Am.  Jour.  Pharm.  \ 
December,  19 17.  J 
Advances  in  Pharmacy. 
591 
with  one  mil  of  acetic  acid,  10  mils  of  chloroform  are  added,  and 
the  excess  of  iodine  is  titrated  with  thiosulphate  solution.  Two 
atoms  of  iodine  combine  with  one  molecule  of  antipyrine.  The 
gravimetric  method  is  as  follows :  A  half  gram  of  antipyrine  is 
dissolved  in  50  mils  of  distilled  water,  two  grams  of  potassium 
bicarbonate  are  added  and  concentrated  iodine  solution  is  added 
drop  by  drop ;  the  brown  turbidity  which  is  produced  by  the  addi- 
tion of  each  drop  should  disappear  before  the  next  drop  is  added. 
The  addition  of  the  iodine  requires  about  thirty  minutes.  Colorless 
crystals  of  iodoantipyrine  begin  to  form  in  about  ten  minutes,  and 
are  colored  black  as  soon  as  an  excess  of  iodine  has  been  introduced. 
At  the  end  of  an  hour  the  mixture  is  decolorized  by  the  addition  of 
sodium  thiosulphate ;  the  resulting  precipitate  is  collected  on  a 
filter,  washed  with  a  small  quantity  of  distilled  water,  dried,  and 
weighed.  A  quantity  of  iodoantipyrine  remains  in  solution  and  this 
is  extracted  with  chloroform.  It  is  asserted  that  99  per  cent,  of 
the  antipyrine  actually  present  is  found  by  this  method  (/.  Pharm. 
Chim.,  1917,  15,  J.  Bougault,  through  The  Analyst,  vol.  47,  276). 
Phenolphthalein  Reagent  for  the  Detection  of  Blood  in 
Urine. — A  modification  of  Meyer's  reagent,  sodium  hydrosulphite 
being  substituted  for  the  zinc  dust,  is  recommended  as  a  reliable 
test  for  the  recognition  of  blood  in  urine.  Two  grams  of  phenol- 
phthalein and  twenty  grams  of  potassium  hydroxid  are  dissolved  in 
130  mils  of  water  and  the  solution  is  boiled  with  the  addition  of  3 
grams  of  sodium  hydrosulphite  until  colorless.  To  detect  blood  in 
urine,  10  mils  of  the  urine  are  mixed  with  10  mils  of  alcohol  con- 
taining 2  per  cent,  of  acetic  acid,  and  4  mils  of  the  reagent,  to  this 
mixture  a  few  drops  of  hydrogen  peroxide  are  added;  the  presence 
of  blood  brings  forth  a  more  or  less  intense  red  color  on  the  addi- 
tion of  the  hydrogen  peroxide  (/.  Pharm.  Chim.,  191 7,  16,  E.  Justin 
Mueller,  through  The  Analyst,  vol.  47,  280). 
