AmjJa°nU"i8P9?arm-}  Notes  on  Essential  Oils.  45 
and  not  weight  percentages  ;  as,  however,  the  specific  gravity  of  the  non- 
aldehyde  in  Cassia  oil  (i"o6o  at  200  C.)  almost  exactly  accords  with  that  of 
cassia  oil  (1  "059-1  "061  at  20°C),  the  actual  difference  is  only  small  and  of 
no  practical  importance. 
If  the  curd  will  not  dissolve  after  a  day's  heating  an  extraordinarily  heavy 
adulteration,  with  a  hard  resin,  may  be  assumed,  in  which  case  a  volumetric 
estimation  of  the  aldehyde  is  impossible.  When  the  oil  is  adulterated  with 
both  resin  and  mineral  oil,  the  separated  non-aldehydes  are  still  liquid  in  the 
presence  of  30  per  cent,  of  resin. 
The  cinnamic  acid  present  in  every  cassia, oil  is  determined  in  this  process  as 
cinnamic  aldehyde.  As,  however,  even  in  very  old  oil  less  than  1  per  cent,  of 
acid  is  present,  this  error  is  insignificant. 
If  the  percentage  of  cinnamic  aldehyde  present  is  less  than  70  per  cent.,  the 
distillation  test  is  serviceable  for  the  detection  of  sophistication.  If  the  residue 
left  at  2900  amounts  to  over  10  per  cent,  and  is  firm,  hard  resin  has  been  used  ; 
if  it  remains  liquid,  after  cooling,  fatty  oils  or  other  liquid  adulterants  have 
been  used. 
In  order  to  determine  the  resinification  of  cassia  oil,  under  the  influence  of 
the  air,  200  cc.of  the  oil  was  placed,  on  September  20,  1889,  in  a  glass  dish 
only  covered  with  perforated  filter-paper  in  a  room  exposed  to  midday  sun- 
shine and  continually  heated  in  winter.  I4ght,  warmth  and  access  of  air,  the 
three  active  agents  for  effective  resinification,  were  therefore  present  in  such 
abundance,  as  they  never  occur  in  keeping  the  oil  in  commerce. 
In  the  course  of  the  experiment  the  oil  underwent  the  following  alterations  : 
Examined.  Distill.  Residue.  Cinnamic  Aldehyde.  Cinnamic  Acid. 
Sept.  20,  1889,  ....  5"5  per  cent.  777  per  cent.  0*7  per  cent. 
May  1,  1890,   io"6       "  —         "  —  " 
Sept.  10,  1890,  ....  T2"6       "  68-5        "  8-5 
The  cinnamic  acid  was  estimated  by  shaking  out  the  oil  with  hot  soda  solu- 
tion and  identified  as  such  by  the  melting-point  131°  C.  (m.  p.  pure  cinnamic 
acid,  1330)  and  by  the  formation  of  benzaldehyde  by  oxidation  with  perman- 
ganate of  potassium. 
Messrs.  Schimmel  have  examined  the  tests  proposed  by  Mr.  Ed.  Hirschsohn 
(see  Amer.  Journ.  Pharmacy,  1890,  p.  294  and  p.  487).  He  found  that  a 
pure  cassia  oil,  shaken  with  three  times  its  volume  of  petroleum  ether,  should 
undergo  no  alteration  of  volume.  They  report  a  variation  observed  in  the 
volume  of  both  pure  and  sophisticated  oils,  though  with  the  former  somewhat 
less.  The  differences  were  too  small  for  a  practical  test.  The  correctness  of 
Hirschsohn's  other  test  is  confirmed.  It  is  :  To  a  solution  of  cassia  oil  in  70 
per  cent,  alcohol  1  :  3  is  added,  drop  by  drop,  half  its  .volume  of  saturated 
solution  of  lead  acetate  in  alcohol  of  same  strength,  no  precipitate  should 
form,  otherwise  colophony  or  similar  resin  is  present.  Oils  without  the  addi- 
tion of  resin  remain  quite  clear,  as  also  the  old  cassia  oils  with  their  slightly 
increased  content  of  cinnamic  acid.  On  the  other  hand,  the  sample  of  oil 
mentioned  above,  as  containing  8*5  per  cent,  of  cinnamic  acid  in  consequence 
of  exposure  to  air,  did  not  satisfactorily  stand  the  test.  As  such  oils,  however, 
are  not  met  with  in  commerce,  the  possibility  of  a  precipitate  of  cinnamate  of 
