egg turning black

Question
well, the egg that was laid second (i'm assuming) has now hatched. that other one with the black marks near where it has tried to peck through still has peeping noises coming from inside and it rolls around all over the place as the baby is trying to get out. so, even though you said to remove it, i'm now wondering if i should leave it since there clearly is a living chick in there.
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-----Question-----
vinny is currently incubating her second clutch of eggs. the first egg should have hatched three days ago. i hear noises from one of the eggs. but the egg, which is partially pipped around the middle, is turning black. i hadn't noticed any blackness on the shells in her first clutch, so this doesn't seem normal. at what point should i worry that it won't hatch itself?
-----Answer-----
Hello Darla! The egg that is turning black probably has a rotting chick inside, as gross as it may sound ;_;
Some chicks fail to thrive in the egg or are too weak to break open the egg shell and die in the egg. They body of a chick can rot quickly so make sure you remove the egg. A normal egg should be white and will hatch within 18-20 days. If it is longer than that, they egg will not hatch ever and should be thrown away to avoid spreading infections to the other hatching chicks. If you want to be sure its not going to hatch, leave it there until the 24th day and see if anything changes. A black egg is never a good sign of a healthy hatching chick so the chances of the egg being a "dud" are 90%. It has nothing to do with the mother or other babies, some chicks just don't survive, its a normal process that takes place. good luck with the other chicks!

Answer
If its peeping then the chick is alive (of course) leave it in the nest and keep an eye on it. The chick probably is having trouble hatching. In this case you can help the chick by carefully removing some of the shell around where the chick is chipping the egg with the egg tooth. If the chicks fails to hatch in time, the chick is lost. If you are really nervous about helping the chick hatch, then wait and see if the mother helps it for a half a day. Any longer than that might be too late. But Defiantly leave it in the nest if the chick is alive. When helping it hatch, peel away the egg and make sure the chick can breathe and hold the chick in a towel or shirt so it can dry off. Normally the mother will eat all the egg membrane so you will have to discard of the membrane yourself.