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Children's Science Through Detective Stories
Excerpts from The Orchid Grower - A Juvenile Science Adventure Novel
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  • Gold Identification

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  • The Orchid Grower - A Juvenile Forensic Science Adventure Novel

    The Orchid Grower
    A Juvenile Science Adventure Novel about Orchids and Genetic Engineering



    Chemistry GumShoes: Identification of Gold

    All That Glitters Isn't Gold

    In silence, Joab and Dina bent over the computer and read the entry on gold, sipping hot tea and eating cookies. When they finished, Joab straightened up.

    “Now we have to find out if what we have here is real gold.”

    Dina read out loud, “‘Gold is an unreactive metal with a bright yellow luster.’”

    “Well, the necklace and the medallion certainly have a bright yellow luster,” Joab said, “but how do we know if it’s also an unreactive metal?”

    “Easy. First, we’ll find out if it’s a metal and after that if it’s also unreactive. We learned about metals in our science lessons.” Dina took a tattered notebook from her schoolbag, leafed through it quickly and finally said, “Here it is…‘a metal is a hard shiny solid substance that can conduct heat and electricity.’ Well, they’re obviously hard and shiny, but how can we see if they also conduct heat and electricity?”

    “Simple.” Joab got a little box the size of a cigarette packet from his toolbox. It had a small red bulb in the middle and two long wires with clips at the end attached to it.

    “This simple device tests electrical conductivity,” he explained.

    “It’s a basic electric circuit—a battery, a bulb and two leads. We attach the leads to the material, and if it conducts electricity the current will flow through, closing the electric circuit, and the bulb will light up. If the material doesn’t conduct electricity, it won’t close the circuit and the bulb won’t light up. Got it?”

    “Okay.”

    Joab touched the clips at the loose ends of the leads to each other. The red light went on. “It’s working.”

    He clipped the leads to the medallion—the light went on again.

    electricity conductivity test

    “That takes care of the electricity part,” Dina said. “What about conducting heat?”

    Joab held one end of the medallion between his fingers and dipped the other into the hot tea. “Now let’s see what happens, Ouch! Ouch!”

    “Well, I guess it conducts heat, too,” Dina said, laughing. “So it’s definitely some kind of metal.”

    ”It sure is!” Joab agreed, licking his painful fingers.

    They bent over the computer again.

    “Now, what’s an ‘unreactive metal?’”

    Dina looked through her notebook again. “It says…‘an unreactive metal is not affected by air or water, it never rusts, tarnishes, or becomes dull,’ like…like gold, platinum, copper, silver…all very expensive.”

    They examined the necklace closely. “No rust…very shiny. It looks like a real unreactive metal.”

    “Gold! Gold!” Dina squealed.

    “But there are lots of unreactive metals,” Joab protested.

    “It doesn’t matter!” Dina said, excited. “They're all very expensive!”

    “But we have to be sure before we go to the police, don’t we?”

    Again, they pored over the screen.

    “‘Another gold mining method is based on the attraction of gold to mercury,’” Dina read. “‘The rocks containing gold are crushed by explosives and heavy machinery and turned into a pulp. The pulp is allowed to flow over metal sheets coated with mercury that attracts the gold and dissolves it.

    “‘By this process is formed a paste composed of gold and mercury—called amalgam—which is removed and heated until the mercury boils off, leaving the gold behind.’”

    “That’s it!” Joab exclaimed joyfully. “Your gold earrings, please.”

    “What on earth are you getting so excited about?”

    “Your earrings are made of gold, aren’t they?”

    “Of course, they are, so what?”

    “Gold is attracted to mercury, right?”

    “So?”

    “So, first we’ll try mercury on your gold earrings and see what happens. And then we’ll try it on the medallion, and if we get the same results we’ll know for sure.”

    “But where are we going to get the mercury, Joby?”

    “I’ll give you one guess.”

    “Are you crazy? From Mom’s thermometer?”

    Joab raced out of the shed and returned a few seconds later with their mother’s thermometer. He put it in the middle of the table and with a little hammer he produced from his toolbox broke the thin glass. A few little soft balls of mercury scattered on the table.

    “The earrings!” he commanded extending his hand.

    “No!”

    “The earrings!”

    Dina reluctantly got the earrings from her jewelry box and handed them over. He held one gently between his fingers and delicately touched it to one of the drops of mercury. The drop disappeared, and a bright stain spread over the whole earring.

    “We know that’s pure gold,” Joab said, satisfied. “Now let’s see what happens with the medallion.”

    Dina tried desperately to clean her earring with her shirtsleeve, but to her dismay the stain wouldn’t come off. “Mom is going to kill me!”

    “That’s the price of fame,” Joab said with a smirk.

    He touched the medallion to one of the remaining drops of mercury. Instantly, the mercury coated the end of the medallion. He touched it to another drop and the stain crept further. He repeated the process till all the drops were gone, and the medallion was almost completely covered with a hard, bright, lustrous, unremovable stain.

    “Hurray! Hurray! Gold! Gold!”

    Dina was still upset.

    “What’s the matter with you? We’re on the brink of fame!”

    “I’m really happy, but I don’t think it’s fair to squeal on the brave Robin Hoods.” …

    * This is an excerpt from The Orchid Grower - A juvenile science adventure novel about orchids and genetic engineering.



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