i86  Quantitative  Methods.  {^'^'Ai!'^\\'ilu.'°'' 
ABSTRACT  OF 
REPORT  OF  THE  COMMITTEE  ON  QUANTEfATIVE 
METHODS 
Division  of  Pharmaceutical  Chemistry 
OF 
American  Chemical  Society. 
Your  Committee  begs  to  offer  the  following  report  of  work 
which  has  been  done  since  the  last  meeting  (July,  1910).  In  the 
search  for  suitable  assays  for  the  various  mercury  salts  included  in 
the  U.S. P.,  for  which  standards  of  purity  are  laid  down  and  no 
assay  processes  are  given,  investigation  was  made  of  a  number  of 
existing  methods  as  indicated  below. 
In  order  that  you  may  know  the  method  of  working  of  the 
Committee,  we  give  an  outline  of  the  plan  pursued  in  this  case. 
The  Chairman  sent  out  requests  to  the  members  of  the  Committee 
for  suggestions  as  to  methods  suitable  for  general  application 
to  mercurous  and  mercuric  salts.  After  going  over  the  suggestions 
received,  the  following  methods  as  proposed  were  again  submitted 
to  the  Committee,  together  with  samples  of  Mercurous  Chloride 
and  Mercuric  Iodide.    The  methods  as  submitted  are  as  follows : 
Method  No.  i. 
Suggested  by  Mr.  L.  A.  Brown. 
(See  Schimpf — Volumetric  Analysis,  page  408.) 
Applicable  to  mercurous  iodide,  chloride,  bromide,  and  mixtures 
of  mercuric  and  mercurous  salts. 
Weigh  out  sample  of  about  0.5  gramme,  place  in  Erlenmeyer 
flask  of  about  300  c.c.  capacity,  add  10  c.c.  potassium  iodide  solution 
containing  2  grammes  KI ;  rotate  and  quickly  add  50  c.c.  N/io 
iodine  solution  by  means  of  a  pipette,  agitate  until  all  of  the  sample 
is  in  solution.  Then  run  in  N/io  NaoSoO...  solution  until  all  the 
free  iodine  has  been  removed,  using  starch  solution  if  desired. 
Reaction— 2HgCl  +  6KI  +  L  =  2KoFgI,  +  2KCI. 
By  mixing  the  HgCl  with  the  solution  of  the  potassium  iodide 
immediately  before  adding  the  iodine  solution,  the  insoluble  salt 
goes  into  solution  more  quickly. 
