A better solution might be found in the "smoke" generators found in
the toy guns which blow smoke rings, made by Zero Toys.  See
http://www.zerotoys.com/products/index.html

They produce a "non-toxic fog" by using a "water based non-toxic liquid
that is used in special effects fog machines."  Three ounces of fluid
is "enough for more than 25,000 fog rings."  They cost less than $20
and use 6 AA batteries. And they're fun -- I've played with one.

Todd Augsburger - Roller Organs
http://www.rollerorgans.com/