AN  IMPURITY  IN  TINCTUEE  OF  CHLORIDE  OF  IRON.  107 
on  a  large  scale,  is  made  to  pass  through  a  solution  of  alkali 
kept  at  the  same  temperature  as  that  of  the  retort  in  which  the 
nitre  is  generated,  in  order  to  free  it  from  aldehyd.  To  this  is 
probably  owing  the  small  amount  of  nitrous  ether  found  in  the 
spirit  of  nitre  of  commerce. 
Louisville^  Jan.  ^Oth,  1870. 
NOTE  ON  AN  IMPURITY  IN  TINCTURE  OF  CHLORIDE 
OF  IRON. 
By  J.  C.  Wharton. 
To  the  Editor  oftlie  American  Journal  of  Pharmacy  : 
Dear  Sir, — Some  four  or  more  years  since  I  addressed  to  you 
an  article  upon  the  subject  of  muriated  tincture  of  iron,  and,  if 
I  mistake  not,  the  same  was  published  in  the  American  Journal 
of  Pharmacy  for  the  month  of  November,  1865.  I  then  made 
the  statement  that  I  had  obtained  a  crop  of  singular  crystals 
from  a  lot  of  the  tincture.  Since  then  I  have  seen  nothing  in 
any  journal  or  circular  that  explained  the  production  of  the  sub- 
stance in  question.  I  am  glad  to  state  that  I  have  at  last  gained 
a  clue  to  the  subject,  and  will  in  the  outset  say  that  I  am  fully 
convinced  that  the  crystals  are  derived  from  the  glass  vessel  in 
which  the  solution  of  iron  is  effected.  A  small  amount  of  the 
vessel  is  dissolved  (either  from  glass  or  porcelain  ware),  and 
crystallizes  out  of  the  solution  in  the  form  of  silky  white  needles 
of  a  lustre  something  like  asbestos. 
I  must  confess  that  soon  after  I  made  the  announcement  above 
mentioned,  I  was  afraid  that  I  had  obtained  the  substance  from 
some  unknown  and  accidental  impurity  in  the  materials  used, 
especially  as  I  did  not  find  it  in  another  lot  of  tincture,  neither 
could  I  find  another  druggist  whose  observations  gave  me  any 
reason  to  believe  that  such  a  crystallization  was  at  all  common, 
— the  reason  for  which  I  now  comprehend,  as  the  substance  does 
not  always  appear  in  crystals,  and  sometimes  not  at  all ;  but 
most  frequently  is  left  behind  either  in  the  filter  or  in  the  dregs 
from  which  the  supernatant  clear  solution  of  sesquichloride  of 
iron  is  drawn  previous  to  the  addition  of  the  alcohol. 
When  it  is  to  be  found  in  the  tincture  at  all,  it  is  most  apt  to 
