NOTE  ON  CARAMANIA  GUM. 
105 
a  large  yield  was  obtained  at  a  high  temperature  is  No.  8, 
which  reached  324  and  325°,  and  subsequently  ran  over  ;  from 
56  fluidounces  of  alcohol  one  ounce  wais  obtained. 
Heavy  oil  of  wine  is  decomposed  into  the  so-called  light  oil 
of  wine  and  sulphovinic  acid,  if  it  is  left  in  contact  with  cold 
water  for  some  time  ;  the  decomposition  is  rapid  and  complete 
if  warm  water,  or  a  solution  of  an  alkali,  or  the  carbonate  of 
an  alkali,  is  used.  It  is  evident,  therefore,  that  in  order  to  in- 
sure the  least  possible  loss,  the  washing  of  the  crude  oil  with 
cold  water  must  be  effected  in  as  short  a  time  as  possible. 
It  has  been  stated  by  Dr.  Squibb  and  by  Mr.  Diehl  that  the 
formation  of  a  crust  of  thiomelanic  acid  on  the  surface  of  the 
liquid  in  the  retort,  is  favorable  for  the  production  of  oil  of 
wine.  This  may,  perhaps,  be  accounted  for  by  an  increase  of 
the  pressure  within  the  liquid,  whereby  the  oil  is  more  easily 
carried  over  with  the  gaseous  sulphurous  acid.  If  this  crust 
is  broken  and  the  liquid  stirred,  the  extrication  of  gases  occurs 
so  rapidly  that  foaming  almost  always  takes  place.  Still  it 
may  be  possible  that  the  yield  of  oil  might  be  increased  by 
preventing  the  formation  of  the  crust  alluded  to  altogether,  be- 
cause the  vapors  of  the  oil  might  thereby  be  more  readily  dif- 
fused through  the  gases  and  vapors  with  which  it  distils  over, 
Necessarily  the  charge  for  the  same  retorts  would  then  have  to 
be  lessened  to  give  room  for  the  frothing  which  inevitably  takes 
place.  Another  question  is,  whether,  even  if  the  yield  was 
thereby  increased  to  a  certain  extent,  it  would  pay  so  well  as 
with  a  comparatively  smaller  yield  from  a  heavier  charge  in 
the  same  time. 
Mr.  Diehl  is  entitled  to  great  credit  for  his  careful  observa- 
tions, for  his  suggestions  of  the  mode  of  re-heating  to  keep  the 
temperature  in  this  troublesome  process  within  certain  limits, 
and  for  by  far  the  best  results  as  yet  obtained. 
Philadelphia,  February,  1865.- 
NOTE  ON  CARAMANIA  GUM. 
BY  WILLIAM  PROCTER,  JR. 
Whilst  engaged  in  the  revision  of  the  U.  S.  Dispensatory, 
Dr.  Wood  was  presented  by  Mr.  Benjamin  R.  Smith,  of  Philadel- 
