Nguyen,+Uyen

__**Tattoo Ink**__

This article talks about what the tattoo ink is made of and ways that tattoos can be removed. I was surprised that there are many ways that ink can be mixed. Some tattoo parlors buy commercial inks, others buy the pigment and mix it with other stuff to make it their own, which I think is a little bit more risky. The author also stated that tattooing has been around for 5000 years. I wonder how did they ( the people in the past) do it? Did they do it with needles (if they created one)? I realize that there are lots of people have tattoos, because 1 out 8 Americans have them. However, there are chemicals in glow- in- the- dark and UV- activated ink that could cause cancer. I wonder if there are any other less harmful chemicals that could substitute those harmful chemicals so it won't cause cancer.

Uyen, Well written post but be sure to follow the prompt and indicate three things you learned and three things you knew. 4 stars. MW

__**Distillation**__

I think this process is relevant to our class, because in class, you explained that there are rarely anything that are pure, and most things are mixed together. This process is used to separate components in a solution. This can also relate to our class discussions because we also talked about heterogeneous, homogeneous, compounds, and elements, which are sorted by purity. By separating components, they will become "pure." I also thought it was interesting that the crude oil as a whole is useless, but when it is separated out, it has many uses.

Linda, Cool beans. Thanks for relating this to our classroom discussions! 5 stars. MW

__**Motion detectors:**__ One of the three things that I knew is that some motion detectors detect warmth as motion, but I didn't know that they are looking for infrared radiation. Plus, I knew that hertz is a light frequency unit, but I didn't kn ow it was named after the German physicist named Heinrich Hertz. Lastly, I knew that some motion detectors use light source to detect motion when there's an object blocking the source, but I never knew there was a beam of infrared ray. These are the three things I knew and three things I've learned.

Linda, OK. Very efficient post! 5 stars. MW