8 
The  Purification  of  Benzin. 
Am.  Jour.  Pharm. 
Jan.,  1890. 
On  agitating  the  benzin  with  the  acid  permanganate  solution,  an 
emulsion-like  mixture  is  produced  which  separates  in  a  few  seconds, 
the  permanganate  solution  slowly  subsiding  and  showing  considerable 
reduction.  The  time  specified  (24  hours)  is  greatly  in  excess  of  what 
is  necessary,  as  the  reduction  takes  place  almost  entirely  in  a  very  short 
time,  and  I  have  no  doubt  that  if  the  process  were  adopted  on  the 
manufacturing  scale,  with  mechanical  agitators,  the  time  could  be 
reduced  to  an  hour  or  two. 
The  quantity  of  permanganate  necessary  is  in  direct  proportion  to 
the  impurities  existing  in  the  benzin.  The  quantity  ordered  in  the 
formula  is  sufficient  for  a  pretty  foul  benzin  and  may  be  reduced  with 
a  purer  distillate. 
The  samples  shown  were  samples  of  commercial  75°  and  88° 
gasoline  which,  as  received  from  the  refinery,  were  anything  but 
sweet.  The  75°  showed  a  sp.  gr.  of  0*6845,  and,  after  being  thus 
purified,  the  sp.  gr.  remained  the  same.  On  evaporating  from  the 
hand,  it  left  no  disagreeable  odor,  and  50  cc.  eveporated  entirely  in  a 
platinum  dish  below  70°  C.  (158°  F.),  leaving  no  residue.  When 
tested  for  sulphur  compounds,  by  boiling  with  ammoniacal  alcohol 
and  then  adding  silver  nitrate  solution,  it  gave  negative  results. 
Shaken  with  warm  distilled  water  and  the  water,  separated,  tested 
with  BaCl2  for  sulphates,  gave  no  reaction. 
The  sample  of  88°,  when  received  from  the  refinery,  was  exceed- 
ingly rank,  as  you  will  perceive  from  the  sample  shown.  It  seems 
that  the  lighter  the  benzin  the  more  it  is  contaminated  with  sulphur 
compounds.  It  showed  a  sp.  gr.  of  0*6476.  After  treating  as 
described,  its  sp.  gr.  was  0*6484.  On  evaporation  from  the  hand,  it 
had  a  peculiar  almost  ethereal,  but  not  disagreeable  odor.  50  cc. 
evaporated  from  a  platinum  dish  entirely  below  50°  C,  leaving  no 
residue  and,  when  tested  for  sulphur  compounds  and  sulphates,  as 
described,  gave  negative  results. 
For  the  preparation  of  petroleum  ether  for  plant  analysis,  etc., 
where  an  exceptionally  fine  article  is  desired,  it  is  only  necessary  to 
rectify  this  last  purified  article  by  fractional  distillation  from  lard  or 
other  fatty  substance,  as  recommended  by  Dragendorff,  collecting  only 
that  portion  which  distils  below  45°  C. 
Sample  No.  5  has  been  thus  prepared  and  show^s  sp.  gr.  of  0*641 
and  is  exceedingly  volatile  and  devoid  of  odor. 
