Am.  Jcmr.  Pharm.  \ 
March,  1918.  i 
Current  Literature. 
211 
liberated.  When  the  procedure  is  reversed,  considerably  more 
methylene  blue  is  adsorbed  and  a  fairly  large  proportion  of  quinine 
bisulphate  is  displaced  from  its  combination  with  the  fuller's  earth. 
The  results  show  that  under  the  special  conditions  of  this  experi- 
ment fuller's  earth  exhibits  a  distinct  preference  for  methylene  blue. 
Dilution  of  the  aqueous  solution,  in  the  case  of  quinine  bisul- 
phate, does  not  diminish  appreciably  the  amount  adsorbed  when  the 
ratio  of  earth  to  alkaloid  is  approximately  that  required  for  com- 
plete adsorption.  In  the  case  of  a  ratio  of  earth  which  is  insufficient 
for  complete  adsorption,  dilution  causes  a  distinct  reduction  in  the 
amount  adsorbed. 
Increase  of  acidity  of  the  aqueous  solution,  likewise,  does  not 
diminish  the  amount  of  quinine  adsorbed  in  case  the  ratio  of  earth 
is  just  sufficient  for  complete  adsorption.  With  less  earth  than 
sufficient  for  complete  adsorption  a  distinct  reduction  in  the  amount 
of  adsorbed  alkaloid  follows  an  increase  in  acidity  of  the  aqueous 
medium. 
Ethyl  alcohol  diminishes  the  adsorption  only  in  cases  where  the 
ratio  of  earth  used  is  insufficient  for  complete  removal  of  quinine 
or  of  methylene  blue. 
The  presence  of  quite  large  amounts  of  cane  sugar  was  found 
to  exert  no  retarding  influence  upon  the  adsorption  of  quinine  bi- 
sulphate by  fuller's  earth. 
In  conclusion  it  appears  that  the  adsorptive  power  of  fuller's 
earth  is  exerted  particularly  towards  certain  compounds,  character- 
ized by  distinct  basicity  and  that,  in  the  case  of  salts,  only  the  base 
unites  with  the  fuller's  earth.  No  marked  selectivity  was  found  in 
the  case  of  the  two  compounds  forming  the  basis  of  the  present  ex- 
periments. The  amount  adsorbed  in  a  given  time  is  a  function  of 
ratio  of  earth  to  adsorbable  material  and,  except  with  insufficient 
earth  for  complete  adsorption,  is  independent  of  dilution,  acidity  or 
presence  of  non-adsorbable  neutral  material.  (From  the  Journal 
of  the  American  Chemical  Society,  January,  1918.) 
Iodine  Test  for  Hydrochloric  Acid  in  Gastric  Juice. — 
Scheltema  remarks  that  the  tests  in  vogue  for  this  purpose  allow 
some  guesswork  as  to  the  findings.  Titration  with  iodine  is  simpler 
and  more  reliable.  When  hydriodic  acid  is  added  to  iodic  acid,  they 
act  on  each  other  with  the  result  that  water  and  iodine  are  formed. 
The  equation  is  HI03  +  5HI  =  3H0O  +  3I0.    This  reaction  can 
