Reddit mentions of The Everything Hard Cider Book: All you need to know about making hard cider at home

People always get wooged out by the whole meat in my beverage thing. The recipe in Experimental Brewing is a modern update on the infamous Digby's Cock Ale. One thing I would do for your experiment though is crack the bones - get the insides exposed so you can extract the collagen and other goodies.

I knew Digby's recipe for years because that naturally gets passed around as a horror story recipe: "ewwww... can you imagine?" Done it a few times, it's actually tasty. But when I was writing my cider book was when I discovered just how ubiquitous meat usage had been in older fermentation processes. You'll see scattered through texts advice like "if your cider isn't dropping bright, suspend a shoulder of pork in it" Note, that's a raw shoulder of pork. Digby's, at least, calls for the chicken to be boiled in the wort and then pulverized. :)

What the old fermenters had stumbled upon was two fold - the addition of collagen as a clearing agent as /u/chromerat mentions and the addition of aminos and nitrogen for yeast health from the meat as it broke down in the wort/must/whatever - aka a little natural yeast energizer!

This one's my recommendation: http://www.amazon.com/Everything-Hard-Cider-Book-making/dp/1440566186/ref=sr_1_3?ie=UTF8&qid=1449552939&sr=8-3&keywords=cider+making

Plus, the author is in this sub all the time :)

one book I borrowed from rev Nats library in the tap room

another local portland cidery's book on homebrewing cider

The book Everything Hard Cider does a great job covering tons of different options and only $16 on Amazon. https://www.amazon.com/gp/aw/d/1440566186/ref=mp_s_a_1_1?ie=UTF8&qid=1521755902&sr=8-1&pi=AC_SX236_SY340_FMwebp_QL65&keywords=everything+hard+cider&dpPl=1&dpID=51GMaGAyTAL&ref=plSrch

I'm pretty sure /u/drewbage1847 would recommend http://www.amazon.com/The-Everything-Hard-Cider-Book/dp/1440566186