57Q 
United  States  Army  Laboratory. 
Am.  Jour.  Pharm. 
December.  1906. 
face  will  be  covered  with  a  black  froth,  which  increases  in  density 
and  thickness  until  the  operation  is  finished,  this  being  indicated  by 
the  paucity  of  distillate  dripping  from  the  condensing  tube  into  the 
receiver.  The  fire  is  then  withdrawn,  the  fire  door  remaining  open 
and  the  draught  door  closed,  so  that  the  sand  bath  and  retort  may 
cool  rapidly.  The  receiver  is  disconnected,  its  contents,  which 
sometimes  are  in  two  layers,  but  mostly  in  one  homogeneous  layer, 
are  transferred  to  an  open  dish,  loosely  covered  with  paper,  and 
allowed  to  remain  for  spontaneous  evaporation  over  night.    On  the 
Fig.  7. — Distillation  of  Heavy  Oil  of  Wine. 
following  morning,  this  distillate,  now  reduced  to  a  few  ounces,  is 
found  in  two  layers — the  lower  is  heavy  oil  of  wine,  the  upper  one 
mainly  water,  retaining  a  little  sulphurous  acid.  The  oil  of  wine, 
after  washing  with  a  little  water,  is  then  ready  for  use,  and  was 
usually  at  once  converted  into  compound  spirit  of  ether,  of  which 
large  quantities  were  constantly  in  requisition.  If  the  process  was 
successful,  the  yield  from  6^  gallons  of  the  mixture,  consisting  of 
equal  volumes  of  alcohol  and  acid,  was  from  6  to  7  ounces  of  heavy 
oil  of  wine,  while  a  solid  crust  of  the  carbonaceous  frothy  matter, 
