How to start a fire with ice

I have actually tried this many many years ago when I was in the Scouts.
http://news.discovery.com/adventure/ice-makes-fire-120127.html
The first few times we tried it we did not succeed, but eventually one of my friends was able to find a really clear piece of ice which worked really well.








Yeah that kinda thing is pretty cool. If you melt a concave curve into it it'll work better than just a flat piece. Less bubbles the better.
Proud Canadian, Enlightened Atheist, Gaming God.