266 
PRESERVATION  OF  SYRUP  OP  IODIDE  OF  IRON. 
syrup  of  iodide  of  iron  tend  to  its  preservation,  i.  e.  to  prevent 
its  acquiring  color  when  exposed  freely  t  to  the  air? 
I  was  the  more  readily  inclined  to  answer  this  question  in  the 
affirmative  from  a  belief  that  I  had  somewhere  seen  recom- 
mended for  the  same  purpose  the  use  of  citric  acid.  (After  a  long 
search  I  have  failed  to  ferret  out  the  paper  in  which  the  observa- 
tion occurred,  and  am  therefore  unable  to  credit  the  author  of  the 
suggestion  with  the  "  kudos  "  due  to  him.) 
I  may  observe  that  a  strong  solution  of  iodide  of  iron,  pre- 
pared with  pure  iodine  and  iron  in  the  form  of  fine  wire,  invari- 
ably reddens  litmus  paper.  Whether  it  is  due  to  impurities  in 
the  iron,  or  is  characteristic  of  neutrally  constituted  iodide  of 
iron,  not  having  by  me  an  absolutely  pure  specimen  of  iron,  I 
cannot  say. 
My  experiments  were  conducted  by  making  seven  specimens 
of  syrup — from  iron  wire,  best  iron  tacks,  common  iron  tacks, 
wire  +acid.  sulph.  dil.  j  per  oz.,  ditto  +  acid.  phos.  dil.  r*l  ij 
per  oz.,  ditto  -j-  acid,  phosph.  dil.  rri  ij  and  acid,  sulph.  dil.  j 
per  oz.,  ditto  +  acid,  phosph.  dil.       viij  per  oz. 
These  were  placed  in  partially  filled  bottles  and  exposed  for 
some  months  to  diffuse  daylight.  It  was  soon  apparent  that  the 
acidulated  syrups  had  a  decided  advantage  over  those  not  acidu- 
lated. The  syrup  made  from  best  tacks  was  superior  to  that 
made  from  wire  ;  that  made  from  common  tacks  was  inferior  to 
either  ;  the  nature  of  the  acid  appeared  to  be  immaterial. 
Since  then  I  have  settled  down  to  the  use  of  dilute  phosphoric 
acid,  of  which  I  add  half  a  fluid-ounce  to  each  pharmacopoeia 
quantity  (31  fl.  oz.).  With  that  proportion  I  find  the  syrup 
keep  perfectly  well  for  any  length  of  time,  and  without  the 
slightest  reference  to  the  bottle  containing  it  being  full  or  only 
partially  full.  If  I  remember  right  a  less  proportion  does  not 
answer  quite  so  well,  and  would  not  meet  the  case  of  a  country 
dispenser  with  irregular  calls  for  the  syrup.  Purists  will,  of 
course,  object  to  this  tampering  with  the  Pharmacopoeia,  so 
should  I  perhaps,  but  I  do  it  permissu  superiorum.  Besides 
which  I  may  truly  say  that  I  have  never  in  the  course  of  dis- 
pensing found  any  reason  to  regret  the  presence  of  the  interpo- 
lated ingredient. 
