Talk about timing— I was researching the use of antiseptic soap for my doctor hero in my current WIP to make sure I could have him insist on washing hands and what he would have used. And now here we are in the midst of a plague that requires we wash our hands all the time, although the antibiotics my Victorian doc needed aren’t the same as the fatty soaps we need to melt a virus.
But as happens, I fell down the research rabbit hole looking up soap. We have solid evidence that a form of detergent made from animal fats and wood ash was used in Babylonia around 2800 BC. From all accounts, it was used in cleaning wools and textiles, and there is some evidence that it was used medicinally, although no one is telling me if they tried drinking the stuff. Uck ptui.