CITROMEL  AND  TARTROMEL  OF  IODIDE  OF  IRON.  65 
posited  a  considerable  quantity  of  brownish-yellow  powder,  and 
exhibited  other  signs  of  being  in  an  advanced  stage  of  decom- 
position at  the  end  of  a  week  ;  whereas,  no  indication  of  decom- 
position could  be  detected  in  the  other  solutions  till  the  follow- 
ing periods : 
Solution  with  1  grain  of  citric  acid,  21  days. 
"  2  grains         «         30  « 
u  3    «  «        60  « 
u  4    <<  «        74  <; 
«  5    «  "        93  " 
With  much  stronger  solutions  (one  part  to  two,  four,  &c,  of 
water),  citric  acid  was  found  to  hasten  rather  than  retard  de- 
composition. 
Similar  courses  of  experiments  were  tried  with  acetic  and  tar- 
taric acids.  The  former  prevented  the  deposition  of  oxide  of 
iron,  but  not  the  separation  of  free  iodine,  and  therefore  failed 
to  fulfil  the  most  important  requirement.  The  latter  answered 
even  better  than  citric  acid.  Solutions  were  prepared  in  the 
same  manner  as  above,  substituting  tartaric  for  citric  acid,  and 
exposed  to  the  same  rigid  test  of  their  stability.  The  solution 
containing  one  grain  of  acid  gave  no  indication  of  decomposi- 
tion till  after  the  lapse  of  ninety-four  days,  and  the  others  not 
till  from  seven  to  eight  months,  when  they  began  to  change 
almost  simultaneously.  The  length  of  time  these  solutions  were 
preserved,  was  not  so  regularly  proportionate  to  the  quantities 
of  acid  as  in  the  experiments  with  citric  acid.  In  strong  solu- 
tions tartaric  acid  exerted  no  preservative  influence. 
It  appears,  then,  that  citric  and  tartaric  acids  would  be  use- 
ful additions  to  weak  solutions  of  iodide  of  iron  intended  to  be 
kept  for  only  a  moderate  period,  as  is  usually  the  case  with  the 
medicines  supplied  to  patients  ;  but  for  preserving  stronger  so- 
lutions, such  as  would  be  adapted  for  officinal  use,  they  are  quite 
ineffectual.  I  have  therefore  tried  them  in  conjunction  with 
saccharine  matter,  and  on  account  of  the  liability  of  cane  sugar 
to  be  converted  into  the  less  soluble  grape  sugar,  I  selected  clar- 
ified honey,  and  found  the  combination  a  very  perfect  vehicle  for 
iodide  of  iron.  The  following  are  the  formulas  I  have  adop- 
ted : 
5 
