A  NEW  WET  ASSAY  OF  IODINE. 
509 
their  own  opinions  as  to  what  effect  had  been  produced  by  the 
continued  boiling  of  Dr.  Squibb's  experiment. 
*  Had  Dr.  Squibb  stated,  in  either  of  his  former  articles,  what 
he  now  states  in  this,  that  the  impurities  consist  in  his  opinion 
chiefly  of  disulphate  of  quinidia,  and  of  neutral  sulphates  of 
quinidia  and  quinia,  we  certainly  never  should  have  troubled  your 
readers  with  any  communication  from  ourselves  on  the  subject. 
A  word  also  about  our  pecuniary  sensibilities.  We  consider 
ourselves  perfectly  justified  in  defending  our  reputation,  and  as 
a  consequence,  our  interests.  With  equal  propriety  might  we 
refer  to  the  circumstances  which  called  into  existence  the  U.  S. 
Naval  Laboratory.  The  outcry  about  the  adulteration  of  drugs, 
chemicals,  and  medicines,  to  which  it  was  mainly  indebted  for  its 
establishment,  we  are  satisfied,  has  been  very  much  magnified. 
Oar  long  acquaintance  with  most  of  the  wholesale  druggists  has 
convinced  us  of  their  fair  dealing  and  general  rectitude. 
Very  respectfully  yours, 
Powers  &  Weightman. 
A  NEW  WET  ASSAY  OF  IODINE  AND  ITS  COMPOUNDS. 
By  Ferd.  Feist  Mater, 
1st.  If  a  solution  of  sulphate  of  peroxide  of  copper,  blue 
vitriol,  be  brought  into  contact  with  that  of  an  iodide,  a  decom- 
position takes  place,  one  half  of  the  iodine  present  forming  in- 
soluble protoiodide  of  copper,  and  the  other  becoming  free  [2 
(CuOS03)  +  2  MI  =  Cu2I  +  MO  S03  +  L]  On  adding  to 
the  mixture  thus  formed  a  solution  of  protosulphate  of  iron  in 
equal  (that  is,  equivalent)  proportions  to  that  of  copper,  the 
iodine  set  free  will  unite  with  another  part  of  peroxide  of  copper, 
and  the  oxygen  of  the  latter  with  part  of  the  protoxide  of  iron, 
to  form  peroxide. 
The  same  reaction,  without  any  loss  from  free  iodine  by  vola- 
tilization, takes  place  on  adding  the  solutions  of  the  sulphates 
already  mixed,  in  the  proportion  of  2  at.  of  the  coppersalt  and 
not  less  than  2  at.  of  that  of  iron  to  that  of  (1  at.)  iodide.  [2 
(CuO  S03  +  2  (FeO  S03  +  MI  ==  MO  S03  +  Fe2  03,  3  S03 
4-  Cu2I]. 
