Am.  Jour.  Pharm.  "» 
November,  19 19.  * 
Purified  Ether. 
735 
purity  alone  can  safely  be  left  to  the  discretion  of  the  pharmacist 
whenever  discretion  becomes  necessary,  but  he  is  not  at  liberty  to 
exercise  this  function  in  requirements  which  are  specifically  med- 
ical. Absence  of  direction  of  this  sort  occasionally  leads  to  vexatious 
proceedings ;  at  times  it  retards  output ;  at  others,  through  ignorance 
in  giving  but  secondary  consideration  to  a  matter  which  may  really 
be  of  primary  importance,  a  very  unsatisfactory  position  of  affairs 
may  be  brought  about. 
The  Impurities. 
The  Pharmacopoeia  prescribes  tests  to  limit  the  quantity  of  per- 
oxide, aldehyde,  vinyl  alcohol,  and  methyl  compounds,  and  the  usual 
supplies  of  purified  ether  behave  with  general  satisfaction  in 
these  respects.  One  or  two  remarks,  however,  may  be  permissible. 
The  test  for  methyl  compounds  would  be  more  correctly  de- 
scribed as  a  test  for  the  presence  of  methyl  alcohol  and  such  sub- 
stances as  break  down  to  formaldehyde  under  the  influence  of  the 
oxidation.  Complaints  have  been  made  that  the  test  is  erratic  in  its 
indication,  and  it  is  believed  the  test  was  not  inserted  in  the  Phar- 
macopoeia with  the  unanimous  approval  of  manufacturers.  Faults 
of  sensitiveness  have  been  mentioned  (Dott,  P.  J.,  1 7/3/1 7,  p.  236) 
and  ascribed  both  to  the  fuchsin  and  to  the  method  of  preparing 
the  reagent.  Different  samples  of  fuchsin  do  undoubtedly  vary, 
but  I  have  been  fortunate  in  having  samples  that  never  failed  to 
detect  so  small  a  quantity  as  1  Mgm.  of  methyl  alcohol  in  5  Cc.  Ex- 
perience has  shown,  however,  that  a  Schiff's  reagent  which  may  be 
very  sensitive  when  freshly  made  is  preferably  not  used  after  six 
weeks'  keeping ;  at  three  months  it  is  useless  for  the  purposes  of  this 
test.  It  has  been  pointed  out  (Dott,  C.  and  D.,  20/2/15,  p.  52)  that 
highly  purified  methylated  ether  and  ether  from  rectified  spirit  will 
give  positive  reactions,  and  this  can  readily  be  confirmed.  It  ap- 
pears to  be  due  to  traces  of  compounds  occurring  in  the  ether,  quite 
apart  from  its  origin,  but  rectified  ethers  seem  to  give  a  fairly  con- 
stant indication  of  about  an  apparent  0.02  per  cent,  of  methyl 
alcohol.  Some  methylated  ethers  approach  this  very  closely,  although 
on  the  whole  they  are  distinctly  higher.  That  the  impurities  re- 
sponding to  this  test  are  not  the  same  in  each  specimen  of  ether  is 
seen  by  the  different  behavior  after  extraction,  first  with  alcohol  and 
then  followed  by  water.    Some  ether  was  taken  and  washed  with 
