Broke...
James is pretty much on target and I only remember pouring tallow into oil until I got the jelly substance. Then I added pine oil to improve the aroma.
It's a rub-it-in-brush-it-clean kind of thing on finished leather, and Lanolin almost never harms leather. Tallow by itself can cake, stiffen, age and stink all at once.
By virtue of being a dressing rather than a finish like, say, tan cote, it had to be replenished.