394  The  U.S. P.  Inorganic  Chemicals.  {AdaS,1#S!TO; 
water  and  purifying  by  extracting  the  dry  residue  with  chloroform 
or  carbon  disulfid,  a  very  stable  crystalline  powder  results.  This 
is  orange  to  red  in  color,  according  to  the  size  of  the  crystals.  The 
same  product  may  be  obtained  on  extracting  the  pulverized  com- 
mercial article  with  chloroform  or  carbon  disulfid  or  even  water. 
Iodid  of  arsenic  thus  prepared  does  not  lose  weight  after  two  hours' 
heating  on  a  bath  of  boiling  water ;  further  heating  at  higher  tem- 
perature causes  the  salt  to  sublime. 
It  is  very  singular  why  our  manufacturers  never  attempted  to 
improve  the  quality  of  this  very  potent  salt.  Presumably,  because 
the  retailers  take  what  is  given  them. 
The  iodid  thus  prepared  or  purified,  assays  83-07,  83-30,  83-88 
per  cent,  iodin  according  to  Volhard's  method,  and  83-36  per  cent, 
gravimetrically.  Theoretically,  the  compound  should  contain  83-54 
per  cent,  of  iodin. 
Two  arsenic  determinations  gave  16-32  and  16  47  per  cent.,  while 
theoretically  the  compound  should  contain  16  46  per  cent,  of  metallic 
arsenic. 
I  think  that  the  limits  of  83  per  cent,  of  iodin  and  16  per  cent, 
of  arsenic,  corresponding  to  a  99  per  cent,  salt,  are  fair  for  all  manu- 
facturers, if  they  will  only  take  the  pains  and  extract  the  pure  product 
irom  the  fused  mass  (mess)  they  have  heretofore  furnished. 
With  such  a  product  we  can  safely  guarantee  uniformity  in  the 
strength  of  Donovan's  Solution. 
Bromids. — Considering  the  quality  of  American  bromin,  it  was 
deemed  advisable  not  to  raise  the  standard  of  the  bromids  and  this 
was  made  uniformly  97  per  cent.  Higher  grade  bromids  are  readily 
obtainable  at  the  same  prices.  The  writer  has  found  more  low- 
grade  sodium  and  especially  ammonium  bromids  than  those  of  the 
other  bases. 
Excessive  alkalinity,  which  frequently  occurs,  has  been  provided 
against  by  a  revised  text.  Many  commercial  samples  examined  showed 
an  alkalinity  exceeding  Pharmacopceial  limits,  I  gramme  of  KBr. 
requiring  from  0-3  to  o-6  c.c.  of  decinormal  acid  V.  S.  Owing  to  the 
strictness  of  the  old  U.S.P.  text  regarding  the  presence  of  sulfates, 
it  was  necessary  for  manufacturers  to  remove  these  by  means  of 
barium  bromid,  hence  the  introduction  of  a  test  for  the  presence  of 
barium.  If  the  presence  of  sulfates  in  bromids  and  iodids  of  the 
alkalies  and  alkaline  earths  are  ignored  in  the  next  revision,  this  test 
for  barium  may  be  dropped. 
