PAPERS  READ  AT  THE  BRITISH  PHARM.  CONFERENCE.  531 
still  expect  to  find  much  that  is  impure,  but  the  results  detailed 
below  lead  us  to  a  different  conclusion.  The  impurities  of 
iodide  of  potassium  are  bromide  and  chloride  of  potassium,  and 
sulphate,  iodate,  and  carbonate  of  potash.  Moisture  in  excess 
is  also  to  be  considered  an  impurity,  for,  besides  giving  the 
sample  a  greater  liability  to  deliquesce,  it  shows  an  article  of 
imperfect  manufacture.  The  first-mentioned  adulterant,  though 
it  has  at  times  been  frequently  used,  has  in  none  of  the  fifteen 
samples  experimented  upon  been  found,  and  the  second  only  in 
quantities  from  3-7  per  cent,  down  to  minute  traces.  Sulphate 
was  never  found  in  ponderable  quantities,  and  iodate  in  only  3, 
all  of  which,  however,  were  of  foreign  manufacture.  (Several 
English  samples  were  analysed  for  the  sake  of  comparison.)  In 
these  three  cases  it  never  amounted  to  1  per  cent.  Carbonate, 
though  more  generally  present,  never  amounted  to  1  per  cent., 
generally  much  under  this.  From  these  results,  it  will  be  seen 
that  the  iodide  of  potassium  now  in  the  market  is  practically 
pure,  the  percentage  in  all  the  samples  being  over  95° 
ON  A  TEST  FOR  METHYLIO  ALCOHOL  IN"  PRESENCE  OP  ETHYLIC  ALCOHOL,  WITH 
REMARKS  ON  METHYLATED  SPIRIT.     BY  MR.  JOHN  TUCK. 
After  referring  to  the  value  of  methylated  spirit  and  the 
composition  of  wood  naphtha,  the  author  stated  it  to  be  his  opi- 
nion, that  wood  naphtha,  once  mixed  with  spirit  of  wine,  could 
not  be  again  separated ;  and  that,  though  the  characteristic 
odor  of  methylated  spirit  could  be  removed,  yet  the  process 
required  such  cumbersome  apparatus,  that  its  use  would  cer- 
tainly be  followed  by  official  detection.  Seeing,  however,  that 
the  illegal  process  might  possibly  be  employed,  and  the  revenue 
be  thus  defrauded,  and  the  inodorus  methylated  spirit  be  used  in 
Pharmacy  and  in  concocting  liqueurs,  he  had  searched  for  a  test, 
whereby  even  the  deodorized  naphtha  could  be  detected,  when 
mixed  with  spirit  of  wine.  Such  a  test  he  had  found  in  an  alkaline 
solution  of  the  double  iodide  of  potassium  and  mercury.  On  boil- 
ing a  few  drops  of  this  with  pure  spirit  of  wine,  a  yellowish-white 
precipitate  was  formed ;  but  when  methylic  alcohol  was  present, 
no  such  precipitate  occurred.  Details  of  the  application  of  the 
test  were  then  given.  In  testing  flavored  spirits,  tinctures, 
etc.,  it  would  probably  be  desirable  to  distil  the  suspected  liquid, 
