Thanks, Ryder. This reminds me of a reference I saw some time ago to everyday chemistry of where things come from.
I know how to make lye, and I think stores rarely carry it anymore. The last time I saw it, it had other chemicals mixed into it, and it would not make pure soap.
Soap is traditionally made in the late autumn, during butchering season.
I wonder if vegetable soaps could be made from the saponins in plants? I would guess so--and it probably actually happened, but we have collectively forgotten how to do it.
The reference--I think it was a book (I should look on Amazon) had references to a lot of other 19th century chemical technology as well.
I do have in my possession 18th-19th century mechanical technology in the form of a book "507 Mechanical Movements".