Dimitri wrote:

>> Back in my Home-Ec days we were taught about the actions of these
>> ingredients which are- Baking powder recipes act on heat, Baking soda
>> recipes act on acid.
>
> I think that was an oversimplification although I am sure it's true.
>
> The acid in the powder starts an immediate reaction when mixed with the
> soda & liquid. It's the # 1 reason to pre-heat your oven.

It was about as much as most 7th grade girls had patience to learn, I
suppose?
I recall the lecture expanded on it some in warning to not mix up
batters with these agents and let the batter sit around or you'd lose
effectiveness.
Goomba