258  What  the  Atmosphere  is  Made  of.      { AmjuJ™ \^rm- 
quick  to  make  public  his  discoveries.  He  did  accomplish,  however, 
most  remarkable  things,  some  of  them  in  other  fields.  He  ac- 
cumulated facts  which  were  accurate  quantitatively;  for  example, 
that  there  is  1-120  of  the  air  that  will  not  combine,  a  figure  that 
today,  one  hundred  and  thirty-five  years  later,  is  set  at  1-84.  He 
computed  the  density  of  the  earth,  arriving  at  the  figure  5.4  with 
water  for  the  standard,  and  more  than  a  century  of  observation, 
measurement  and  computation  has  changed  only  the  decimal  places, 
the  accepted  constant  being  now  S-S777- 
The  work  that  this  man  did  was  wonderful  whether  taken  in 
quantity  or  quality.  He  worked  a  great  deal  with  the  air,  he 
analyzed  it  for  sixty  days  and  in  many  places,  he  showed  its  con- 
stant composition  and  really  paved  the  way  for  the  discovery  of 
argon.  One  series  of  experiments  was  made  to  find  out  when 
a  quantity  of  air  was  diminished  by  phlogistication,  where  the  miss- 
ing air  went  to. 
How  argon  came  to  be  discovered  was  one  of  the  most  charming 
of  the  series  of  lectures,  for  here  Sir  William  Ramsay  spoke  of 
his  relations  with  Lord  Rayleigh  and  drew  a  pen  picture  of  this 
distinguished  and  broad  minded  investigator,  whose  experiments  in 
determining  the  relative  weights  of  oxygen  and  hydrogen  led  first 
to  publications  from  1882  till  1893,  the  last  year  seeing  a  comparison 
between  oxygen  and  nitrogen ;  next  to  the  request  to  the  members 
of  the  Royal  Academy  for  suggestions,  and  last,  to  a  meeting  with 
Ramsay.  Rayleigh  had  been  working  out  the  comparative  densities 
of  the  gases  and  to  check  his  observations  he  made  use  of  gas 
produced  in  a  number  of  different  ways.  He  had  oxygen  from 
three  different  sources  and  found  an  agreement  in  the  weights  be- 
tween them,  but  nitrogen  when  derived  from  ammonia  he  found 
to  be  lighter  than  when  taken  from  the  atmosphere. 
At  this  juncture  Ramsay  suggested  to  Lord  Rayleigh  that  the 
repetition  of  some  of  Cavendish's  old  experiments  might  give  a 
clue  to  the  mystery,  and  Rayleigh  said,  "  Try  it  out  yourself."  The 
experiments,  which  were  repeated  on  the  platform,  developed  a 
method  of  consuming  the  nitrogen  from  ordinary  air.  The  oxy- 
gen was  first  removed,  then  any  traces  of  water  and  then  again 
a  trap  was  laid  for  any  remaining  oxygen.  The  nitrogen  that  was 
left  was  forced  through  chips  of  magnesium  and  was  more  or 
less  consumed.  At  first  there  was  a  simple  device  for  returning 
the  nitrogen  again  and  again  to  the  magnesium  and  later  automatic 
