140 
ON  THE  PURIFICATION  OF  SAL-AMMONIAC. 
some  have  been  kept  a  year,  and  then  beaten  anew  into  a  mass 
and  made  again  into  pills.  Neither  does  any  perceptible  altera- 
tion appear  in  their  color,  taste  or  smell.* — N",  Y.  Jour.  Pharm., 
January,  1853. 
ON  THE  PURIFICATION  OF  SAL-AMMONIAC. 
By  Henry  Wurtz. 
Many  chemists  must  have  become  aware  that  the  loaves  of  sal- 
ammoniac  which  occur  in  commerce  almost  invariably  contain 
iron  in  some  form  of  combination.  It  is  the  separation  of  this 
iron  which  is  particularly  to  be  brought  under  consideration  in 
this  paper.  The  occurrence  of  this  contamination  is  not  noticed  by 
Gmelin,  but  I  find  that  Pereira  in  his  Materia  Medica,  mentions 
it,  apparently  entertaining  the  opinion,  however,  that  the  iron  is 
contained  exclusively  in  the  brownish  yellow  layers  which  usually 
appear  in  a  section  of  one  of  the  loaves.  He  remarks,f  "For 
several  years  past  I  have  been  accustomed  to  demonstrate  in  the 
Lecture-room  that  a  solution  of  these  yellow  bands  in  water  gives 
no  traces  of  iron  on  the  addition  of  ferrocyanide  of  potassium,  until 
a  few  drops  of  nitric  acid  be  added,  when  a  copious  blue  precipitate 
is  formed  ;  and  I  therefore  inferred  that  this  yellow  matter  was  a 
double  chloride  of  iron  and  ammonium.  My  opinion  has  been 
fully  confirmed  by  the  experiments  of  Dr.  G.  H.  Jackson." 
In  the  examination  of  several  specimens  of  commercial  sal-am- 
moniac, however,  I  have  myself  found  the  quantity  of  proto- 
chloride  of  iron  in  the  transparent  colorless  portions  of  the  mass 
to  be  apparently  equal  to  that  in  the  yellow  portions.  Neither 
the  colorless  nor  the  yellow  portions  give  any  reaction  with  yel- 
low prussiate  of  potash  or  with  sulphocyanide  of  potassium,  or 
any  precipitate  upon  heating  with  ammonia;  but  strong  solutions 
of  each  are  equally  blackened  by  sulphide  of  ammonium,  and 
after  boiling  with  a  drop  of  nitric  acid  give  quite  considerable 
and  apparently  equal  flocky-brown  precipitates  of  hydrated  ses- 
quioxide  of  iron  upon  heating  with  ammonia,  and  apparently 
*  The  reader  is  referred  to  a  formula  for  pills  of  iodide  of  iron,  suggest- 
ed by  Mr.  H.W.Worthington,  (Amer.  Jour.  Pharm.,  vol.  xv.  p.  71)  in  which 
tragacanth  and  honey  are  employed  very  much  in  the  way  recommended 
above  by  Mr.  Loines,  for  gum  and  sugar. — Editor  Amer.  Jour.  Phar. 
tPereira's  Materia  Medica,  i.,  446. 
