The Case of the Graveyard Ghost (7 page)

Even though mistakes are a part of science, sloppiness is not. Good scientists read instructions and practice good laboratory technique.

I
n 1928, scientist Alexander Fleming was busy conducting an experiment. He was growing bacteria in petri dishes, and the bacteria were multiplying nicely. However, when he returned after a holiday, the petri dishes had been contaminated with mold. Oops! That wasn’t supposed to happen!

But he noticed something interesting. In the areas of the contaminated culture, the bacteria didn’t grow. Now, Fleming could easily have thrown his experiment away and started over, but instead it got him thinking.

Why didn’t the bacteria grow in the presence of the mold?

At this point, Fleming likely developed a
hypothesis
. A hypothesis is a scientist’s guess as to what is happening and why. Fleming’s hypothesis might have sounded something like this:
Based on my observations, I believe the mold is producing a substance that prevents the growth of bacteria.

Fleming then set about to test his hypothesis. What he discovered changed the course of the medical world. Quite by accident, Fleming had discovered a mold called
penicillin
, which is now one of the most widely used antibiotics. Penicillin prevents the growth of bacteria. By 1940, people who might have died from infections like pneumonia could take penicillin and recover. From penicillin, the search for other antibiotics began, and now we have many to choose from.

The point is, Fleming did not set out to discover a new antibiotic. (He didn’t even know what one was, since it hadn’t been discovered yet!) But when things went wrong, Fleming didn’t cry, panic, scream, or ignore it. Instead, like a good scientist, he wondered
why
the bacteria couldn’t grow in the presence of the mold.

A
ll right, so it’s not Sloane, it’s an egg. And, well, it’s not a laundry chute either, it’s a pipe. But TOUGH TOENAILS!!! IT’S KINDA THE SAME!!! AND BESIDES, IT’S FUN!!! (You can draw a frowny-face on the egg and pretend it’s Sloane if that makes you feel better.)

MATERIALS

• PVC pipe, with a
-inch inner diameter
*

• sandpaper

• 1 medium hard-boiled egg
**

• tablespoon

• baking soda

• tissue

• vinegar

• measuring cup

• plastic sandwich bag

*
Note #1:
Diameter
is the distance of a straight line that passes through the center of a circle. Measure the pipe’s
inner
diameter at the hardware store.

**
Note #2: Large eggs are
too
large for PVC pipe. Medium eggs are just right. To hard-boil an egg, have an adult boil it in water for 15 minutes. Cool the egg before you peel it.

PROCEDURE

1. Ask a handy adult to cut the PVC pipe to a length of 7 inches. (If you buy it from a store, they will cut it for you.) Smooth any rough edges with sandpaper.

2. Peel the egg and insert it
inches into the bottom of the pipe. It should be a tight fit.

3. Measure 2 tablespoons of baking soda into a tissue and fold it up tightly so that none of it leaks out. Keep it handy, because you’ll need it in a hurry.

4. Pour vinegar into a measuring cup to the
–cup mark, then add water to the
–cup mark.

5. With one hand, hold the pipe (egg side down) over a sink.

6. Put your other hand into the plastic sandwich bag. This is your glove.

7. Pour the vinegar-and-water mixture into the top of the pipe. The egg should keep the liquid from seeping through.

8. Add the entire baking-soda packet (including tissue) to the vinegar and water mixture.
Quickly
seal the top of the pipe with your gloved hand, and shake.

9. PLOP! SPLAT! Out comes the egg!

How does this work?

Vinegar and baking soda react together to form completely new substances: water, salt, and carbon-dioxide gas. So much gas is produced that it builds up pressure. The pressure forces the egg out the end of the pipe.

T
hink about it. Capillary action might come in rather handy. You’re thirsty. You’re stumbling along. There’s a mud puddle. You stick in your big toe and soak up some swampy water. Gulp . . . gulp . . . gulp . . .
ahh
. . .

Plants draw up water through capillary action. Tiny capillaries carry moisture and nutrients from the roots throughout the entire plant. Try this simple activity and observe capillary action “in action.”