I was looking at a Jenkins projection television system thats a bit different using a light cell ..some information on the page said the chemical he used was carbon bisulphide but i think its a mistake its carbon Disulphide.
In fact theres even a you tube video how to make the stuff but sounds pretty nasty !!!
http://www.youtube.com/watch?v=IkBFlPagRgA
I like the inkwell one....only trouble with these every things a bit Dangerous !