Conversation in a bath

I am reading while the boys soak, and not paying attention to their blatherings.
Marcus:  Blah blah water
Michael: Blah blah blah skin on the water!
Marcus: Yes, blah blah skin on the water. It's made of different stuff.
Michael: Is it?
Me (tuning in): Hang on, no it's not. It's just surface tension - the water on top is the same stuff as the water underneath.
Marcus: No, scientists have actually managed to extract the skin of water. Its made of hydrogen and nitrogen.
Michael: That's ammonia!!! Three hydrogens and a nitrogen!!!!
Me: Excuse me I just have to go upstairs now and tell everyone else about this.