^'"'ji^rian*'"""'}     ^^^^^^^  ^^^'^  S^^^^^o^'  339 
From  a  series  of  examinations  made  by  Sodan  and  Muller,  these 
authorities  suggest  the  following  constants  for  sandalwood  oil : 
Specific  gravity  0-975  to  0.982 
Optical  rotation   16°  to  20° 
Refraction  index    Not  below  1.5030 
Santalol  (total)   At  least  90  per  cent. 
Esters  as  santalyl  acetate  4  to  6.5  per  cent. 
Rotation  of  first  and  second  fractions  of  10  per 
cent   Not  below  16° 
Sandalwood  oils  found  on  the  drug  markets  of  London  and  the 
Continent  are  now  sold  with  a  guarantee  of  94  per  cent,  of  santalol,. 
but  this  guarantee  should  not  be  taken  too  seriously,  since  repeated 
examinations  of  various  brands  show  that  they  vary  between  90.9 
and  93.6  per  cent,  of  santalol  with  from  1.5  to  6  per  cent,  of  the 
esters  of  santalol.  Occasionally  an  oil  is  found  which  gives  as  high 
as  98%  of  santalol.  These  variations  explain  the  variable  specific 
gravity  of  the  oils  found  in  commerce.  The  U.S.  Pharmacopoeia 
gives  the  specific  gravity  as  .965  to  .980  at  25°  C.  We  see,  there- 
fore, that  the  requirements  of  the  U.S. P.  are  moderate  and  allow 
for  variation  in  the  percentage  yield  of  santalol. 
Since  the  santalols  are  responsible  for  the  medicinal  efi^ects  of 
sandalwood  oil,  it  is  with  these  definite  products  that  we  have  chiefly 
to  deal.  Sandalwood  oil  and  santalol,  however,  are  not  well  toler- 
ated by  most  patients,  and  chemists  have,  in  recent  years,  attempted 
to  form  compounds  with  these  alcohols  in  order  to  obtain  less  irri- 
tating esters,  while  retaining  their  beneficial  medicinal  effects.  Many 
processes  have  been  patented,  the  patentees  claiming  that  santalol 
esters  are  better  tolerated  and  less  objectionable  in  taste,  while  their 
therapeutic  activities  are  retained.  The  general  principle  for  the 
production  of  these  esters  is  to  act  on  the  santalol  with  an  anhydride 
or  by  obtaining  compound  esters  by  action  between  a  santalol  halogen 
and  an  alkaline  ethylate,  phenylate,  etc.  Solid  esters  in  fine  white 
crystalline  needles,  such  as  the  santalol  ester  of  allophanic  acid, 
containing  72  per  cent,  of  santalol,  have  been  obtained.  The  neutral 
esters  of  the  aromatic  acids,  however,  are  the  best  known,  and 
amongst  the  rather  long  list,  the  following  have  had  a  passing 
notice  and  are  used  to  some  extent :  Santalol  benzoate,  salicylate, 
cinnamate,  succinate.    A  ])hosphate  has  also  been  obtained. 
As  these  santalol  compounds  are  incompatible  with  alkalies,  the 
