Am.  Jour.  Pharm.  | 
November,  1919.  > 
Purified  Ether. 
737 
somewhat  over  a  year,  emphasizes  very  clearly  the  absolute  neces- 
sity of  the  proper  storage  of  ether  and  the  desirability  of  not  hold- 
ing stocks  too  long.  On  one  occasion,  however,  when  requiring  a 
very  pure  ether  for  some  manufacturing  purpose,  it  was  thought 
desirable  to  estimate  the  amount  of  acetone  or  ketone  present.  The 
results  are  given  in  the  table,  and  speak  for  themselves.  Acetone  is 
of  fairly  constant  occurrence  in  methylated  ethers,  but  one  or  two 
makers  produce  an  ether  of  such  purity  as  to  give  an  all  but  negative 
reaction  with  the  nitroprusside  test.  For  the  determination  an  adap- 
tation of  Scott-Wilson's  method  was  employed,  and,  for  the  purpose 
of  comparison,  was  quite  satisfactory,  although  not  exactly  precise 
as  here  used.  But  I  believe,  by  a  little  further  development,  it  is 
capable  of  consistent  accuracy  when  applied  to  ether. 
Experimental. 
The  distillation  was  made  with  100  Cc.  of  the  ether  in  a  three- 
bulbed  Ladenburg  flask  connected  with  a  small  worm  condenser,  and 
using  a  standardized  thermometer.  A  few  pieces  of  pumice  were 
placed  in  the  flask.  The  correction  for  temperature  was  about  0.05 
of  a  degree,  and  was,  therefore,  negligible.  The  source  of  heat  was 
a  small  water  bath,  the  cover  having  a  hole  cut  in  the  center  so  as  to 
expose  only  a  small  section  of  the  bottom  of  the  flask.  Methyl 
Compounds  Test. — A  slight  modification  of  the  B.P.  procedure  is 
adopted  for  this  test.  The  Schiff's  reagent  is  prepared  by  powder- 
ing 0.5  Gm.  of  fuchsin  and  digesting  with  90  Cc.  of  sulphurous  acid 
(B.P.)  overnight,  by  when  it  should  be  decolorized,  then  adding 
water  up  to  250  Cc.  and  filtering.  For  the  test  5  Cc.  of  the  ether  is 
shaken  up  with  5  Cc.  of  a  10  per  cent,  mixture  of  absolute  alcohol 
with  water,  and,  after  separating,  drawn  off  into  a  boiling-tube. 
For  comparisons  a  dilution  of  1  Cc.  of  pure  methyl  alcohol  in 
500  Cc.  of  water  is  made,  so  that  each  half  of  a  Cc.  represents  0.001 
Cc.  of  methyl  alcohol.  A  series  of  three  test-tubes,  similar  to  the 
above,  are  taken,  and  0.5,  1.0,  and  1.5  Cc.  of  the  dilution  run  in, 
followed  by  Yi  Cc.  of  absolute  alcohol,  and  then  4^,  4,  and  3^/2  Cc. 
of  water  added  respectively,  to  make  a  total  of  5^2  Cc,  which  is 
approximately  the  volume  of  the  ether  extraction.  The  B.P.  test 
is  now  followed,  but,  after  adding  the  5  Cc.  of  Schiff,  each  tube 
is  thoroughly  stirred  with  a  thermometer,  and  carefully  brought  to 
a  temperature  between  45 0  and  500  C.    The  test  is  then  set  aside 
