The Microscope - Volume 60, Second Quarter 2012
IN THIS ISSUE:
On the cover: Spherulites of the stable polymorph of cholesteryl acetate growing in the liquid crystalline phase on cooling after complete melting (crossed polars). See “The Microscope Past: 50 Years | Some Simple Chemical Experiments with the Microscope” by Walter C. McCrone, page 87. Photomicrograph courtesy of Gary J. Laughlin, McCrone Research Institute.
Editorial | Simple Chemical Experiments 50 Years Ago and Today
Gary J. Laughlin
The Microscope 60 (2), p ii
Excerpt: Fifty years ago, in the 25th anniversary issue of The Microscope, Walter McCrone proposed some simple chemical experiments using a polarized light microscope (PLM), some glass slides and coverslips, and an alcohol lamp. He believed it might be possible to teach a full curriculum in chemistry using this equipment together with experiments adapted for the microscope. (See “Microscope Past: 50 Years Ago” on page 87). At first, this may seem farfetched, and we may wonder what his motivation was or why it is still important for chemistry students to learn the PLM as an analytical tool or chemical microscopy as the solution to chemical problems today. The answer remains the same. Full article (PDF)
Effect of Sample Preparation on Observed Airborne Fiber Characteristics
D.R. Van Orden, M. Sanchez and J.M. Wilmoth
The Microscope 60 (2), pp 51-61
Abstract: Natural occurrences of asbestos and potential exposures to such materials have drawn significant public and regulatory interest in recent years. Proposed revisions to a published analytical method (ASTM D7200) that is designed to monitor airborne fiber concentrations are based on data developed using inappropriate sample preparation strategies, including over-grinding the samples and the use of ultrasonication. Tests demonstrating the effects of grinding and preparation of asbestos minerals have been conducted. Sample preparation procedures used by some laboratories destroy the characteristics of asbestos, thereby limiting the usefulness of ASTM D7200 and similar analytical methods. The effects of sample preparation on the morphology of particles must be considered when creating or revising asbestos analytical procedures. Full article (PDF)
Critical Focus | Solving the Mystery of Spontaneous Human Combustion
Brian J. Ford
The Microscope 60 (2), pp 63-72
Excerpt: Last November, a 42-year-old man was standing outside a record store in Sweden, apparently waiting for someone. Suddenly fire appeared from his clothing and he burst into flames. He blazed from within and formed into a fireball as he fell to the ground. The man, who remains anonymous, narrowly escaped with his life. It was an astonishing and ghoulish episode — but it wasn’t the first. There have been a number of reports of people catching fire, and most of them are almost completely destroyed in the conflagration. In the space of minutes, people have been consumed by fire, and all that remains is a heap of ash from which the legs protrude. It is a horrifying spectacle, which has been written about for centuries. Full article (PDF)
Professor Ford’s new theory has also been published as The Big Burn Theory in New Scientist, August 18, 2012, pp 30-31.
Characterization of Coal Ash Including Fly Ash Particles
J.R. Millette, S. Compton, W.L. Turner Jr., S.M. Hays, S. Kenoyer, W.B. Hill and P.S. Chepaitis
The Microscope 60 (2), pp 73-84
Abstract: Particles of coal ash can be distinguished from other dust particles based on optical microscopy examination and electron microscopy analysis. This paper provides some background information about coal ash/fly ash and augments the information in the published literature about the particle characteristics as determined by light and electron microscopy. The authors also describe a method for determining the number of fly ash particles per unit area of surface dust. Full article (PDF)
The Microscope Past: 50 Years | Some Simple Chemical Experiments with the Microscope
Walter C. McCrone
The Microscope 60 (2), pp 87-92
Originally published in The Microscope, Vol. 13, No. 8, July – August, 1962.
Excerpt: I have sometimes thought it would be possible to teach a full university chemistry curriculum at a laboratory bench equipped with a simple student’s microscope, some slides and coverslips in lieu of beakers, and an alcohol lamp in lieu of a Bunsen burner. Simple microscopical experiments could be chosen to illustrate general chemistry as well as inorganic, organic, physical and analytical chemistry. I have yet to prepare such a curriculum in detail, but the following representative experiments will illustrate the possibility. Full article (PDF)
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