After busily cleaning out the pantry, I discovered two open, but only partially used, containers that I didn't know I had. One was baking powder and one was baking soda. It's always useful to have extra on hand in case of a baking emergency, but I figured that it would be a good idea to test them to see if they still worked, since chemical leaveners can lose their potency over time for various reasons, including poor storage conditions.
The procedure for testing these two products is simple. Get out two small glasses or bowls and fill one with 3-4 tablespoons of white vinegar and fill the other with 3-4 tablespoons of room temperature water. Add about 1/2 teaspoon baking soda to the bowl containing the vinegar and the same amount of baking powder to the water bowl. Each mixture should fizz up, with the soda/vinegar producing a bigger reaction. If they both work, mark the containers with the date and check them again in 6-12 months (if you haven't used them up by then) to make sure they're still active. And if they don't fizz up, you better stop by the store before the next time you want to whip up a batch of cookies.
In the early and mid 1800’s, rural Ireland did not have a strong tradition of yeast bread
making. Baking was done in the home and, in addition to having limited supplies, time was often at a premium. The use of
baking soda as a leavening agent was quick, effective and it produced a much more consistent result than yeast did. It
caught on quickly and made 
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