Aro ^ober,l5o2rm' }    American  Pharmaceutical  Association.  501 
actually  found  to  be  present  is  equivalent  to  the  amount  of  car- 
bonate originally  present  in  the  sulphite.  The  amount  of  hydriodic 
acid  in  the  solution  after  titration  with  thiosulphate  can  be  deter- 
mined by  direct  titration  with  a  tenth  normal  solution  of  sodium 
hydrate,  using  methyl-orange  as  an  indicator,  but  it  was  found  more 
satisfactory  to  add  an  excess  of  the  standard  solution  of  sodium 
hydrate  and  to  determine  the  excess  with  tenth  normal  sulphuric  acid, 
using  the  same  indicator,  because  the  end  point  is  more  easily  recog- 
nized than  when  titrating  from  acid  to  alkali.  Thus  the  amount 
of  hydriodic  acid  present  in  the  solution  is  found  after  the  reac- 
tion of  the  iodine  on  the  sulphite  is  complete  and  after  the  excess  of 
iodine  has  been  removed  by  thiosulphate.  If  this  amount  of  hydri- 
odic acid  found  be  subtracted  from  the  amount  calculated  to  have 
been  formed  from  the  amount  of  iodine  used,  the  difference  is  equiv- 
alent to  the  amount  of  sodium  carbonate  originally  present  in  the 
sulphite.  Of  course,  the  method  is  equally  applicable  to  the  deter- 
mination of  sodium  bicarbonate. 
Assay  of  Moist  Opium  and  Tinctures  of  Opium. 
By  A.  B.  Stevens. 
Before  the  lime  method  of  assay  can  be  applied  to  moist  opium  it 
is  necessary  that  the  moisture  be  determined  ;  then  4  grammes  of 
the  dried  sample  are  powdered  and  mixed  with  2  grammes  of  freshly 
slaked  lime  and  continuously  rubbed  with  10  c.c.  of  water;  then  pro- 
ceed as  in  powdered  opium.1  The  per  cent,  of  morphine  obtained 
multiplied  by  1  minus  the  per  cent,  of  moisture,  and  then  the  cor- 
rection for  loss  of  morphine  is  added. 
Granulated  opium  should  be  powdered  and  rubbed  with  the  lime 
and  water  at  least  fifteen  minutes,  or  until  a  smooth  paste  is  formed, 
and  then  proceed  as  in  powdered  opium. 
Tinctures  of  Opium  Evaporate  40  c.c.  of  the  tincture  to  about 
10  c.c,  and  rub  with  2  grammes  of  freshly  slaked  lime;  transfer  to 
a  graduated  cylinder  and  add  water  to  about  30  c.c;  then  add  five  or 
ten  drops  of  ether  to  destroy  the  foam  upon  the  surface  of  the 
liquid  ;  then  add  water  to  exactly  3  [  c.c.  Agitate  frequently  for 
half  an  hour  and  filter  off  15  c.c,  and  proceed  as  in  powdered  opium. 
1  Pharm.  Archives,  5,  p.  41. 
