How to make a thermometer

Question

i know that you add part rubbing alcohol and part water and 10 drop o food colorent. but how to make the numbers like 70 degrees???? HELP

oh yah also for those who dont know how to make one chek it out!!

http://www.youtube.com/watch?v=syXNPEpwo4g&feature=user

Answer 1

You have to calibrate it against a known good thermometer.

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Answer 2

or measure it at freezing and at boiling, and make 100 even marks between, which would give you Celsius. (since celsius is 100 even increments between freezing 0 and boiling 100)

however this is quite a bit of work and a known thermometer would probably be easiest.  

if you use a known thermometer you can find a few random points, and knowing that there are even increments between degrees you can assume where 0 and 100 would be.  

and if you don't use Celsius, you can convert to Fahrenheit, with

Tc = (5/9)*(Tf-32); Tc = temperature in degrees Celsius, Tf = temperature in degrees Fahrenheit