Alan Izhar-Bodner, an Israeli inventor, has developed a swimming suit for divers to breathe underwater without carrying heavy oxygen tanks. His suit makes use of the air that is dissolved in water, just like fish do. The system uses the Henry Law which states that the amount of gas that can be dissolved in a liquid is proportional  to the pressure on the liquid. Raise the pressure ---more gas can be dissolved in the liquid. Decrease the pressure --- less gas dissolved in the liquid releases the gas. This is exactly what happens when you open a can of soda; carbon dioxide gas is dissolved in the liquid and is under pressure in the can. Open the can, releasing the pressure, and the gas fizzes out. Bodner's System obviously uses a special machine to lower pressure in part of a small amount of seawater taken into the system; dissolved gas is taken out. The patent reads: A self-contained open-circuit breathing instrument for use within a body of water naturally containing dissolved air. The instrument is adapted to provide breathable air. The instrument contains an inlet for taking out a quantity of water from the body of water. It further contains a separator for separating the dissolved air from the quantity of water, thus gaining the breathable air. The instrument further contains an outlet for expelling  the separated water back into the body of water, and another outlet for removing the breathable air and supplying it for breathing. The air is supplied so as to enable it to be expelled back into the body of water after it has been breathed . Human beings have been thinking about how to breathe underwater since they started swimming. This long-held desire plays an important part in one of the first great science fiction novels, Jules Verne's 20,000 Leagues Under the Sea. This passage is mainly about   _  .
how Bodner invented the instrument for breathing underwater why Bodner invented the instrument for breathing underwater how Bodner's instrument for breathing underwater works how Bodner's instrument is used by divers for breathing underwater