ABSTRACT
T he atm osphere is a m ix tu re o f gases com prising approx im ately 21 per cent oxygen and 79 per cent n itrogen . T he o x y g en is continually being consum ed by liv ing creatures and in fire, and continually being regenerated by p lan t life. In add ition to the ox y g en and n itro g en , the atm osphere contains small quantities o f various norm ally inert gases, nam ely argon , neon, k ry p to n , xenon , and helium , the latter being in the largest quantity . T here are also small quantities o f carbon dioxide, largely p roduced by liv ing m etabolism , as w ell as w ater vap o u r, and, o f course, sundry chem ical po llu tan ts.
