Hal.

Isn't the egg a complex thing altogether ? We could probably find volumes of studies about it if we looked and take lifetimes to try to understand it's inner workings . The wiki describes chicken eggshell as being .................. " 95 - 97 % Calcium Carbonate crystals , which are stabilized by a protein matrix . Without the protein the crystal structure would be too brittle to keep it's form " . They also think at the wiki that .................. " lower protein compositions are associated with lower shell strength " . Calcium Carbonate is an ingredient in some cements . So , it has a reputation for use as one ingredient in high strength materials ( relatively speaking ) . Another source suggests that chicken eggshell is 95 % Calcium Carbonate and the remaining 5% includes Calcium Phosphate , Magnesium Carbonate and soluble and insoluble proteins . The composition of a shell is like an index of a chemistry book . I think to bring an egg under water to apply the pressure is not what I want to do if I don't have to . I did a calculation which concludes that I must take an egg 10 metres ( give or take a few centimetres ) under seawater to add 1 atmosphere of pressure to the 1 atmosphere of pressure it would already be at , at the surface , to give me 2 atmospheres of absolute pressure at this depth . 10 metres is about 10 metres too many for me in seawater . I suppose an apparatus could be made with some hoses , a bucket with view window , some seawater and a 3 storey building to get the same absolute pressure without too much danger . Pistons , weights and seawater could be an alternative . Again , don't injure yourself following your dreams !

There are only 2 choices I have , namely to assume that the shell will crack or to assume that the shell won't crack . If I assume that the shell won't crack then my experiment is pointless and effectively over before it has begun . I will have not conducted an experiment and I will be no nearer designing a container to test shells . I accept that the shell may withstand a high pressure which could be beyond anything that I can apply to it at a reasonable cost . But , to say that the shell will not crack ever is a statement that to me implies infinite pressure . I can't apply infinite pressure , of course . So , if I happen to apply a pressure of 100 psi absolute and measure the pressure properly to confirm this and also see that there is no damage to the shell and also have a container at the end of it which will be designed to withstand 100 psi absolute with a significant margin of safety , then I will have progressed my experiment . I would not assume from such an experiment that the shell will never crack . Who knows what sort of a weird phenomena may suddenly occur in shells at heightened pressures . I would only have confirmed to myself , that under my conditions of experiment on that day , I found a shell which was able to withstand 100 psi absolute . I now know that shells are porous which I did not know before I asked about them here . So I had never previously thought that anything I was looking at while cooking one was originating from within it . I will definitely put a thermometer in a pot of water at 150 F ( 65.55 deg C approx. ) to see with my new knowledge what is going on . Anybody reading this should always remember the important things in life . Be careful around high pressure objects .

I would like to proceed on the assumption that the egg will crack . Theories or facts describing otherwise are welcome . What I am trying to do is to imagine some circumstances for an experiment . If I make my container to fail at 25 psi absolute this may well be a lot of work for nothing , if the egg is still structurally fine near to this pressure . If I make my container to fail at 50 psi absolute then this may also be a lot of work for nothing , if the egg is uncracked near to this pressure . I don't want to excessively shock the egg . I want to apply the pressure slowly and see what happens . If the egg can withstand 100 psi absolute then my container must also . If on the other hand I make a container to withstand 500 psi absolute and the egg happens to crack at 25 psi absolute , I'll be cursing my expensive spending on my strong container . Although on second thought's , my strong container could have other future uses . I see there are suggestions that the air can leak into the egg . Can the contents of the egg also leak into the air ? ( A kind of egg gu / air flow through porous eggshell ! ) I would try to make sure that no amount of heat big enough to cause rupture from within can happen . ( An interesting concept ! ) Anybody reading this should always remember the important things in life . Be careful around high pressure objects .

Could I first make it clear that a container exists which will be able to withstand whatever pressure I put on it , so it need not be considered here for the purpose of the following ? Assuming I can , I shall also assume that at the centre of this container I can place a normal , regular , ordinary egg which is not being supported by anything . If the egg was surrounded by air and a facility existed which could allow me to vary the pressure in the container , what type of a Maximum Pressure ( in psi or bar or n/m^2 or indeed hectopascals if need be ) could I expect to get before the egg cracks ? Thanks to all in anticipation of replies !

I've always thought this exact same thing when my mother put some batteries in a drawer with paper clips . What will happen ? I once observed 2 AA batteries in series shortcircuited with copper wire . After a couple of minutes the heat built up and a battery burst which of course could be described as a low pressure explosion , I suppose .