500  American  Pharmaceutical  Association.  ^"o'^oberjS^"1' 
Relative  Strength  of  Various  Preparations  of  Digitalis  and 
Kindred  Drugs  as  Shown  by  Experiments  with  Frogs. 
By  L.  W.  Faumlener  and  A.  B.  Lyons. 
The  authors  experimented  with  digitalis  as  well  as  a  number  of 
other  drugs  that  act  like  digitalis  on  the  frog's  heart.  The  authors 
conclude  that  (i)  the  determination  of  the  relative  strength  of  differ- 
ent samples  of  the  same  drug  may  be  made  with  a  precision  sufficient 
for  practical  purposes  by  physiological  experiments  on  animals. 
Duplicate  determinations  do  not  differ  from  one  another  as  much  as 
10  per  cent. — a  difference  which  as  yet  we  have  to  tolerate  in  chem- 
ical assays  of  such  drugs  as  opium.  (2)  As  might  be  expected,  the 
relative  medicinal  strength  of  different  drugs  cannot  be  correctly 
inferred  from  the  observation  of  a  single  symptom  produced  in  an 
animal  like  the  frog.  Through  a  comparative  study,  however,  of 
drugs  by  this  manner  we  may  hope  to  gain  a  more  complete  insight 
into  the  action  of  remedies,  whose  effects  are  usually  a  complex  of 
several  different  influences  over  vital  functions. 
Determination  of  Sodium  Carbonate  in  Sodium  Sulphate. 
By  Charles  E.  Caspari  and  Miles  R.  Moffatt. 
The  authors  describe  a  method  based  on  that  proposed  by  Giles 
and  Schearer  (Jour.  Soc.  Chem.  Ind.,  Ill,  .197,  and  IV,  303)  for 
the  determination  of  sulphites.  In  accordance  with  the  equation 
Na2S03-j-I2+H20=Na2S04-|-2  HI,  a  definite  amount  of  iodine  which 
is  used  to  oxidize  the  sulphite  will  give  rise  to  the  formation  of  a 
definite  amount  of  hydriodic  acid,  and  this  amount  of  acid  can  be 
calculated  from  the  amount  of  iodine  consumed,  so  that  the  total 
amount  of  acid  in  the  solution  after  titration  is  known,  because 
when  the  excess  of  iodine  is  determined  with  thiosulphite  no  acid  is 
formed,  as  the  reaction  takes  place  in  accordance  with  the  equation 
2  Na2S203+I2=2  Nal-f  Na2S406.  If  any  carbonate  had  been  pres- 
ent in  the  sulphite,  it  would  have  been  neutralized  by  the  hydriodic 
acid,  which  was  formed  in  the  oxidation  of  the  sulphite,  and  at  the 
end  of  the  titration  the  amount  of  hydriodic  acid  present  would  not 
be  equal  to  the  amount  calculated  to  be  present  from  the  amount  of 
iodine  used  in  the  oxidation.  Hence,  the  difference  between  the 
amount  of  hydriodic  acid  calculated  to  be  present  and  the  amount 
