160  Minutes  of  the  Pharmaceutical  Meeting.  {Ami&0rch,^5fm" 
some  of  the  oil  adherent,  but  the  pure  and  perfect  crystals  are  more  free  from 
oily  matter.  When  the  oil  is  reduced  to  zero,  the  yield  of  menthol  crystals  is 
about  twenty  per  cent,  of  the  oil  subjected  to  the  process,  but  varies,  and, 
strange  as  it  may  seem,  the  specific  gravity  of  the  oil  has  changed  but  one  one- 
thousandth  from  its  original  density.  So  far  as  observation  has  gone  no  differ- 
ence in  therapeutic  value  or  power  has  been  noticed  between  the  crystals  and 
.the  liquid  portion  of  the  oil,  when  a  pure  oil  is  compared  with  it.  As  a  rule, 
the  oils  produced  in  Michigan  are  of  good  qualit;. ,  the  farmer  being  careful  of 
the  character  of  the  crop ;  some  lots  of  oil  have  been  observed  containing  as 
much  as  forty  per  cent,  of  alcohol.  The  first  portion  of  the  distillate  obtained 
in  rectification  is  inodorous,  and  at  — 8°  F.  yields  no  menthol,  while  the  last 
portion  is  extremely  odorous  and  is  also  destitute  of  menthol,  but  the  tempera- 
ture at  which  the  separate  fractions  boil  has  not  been  tabled.  In  fractioning 
400  lbs.  of  pure,  natural  oil  of  '9L5°  sp.  gr.  in  twenty  pound  fractions,  extremely 
interesting  results  were  obtained  as  to  the  variations  in  specific  gravity,  but 
not  having  his  memoran  la  at  hand,  Mr.  Todd  could  not  state  the  changes  with 
sufficient  exactness.  The  first  fraction  was  obtained  in  about  30  minutes,  the 
last  required  six  hours. 
Professor  Maisch  inquired  whether  the  first  or  inodorous  portion  was  as  use- 
ful as  the  middle  or  aromatic  portion,  which  one  would  seem  to  regard  as  more 
desirable. 
Mr.  Todd  replied  that  he  had  never  investigated  the  therapeutic  action  of  the 
first  or  light  portion  separately,  yet  he  did  not  consider  it  as  valuable  by  itself 
for  all  the  purposes  for  which  the  united  fractions  were  useful,  though  it  may 
contain  some  distinct  and  valuable  properties  peculiar  to  itself.  He  has  recently 
undertaken  the  study  of  these  fractions  in  their  physical  aspects,  and  it  would 
also  be  interesting  to  determine  their  therapeutic  relations.  .  The  true  char- 
acteristics of  pure  essential  oils  seem  not  to  have  been  determined  and  laid 
down  in  the  books  with  sufficient  exactness,  and  their  study  affords  a  field  for 
the  most  fruitful  research. 
Mr.  Bullock  moved,  and  it  was  seconded,  that  the  thanks  of  the  meeting  were 
due  and  should  be  tendered  to  Mr.  Todd  for  his  very  interesting  remarks  upon 
oil  of  peppermint  and  menthol  with  which  he  had  favored  the  meeting.  This 
was  unanimousty  adopted. 
There  being  no  further  business,  on  motion  adjourned. 
T.  S.  Wiegand,  Registrar. 
