The chicken eggs in the incubator

With only two of the twenty duck eggs hatching successfully I am determined to have most of the 40 chicken eggs that are now in the incubator hatch.  They've been in the incubator for a week, two more to go.  Today I did my first candling.  You are supposed to candle the eggs at a week and then again at two weeks. 

Three of the eggs had no shadow in them, which is supposed to mean that there isn't a chick developing.  I removed those three eggs.  Two of the eggs were on opposite outside corners and the third was on the outside row.  Perhaps the edge of the incubator is letting in some outside air and cooling down the outside rows of the eggs?  One of the interesting things I learned was that I could tell when I picked the egg up whether it was going to have a developing chick in it or not.  How?  The egg was warmer than the egg that didn't have the developing chick.  Sure, they are all in the 99.5 degree incubator but the chick itself is producing a little heat.  So the developing chick should have a warmer shell.  Nobody ever told me that before.  Wow, I made a new discovery!

The only thing I've been told was that you have to candle the eggs and remove the ones that aren't developing.  I wanted to know why.  My friend said that the non-developing eggs would produce some sort of smell or infection or something.  She said that the non-developing eggs would cause the rest of the eggs to not develop.  Since I know nothing about hatching eggs that sounded interesting but since I'd never read that I thought I'd research it some.  The manual which came with the incubator said to candle the eggs and remove the ones that aren't developing.  It didn't say why. 

I researched this question on like and read that you remove the non-developing eggs because very rarely, but it's possible, they can explode!  They can also just start to ooze.  Either way, bacteria can contaminate the good eggs, causing them to go bad. 

How did I candle the eggs?  I took a roll of toilet paper and laid each egg on top, having it rest in the center of the cardboard tube.  I shined a flashlight through the bottom.  The roll of toilet paper blocked the light so the light only came through the tube straight into the egg.  The egg had a nice cushion to rest on and I didn't have to worry about it rolling off.  The room was dark although I had a light on in the adjacent room.  I figured that I'm enough of a klutz I didn't need to try this in complete darkness other than my flashlight. 

The two ducks in the yard that are sitting on nests haven't had any ducklings hatch yet.  I keep watch each day so we can scoop up the ducklings and put them into the stock tank with the two other ducklings.  I wonder if the chicks will be able to be put into the tank with the two ducklings?  Since the ducklings will be almost four weeks old they will be a lot bigger than the chicks.  I'll probably put some sort of divider in the tank so they can all be in the house but not right on top of each other.  Unless someone tells me that they've put ducklings and chicks together and all worked out fine.