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The Joy of High Tech


Rodford Edmiston

Being the occasionally interesting ramblings of a major-league technophile.

     Please note that while I am an engineer (BSCE) and do my research, I am not a professional in this field. Do not take anything here as gospel; check the facts I give. And if you find a mistake, please let me know about it.


     Bismuth is, in some ways, too innocuous for its own good. It is an element with no known biological function in the human body, yet which is not normally dangerous to it. (Only one person is known to have died from taking too much bismuth, though taking large doses for long periods can damage the liver.) While sharing some physical properties with lead, it's toxicity is so low that bismuth compounds have been used as stomach remedies for centuries. (It is from bismuth that Pepto-Bismol gets part of its name.) Which makes it pretty unusual for a heavy metal.

     In its pure state bismuth is a silvery grey metal with a slight pinkish tinge. (And you thought the color was due to an additive.) Most isotopes of bismuth are unstable, with half lives running from five days to twenty minutes. However, Bi-209 is either stable (which would make it the heaviest stable element) or has a half-life so long that decay has never been observed.

     Because of its low toxicity and optical characteristics bismuth has a number of cosmetic uses. For instance, bismuth oxychloride is a lustrous crystalline powder used in nail polish and lip gloss.

     Besides being dense and looking much like lead, bismuth also has a low melting point, actually lower than that of lead. Wood's Metal, an alloy of bismuth and cadmium, melts below the boiling point of water (note that cadmium is most definitely toxic). Wood's Metal is used in plugs for automatic fire sprinklers, and bismuth itself has been used in electrical fuses.

     Because of its high density (9.7, compared to 11.4 for lead, around 8 for steel and 19.3 for tungsten) and low price compared to tungsten, it is a candidate for replacing lead in birdshot. While the risk to waterfowl from lead shot is as much theoretical as factual, using bismuth would address those concerns quite neatly. It might even make any birds which ingest it healthier! (Or at least give them better digestion.)

          This document is Copyright 2005 Rodford Edmiston Smith. Anyone wishing to repost it must have permission from the author, who can be reached at: stickmaker@usa.net