Step 1 : Introduction to the question "2. This preparation is also known as Hahnemann's Calcium Sulphide. A clue to help is that it has the same initials as Truman's first two initials. What preparation is it?"
...1. Nitricum Acidum 2. Rhus Toxicodendron 3. Argentum Nitricum 4. Hepar Sulph Harry S. Truman, hence HS leads to Hepar Sulph. Historically this preparation was proven by Hahnemann himself, hence its other name. Proven in this case does not refer to scientific proof but the way homeopaths decide what is a remedy and what is not. It is made from the flaky inner layer of oyster shells and flowers of sulfur.
