322  Solution  and  Tincture  of  Ferric  Chloride.  {^*™^xm' 
When  thus  properly  prepared,  the  solution  can  be  diluted  until 
the  color  corresponds  exactly  with  that  of  the  standard. 
A  little  calculation  will  then  show  the  amount  of  antipyrine 
present. 
Tubes  or  beakers  of  white  glass  placed  upon  a  white  surface  are 
convenient  for  the  color  comparisons. 
Since  the  reagents  employed  do  not  react  with  other  substances, 
except  pyrazolone  compounds,  which  are  not  of  frequent  occurrence, 
and  as  antipyrine  is  readily  extracted  from  mixtures  by  the  use  of 
chloroform,  this  method  admits  of  wide  application. 
It  may  also  be  mentioned  that  as  this  reaction  does  not  take  place 
in  the  presence  of  nitrites,  but  requires  free  nitrous  acid,  the  incom- 
patibility of  antipyrine  and  (acid)  sweet  spirit  of  nitre  "may  be  pre- 
vented by  having  the  spirit  neutral  or  neutralizing  with  potassium 
bicarbonate. 
Brooklyn,  N.  Y.,  June  i,  1894. 
THE  SOLUTION  AND  TINCTURE  OF  FERRIC  CHLORIDE. 
By  Harvey  G.  Beck,  Ph.G.— - 
In  the  whole  history  of  mankind  there  is  found  no  other  metal 
upon  which  depended  the  progress  and  civilization  of  nations  as 
much  as  that  of  iron.  Its  prominence  in  the  arts  as  well  as  in 
medicine  gives  it  a  universal  popularity. 
Therapeutically  it  has  been  employed  for  3,300  years.  To-day 
it  comprises  a  larger  area  in  the  field  of  medicine  than  any  of  the 
other  elements. 
Owing  to  the  many  preparations  of  iron,  but  two  will  be  sub- 
jected t@  investigation,  namely :  The  Tincture  of  Ferric  Chloride 
which  has  been  used  for  many  years,  and  the  solution  of  Ferric 
Chloride  which  recently  became  the  source  of  the  tincture. 
These  will  be  considered  together,  not  with  the  object  of  present- 
ing new  methods  or  formulas,  but  to  properly  investigate  the  merits 
and  demerits  of  the  U.S.P.  formula,  to  study  the  relationship  existing 
between  the  solution  and  the  tincture,  and  to  determine  the  value 
of  the  various  productions  as  obtained  by  this  method. 
Ten  carefully  selected  samples  of  solution  of  ferric  chloride 
appear  in  Table  I,  showing  specific  gravity,  percentage  of  ferric 
chloride,  percentage  of  hydrochloric  acid  and  the  presence  of  nitric 
