The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
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Thallium is a metal element denoted by the atomic symbol Tl. It has an atomic number of 81 and the average atomic weight of its isotopes is 204.3833. It is normally found as a bluish-gray metal that is so soft it can be cut with a knife. It has a melting point of 579.2°F (304°C) and a boiling point of about 2683.4°F (1473°C).
Thallium was discovered by the British physicist William Crookes while he was examining selenium and other compounds using a spectroscope. While examining the spectra of these elements he noticed a bright, lime green band that did not correspond to any known element. He named the element thallium after the Greek word thallos meaning "green twig." At about the same time, this element was isolated by the French chemist C. A. Lamy. Lamy announced his findings shortly after Crookes, and a brief controversy over priority ensued.
In its pure form, thallium is dangerous, particularly when in contact with skin. It is a suspected carcinogen. It is often used in electronic equipment, and one of its compounds, thallium sulfate, is used as a rodenticide and ant poison. Its use as a biocide, however, has been prohibited in the United States since 1975. Another compound, thallium bromide-iodide, is used in crystalline form as an infrared detector. Other thallium compounds are used in the manufacture of imitation diamonds, glass, and as a catalyst.