ESSENTIAL  OIL  OF  CHINA  ORANGES. 
13T 
composition  is  represented  by  the  formula  C20  H16.  Three 
analyses  gave, — 
I.  II.  III.  Calculated. 
C  8748  87-45  87-70  20  88-2 
H    11-97      11-97      11-96      16  11-8 
This  essential  oil  is  insoluble  in  water,  to  which,  however,  it 
imparts  its  aroma  by  agitation  ;  it  is  soluble  in  about  ten  times 
its  volume  of  alcohol,  and  dissolves  in  all  proportions  in  sulphu- 
ret  of  carbon,  which  may  be  advantageously  employed  for  its 
extraction  ;  it  is  also  soluble  in  ether  and  in  crystallizable  acetic 
acid,  dissolves  iodine,  bromine,  the  resins,  the  oils,  wax,  phos- 
phorus and  sulphur,  and  mixes  with  the  other  essential  oils. 
Gold  concentrated  sulphuric  acid  gives  it  a  red  color,  but  this 
disappears  on  the  addition  of  water,  giving  place  to  a  yellowish 
tint  and  turbidity ;  the  same  acid,  when  hot,  decomposes  and 
carbonizes  it  with  evolution  of  sulphurous  acid.  Cold  nitric  acid 
does  not  act  upon  it,  or  color  it  red,  but  it  acquires  the  yellowish 
tint  of  the  crude  oil ;  the  same  acid,  when  hot,  attacks  it  readily, 
with  evolution  of  nitrous  vapors,  and  on  the  addition  of  water, 
a  yellow,  insoluble  and  nearly  solid  matter  separates. 
When  cold,  it  absorbs  dry  muriatic  acid  gas,  and  acquires  a 
brown  color  ;  concentrated  muriatic  acid  at  the  ordinary  tempera- 
ture gives  it  a  brown  color,  and  after  two  or  three  days'  contact, 
gives  rise  to  a  crystallized  matter  of  peculiar  odor,  the  composi- 
tion of  which  corresponds  exactly  with  the  formula  C20  H16,  2HC1. 
This  compound,  produced  by  the  direct  combination  of  the 
essential  oil  with  muriatic  acid,  and  representing  the  bimuriate, 
is  solid,  and  form3  small,  transparent  lamellae,  which  are  fusible 
and  volatile,  insoluble  in  water,  and  soluble  in  alcohol  and  ether. 
Mixed  with  alcohol  and  nitric  acid,  the  essential  oil  gives 
origin  to  a  crystallized  matter,  probably  the  hydrate  ;  the  small 
quantity  obtained  did  not  allow  a  complete  examination  to  be 
made. 
This  essential  oil  has  the  remarkable  property  of  presenting 
the  phenomenon  of  epipolic  dispersion,  discovered  by  Mr. 
Stokes,  when  it  is  looked  at  under  certain  incidences  of  light, 
exactly  like  the  solutions  of  sulphate  of  quinine  which  present  a 
characteristic  blue  tint  upon  their  surface.  The  same  coloration 
is  presented,  not  only  by  the  pure  essential  oil,  but  also  by  its 
