Okay, so how about just cutting out the middle man and going straight to the gills?  That was another option that scientists in the '60s tried to chase down, but the results were still less than encouraging.  Semi-permeable membranes had a lot of promise as the basis for an artificial gill, since they allow oxygen to pass through and not water, and they made for really cool laboratory demonstrates where you plunged a mouse in a box fitted with membranes into an aquarium and watch it stay alive-- cheesed off, but alive. 

But, as with the fluorocarbons, big problems developed quickly.  Human beings are very large animals with relatively fast metabolisms, which means they need a lot of oxygen, so the gills would have to have the surface area of a bedspread-- king size.  They also discovered that if a man is breathing air from a gill, the membranes lost inert gases going the other way, which caused the gill to collapse.  Even if that could be fixed, human skin loses air through the pores anyway, so same outcome.  One solution was the Cousteau route of bypassing the lungs and running blood from the neck arteries to the gills, but the universal reaction to that idea was, "you go first."

The ironic thing is, that the fluorocarbon tests highlighted one other problem.  The scientists learned that even if you could get men to breathe liquid, they still suffered from all the other difficulties of diving; especially cold and pressure.  It looked as though the real problem of man in the sea was not because of his breathing, but because he's man.

Tales of Future Past | Ephemeral Isle | Freelance Writing | Radio Plays | Shop