The most appreciated use of these things is to relieve oneself first thing on a winter morning to avoid a trip to the outhouse.  Inside toilets just about made them obsolete, although one might be handy beside a sickbed to spit, vomit, whatever (Annie, a waste basket is a poor substitute.)  Chamber pots are the origin of the expression to "potty train" a child and the lament "don't have a pot to piss in".  Usually called a "slop jar" and "thunder jug" is a common euphemism.  The pots are steel construction with heavy baked-on enamel and hold 2 1/2 gallons.  A piss pot is typically dumped early in the day, rinsed from the well or cistern, and left to stand with a splash of fresh water in the bottom.