source: David Lebovitz
To find out if the chemical yeast is “alive”, put ½ teaspoon in a small bowl and pour ¼ cup (60ml) of boiling water over it. What should happen from there is that many bubbles are formed, almost like a white volcanic eruption without explosions. Okay, the example was quite drastic. Again, then. What should happen from there is that the mixture bubbles violently. If you tried it and it worked, great, the yeast is still good. If not … Time to discard this one and buy a new one.
