338 
ON  OTTO  OF  ROSE. 
by  polarized  light,  whereas,  French  Oil  of  Geranium  possesses 
the  power  of  right-handed  rotation.* 
2.  In  chemical  properties,  inasmuch  as  when  exposed  to  the 
vapor  of  iodine,  it  does  not  acquire  the  intense  coloration  that 
occurs  when  Oil  of  Geranium  is  so  treated. 
4.  In  commercial  value,  true  Oil  of  Geranium  being  worth 
six  times  the  price  of  Idris  Yaghi,  and  ten  times  that  of  the 
Bombay  Roshe  Oil. 
Before  being  mixed  with  Otto,  the  Idris  Yaghi  is  subjected 
by  the  Turkish  dealers  to  some  purifying  process,  chiefly,  it 
would  seem,  with  a  view  to  diminish  its  color,  a  pale  color  in 
Otto  of  Rose  being  deemed  a  sign  of  goodness. 
Chemical  Characters  of  Otto  of  Rose. 
As  I  have  already  observed,  there  exists,  regarding  the  tem- 
perature at  which  Otto  of  Rose  liquefies,  great  discrepancy  be- 
tween the  statements  of  authors  and  the  result  of  observations 
made  upon  the  Otto  of  commerce. 
Otto  of  Rose,  it  is  well  known,  consists  of  two  bodies,  a 
liquid  essential  oil  or  elseoptene  (upon  which  I  have  made  no 
experiments)  and  a  stearoptene.  The  stearoptene  I  find  to  be, 
when  pure,  a  colorless  crystallizable  substance,  devoid  of  odor 
and  taste,  fusing  at  95°  F.,  very  slightly  soluble  in  alcohol  of 
sp.  gr.  -838  in  the  cold,  but  more  soluble  if  heated.  It  is  solu- 
ble in  the  liquid  portion  or  elseoptene  of  Otto  of  Rose,  but,  ac- 
cording to  its  abundance,  separates  more  or  less  readily  with  a 
depression  of  temperature.  It  dissolves  readily  in  ether,  chloro- 
form, or  olive  oil,  but  not  in  solution  of  potash  or  ammonia. 
These  two  bodies,  the  elseoptene  and  stearoptene,  exist,  ac- 
cording to  my  observations,  in  the  Otto  of  different  districts  in 
very  different  proportions,  and  to  their  relative  amounts  I  attri- 
bute much  of  the  variation  which  I  find  in  the  specimens  ex- 
amined. The  amount  of  stearoptene  was  determined  in  a  series 
of  parallel  experiments,  conducted  simultaneously  by  treating  a 
given  weight  of  Otto  with  alcohol  (sp.  gr.  .838),  throwing  the 
precipitated  stearoptene  upon  a  filter  and  thoroughly  washing  it 
with  fresh  alcohol ;  the  same  amount  of  alcohol  being  employed 
*  But,  as  some  essence  of  geranium  from  Algiers,  examined  by  the  same  ob- 
server, was  found  to  have  the  power  of  left-handed  rotation  to  an  almost  equal 
extent,  it  is  obviously  possible  that  by  mixing  the  two,  an  essence  having  no 
rotatory  power  might  be  produced — an  improbable  explanation,  certainly,  of  the 
absence  of  rotatory  power  in  the  Idris  Yaghi,  but  one  which  it  is  fair  to  mention. 
