Glycerin and Light...
Last week, Mr Lim did an experiment with glycerin. He put a test tube into a boiling tube and pured glycerin in. When he filled it up, the test tube "disappeared". However, words on the test tube could still be seen...so what exactly happened to the test tube?
Firsty, some background information on glycerin...in case you were wondering what in the world it was.
Glycerin is a neutral, sweet-tasting, colorless, thick liquid which freezes to a gummy paste and which has a high boiling point. Glycerin can be dissolved into water or alcohol, but not oils. On the other hand, many things will dissolve into glycerin easier than they do into water or alcohol. So it is a good solvent.
Glycerin is also highly "hygroscopic" which means that it absorbs water from the air. Example: if you left a bottle of pure glycerin exposed to air in your kitchen, it would take moisture from the air and eventually, it would become 80 per glycerin and 20 percent water.
Because of this hygroscopic quality, pure, 100 percent glycerin placed on the tongue may raise a blister, since it is dehydrating. Diluted with water, however, it will soften your skin. (Note: While people say this softening is the result of the glycerin attracting moisture to your skin, there is heated debate as to whether or not the glycerin has some other properties all its own which are helpful to the skin. Summed up, the current thinking is "We know glycerin softens the skin. Some people think its because it attracts moisture, but there could be other reasons.")
http://www.pioneerthinking.com/glycerin.html
Light waves are bent when they travel from water into air or air into water. Refraction, the bending of light, occurs whenever light goes from one substance into another. The light is bent when it goes from air to water because light waves travel more slowly in water than in air. Two substances in which light travels at different speeds will cause refraction if the light goes from one substance to the other at an angle (not straight).
Scientists use the index of refraction as a measure of how much light bends when it passes from one substance into another. The index of refraction is the ratio of the speed of light in a vacuum to the speed of light in specific substance. A device called a refractometer can measure this extent of bending. Measuring the index of refraction with a refractometer is one-way scientists identify unknown liquids or determine the amount of liquids in a mixture.
When light passes from air into glass and then out of the glass, it can be bent. Different colors of light are not bent by the same amount, and so the effect of this bending, or refraction, is to spread white light into the colors of the rainbow: red, orange, yellow, green, blue, indigo, and violet. 
http://www.marylandfamilymagazine.com/2009/11/13/bending-light-experiment-courtesy-of-the-maryland-science-center/
The refractive index (or index of refraction) of a medium is a measure of how much the speed of light (or other waves such as sound waves) is reduced inside the medium. For example, typical soda-lime glass has a refractive index close to 1.5, which means that in glass, light travels at 1 / 1.5 = 2/3 the speed of light in a vacuum. Two common properties of glass and other transparent materials are directly related to their refractive index. First, light rays change direction when they cross the interface from air to the material, an effect that is used in lenses. Second, light reflects partially from surfaces that have a refractive index different from that of their surroundings.
http://en.wikipedia.org/wiki/Index_of_refraction
Index of Refraction of a material is the ratio of the speed of light in vacuum to the speed of light in that material:
n = c / v
where v is the speed of light in the material.
The more dense the material, the slower the speed of light in that material. Thus n > 1 for all materials, and increases with increasing density. n = 1 in vacuum.
http://theory.uwinnipeg.ca/physics/light/node5.html
The indices of refraction of some common substances are given below.
GLYCERIN
hii... welcome to my blog. 안녕하세요! 저는리산입니다. こんにちわ！私はﾘｼｬﾝです。This blog is MY teritory, please respect that. 