbiliition. It, is then sulwqucntly rcsmovcd as before. Replication of Frozen Liquids l)y \-acuum Evaporation. IIaRoLn T. h h w n r a s , Naval \Iedic:d Rcsmrch InstitUtje, Bethesda, Rld. One of the prime considerations in the interpretation of elect ron microscope images of specimens, which under normal rircumstances contain liquids, has t,o do with the effect of drying out, liefore or during examinat,ion in the instrument. This techniqiie is a step in the direction of evaluating this loss in liquid o r , Iiettcr, of examining the specimen still containing the originill liquids. The replication of biological specimens in their original wet state is an important application of the procedure described in this paper. Ice crystals, formed under liquid nitrogrn, hsw h e n studied rather eshaust.ively. Xeasurcment of Cellulose Piivticle 1,ength by the Electroll Microscope. E’. F. MOREHEAD, -4rnerican Viscose Carp.. 1Iwrus I€ook, Pa.
Ultramicrotomy by a New Method. SAXFORD 13. ? ; ~ \ \ - ~ r a x , This paper described a technique f o r measuring crj-stallilc EMILBORYSKO,A N D MAX SWERDLOW, Kational Rurc,nu of length in highly crystalline and amorphous areas in viscose rayon. Standards, Washington, D. C. Three nen- significant aspects pertinent to thin sectioning were described in this paper: the embedment of the biological sumplr in a plastic monomer (n-butyl methacrylate) followed by polymerization; the advancing of the embedded specimen by thermal espansion of the supporting brass block rather than by the usual mechanical mechanism; and the sharpening of the cutting knife h y means of stropping on leather in conjunction with a small amount of diamond dust and subsequently with rouge. Some Refinements of the Rotary Microtome LIodified for Ult’rathin Sectioning. JAMES HILLIER, RCA Laboratories, Princeton, S . J., AND MARKGICTTNER, Sloan-Kettering Institute, Kew York, N. Y. Several refinements of the Spencer Model 820 rotary microtome as applied to cutting sections i n the 0.05- to 0.1-micron range were described. These instrument modifications may be outlined as follows: The advancing mechanism is motor driven to eliminate vibration and irregularities normally introduced in hand operation. A spring mech:inism is used to support, the horizontal member of the advancinq mechanism so that st,atic friction during the horizontal travel is reduced. The instrument, thus modified and used in conjunction with the rcsrrvoir has been
new technique for casting extremely thin films of viscose permits the detection of “skin” and (‘core” areas. Apparently zinc ions cross link with the ccllulosc s$nthate t o give a skin vffect. The crystallitrs are6niallcr (75 A,) on the surface th:m they are in the core (150 A , ) . These cryst.allite lengths m r f ’ compared with those observed on fibers after acid hydroly+ plus ultrasonic disintegration. Good :tgrecmcnt was found. Iteproducilily Representative Specimen Fields in Electron Microscopy. ROBERTC . B.icscs AND ROBLEYC . ~ f - I L L I A l f ~ , University of Michigan, Ann a r b o r , llich.
This paper described a new tcchrliquc for preparing electron microscope specimens that can be used for quantitatively assaying :t specimen having one or more components. A number disirihution count is based on a reference component (polystyrene htcx spheres) whose assay is knob7-n. Tiny droplets (100 cU. P or greater) are sprayed with clean air (20 to 40 pounds pressure per square inch) onto a substrate. The droplets dry very rapitllv. .‘in aqueous ammonium acetate solution is used to sld in th(! dispersion; it is completely volatile. 1l)eterminntion of the IYcigtit of the Bushy Stunt \-irus 1’:tr-
ANALYTICAL CHEMISTRY
1436
ticle by Electron Microscopy. ROBLEYC. WILLIAMSAND ROBERT C. BACKUS, University of hfichigan, Ann Arbor, Mich. This scheme is unique in that the magnification of the electron microscope does not have to be calibrated, and molecular weights as low as 70,000 can be determined. The method of counting the number of particles is based on the procedure described in the previous paper. The particle may have any configuration; its size must be sufficiently large so that i t can be resolved. By determining the dry weight of the particle (virus) in a known volume, it is easy to calculate the weight of a single particle. The weight of a bushy stunt virus particle so determined checks well with data determined in a variety of ways. Electron Metallography of Cast Irons. Dow Chemical Co., Midland, Mich.
CHARLES H. GEROULD,
The nature of the graphite in normal cast iron as compared with that in under- and overtreated cerium- and magnesiumtreated cast irons was related to the physical properties of these various samples. The nodular structure of graphite is readily detected by a two-step replica technique. Cleaning the etched metal surfaces by stripping collodion from the surface improves the quality of the replica. Quantitative Metallography with the Electron Microscope.
The Molecular Configuration in Seed Globulin Crystals.
C. E. HALL, Massachusetts Institute of Technologv, Cambridge, Mass.
This paper illustrated the application of the electron microscope in the determination of structure of macromolecules present in extremely small protein crystals, Preshaded silica replicas of crystalline edestine exhibited the molecular configuration from which the face-centered cubic nature of the crystal was derived. The unit cell dimension is 114 A. (dry state), which was corroborated by x-ray diffraction data. The Friday afternoon session consisted of a series of invited papers on complementary methods of microscopy. Recent Developments in Conventional Microscopic Equipment and Techniques. A. H. BENNETT,American Optical Co., Stamford, Conn. Three modifications of the standard light microscope represented the main thesis of this paper. They were the phase contrast microscope, the polanret microscope, and the fluorescent microscope. Although these optical systems are no longer new, the theory and particular applications were reviewed in a comprehensive way.
F. K. IVERSON AND ALFREDL. ELLIS, International Harvester Co., Chicago, Ill.
Recent Developments of the Optical PIIicroscope. DAVIDS GREY,Polaroid Corp., Cambridge, Mass.
The usefulness of the electron microscope in corroborating and improving light microscopical data pertaining to structure in the 0 . 5 range ~ was demonstrated. Almost round carbide structures in an annealed steel were counted by means of a replica techni ue. Based on a calibration against light microscopical data, onqy ten plates of five different exposures each are necessary for an accuracy of *0.5% of the mean. Fewer exposures are required for slightly poorer accuracy. This method vias used to determine quantitatively the carbide content of steels, followed by relating this content to the physical properties of the steel.
-4nevi family of microscope objectives developed primarily in England and this country was discussed from the standpoint of aberrations, depth of focus, resolving power, etc. For example, the adaptation of Schwarzschild aplanatic mirrors for use in light microscope objectives has afforded high numerical apertures with good apochromatic correction between 220 and 800 mp. This system has admirably lent itself for use in the color translating ultraviolet microscope. The optics and mechanical features of this more recent development a t the Polaroid Corporation were described.
Electron Metallography of Cemented Carbides. General ?\lotors Corp., Detroit, Mich.
\Ti. L. GRUBE,
This application is somewhat similar to that described in the previous paper in that the electron microscope was used as an analytical tool in studying the microstructure of carbide tools, with special emphasis on the cemented carbides. The physical properties of these carbides, not completely resolved in a metallograph, are well exhibited by replicas in the electron microscope. These properties may then be correlated with the high speed tool performance. Electron Diffraction Studies of Thin Iron and Chromium Films. LELAND L. ANTES,University of Teuas, Austin, Tex. The rate of air oxidation of thin films of iron, chromium, and nickel was followed by means of electron diffraction, the RCA EMU electron microscope having been set up as a diffraction camera. The effect of thinness of the metal film on the rate of oxidation was demonstrated. Electron Microscopy of Enamel and Dentin. DAVID B. S c o w A N D RALPHW. G. WYCKOFF,National Institutes of Health, Bethesda, hfd. This paper was primarily concerned with the structure of the dentin as illustrated by shadowed collodion replicas of etched ground sections of teeth. Apparently human tooth dentin consists of relatively large fibers within tubules with collagen in the matrix. These fibers may contain other finer fibers. Studies of the Action of Sodium Fluoride on Human Enamel by Electron Microscopy and Electron Diffraction. DAVIDB. Scow AND RALPHW. G. WYCKOFF,National Institutes of Health, Bethesda, Xld., AND ROBERTG. PICARD, RCA Victor Division, Camden, X. J. Calcium fluoride forms gradually on the surface of human tooth enamel if the enamel is immersed in a 2 to 4y0 sodium fluoride solution. The normal apatite diffraction pattern is gradually replaced by the calcium fluoride pattern. This calcium fluoride can be washed off with water, but this becomes more difficult as the immersion time (in sodium fluoride) increases. The effect of fluoride ion on enamel could not be related to clinical data.
.4n Approach to X-Ray Microscopy. Stanford University, Stanford, Calif.
PAVLH. KIRKPATRICK,
This paper traced the development of the idea of an x-ray microscope from Roentgen’s time to the present day x-ray microscope which has resolved structures on the order of lp. The importance of the x-ray microscope stems primarily from the fact that x-rays have much more penetrating power than electrons. Furthermore, the resolving power is independent of wave length and is on the order of 70 A. theoretically. Elliptical metal-coated glass mirrors are used instead of glass lenses so as to minimize absorption and astigmatism. The critical angle of incidence limits the numerical aperture, which in turn limits the resolution. The system is clled with helium, x-rays of wave length on the order of 2 to 3 A. are used, and the image is focused on a fluorescent screen just as in the electron microscope. Magnifications of 100X have been realized. Electron Microscope Research in Europe. RCA Laboratories, Princeton, N. J.
E. G. RAMBERG,
There are two spheres of electron microscopy in Europe-the German and all the other countries in combination. Apparently there is little or no interchange of ideas between these two spheres of influence. Brucke in Mosbach is leading the way in so far as instrumental developments are concerned. The new A.G. electrostatic microscope is unique in that the gun and condenser are combined and focusing is done by varying the accelerating voltage, The special instrument built at the Philips Institute in Delft for the Royal Dutch Shell Corp. was also described. I t is essentially a combination electron diffraction camera and electron microscope limited to 3000 diameters. A description of the British laboratories was also included. The Saturday morning session was devoted exclusively to the application of electron microscopy to biological problems. The last session consisted of papers dealing with a variety of topics. Use of Polystyrene Latex 580 G, Lot 3584, in Electron Microscopy. CHARLESH. GEROULD,Dow Chemical Co., Midland, Mich. The results of a survey from 16 different laboratories concerning the size distribution of Dow latex spheres were presented.
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V O L U M E 21, NO. 11, N O V E M B E R 1 9 4 9 The consensus of opinion suggests that this material serves a useful purpose as an internal standard if it is used properly. Precautions in using the latex were critically reviewed. Particle Size and Density of Dow Latex 580 G Measurements with the Ultracentrifuge. D. GORDON SIIARP,Duke University, Durham, N. C. Sedimentation velocity studies of the Dow Latex 580 G spheres corroborate the size and uniformity data compiled by the electron microscopists. Furthermore it was proved that this latex does not hydrate; hence it may also be used as an internal standard in ultracentrifugation studies of materials that do hydrate (viruses). This independent check on the size distribution of this Dow latex is a significant contribution.
Continuous Observations on the Formation of Metallic Films in the Electron Microscope. R. S. SENNETTAND T. A. McLAUCHLAN, University of Toronto, Toronto, Ontario, Canada. This was probably the fist report on a continuous observation on the formation of thin evaporated metallic films in situ. The first deposition of condensed metal vapor (silver, gold, cadmium, etc,) in the electron microscope under operating conditions always occurs with the formation of a large number of small nuclei. Additional evaporation causes these nuclei to increase in size rather than in number.
A. Apparent Size of Small Semiopaque Objects. RAYMOND KERNAND S. F. KERN,Lilly Research Laboratories, Indianapolis, Ind. This paper disclosed an interesting proposed explanation for the apparent differences in size and shape of certain objects in certain types of specimens. For example, various investigators have reported elongated and nonmniformly sized Dow polystyrene latex spheres (580 G), which are presumably true spheres of very uniform size, The authors speculate that some unshadowed particles (including the Dow latex) charge up negatively and affect the beam as a lens. Thus, the h a 1 image appears larger than it should be. Shadowed specimens would dissipate this charge to the substrate wherever contact is made. Elongation would therefore result from some portions of the specimen not being shadowed. Specimen contamination as related to image size was also discussed. A Removable Intermediate Lens for the RCA Model EMU. HILLIER,RCA Laboratories, Princeton, N. J.
JAMES
This new development is a very significant contribution for several reasons. Magnifications between about 1000 and maximum instrument magnification are possible without modifying the objective or projector lens pole pieces. Spherical aberrations manifest as projector lens distortion are minimized. Within limits of about 5 kv., one value of magnification is independent of accelerating voltage. The lens is placed directly above the projector lens and only minor changes in the projector lens circuit are necessary. Optical Method for the Thickness of Thin Films. G. D. SCOTT, University of Toronto, Toronto, Ontario, Canada. This y p e r described the application of Tolansky’s (S. Tolansky, Multiple Beam Interferometry,” Clarendon Press, New York, 1948) method to the determination of thickness of thin films normally used as electron microscope specimens. The author of this paper has modified the original techcique so that it may be applied to very small and very thin (10 A.) films with improved precision.
A Technique for Studying the Electron Microstructure of Steel. D. M. TEAGuE AND L. H. ZIMMERMAN, Chrysler Corp., Detroit, hlich. This paper was divided into two parts. The first was devoted to a discussion of the Joint Committee on Electron Microstructure of Steel. The membership and aims of this group were outlined. Standardization of techniques and terminology are the chief goals. The second portion was used to describe a modified Formvar replica technique as applied to steels. The use of a monolayer of soap on the metal surface facilitates removal of the plastic replica. Recent Advances in Electron-Microscopical Resinography.
M. C. BOTTY,T. G. ROCHOW, AND F. G. ROWE,American Cyan-
amid Co., Stamford, Conn.
The application of electron microscopy to the study of singlephase and polyphased resin systems was described with emphasis placed on specimen preparation and micrograph interpretation, Replication of molded or fractured surfaces reveals information concerning the compatibility, distribution, size, shape, etc., of the componcnt units. These units are believed to be the macromolecular units. Correlation between structure and physical properties is possible.
Philadelphia Analytical and Microchemical Groups The Analytical and Microchemical Group of the Philadelphia Section, AMERICANCHEMICAL SOCIETY, has arranged the following program. Albert B. Sample, John s. Sharpe Research Foundation, Bryn Mawr Hospital, Bryn Mawr, Pa., is secretary of the group. December 6 Radiochemistry, a New Tool for Analytical Chemistry. CLEMENT J. RODDEN February 7 Microchemistry in the Petroleum Industry, HARRYLEVIN March 8 Pharmaceutical Control. CEURLES M, MITCHELL Microbiological Analysis. ROBERTJ. FERLAUTO The March meeting will be held in the new Smith, Kline & French Laboratories, and after the formal program the laboratories of the Research and Control Departments will be open for inspection.
International Microchemical Congress The Austrian Society for Microchemistry is planning the first International Microchemical Congress in Graz, Austria, birthplace of microchemistry, July 2 to 6, 1950. A group of microchemists in the United States has proposed to the Mayor of Graz that a street be named in honor of Friedrich Emich, famous microchemist, especially in commemoration of the tenth anniversary of his death, in 1950. The Austrian Society of Microchemists, whose present chairman is Hans Lieb, successor of Fritz Pregl a t the University of Graz, proposes also to erect a stone tablet a t the Felix Dahn Platz, near which the new Chemical Institute of the Technische Hochschule will be built. A monument in honor of Emich is to be placed in the entrance hall of the Technische Hochschule a t a later date. The Division of Analytical Chemistry of the AMJCRICAN CHEMICAL SOCIETY has been invited to participate in the undertaking and to send representatives. It is expected that Fritz Feigl, now in Brazil, will attend the international meeting in Graa and will arrange for the cooperation of chemists in South American countries.
I
i American Council of Commercial Laboratories. Miami, Fla., December 5 to 7 Third Symposium on Analytical Chemistry. Louisiana State University, Baton Rouge, La., January 30 t o February 2, 1950 Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. William Penn Hotel, Pittsburgh, Pa., February 15 to 17, 1950 Chemical Institute of Canada, Analytical Division. Royal Connaught Hotel, Hamilton, Ontario, March 2 and 3, 1950.
Second annual symposium Third Annual Summer Symposium. Ohio State University, Columbus, Ohio, June 16 to 17, 1950
