602  Revision  of  the  U.  S.  Pharmacopoeia.  {AmDT^uriS.arm' 
forms  a  hard,  unctuous  mass.  This  should  have  been  the  impal- 
pable powder  obtained  by  precipitation  from  solutions  of  alkaline 
oleate  and  zinc  sulphate.  Almost  all  the  zinc  oleate  of  commerce 
is  the  latter. 
The  entire  class  of  oleoresins  is  directed  to  be  prepared  by 
exhausting  the  powdered  drug  with  ether  (stronger  ether  of  U.  S.  P. 
1880*.  The  complete  exhaustion  of  the  drug  directed  is  wasteful  of 
the  ether,  as  experiments  have  shown  that  it  is  not  advantageous  to 
continue  the  percolation  beyond  that  point  necessary  to  obtain  150 
to  200  cc.  of  percolate  for  even*  100  gm.  of  the  drug.  The  small 
amount  of  oleoresin  yielded  by  continuing  the  percolation  till  the 
drug  is  completely  exhausted  will  not  pay  for  the  ether  lost.  For 
some  of  these  oleoresins  a  cheaper  solvent  would  have  been  acetone. 
(See  Amer.  Journal  of  Pharmacy,  1892,  145.) 
In  the  statements  regarding  the  characters  and  properties  of 
both  the  fixed  and  volatile  oils  we  notice  a  decided  improvement. 
Many  of  the  errors  in  the  Pharmacopoeia,  1880,  in  stating  the  physical 
properties  of  the  essential  oils  are  corrected. 
It  is  to  be  noted  that  in  the  Expressed  Oil  of  Almond  the  solubility 
of  the  separated  fat  acids  in  alcohol  is  adopted  to  detect  the  admix- 
ture of  other  fixed  oils,  and  in  lard  oil  and  olive  oil  the  reduction  of 
silver  nitrate  in  acidified  alcoholic  solution  is  applied  for  the  detection 
of  cotton-seed  oil.  The  iodine  absorption  test  of  Hubl  is  generally 
accepted  by  chemists  as  a  valuable  test  for  adulterants  in  these  oils. 
It  has  nowhere,  in  the  volume,  been  directed,  probably  because  it 
wras  thought  too  difficult  for  the  average  pharmacist.  Yet  the  only 
apparatus  it  requires,  a  burette  and  a  bottle  or  a  beaker  should  be 
in  every  pharmacy.  In  marked  contrast  to  this,  we  note  that  in 
a  number  of  the  essential  oils  the  optical  rotary  values  are  given  and  on 
p.  512,  we  find  instructions  for  determining  the  same.  The  polari- 
scopic  apparatus  needed  is  not  in  the  possession  of  the  pharmacist. 
In  many  cases,  the  natural  variations  of  the  oils  in  the  optical 
behavior  and  the  causes  affecting  the  same  are  still  to  be  further 
investigated. 
The  Oil  of  Bitter  Almond  should  have  been  "  sine  prussic  acid  "  or 
if  that  was  deemed  unnecessary,  at  least  the  percentage  of  hydro- 
cyanic acid  allowable  should  have  been  stated.  The  test  for  synthetic 
oil,  by  detecting  chlorinated  compounds  has  proven  very  satisfactory 
in  the  writer's  experience. 
\_To  be  continued J\ 
