194  OLEUM  iETHEREUM  AND  SPIRITUS  iETHEMS  COMPOSITUS. 
tilled  in  two  charges,  after  prolonged  contact,  yielded  3  f.^  of 
crude  oil,  or  9  f.3  finished  oil.  This  was  not  regarded  at  the 
the  time,  however,  as  a  fair  experiment  with  the  proportions 
used,  as  the  two  charges  yielded  very  unequally,  though  the 
cause  of  the  inequality  was  not  then  detected. 
At  these  rates  of  yield, — and  the  manipulation  was  not  very 
faulty, — Hoffman's  anodyne  cost  about  one  dollar  per  pound. 
In  the  next  operation  (1855)  the  proportions  of  Serrulas  as 
given  by  Brande  were  adopted;  namely,  "  1  part  alcohol  to  2-5 
parts  concentrated  sulphuric  acid."  In  this,  7  pints  =5  lbs. 
14  oz.  av.  of  alcohol  s.  g.  -835  and  8  pints  =15  lbs.  av.  of  sul- 
phuric scid  s.  g.  1-845,  distilled  after  prolonged  contact,  yielded 
1  f.g  of  finished  oil  s.  g.  1-16,  or  -9  per  cent,  of  the  volume  of 
the  alcohol  used.  The  density  of  this  oil  is  greater  than  that  of 
any  known  authority.  It  was  purified,  after  12  hours  exposure, 
by  frequent  washing  with  distilled  water  at  first  rendered  very 
slightly  alkaline,  and  then  by  drying  in  a  partial  vacuum.  A 
specimen  preserved,  has  undergone  the  same  change  of  color 
with  the  first,  but  appears  otherwise  unchanged. 
At  the  next  following  operation  (1855)  a  set  of  comparative 
experiments  was  determined  upon,  and  ten  charges  were  worked 
off  in  the  same  retort,  and  under  similar  circumstances  as  far  as 
practicable. 
The  first  five  charges  were  nearly  in  the  proportion  used  by 
Serrulas. 
1st  charge.  Alcohol,  s.  g.  -832  at  62°  124  1^=6  fib.  8  oz.  av. 
Acid,       «  1-842  «  65°  135f.3  =  16«  4  «  « 
distilled  after  prolonged  contact,  yielded  2J  f.^  of  crude  oil,  or 
7  f.3  of  finished  oil  s.  g.  1-1466  at  72*. 
2d  charge.  Alcohol,  s.  g.  -835  at  58°  125  Ll=  6  lb.  9  oz,  av. 
Acid,  "1-842  «  65°136f.3  =  16«  6  «  « 
distilled  without  prolonged  contact,  yielded  5}  f.g  of  crude  oil, 
or  6  f.3=  395  grains  of  finished  oil,  s.  g.  1-129  at  72°. 
3d  charge.  Alcohol,  s.  g.  -835  at  58°  126  f.  .1=6  Tb.  12  oz.  av. 
Acid,       «  1-846  «  60°142Jf.3=16«14  «  « 
distilled  after  prolonged  contact,  yielded  9  f.^  of  crude  oil,  or 
4  f.3  =  252  grains  finished  oil  s.  g.  1-066  at  72°. 
4th  charge.  Proportions  and  materials  same  as  third,  distilled 
after  prolonged  contact  yielded  14  f.g  of  oily  upper  stratum,  or 
10  f.3=651  grains  of  finished  oil  s.  g.  1-0866  at  72°. 
