Lemon Egg recipie

Just discovered this forum and saw this recipie from Speedy further down...
Pl elaborate..... the fresh, clean egg that you mentioned is still in its shell??? I take it that the calcium is leached from the eggshell that´s sitting in the acidic lemon juice. Do you top up the lemon juice after you´ve subtracted a 1/2 tsp.? Or do you start anew?? Meaning finish up the first batch and start with a new egg?
THANKS for the info! This sounds so easy and I´d like to try it out.