The Chemical Battery is described in gorry detail in the book I think the main things are:
The light lit up when the bars were dunked in the acid
There is energy associated with making the light lite. Yes.
Where did this energy come from?
A chemical reaction took place--sort of like the chemical reaction that
takes place in your body when you burn calories.
This chemical reaction releases potential energy stored in the chemical make up
of the involved parties.
This type of potential energy is released via the electrical forces at work in molecules
and atoms.
This was a demonstration of the ability to convert from
electrical potential energy to other forms, i.e. light. And how
this can be accomplished through a chemical reaction.