<£i»itorinl  ^Department. 
Ammqnio-Ferric  Alum. — The  following  addition  to  the  paper  of  our 
valued  contributor,  at  page  305  of  the  July  number,  arrived  too  late  for  in- 
sertion among  the  original  communications.,  and  as  it  adds  to  the  value  of 
that  paper,  we  have  preferred  to  place  it  here  rather  than  postpone  its  pub- 
lication till  November. 
Addendum  on  Ammonia- Ferric  Alum. 
By  W.  Hodgson,  Jr. 
From  want  of  time  to  satisfy  myself  in  regard  to  some  of  the  details,  I 
omitted  in  my  paper  on  the  above  article,  in  the  last  number  of  the  American 
Journal  of  Pharmacy,  to  state  certain  precautions  which  are  important  in 
the  preparation  of  that  substance,  in  order  to  obtain  an  elegant  salt.  The 
excessive  heat  of  the  present  summer  for  several  weeks  prevented  sponta- 
neous crystallization,  the  thermometer  during  that  time  ranging  from  80°  to 
103?  Fahrenheit,  whereas  it  appears  that  the  ammonio-ferric  alum  will  not 
spontaneously  part  with  its  mother  water  and  assume  the  crystalline  form 
under  ordinary  states  of  the  atmosphere,  with  the  temperature  over  80°. 
If  artificial  heat  is  applied,  beyond  a  certain  point  of  concentration,  the 
salt  falls  down  in  a  granular  form  very  difficult  of  solution,  and  probably 
anhydrous,  or  nearly  so,  instead  of  having  twenty. four  atoms  of  water  of 
crystallization.  Again,  if  subjected  to  the  direct  rays  of  a  hot  sun,  a 
change  takes  place  which  gives  the  crystals'  a  very  dark  brown  orange 
color,  evidently  from  free  oxide  of  iron.  The  solutions  should,  in  order 
to  avoid  the  tendency  to  develope  free  oxide  of  iron,  be  rendered  acid  by 
addition  of  a  little  sulphuric  acid.  The  crystals  first  formed  should  be  re- 
dissolved  in  an  equal  weight  of  hot  water  thus  slightly  acidified,  and  then 
set  aside  for  spontaneous  evaporation  in  a  cool  shady  place  with  a  current 
of  air.  They  must  be  washed  with  cold  acidified  water,  and  pressed  in 
bibulous  paper,  or  something  similar  thereto.  They  are  then  of  an  elegant 
violet  tint,  and  of  a  more  or  less  regular  octohedral  form.  In  order  to  pre- 
serve this  appearance  (as  they  readily  change  by  exposure  to  moisture  and 
warmth)  they  should  be  kept  bottled  up. 
American  Pharmaceutical  Association. — We  take  the  opportunity 
which  now  offers  immediately  before  the  Meeting  of  this  body,  to  again  call 
the  attention  of  members  and  others  to  the  fact,  and  urge  the  acceptance  of 
the  invitation  to  attend  it  which  has  been  extended  officially  by  the  Pre- 
sident and  Executive  Committee  to  all  respectable  members  of  the  Pharma- 
