Breathable waterproofs rely on the fact that water is very sticky. Water has an oxygen atom stuck onto two hydrogens, and looks like a tiny boomerang. The oxygen atom is quite negative and pulls electrons towards it. This means that there are plus and minus bits on the molecules which attract plusses and minuses on other molecules, making the molecules stick together. This attraction is known as hydrogen bonding and is the reason why water has a surface tension. When water forms into drops, they are very large and don't easily break into smaller ones. The fabric in breathable Gore-tex raincoats is called Teflon; the same material used on non-stick frying pans. The holes in the fabric are so tiny that 9 billion can fit into one square inch of the raincoat! When water leaves your body as water vapour, the molecules are small and can fit through the holes. When it reaches the outside of the raincoat, it condenses into big sticky raindrops that can't get back through. But your raincoat will only stay breathable if you keep it well waterproofed. Waterproofing creates a gradient between the inside and outside of the coat: the inside has lots of water vapour while the outside has no water because it has formed drops and run off the fabric. This gradient ensures water is pulled away from your skin and stops you getting sweaty inside your raincoat!

Bony fish that live in the sea have blood that is less concentrated (in terms of salt) than the water they live in. By a process called osmosis, these fish will lose lots of water into the sea. To stop them from dehydrating, bony fish drink lots of water. Although drinking salt water is never a good idea if you're a thirsty human, fish have special mechanism on their gills that enables them to excrete the excess salt they are drinking. By pumping the salts back out again, they are able to drink water without become even more dehydrated. In contrast, sharks make their bodies as concentrated as the water around them. They do this by building up levels of urea in their blood. This is why dead sharks smell like urine. Having highly concentrated blood also means that sharks won't do very well if put into freshwater - water will rush into the shark by osmosis and it might even explode! Sweating is a process designed to help organisms cool down. On land, sweat on the skin evaporates and takes heat away from the body, making you feel cooler. In the sea, water can't evaporate off the fish because they are already in water! So no, fish don't sweat.

Just as if you have a cut and get a scar, having syphilis will also leave a scar in your blood. This scar will be in the form of antibodies that won't disappear, so your blood screenings will always come up positive. If you are keen to give blood, you should probably go along to your local health clinic and ask for a test for syphilis. If you actually had another disease (such as gonnhorea) that leaves no trace, you will be able to give blood, But you are unlikely to be able to give blood if syphilis antibodies are present. As to your penicillin allergy, some people don't know they are allergic to something until they get exposed to it. If you were slightly allergic to penicillin before, receiving it for syphilis will have made your body expert at reacting to it with the result that any time you now take penicillin, your immune system will go into overdrive and give you an allergic reaction.

To block out the moon it would have to have been a huge chunk of rock a long way off, or a smaller piece much closer to the Earth. But in either case we would have known about it because of the obvious risk to satellites and to the Earth itself. Also, it probably would have gone on to burn up in the atmosphere, producing a bright light which we would have seen. But it seems very unlikely that what you saw was actually in space. As it appeared so large, it could well have been an aeroplane, or possibly a helium weather balloon...or perhaps a stealth aeroplane or even a UFO !?

I'm not sure whether it can affect genuine restless leg syndrome, but tonic water can certainly help leg cramps because it contains quinine which is added to give it is bitter taste. Doctors sometimes prescribe quinine to people who complain of night time leg cramps. Perhaps your legs are restless because of cramps and the quinine in the tonic water you drink settles them down ?