AFebrXy!f9aor8ra"}      Comparative  Composition  of  Milks.  55 
Loescher  &  Webb,1  that  their  oils  have  rotatory  powers  as  low  as 
— 14-36°  on  the  average,  and  we  have,  in  our  opinion,  ample  evi- 
dence to  justify  the  lowering  of  the  optical  rotation  of  santal  oil 
to  — 12°  to  — -20°,  and  above  all  the  passing  of  optical  rotation 
as  of  crucial  value  in  determining  the  value  of  santal  oils.  Let  us 
take  lots  III  First  Distillate  with  specific  gravity  0-951  insoluble  in 
70  per  cent,  alcohol,  containing  only  70  per  cent,  santalol,  and  hence 
to  be  rejected,  as  first  distillates  usually  are,  and  yet  this  has  an 
optical  rotation  of — 18-1°  higher  than  any  other  oil  in  above  table, 
and  should  on  this  rotation  be  acceptable.  Dozens  of  similar  cases 
could  be  given  to  show  the  same  thing,  viz.,  an  acceptable  optical 
rotation  for  an  inferior  oil.  Again,  West  Indian  sandalwood  oils  or 
cedar-wood  oil  would  be  detected  because  they  decrease  the  solu- 
bility in  70  per  cent,  alcohol  or  materially  reduce  the  percentage  of 
santalol  in  the  oil.  It  might  still  be  possible  to  make  a  sophisticated 
oil  pass  muster  as  to  santalol  percentage,  provided  the  oil  originally 
contained  98  per  cent,  santalol  and  were  diluted  with  cedar-wood 
oil  to  reduce  it  to  90  per  cent.,  but  this  could  be  detected  by  the 
solubility  in  70  per  cent,  alcohol  at  30°  C,  as  it  would  not  be 
soluble.  In  fine,  in  our  opinion,  the  requirements  calling  for  a  con- 
tent of  90  per  cent,  sanatol  and  a  solubility  of  5  volumes  of  70  per 
cent,  alcohol,  at  30°  C,  and  a  specific  gravity  of  0-965  to  0*980  at 
25 0  C,  are  ample  to  insure  efficient  santal  oil  to  the  buyer,  and  we 
would  even  dispense  with  the  specific  gravity  and  feel  perfectly  safe. 
We  see  no  objection,  further,  to  determining  the  acid  number,  as 
that  will  tell  us  at  once  if  any  fixed  oil  or  rosin  has  been  added  as 
an  adulterant. 
COMPARATIVE  COMPOSITION  OF  MILKS. 
By  Joseph  w.  England.1 
On  examining  the  chemical  analyses  of  milk  published,  one  is 
impressed  with  the  enormous  amount  of  work  that  has  been  done, 
and  the  apparent  discrepancies  in  the  results.  These  latter  are  due, 
partially,  to  technical  difficulties  in  chemical  analysis,  but  largely, 
to  the  fact  that  milk  is  an  organized  tissue,  so  to  speak,  as  much  so 
as  blood,  and  that  it  varies  in  composition,  not  only  during  the  act 
of  nursing,  but  also,  during  the  entire  period  of  lactation. 
1  From  the  Research  Laboratory  of  Smith,  Kline  &  French  Co. 
