Am.  Jour.  Pharm. 
June,  1906. 
American  Pharmacopoeia. 
259 
6o°  j1  of  the  first  10  per  cent,  of  the  distillate  may  only  differ- 
2°  from  the  angle  of  rotation  of  the  oil.2 
Menthol. — Colorless  needle-shaped  or  prismatic  crystals,  melting 
point  430;  boiling  point  21 2°;  alcoholic  solution  neutral  and 
lsevorotatory. 
Mustard  Oil  (Oleum  sinapis  volatile). — Colorless  or  faintly  yellow ; 
d25o  1013  to  ro20  ;3  boiling  point  148  to  1520;  lowest  content  of 
allyl  isothiocyanate  920  ;4  soluble  in  every  proportion  in  alcohol. 
Nutmeg  Oil  {Oleum  myristicce). — Colorless  or  faintly  yellow  ; 
d25o  0-862  to  0-910  ;5  aD25o  -f  14  to  4-  280;6  soluble  in  an  equal  vol. 
alcohol,  and  in  3  vol.  90  per  cent,  alcohol.  When  2  to  3  c.c.  oil  are 
evaporated,  no  crystallizing  residue  should  remain  behind. 
Peppermint  Oil7  {Oleum  menthce  piperita.) — Colorless  ;8  d25o  0-894 
to  0914;  aD25o  —  25  to  —  330  ;  ester  (menthyl  acetate)  at  least  8 
per  cent.;9  total  menthol  (free  and  esterified)  at  least  50  per  cent.; 
soluble  in  an  equal  vol.  alcohol ;  the  solution  in  4  volumes  70  per 
cent,  alcohol  may  at  most  show  a  feeble  opalescence. 
1  The  rotation  of  lemon  oil  varies  considerably  with  the  temperature  ;  the 
one  given  above  would  correspond  to  a  rotation  of  6o°  41'  at  the  usual  observa- 
tion temperature  of  200.  As  pure  oils  are  frequently  met  with,  with  a  rota- 
tion down  to  580,  and  as  most  oils  rotate  about  6o°,  the  above  requirement  of 
the  Pharmacopoeia  does  not  take  the  actual  facts  sufficiently  into  account. 
2  According  to  our  experience,  the  difference  in  pure  oils  frequently  amounts 
to  up  to  50. 
3  The  lower  limit  is  given  too  high,  and  should  be  I'ooS  (comp.  table). 
4  With  regard  to  the  determination,  comp.  the  April-May  Report,  p.  44. 
5  The  upper  limit  is  given  too  low  and  must  be  increased  to  0*924  as  other- 
wise just  the  oil  from  the  best  material  is  excluded  from  medicinal  use.  Comp. 
Report  October,  1904,  65;  see  also  table. 
6  We  have  observed  in  our  own  distillates  from  nutmeg  of  best  quality, 
rotations  down  to  -f-  70  52' '.    Comp.  Report  October,  1904,  65. 
7  The  requirements  given  for  peppermint  oil  are  partly  contradictory,  so  that 
it  is  not  clear  whether  the  oil  from  the  State  of  New  York  ("  Wayne  County 
Oil  " )  or  that  from  Michigan  ("  Western  Oil  " )  is  to  be  the  official  oil.  Whereas 
the  rotation  applies  chiefly  to  the  first-named  oil  ( Michigan  oil  rotates  between 
— 18  and  —  290),  the  requirements  of  solubility  exclude  the  former,  as  the  New 
York  oil  is  not  soluble  in  70  per  cent,  alcohol.  It  is  difficult  to  understand  why 
both  oils  are  not  admitted. 
8  Peppermint  is  not  always  colorless,  but  sometimes  yellowish  or  greenish 
yellow. 
9  The  ester-content  is  frequently  lower;  we  have  observed  in  authentic  oils 
down  to  4  per  cent. 
