594  U-       P-  Test  for  Methyl  Alcohol.  {Am-££-™£m- 
THE  U.  S.  P.  TEST  FOR  METHYL  ALCOHOL  IN  ETHYL 
ALCOHOL.1 
By  Joseph  W.  Ehman,  Ph.G., 
PHILADELPHIA,  PA. 
The  U.  S.  P.  test  for  methyl  alcohol  in  ethyl  alcohol  having 
failed  to  give  satisfactory  results  in  the  hands  of  some  workers  the 
writer  has  made  a  series  of  experiments  to  determine  the  cause  or 
causes  of  the  variable  results  which  have  come  under  his  notice. 
The  fuchsin-sulphurous  acid  T.  S.  of  the  U.  S.  P.  is  made  by 
dissolving  sodium  bisulphite  and  basic  fuchsin  in  water  and  adding 
hydrochloric  acid,  forming  a  practically  colorless  solution. 
The  test  for  methyl  alcohol  is  made  as  follows : 
The  alcohol  is  diluted  to  10  per  cent,  by  volume,  5  Mils  of  this 
are  mixed  with  2  Mils  of  3  per  cent,  potassium  permanganate  and 
0.3  Mil  of  sulphuric  acid;  after  five  minutes  the  precipitated  man- 
ganese dioxide  is  dissolved  by  adding  sulphurous  acid.  Then  1  Mil 
of  sulphuric  acid  and  5  Mils  of  the  fuchsin  T.  S.  "  After  standing 
for  ten  minutes  a  colorless  liquid  results  "  (U.  S.  P.). 
The  difficulty  has  been  that  when  this  test  was  applied  to  5  Mils 
of  pure  10  per  cent,  ethyl  alcohol  a  positive  reaction  (a  violet  color) 
appeared  which  remained  for  a  long  time.  It  is  not  considered  nec- 
essary to  describe  all  of  the  following  experiments  in  detail,  as  a 
summary  will  be  sufficient  for  the  purposes  of  this  paper. 
Ordinary  U.  S.  P.  ethyl  alcohol,  deodorized  alcohol  and  alcohol 
purified  by  the  U.  S.  P.  process  for  use  in  making  alcoholic  potas- 
sium hydroxide  V.  S.  were  tested  with  the  fuchsin  reagent  and  all 
gave  a  positive  reaction  for  methyl  alcohol.  In  all  other  respects 
these  met  the  requirements  of  the  U.  S.  P. 
Several  samples  of  fuchsin  from  different  sources  were  subjected 
to  the  U.  S.  P.  tests,  but  while  there  was  a  slight  difference  in  the 
color  given  by  some  on  the  addition  of  hydrochloric  acid,  and  one 
did  not  decolorize  so  readily  with  sulphurous  acid,  they  all  gave  the 
same  reaction  in  the  test  for  methyl  alcohol. 
Elvove  recommends  cooling  the  solution  after  the  final  addition 
of  sulphuric  acid  and  before  the  addition  of  the  fuchsin  reagent.  A 
1  Read  before  the  forty-second  annual  meeting  of  the  Pennsylvania  Phar- 
maceutical Association,  June  26,  1919. 
