Kelvin Wave

Is limonene poisonous?

When planning this experiment, I did not know exactly what kind of substance limonene was, so I asked a Chemistry professor.

             Me:"Is limonene poisonous, or somehow dangerous?"
Chemistry prof.:"Limonene is an oil you extractfrom mandarin skin, 
                 and it's used as a fragrant base,
                 so it shouldn't be harmful at all."
             Me:"Oh, good. 
                 I'll be able to use it for student experiments, then."
Chemistry prof.:"By the way, how much will you be using?"
             Me:"Oh, about a bucketful."
Chemistry prof.:"Huh? (silence.....) you'd only normally use 
                 a couple of milliliters when using it as a fragrance,
                 so I can't make any guarantees about what would happen
                 if you used that much." 

Nice smells come in small amounts...

Although I didn't get any reassurances about safety from the Chemistry professor, it didn't seem too dangerous, so I ordered a "bucketful" of the limonene, and put it in a container in the lab. It did indeed have a mandarin fragrance. Well, actually it was more of an overwhelming mandarin stench, which spread throughout the lab, and the floor of the building where we were located. I use the lab as my office, and the stench was almost too much.

Using bromide methylene to increase the specific gravity of the limonene, for use as the lower layer of the experiment's body of fluid also turned out to be a good way to cap off the stench with a "lid" of water.

That should be around somewhere?

The relation between wavelength and limonene's angle of optical rotation (the angle at which the light's polarizing surface rotates) is the most important data needed for this experiment. However, in the paper of Hart and Kittelman, there isn't much detail provided about this, so I asked a Chemistry professor if he had that kind of data. "That sort of data should be around somewhere... I don't have it at hand, but you should be able to find it at the Pharmacology Library."

I headed straight for the Pharmacology Library and asked at the desk, however they didn't have much idea, so they introduced me to a Pharmacology professor. When I asked the Pharmacology professor, he replied that "that data should be around somewhere, but wouldn't it be faster simply to measure it yourself?", and he introduced me to a professor in the Agricultural department who he said had the necessary measuring instruments. I called the Agriculture professor, and the reply was: "I do actually have the equipment you need, but it's broken at the moment... There is a working one at the Uji Chemical Research Center, how about asking there?" Feeling I was gradually getting closer to the data I needed, I rang the Chemical Research Center only to be told that they did not have the optional accessory necessary for getting "angle data".

Having come this far, I decided I was going to have to spend a little money to get the precious data. I started calling private corporations for help. I began with the nearby Shimadzu Corporation. They didn't have the equipment, but I was told that "the Toray Research Center would probably have a measuring instrument." With high hopes, I called the Toray Research Center, and they immediately asked: "How many samples do you want done?" Elated, I started giving them the details of the necessary data, and just about when we started to discuss costs, the technician asked: "Hang on a second. Exactly what kind of data was it you needed again?" It turned out that the Toray Research Center didn't have the option necessary for "angle data" either.

Since this little experience I have never believed the words "it should be around somewhere.." until I've seen the goods with my own eyes.

Back to square one

The data I needed couldn't be found anywhere, and I couldn't get the measuring instrument necessary to do it myself. However the data I needed wasn't really all that complex. I wanted the angle at which a polarizing surface rotates, so according to principles, all I needed was two polarizing panels and a light source that could give out a monochromatic light. While grumbling about the lack of such basic equipment, I came across the solution to my problems! A handy little instrument called a spectrophotometer, and it was in my lab, too. This measures the transmissiveness and reflectivity of a sample as a variable of the wavelength, and is a fairly common piece of equipment. I should have used it from the start...

Why a yellow filter?

I didn't plan from the beginning to use a yellow filter, however I couldn't seem to get clear footage of the experiment, so I went through all of the filters I had at hand, and yellow came up with the clearest image.

Looking at it in retrospective, the shorter the wavelength, the larger the rotation angle of the polarized light, so if blue, which has a short wavelength, is turned nearly 180 degrees, it would become almost indistinguishable from red, which has a long wavelength, making the image blurry.