Nitrogen  and  Oxygen  and  of  Argon  and  Oxygen. 
649 
contraction  would  of  course  make  this  calculated  value  wrong  ; 
but  the  error  thus  introduced  would  be  of  a  higher  order 
than  the  differences  in  density  of  different  mixtures  of  the 
same  two  liquids.     Measurements  of  the  density  of  liquid 
600 
-500 
-40  0 
300 
200 
100 
A/p  Mols  % 
100 
Vapour-pressures  at  74°  "70  Abs 
nitrogen  and  oxygen  have  been  made  by  Baty  and  Donnan 
(Trans.  Chem.  Soc.  1902,  p.  907);  and  they  found  the  values 
0*8225  and  1-2160  respectively  at  that  temperature  at  which 
Baly's  curve  for  the  vapour-pressure  of  oxygen  gives  the 
Phil  Mag.  S.  6.  Yol.  11.  No.  65.  May  1906.  2iU 
