"Lamping" eggs by dipping them in water.
Of course, it is not the classic lamping, but a slightly different method that is ideal if the egg is dark in color or is already in a late stage of development when it is not possible to see if the chick is alive by the lamping.
Why is it important?
It often happens that the chick simply dies in later development (15-21 days), we leave the egg in the incubator hoping that it will still hatch, thereby wasting electricity, time and nerves.
That's why it's best (at least that's how I do it), on the 18th day of incubation when we put the eggs in the resting phase, immerse the egg in water and check if it moves.
If it is still, the chicken has died.
Personally, I immerse myself in tap water, which is a little colder and encourages the chicken to move, because experience has taught me that by dipping in lukewarm water, the chicken can stay still (I guess it is sleeping), so we can wrongly conclude that it is dead.