Tiwari, R. D., Sharma, J. P., Shukla, I. C., Talanta 13, 499 (1966). (297) Totir, N., Dragusin, I., Rev. Chim. (Bucharest) 16, 516 (1965). (298) Trzesniewska-Wilk, M., Chem. Anal. (Warsaw) 10, 1373 (1965). (299) Tulyakov, E. N., Kalabina, R. A., Zavod. Lab. 30, 1449 (1964). (300) Uchen’, M. T., Fedoseev, P. N., Isv. Vysshyhk Uchebn. Zavedenii Khim. i Khim. Tekhnol. 8, 619 (1965). (301) Ibid., p 792. (302) Urbanski, J., Kainz, G., Mikrochim. Acta 1965, 60. (296)
(303) Vajda, L., Magy. Kem. Lapja 19, 497 (1964). (304) Van der Laarse, J. D., Van Leuven, H. C. E., Anal. Chim. Acta 34, 370 (1966).
Van Stevenin&, J., &,laas, M., Ret. Trau. Chim. 84, 1166 (1965). (306) Vecera, M., 2. Anal. Chem. 208, 15 (305)
(1965). (307) Vecera, ?vl*, Lakomy, J*,Mikrochim. Acta 1966, 370. (308) Vecera, AI., Lakomy, J., Lehar, L., Ibid. 1965,674. (309) Veibel, S., Wronski, SI.,Acta Chem. S c a d . 20,849 (1966).
(310)
Waledziak, H., Chem. Anal. ( W a r -
saw) 10,579 (1965).
Walisch, w.7 Scheuerbrandt, G.9 Marks, W.,Microchem. J . 11, 315
(311)
(1966). (312) Wenninger, J. A*, J *Ass* Of*Agric. Chem. 48,826 (1965). (313) Wetzel, D. L., Meloan, C . E., ANAL. 36, 2474(1964). (314) Wojtasiewicz-Obrzut, D., Chem. Anal. (Warsaw)10, 1133 (1965). (315) Wronski, N., Ibid. 10, 687 (1965). (316) Yeh, C. S., Microchem. J . 11, 229 (1966). (317) Yu, H. Y Sha, I. H., Chem. Bull. (Peking) 1965,’>57.
cHEM.
Chemical Microscopy George G. Cocks, Cornell University, Ithaca,
T
in this series by Cocks (33) covered the two-year period ending in October 1965. This review covers the period from October 1965 through December 1967. As is usually the case, a number of references concerned with chemical microscopy were inadvertently omitted from the previous review. Some of these are included in this review. It is the purpose of this review to report on articles and books of potential interest to those who use the microscope to solve chemical problems. However, “chemical problems” are so diverse and the use of the microscope is so widespread that this kind of review must be restricted in various ways. Therefore, in the review, no attempt has been made to include biochemical, metallographicall or petrographical applications of microscopy except when they appear to be of direct interest to chemists. The chemical applications of electron microscopy are not reported here because they are the subject of a separate review. An attempt has been made to include references to publications in the fields of optics and crystallography which appear to be of potential interest to chemical microscopists. The great diversity and number of publications, concerned with the microscope and its use in chemical studies, makes it impossible to find and review all of them. The author would greatly appreciate comments or suggestions, particularly with regard to the omission of important publications. HE PREVIOUS REVIEW
MEETINGS A N D SYMPOSIA
The year 1966 was the Royal Charter centenary year for the Royal Microscopical Society. I n celebration of the centenary, a number of meetings were held. The first of these, a conference on Historical -4spects of Microscopy, was held at Oxford on 18 March 1966. The 158 R
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papers read at this conference were published in the Proceedings of the Royal Microscopical Society 2, Part 1 (1967). -4paper by A. C. Crombie (40) was entitled “The Mechanistic Hypothesis and the Scientific Study of Vision,” and subtitled, “Some Optical Ideas as a Background to the Invention of the Microscope.” Bradbury (22) reported on “The Quality of the Image Produced by the Compound Microscope: 1700-1840.” He tested the optical quality of 16 microscopes from various collections by photographing standard test objects such as an Abbe test plate and a test plate mounting several diatoms. H e also measured the numerical aperture and focal lengths of the lenses, and, in addition, he compared the images produced by these lenses with the image produced by a modern well corrected lens. G. L’ E. Turner (224) spoke on “The hlicroscope as a Technical Frontier in Science,’, reporting, among other things, the numerical apertures and resolutions attained as a function of date. These data are based on measurements made by the best microscopists of the time, using as a test object a Sorbert plate. A second meeting celebrating the Royal Charter centenary was held in London, 18-22 July, 1966. Survey papers read a t this meeting included; “The future of the optical microscope” by R. Barer, “The future of the electron microscope” by V. E. Cosslett, “The history of the microscope” by hl. Rooseboom, “The role of the microscope in the study of dynamic processes” by -1. T. IF’, Hughes, “The role of the microscope in the study of metals” by A. G. Quarrell, “Microscopy in crime detection” by K. Simpson, and “The design of the biological students microscope” by J. R. Baker. Group sessions were held on a great variety of topics including autoradiography, animal fibers, miiier-
alogy, photomicrography, metallurgy, fluorescence, interference, plastics, crystallography, man-made fibers, teaching and techniques. Another meeting entitled R.M.S. Chicago-66, also celebrating the R.M.S. Charter centenary, was held in Chicago 15-19 August 1966. This meeting was subtitled, “The role of the microscope in scientific investigation.” Papers of particular interest to chemical microscopists included : “Developments in the use of the scanning microscope” by A. D . G. Stewart, “Color photo-micrography with slightly uiicrossed polars” by R. Draftz and J. Delly, “The combination of microscopes and computers for the analysis of chromosomes” by A. Stroud, J. Butler, and SI. Butler, “The S i k o n differential interference microscope with reflected light” by T. Yamamoto, “.1 series of flat field objectives” by R. L. Seideiiberg, “The schlieren microscope,” by J. S. Dodd “Oblique metal shadowing as an aid in interpreting detail in transparent specimens” by J. Facq, “Refractive index determination by crystal rotation methods” by F. T. Jones, “Microchemical tests on sub-nanogram particles” by J. Teetsov and A. Teetsov, and a “Study of porous materials by interference microscopy” by D. G. Grabar. The State Microscopical Society of Illinois held an all-day symposium on 23 February 1967. Among the papers presented were ‘Wicroscopy or Microscopies” by G. G. Cocks, “Differential color illumination” by J. G. Delly, “Detection and identification of drugs by microchemical techniques” by A. Principe, and “Identification of gas chromatography effluents” by J. Reffner. The New York Microscopical Society has continued its active program in microscopy with a series of moiithly meetings, and with a symposium entitled “Microscopists and instrument mak-
dialogue.” The symposium was held oil 29-31 March 196i and included seasions 011 “The design of instruments, Procedures in microscopy, and Information content of the image.” The meeting was intended to stimulate discussion, and panels of experts gave brief introductory talks, then discussed various topics with the audience. wa-a
BOOKS OF GENERAL INTEREST
The historical aspects of microscopy are treated by Bradbury ( 2 1 ) , and by Freund and Berg (67‘). Bradbury’s book is concerned with the historical development of the microscope. Freund and Berg were primarily interested in the microwopists, their lives and works. Cosslett’s book “Modern Microscopy” (58)is based on the 131st course of Royal Institution Christmas Lectures. I t treats of light and electron microscopes including point projection miuoicopes for x-rays and electrons, and flying spot microscopes. I t is an eycellent introduction to the field of microscopy in a broad sense. White (238) and Casartelli (26) have produced introductory books on microscopy which are directed more toward teaching the use of the microscope. Anderson’s book (6) entitled “Modern Knowledge Through the Microscope” is a mixture of intereating items about microscopes and microscopists. I t is a book containing many pictures, pictures of microscopes, old and new, pictures of microscopists, and many photomicrograph”. Barron (11) has produced a film strip with accompanying text, designed for teaching microscopy to beginners. =ilso helpful to beginning microscopists, as well a3 to those with experience, are varioua “house organs” published by microbeope manufacturers-e.g., “Zeiss Information,” W i l d Xicroskopion (242), and “Technical and Information Bulletin” (136). These publications contain excellent articles on such items as: micrometry, automation in microscopy, television microscopy, illumination, quantitative microscopy and also, of course, excellent descriptions of equipment. Of special interest to chemists are several recent books dealing directly with matters of chemical interest. Hinnawi (98) has published a book on “Methods in Chemical and Mineral Microscopy.” Schaeffer’s book (191) “Microscopy for Chemists” has been reprinted by Dover, and a third edition of “Analytical Microscopy” by Wallis (235) has been published. Wallis’ book deal3 with the microscopy of foods, water, spices, and drugs. -4 textbook on the microscopical identification of minerals by Heinrich (95) emphasizes the identification of particulate materials by immersion methods. The iden-
tification of minerals in thin sections is mentioned only briefly. A large part of the book consists of descriptions of minerals. The structure and properties of natural organic materials is discussed by Holzl and Bancher (100) in a book which contains sections on microchemistry, light microscopy, and electron microscopy. Lautenschlager’s book (134) entitled, “Die Technik der Kunstoffeingusse” also has sections on microscopy and microtomy. An atlas containing micrographs of numerous drugs has been compiled by Eschrich (55). h series of articles, concerned with the chemical and physical characterization of trace amounts of materials, has been compiled by hleinke and Scribner (161). The compilation has large sections devoted to microscopy. Moenke and hloenke (155)have written a monograph which describes the principles, method of functioning, and scope of modern optical instruments, available to chemists and mineralogists, for the analysis and identification of substances. About one fourth of this book deals with microscopy. I t is largely a description of instruments manufactured by various companies. -4 symposium on cytophotometry and interference microscopy, held in Giessen in 1963, has been published (188). The theory of the microscope is the subject of an excellent book by L. C. hIartin (148). Although this book is generally mathematical, it will be of considerable value to any serious microscopist. h series entitled “Advances in Optical and Electron Microscopy” is being published under the joint editorship of R. Barer and V. E. Cosslett. Volume I (8) contains articles on methods of measuring the velocity of moving particles, the accurate microscopical determination of the optical properties of one small crystal, image contrast and phase modulated light methods in polarization and interference microscopy as well as several sections on electron microscopy. The applications of microscopy to chemistry are often closely associated with crystallography. Therefore, the inclusion in this review of a number of books on crystallography seems justified, especially since crystallography is one of the author’s principal interests. A very interesting little book on the “Origins of the Science of Crystals’’ has been written by Burke (23). Sicholas (161) has published a n atlas of models of crystal surfaces which is extremely useful in visualizing the arrangement of atoms in various crystal faces. Zhdanov (246) has written a large monograph on crystal physics, and Bhagavantam (17) has written a highly mathematical treatise on the relationships between crystal symmetry and physical properties. “Polymorphism and Polytypism
in Crystals” is the title of a book by Verma and Krishna (231). Of a more specialized nature is Sharpleb’ “Introduction to Polymer Crystallization” (.ZOO),which describes the behavior of polymers as observed under the microscope. The performance of polymeric materials is related to structure. Collections of papers on a wide variety of topics related to crystal growth have been edited by Shubnikov and Sheftal (206) and by Peiser (168). The books by Shubnikou and Sheftal are part of a continuing series. Peiser’s book is a report of the proceedings of an iiiternational conference on crystal growth held in Boston 20-24 June 1966. An article by Kasper (116) reviews the literature of crystallography. Kasper make no attempt to give a comprehensive review, but rather he shows how and where to find information on the various aspects of crystallography. ARTICLES OF GENERAL INTEREST
“The Yeast Cell: What Did Leeuwenhoek See?” is the title of an extremely interesting report by Svihla (215). To discover what Leeuwenhoek saw, Svihla built a microscope including grinding and mounting his lenses. H e then examined yeast cells following Leeuwenhoek’s papers and reproducing conditions as nearly as possible. A number of brief articles of historical interest have been published in The Viclcers Magazine (189). These include electron micrographs of Korbert test gratings, and an article by Smith on interference microscopy. Mollring (164) has written a fairly long article on early microscopists. I n an article entitled “The AIicroscope as a Scientific Instrument,” Xalies (146) discusses various aspects of present microscope construction in an historical context, pointing out where historical developments conflict with logical design. I n a similar paper on “The microscope, a tool and an object of science,” Haselmann (90) considers the historical development of microscope types and of ideas about microscopes. The use of a number of simply made test slides for checking the factors which influence image quality in microscopy, photomicrography and cinemicrography is discussed by Gander (74). Otto (166) uses micrographs of test objects to compare the efficiency of old microscope objectives, made by Zeiss between 1860 and 1875, with modern day objectives. The old objectives were made by trial and error, that is, no calculations were used in the design of the objectives. This article contains many interesting comparison micrographs which show the extent of improvement made over the years. The eye is quite often a part of the optical system of the microscope, but, apparently, there has been little VOL. 40, NO.
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work done on the function of the eye in light microscopy. Baker ( 7 ) attacked this problem, measuring the accommodation of the eye, the acuity of the eye, the effect of luminance on acuity, and the mean diameter of the pupil for a number of experienced microscopists. These measurements were made while the microscopists were actively using the microscope. OPTICS
Martin’s book (148), mentioned previously, is a complete and thorough exposition of the optics of the microscope. hlarhchal (147) has reviewed the theory and practice of image formation emphasizing three aspects-the effects of the development of the newer mathematical tools, recent progress in physical optics, and improvements in the technical aspects of instrument making. hIcCutchen (144) discusses “Superresolution in Microscopy and the albbe Resolution Limit.” Recent articles on the optics of the eye include two already mentioned (8,lo), and one by Rowe (186) entitled, “The Role of the Mach Effect in Critical, bficroscopical Investigations.” The Mach effect is a subjective effect which causes light and dark fringes to appear adjacent to edges in an image when objective physical measurements show that no comparable intensity differences exist. The luminance of these fringes was measured for a number of observers, and it appears that the differences between individuals are so great that there is little hope of defining a standard observer with respect to the Mach effect. A method of precisely testing microscope objectives for longitudinal spherical aberration has been proposed by Uhlig (226). The method involves interferometry according to principles suggested by Nomarski. The details of the method and some illustrations of its application are given. Gander (74) describes a number of easily made test slides which can be used for checking the factors which influence image quality. These slides are suitable for testing photomicrographic, and cinemicrographic setups as well as microscopes for visual microscopy. The optical testing of the quality of a number of old microscopes has been discussed in previous sections of this review (21, 166). Some of the possibilities of testing light microscope objectives using test objects which can be examined in the electron microscope are demonstrated by Rochow et al. (184) in their study of Pleurosignia angulatum. This study was an extension of work begun by the late Alan F. Kirkpatrick and is dedicated to his memory. Hewlett (96) also used images of the diatom Amphipleura Lindheimeri to study the visibility and 160 R
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resolution of periodic structure in oblique darkground illumination. The resolving power is better in oblique dark-ground illumination than it is in bright field. The theory is given, and formulas for the resolving power are derived. When stained or colored specimens are examined in dark-field or phase contrast illumination, the colors observed are not the same as those which are observed in bright-field illumination. Huber (103) discusses these effects and points out that these color changes can, in some instances, be used to advantage in the identification of certain structures. Certain types of agate, called iris agate, show beautiful prismatic colors when properly illuminated. Jones (111) shows that these colors result form the presence of a fine phase grating in the agate. The cause of the formation of the grating is not known. INSTRUMENTS
Microscopes. Although it is soniewhat out of date, Moenke and Moenke’s book (155) on optical instruments and apparatus for mineralogists and chemists describes most of the modern microscopes produced. I t does, however, fail to describe the instruments produced by Zeiqs-Oberkochen. The evolution of the modern microscope is described, and some logical ideas about various aspects of microscope design are discussed in two papers mentioned above (90, 146). Hallimond and Payne (84) describe the recently developed Vickers polarizing microscopes and discuss their use. Dodd (47) describe. a schlieren microscope, and Wilson (244) describes a special microscope arrangement for observing diatoms. This latter microscope uses both reflected and diffracted light to give the diatoms a color contrast depending on their periodic structure. Pope et al. (175) have designed a comparison microscope which presents to the viewer, in rapid sequence, the two images to be compared. The time of alternation can be varied from 0.1 to 10 cycles per second. If the two images are identical and are superimposed, the resulting image appears normal; however, differences between the two objects result in a flicker effect. This idea can also be used to compare photographs and is particularly valuable for revealing changes in before-and-after micrographs or photographs. Cole (34) describes an instrument called the Metals Research Quantimet (Q.T.M.) which analyzes images by a line scanning technique, I t measures three parametersarea, projected diameter, and numberusing techniques developed for television. The instrument can be used in conjunction with a microscope, or to analyze photographic prints or nega-
tives, x-radiographs, or other typei of images. Schumann (197) dewribei an optical goniometer which u\ez a microscope in place of the regular telewope. Stages. Four articles dealing with cold stages have been found. Two of these (32, 220) operate a t or near liquid nitrogen temperature. Clothier (32) uses an aluminum bar to conduct heat from the qiecimen to liquid nitrogen kept in a dewar flask. The inzulation is expanded polystyrene. There is no temperature control. The microscope uses a reflecting attachment for the objective to gain working diitance. Thorell et al. (220) have built a stage especially designed for the microipectrophotonietry of cytochroniea in
