Is cold/neglected embryo in egg dead/alive? less intrusive method

Lots of other good troubleshooting information on this webpage as well, but found this particular bit interesting and answered the question that I had. We had 2 eggs that were fully dark when they were candled after the hatch appeared to be done and we wanted to know more. Thought I'd share my findings about how to tell if there is an embryo still alive in the shell without opening it, because as all of you will know, once opened...

I found my treasure on avianweb.com, near the bottom if the page:
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By the way, we now have 9 out of 11 new LB chicks, broody hatched, now 2 days old! They are all good and healthy so far.

Interesting. I have never done this.

Generally, I smell the egg. A dead chick sitting in a warm bator very soon begins to develop an 'off' smell. Hold that egg right under your nose and smell. If you smell enough good eggs, you will soon recognize a bad one! When your eyes can't help you, the nose can!