Square Meal Tablets are small pills the contain the equivalent of a six-course meal.
Each tablet is about the size of a fingernail. It contains soup, fish, roast meat, salad, apple-dumplings, ice cream, and chocolate drops all boiled down to a small size that is convenient to carry. They were invented by Professor Wogglebug, and the Shaggy Man sometimes takes them on his wanderings. (The Patchwork Girl of Oz).
When the professor tried to make his students eat the tablets instead of ordinary meals, they refused and even revolted when he insisted. (The Magic of Oz)