May I suggest using unicode to display subscript in the formulas?

System.out.println("CO\u2082); would print "CO₂".

http://www.fileformat.info/info/unicode/char/2082/index.htm

Ah, thank you. I hadn't looked into what it would take to add subscripts. This should be available in the next release

v0.7.8 is now available with this feature