66 
CONTRIBUTIONS  TO  PHARMACY. 
with,  the  sesquisalts  of  iron,  which,  to  the  present,  was  considered 
the  most  sensitive  reagent  for  those  salts  except  the  sulphuret  of 
ammonium.  . 
M.  Dollfus  prepared  a  solution  of  sesquichloride  of  iron  con- 
taining one  part  of  the  salt  in  1000  parts  of  the  liquid.  This  was 
reduced  in  strength  by  dilution  with  an  equal  volume  at  each  re- 
duction, testing  the  liquid  each  time  until  it  ceased  to  be  sensible 
to  the  test.  In  this  way  he  found  that  a  solution  containing 
1-64000 th  of  the  iron  salt  was  fully  colored  by  sulphocyanuret 
of  potassium,  and  the  l-128000th  not  at  all,  whilst  the  salicylic 
acid  produced  a  light  violet  tint  in  the  solution  containing  but 
l-572000th.  M.  Dollfus  recommends  this  test  as  meriting  the 
attention  of  chemists,  and  as  being  easily  prepared  from  salicin.* 
Nevertheless,  it  is  necessary  to  be  aware  that  the  ferric  solution 
should  be  neutral  as  the  reaction  is  hindered  by  free  acids  and 
even  by  the  acetic  acid,  which  is  not  the  case  wich  sulphocyanu- 
ret of  potassium.  Further,  salicylic  and  salicylous  acids  do 
not  act  with  neutral  salts  of  the  sesquioxide  of  iron  with  such 
organic  acids  as  the  citric  and  tartaric,,  and  in  this  respect  it  is 
like  potassa.  It  may  be  remarked  that  sulphocyanuret  of  po- 
tassium is  also  incapable  of  reaction  with  these  salts.—  Jour,  de 
Pharm.  Sept,  1853. 
CONTRIBUTIONS  TO  PHARMACY. 
By  John  P.  Mettatter,  M.  D  ,  LL.  D.  of  Virginia, 
Professor  of  the  Principles  and  Practice  of  Medicine  and  Surgery,  in  the  Medical  Department  of 
Randelph  Macon  College. 
It  will  not  be  denied  that  the  operation  of  therapeutical  agents 
is  essentially  influenced  by  the  mode  by  which  they  are  prepared. 
This  fact,  so  generally  true,  is  particularly  exemplified  in  the 
preparations  of  cinchona,  cantharides,  colchicum,  guaiacum,  and 
several  other  medicinal  substances  of  which  I  shall  speak  pre- 
sently. 
For  more  than  twenty-five  years,  my  attention  has  been  parti- 
cularly directed  to  this  subject,  and,  during  this  period,  I  have 
*  [Salicylic  acid  is  most  readily  prepared  by  adding  oil  of  Gaultberia 
prceambens  to  a  hot  solution  of  potassa  as  long  as  its  odor  is  destroyed,, 
and  then  adding  pure  muriatic  acid,  Vnen  the  salicylic  acid  precipitates-  iu 
crystals, — Editor  Am.  Jour.  Pharm.} 
