(1) When I was in 6th grade, the science teacher passed around a kind of porous solid, that had an awful odor. It felt like something between a whetting stone and brittle styrofoam. I can’t describe the smell exactly, although it is forever etched into my olfactory memory. It was a little caustic, like ammonia, and had an overpowering, nauseating stench like rotting flesh. Its color, as I recall it, was a kind of bluish-grayish-brown, like beef that had just turned bad. It gave me an immediate headache at the time, and I sorta feel a headache coming on just remembering it.
What could that substance have been?
(2) In 8th grade, the teacher had a “black box” in which what appeared to be plain tap water was introduced into a hole on the top, and a colored liquid exited the only other opening in front. Every time water was put into the top, a different color water came out the front. The teacher had us guess how this device worked. She said there was no dyeing, and no mechanism to divert the water through different outlets. We never guessed what it was.
Was the “coloured liquid” allowed to fill a container or drain away? Could the effect have been produced with different coloured lights inside the box?
What was the order of the colors? I did a similar demo with different indicators in a dilute solution of “semi-strong” acid and slowly added a concentrated solution of strong base. Depending on the indicators and the color change range, one could get about two or three colors from the solution, usually ending with the dark purple of phenolphthalein.
I’m not sure exactly how it works, and my explanation may not exactly fit, but solutions of Sodium Ferrocyanide are perfectly clear, like water. They’re relatively safe, too, despite the name (so the experiments I’m about to describe are often put into educational “chemistry sets”). If you pour a solution of Sodium Ferrocyandide into one of Ferric Ammonium Sulfate you get a blue solution (actually a suspension of blue precipitate – “Prussian Blue”). If you pour it into a solution of Cobalt Chloride you get a Green solution. There’s at least one other color-change you can get from a mixture of SF with something else. Of course, the solutions you mix them with have to be different, and I’m not sure how you could work it with the box you describe. But the dramatic color changes with the addition of only “water” sounds similar.
As for your other question, I really have no idea.
My first thought was ambergris, which is produced by sick sperm whales and is used in the production of perfume. Reading the page I linked made me think I may be incorrect, but it’s worth a look…
No idea if this is the correct answer but the black box could be a density demonstration. I could imagine layers of colored oil or other liquids lifted by a precise amount of water introduced by a pipe leading to the bottom of the box.
My recollection (going back 20-odd years) is that the outgoing liquid flowed through a spigot into empty glasses. I don’t remember the order of the colors.
How about another Junior High science question that recently escaped out of my repressed memory:
We had a “contest” consisting of designing and building a contraption that would protect a raw egg from breakage after being thrown onto the concrete sidewalk from a third-floor window. Some students made cradles, some attempted propellers or helices… I put the egg in a plastic drinking cup filled with peanut butter.
It worked, as the egg survived the fall, but I never ascertained why. I think I remember that there was not much peanut butter displacement, and the plastic cup suffered a minor fissure. Did the PB absorb the all shock of sudden deceleration? Did the cup’s fissure release the shockwave, such as a radial splinter when you fall flat onto your hands? Did the density of the PB hold the eggshell so tightly that there was no room to break? I ask here: wha’ happened?
That was good thinking. I suspect the breaking cup probably didn’t do much but I can’t really make up my mind. The PB would accomplish 2 things, first it would spread the impact over the egg’s surface and second would allow energy to be dissipated in the displacement of the peanut butter as the egg was pushed down into the cup on impact.
With the black box, did he measure the amount he put in each time?
Yup, definitely a Pumice Stone . . At least in Mexico, they are used as a heavy duty type of sandpaper and look like a brick, except a grayish color. . and the most horrible stench imaginable . . .
