Jil101
Neatsfoot oil can be found in farm supply, harness shops, or even Home Hardware. It is used for softening leather and cleaning tack. The Ivory soap (1/4 bar) and the neatsfoot oil are mixed and used for tanning.
I do all of my own tanning, mostly buckskins but some with hair on. Go to braintan.com they have lots of articles there and you can get their book and video which is great. I use ivory soap and neatsfoot oil to tan the hide and it comes out soft and white. Bill