Am.  Jour.  Pharm.  ) 
February,  1Q13.  J 
Abstracts  of  Papers. 
8.3 
He  gives  the  results  of  a  series  of  tests  and  states  that  he  feels 
justified  in  recommending  the  charcoal- water  method  of  keeping 
leeches  because  the  odors  from  which  leeches  die  are  largely  absorbed 
by  the  charcoal,  insects  cannot  be  attracted  to  the  dead  leeches,  the 
leeches  can  easily  be  caught  by  pouring  the  mixture  through  a  coarse 
sieve,  and  dead  ones  can  readily  be  removed  in  the  same  manner. 
From  Proc.  Penn.  Pharm.  Assoc. 
The  Purity  of  Gelatin. 
By  J.  G.  Roberts. 
The  author's  attention  having  been  brought  to  a  report  in  foreign 
journals  that  arsenic  had  been  found  in  excessive  amounts  in  gelatin 
of  German  manufacture,  he  deemed  it  worthy  of  investigation,  and 
accordingly  several  brands  found  on  the  market  were  examined. 
The  presence  of  arsenic  is  explained  by  the  fact  that  hides  and 
trimmings  used  in  the  manufacture  of  gelatin  had  been  treated  with 
an  arsenic  solution  during  the  process  of  curing. 
As  gelatin  is  of  much  use  for  household  and  pharmaceutical  pur- 
poses its  purity  is  of  some  importance. 
Arsenic  in  quantities  greater  than  one  part  in  a  million  was 
found  in  two  samples  of  German  manufacture.  Samples  made  in 
Belgium,  one  from  Austria,  and  two  samples  of  ground  gelatin  of 
domestic  manufacture  contained  no  arsenic,  while  two  others  of 
domestic  manufacture  contained  only  traces. 
In  order  to  extract  the  arsenic  the  author  subjected  the  gelatin 
to  special  treatment  in  order  to  change  it  into  a  soluble  form  and 
obtain  a  sufficient  quantity  of  arsenic  to  get  a  distinct  reaction. 
Twenty  grams  were  heated  in  an  evaporating  dish  with  35  c.c.  of 
arsenic-free  sulphuric  acid  until  a  dried,  charred  mass  remained. 
Fifteen  cubic  centimetres  of  nitric  acid  was  then  added  in  small 
portions  while  heating  cautiously,  and  the  heating  continued  until  the 
excess  of  acid  was  expelled  and  the  residue  dry.  Residue  was  then 
extracted  with  30  c.c.  of  hot  water,  the  solution  filtered  and  Marsh's 
test  applied  in  the  usual  way. 
From  Proc.  Penn.  Pharm.  Assoc. 
