Am.  Jour.  Pharm. 
Aug.,  1886. 
Examination  of  Spruce-Gum. 
397 
The  resin  remaining  after  the  distillation  of  the  volatile  oil  from  the 
so-called  gum  formed  a  transparent,  amorphous  and  brittle  mass, 
which  was  soluble  in  alcohol,  methyl  alcohol,  ether  and  chloroform, 
sparingly  in  benzol,  and  insoluble  in  petroleum  ether.  When  the 
finely-powdered  resin  was  brought  into  a  boiling  solution  of  potassium 
or  sodium  hydrate  it  readily  dissolved,  forming  a  soap-like  compound, 
which  separated  on  cooling,  but  which  was  of  a  much  darker  color 
than  the  corresponding  soap  prepared  from  common  rosin  or  colo- 
phony. With  potassium  or  sodium  carbonates  it  seemed  incapable  of 
dissolving  or  forming  such  soap-like  compounds. 
Several  experiments  were  made  with  the  view  of  separating  a  crys- 
tallizable  acid  or  other  crystallizable  principle  from  the  spruce  resin, 
but  without  success,  as  may  be  shown  by  the  following  results : 
1.  A  portion  of  resin  of  spruce  was  digested  with  alcohol  of  the 
specific  gravity  0.89,  in  which  it  was  found  to  be  completely  soluble, 
whereas  colophony  digested  with  alcohol  of  this  strength  readily 
affords  crystals  of  abietic  acid ;  with  alcohol  of  specific  gravity  0.92  a 
similar  result  was  obtained. 
2.  The  resin  was  boiled  with  a  solution  of  caustic  soda  for  the  pur- 
pose of  combining  the  acid,  and  the  clear  solution  subsequently  pre- 
cipitated by  hydrochloric  acid ;  but  the  precipitate  was  entirely  devoid 
of  crystalline  structure  and  had  simply  a  resinous  appearance. 
3.  Ten  grams  of  resin  were  dissolved  in  alcohol,  and  the  solution 
precipitated  by  an  alcoholic  solution  of  lead  acetate.  The  resulting 
precipitate  was  collected  on  a  filter,  washed  with  alcohol,  and  after- 
ward suspended  in  alcohol  and  decomposed  by  hydrogen  sulphide. 
The  filtrate  from  the  lead  sulphide  was  allowed  to  evaporate  sponta- 
neously, when  a  reddish-brown,  amorphous  residue  was  obtained, 
corresponding  to  14  per  cent,  of  the  original  resin.  It  was  readily 
soluble  in  alcohol,  ether  and  chloroform,  but  did  not  crystallize  from 
these  solutions.    It  fused  completely  at  about  100°  C. 
The  filtrate  from  the  lead  acetate  precipitate  was  then  treated  also 
with  hydrogen  sulphide  in  order  to  remove  the  excess  of  lead  salt,  and 
filtered.  The  latter  filtrate,  upon  evaporation,  afforded  a  non-crystal- 
lizable  residue  of  a  bright  reddish-brown  color,  corresponding  to  86 
per  cent,  of  the  original  resin.  Its  fusing  point  was  about  the  same 
as  that  of  the  preceding  portion.  Both  of  these-  constituents  of  the 
resin,  when  moistened  with  a  drop  of  concentrated  sulphuric  acid, 
produce  a  bright  purple  color,  somewhat  similar  to  the  strychnine 
