Sorry for the minor blurriness of the ad toward the bottom. It’s difficult when it’s cloudy outside to get a decent, non-blurry photo! The funny thing about this ad, after doing a tiny bit of research, is that it was most likely toxic. Calcium sulfide, which is what these tablets are supposedly made of, dissolves upon contact with water, but reacts to acids. When mixed with hydrochloric acid, one of the acids found in a human’s stomach, calcium sulfide releases toxic hydrogen sulfide gas. Calcium sulfide is also a component in some insecticides. Now, I’m not a doctor, or a chemist, but I say this spells a recipe for disaster. My advice? Don’t try Stuart’s Calcium Wafers!