In the past I've scraped all the meat and fat from the bone I can, then boiled it 3 times (in fresh water each time) to clean out the marrow and remove all the fat. By the third boil, you shouldn't see much fat or oils in the water. Then I let them dry for a couple days, cut it in to moderate sized sections, and let it sit for a week or so in white gas to soften and pull out the last of the fats and grease. I think a number of petroleum distillates will work fine - a bowmaker friend told me turpentine is traditionally used as well, and I'd be willing to be gasoline would work just fine as well.
One thing I learned the hard way not to do, is use a pressure pot. I tried it thinking the higher temperature would speed things up, but I think I actually just drove the fats further in to the pores in the bone than an open boil would. The first time I did it I just hung the bones from a tree for a few weeks to let the weather and the animals take care of most of the work before I started the boiling. I think I'll go back to this with the next batch, as it did seem to take less to degrease them. I think bones don't naturally contain much grease or fats to begin with, but rather get contaminated as it's heated and boiled. I not really sure, but it seems to make sense.
I tried buffalo femurs on this last batch, assuming they would be a bit larger or have thicker walls to offer a better yield. Not so. It's really hard to tell them from the cattle bone from what I can tell so far actually. If anything, they seemed a bit more difficult to degrease than the cattle bone, though since I only do this maybe twice a year I may be imagining it. I think next time I will either leave then hanging outside longer to take care of more of the dirty work, or halve them lengthwise and scrape out the marrow before boiling. The less soft tissue you start with in the pot, the easier they are to degrease.
![[headinwall]](./images/smilies/headbangwalluf8.gif "Mad")