She/He almost got out of the shell by herself without being harassed by Black, but Black must have noticed her/him at some point, because when I got out there, she was pecking the baby and the shell like crazy. In fact, she'd pecked him/her so much that the chick just shot out of the bottom of the shell like a cannon, trying to get away. Black proceeded to pick the chick up by his/her foot and try to fling him/her.
The chick was rescued and dried under the makeshift incubator, and Black is done with mommyhood. Her last two eggs are duds, and I'm trying to break her back into the swing of normal chicken life again. I am thankful to Black for setting so nicely for 3 weeks. She was extremely faithful to those eggs and hardly ever got up. Her tenaciousness got the eggs right up to the point of hatch, which I couldn't have done, as I don't have an incubator right now. She gave us 4 more chickens, and I appreciate that. I don't appreciate that she killed one of them, and would have killed the other four, had I not intervened. My son has suggested that Black only wants an egg family, not a chick family, and it seems that he's right. I will put Black on the list of broodies I will use only if I have no other choice.
But anyway, well done and thank you, Fat Black. Nice work and enjoy your retirement.