550 
History  of  Argon  and  Helium. 
( Am.  Jour.  Pharm. 
1  November,  1895. 
Yellow  line,  wave  length 
Green  line,      *'  " 
603-84 
561*00 
Strong. 
And  four  other  green  lines. 
Blue-violet  line,  wave  length 
Violet  line,  " 
470-2 
420*0 
Strong. 
And  five  other  violet  lines,  all  strong. 
Professor  Crookes,  who  is  studying  the  spectrum  of  argon,  has 
concluded  that  this  gas  possesses,  most  likely,  two  spectra,  which 
he  thinks  he  can  separate.  This  would  indicate  that  argon  is  a 
mixture  of  two  gases.  Argon  is  about  two  and  one-half  times  as 
soluble  in  water  as  nitrogen,  and  possesses,  approximately,  the  same 
solubility  in  water  as  oxygen.  We  hence  find,  as  we  would  expect 
as  a  result  of  these  determinations,  that  rain-water  contains  more 
argon  than  nitrogen. 
Professor  Olszewski,  of  Cracow,  has  liquefied  argon,  and  also 
solidified  it  by  the  combined  action  of  extremely  high  pressure  and 
low  temperature  upon  it.  He  obtained  it  in  white  crystals  which 
melt  at  — 189-6°  C.  Its  critical  temperature  is  — 121°  C,  and 
its  boiling  point  is  — 187°  C,  both  of  which  are  lower  than  the 
respective  constants  of  oxygen. 
By  determining  the  velocity  of  sound  in  a  gas,  we  can  determine 
the  ratio  of  the  specific  heat  at  constant  pressure  to  that  at  constant 
volume.  In  the  case  of  argon,  this  ratio  was  found  to  be  1*66,  which 
is  proper  for  a  gas  in  which  all  the  energy  is  translational,  i.  e.,  to  a 
gas  that  is  monatomic  in  its  condition.  The  only  other  such  known 
gas  is  that  of  mercury  at  high  temperatures. 
All  attempts  to  induce  argon  to  combine  with  other  elements 
have  proven  abortive,  and  the  gas  has  well-earned  its  name  of  "  no 
energy  "  from  the  Greek  words  a  and  epyov,  contracted  into  dpyov. 
The  amount  of  argon  in  the  air  is,  approximately,  1  per  cent. 
From  Avogadro's  law  we  know  that  the  density  of  a  gas  is  half 
its  molecular  weight ;  and  as  the  density  of  argon  is,  approximately, 
20,  its  molecular  weight  must  be  40.  But  its  molecule  is  identical 
with  its  atom  ;  hence,  its  atomic  weight  is  40,  if  it  be  an  element,  or 
the  mean  of  the  atomic  weights  of  the  gases  constituting  argon,  if 
argon  is  a  mixture  of  gases.  The  spectrum  work  of  Professor  Crookes 
argues  that  argon  is  a  mixture  of  gases,  while  Professor  Olszewski's 
work,  showing  that  it  has  a  definite  melting-point,  a  definite  boiling- 
point,  and  a  definite  critical  temperature  and  pressure,  and  that  on 
compressing  it  in  the  presence  of  its  liquid,  the  pressure  remains 
