196  OLEUM  JETHEREUM  AND  SPIRITUS  JETHERIS  COMPOSITUS. 
ly  acid,  and  when  dropped  into  water  is  much  diminished  in  bulk  ; 
and  the  water  used  reacts  strongly  with  solution  of  chloride  of 
barium.  The  proportion  of  this  lower  stratum  to  the  upper  is  in 
ratio  of  the  original  s.  g.  of  the  specimen. 
In  the  two  charges  next  following  the  proportions  of  the 
London  Pharmacopoeia  as  given  by  Pereira,  are  closely  followed, 
the  quantity  of  alcohol  still  remaining  the  same  as  before. 
1st  charge.  Alcohol,  s.  g.  -885  at  58°  126  f.g=6  lb.  12  oz.  av. 
Acid,      «  1-846  «  60°  116fJ=13  «   8  «  « 
distilled  after  prolonged  digestion,  yielded  18  J  f.g  of  oily  stratum 
(above),or  4  f-3  =270  grains  of  finished  oil  s.  g.  1-0667  at  72°. 
2d  charge.  Proportions  and  materials  the  same  as  the  first, 
distilled  without  digestion  yielded  22  f.s  of  oily  stratum  (above), 
or  6§  f.3  =  408  grains  of  finished  oil  s.  g.  1-0933  at  72°. 
In  these  the  alcohol  yielded  -52  per  cent,  of  its  volume.  Speci- 
mens of  these  oils  are  decomposed  like  those  of  the  last  series. 
These  experiments,  though  very  unsatisfactory  in  their  results, 
were  considered  to  have  established  the  proportions  given  by 
Serrulas  as  the  best, — the  utility  of  a  prolonged  contact  of  the 
materials, — and  the  sufficiency  of  washing  with  distilled  water  only, 
in  the  purification. 
Therefore,  in  the  operation  of  1856,  four  charges  were  worked 
oif,  with  an  aggregate  of  materials,  as  follows : 
Alcohol,  s.  g.  -821  at  60°  4  gallons  =  27J  ft>.  av. 
Acid,       «  1-834  «  60°  4|    «    =68i  «  « 
The  yield  from  these  was  44  f.§  of  crude  oily  stratum  (above), 
or  4i  f.5  =2280  grains  of  finished  oil,  s.  g.  1-097  at  60p,  or  1-2 
per  cent,  by  weight,  or  «88  per  cent,  by  volume,  of  the  alcohol 
used. 
In  a  subsequent  operation,  and  the  last,  the  yield  was  1-32 
per  cent,  by  weight,  or  1  per  cent,  by  volume,  of  the  alcohol, 
with  the  above  proportions ;  and  these  results  are  now  regarded 
as  the  expression  of  all  the  skill  and  knowledge  of  the  writer  on 
the  subject,  after  having  watched  it  with  accumulating  experience 
and  close  observation,  stimulated  by  disappointment ;  for  this 
best  yield  is  but  little  over  one-third  of  that  stated  to  have  been 
obtained  at  Apothecaries  Hall,  London  ;  and  by  Mr.  E.  N.  Kent, 
(Amer.  Jour.  Pharm.,  1852,  p.  257,)  on  the  very  small  scale. 
Early  in  the  management  of  this  preparation  it  was  observed 
