30 
Aldehyde  Resin. 
Am.  Jour.  Pharm. 
Jan.,  1888. 
the  substance  has  the  composition  C^gHg^Oio  =  8  (CgHgO)  +  O2,  which 
varies  slightly  with  the  rate  of  drying.  When  the  increase  in  weight 
has  become  constant,  the  composition  is  C^gHg^Oia  =  SCgHgO  -f  O4. 
If  the  resin  is  exposed  to  moist  air,  its  weight  increases,  and  becomes 
constant  after  some  weeks  ;  if  it  is  then  exposed  to  dry  air,  the  weight 
diminishes  until  it  reaches  a  new  limit.  The  composition  at  this  last 
stage  is  not  constant,  but  approximates  to  ^^^^^12-  The  substance 
formed  in  contact  with  moist  air  is  probably  a  hydrate,  but  its  compo- 
sition was  not  determined. 
In  some  cases,  the  crude  resin  was  first  placed  in  dry  air,  then  before 
the  loss  of  weight  was  complete,  in  moist  air,  and  finally  in  dry  air 
again.  After  this  treatment,  it  had  the  composition  C^gHggOig  = 
C^gHg^Ois  +  II2O,  but  this  result  was  not  constant.  In  another  case, 
the  composition  was  C^gHgj^Oig.  The  change  of  weight  which  the 
resin  undergoes  shows  that  the  increase  of  weight  is  not  due  to  simple 
combination  with  oxygen,  but  there  is  simultaneous  loss  of  carbon, 
increased  weight  being  always  less  than  corresponds  with  the  increased 
percentage  of  oxygen.  Either  of  the  resins  first  mentioned  increases 
in  weight  in  moist  air,  but  regains  its  original  weight  in  dry  air, 
the  hydrate  formed  under  the  first  conditions  being  decomposed  in 
the  dry  air.    Hydrates  are  obtained  containing  2,  3,  5,  or  7  mols. 
The  resin  was  placed  alternately  several  times  in  dry  air  and  in  air 
saturated  with  the  vapor  from  a  saturated  solution  of  sodium  chloride. 
The  dry  substance  had  the  composition  C^gHggOj^.  In  the  moist  at- 
mosphere, there  is  an  increase  in  the  percentage  of  oxygen,  but  a 
decrease  in  the  percentage  of  carbon,  which  may  be  due  either  to 
formation  of  a  hydrate  or  to  oxidation  with  simultaneous  loss  of 
carbon. 
From  these  results  it  follows  that  crude  aldehyde  resin  loses  water, 
and  forms  the  compound  C^^qA^^  ^  (C'eHgO)  +  O2,  which  may 
be  regarded  as  an  oxidized  polymeride  of  trialdane.  This  substance 
yields  more  highly  oxidized  products  which  may  be  regarded  as  hy- 
drated  oxides  of  the  same  aldane.  Members  of  the  latter  series  absorb 
water  from  a  moist  atmosphere,  and  form  hydrates  which  decompose 
in  dry  air.  When  aldehyde  resin  is  gradually  heated  from  120°  to 
the  boiling  point  of  sulphur,  it  undergoes  condensation.  Water  and 
an  oily  liquor  are  given  off,  and  a  non- volatile  residue  containing  a 
high  percentage  of  carbon  is  left  in  the  retort. 
