Most children of school age who wet the bed at night have what doctors term primary enuresis.. They have never had nighttime control of their bladder. Family history plays a role, too, in incontinence in children. If you wet the bed as a child, don't be surprised when your child does, too.
One thing to notice is that if you put a gallon of air on a scale, (in a wieghtless container, of course) you would measure zero, exactly. That's because the buoyancy caused by the surrounding air exactly counteracts the weight of the air in the container. If you pressurized the air in your gallon container to, say ten times the outside pressure (or 147.0 psi absolute, or 132.3 psi gauge) it would now weigh nine times 0.01, or 0.09 lb.
1 The exhaust air would carry out 14 gallons of water. 2  The incoming air would carry in 15 gallons of water. 3  An uncovered soil crawl space would produce 18 gallons of water.  So, even though the exhaust air carried out 14 gallons, the space actually carried 19 gallons of water into the building.