So I am curious, why does the plasma streamer in the plasma balls change color? I understand electrical discharge through a given gas having a given color, and that the pressure has some effect on the color, but within the sphere the pressure has to be pretty much identical at all points. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .